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Kev loj hlob sai ntawm nanotechnology thiab nws kev koom ua ke rau hauv cov ntawv thov niaj hnub tuaj yeem cuam tshuam rau ib puag ncig.Thaum ntsuab txoj kev rau degradation ntawm cov organic contaminants yog tsim tau zoo, kev rov qab los ntawm inorganic crystalline contaminants yog ib qho kev txhawj xeeb loj vim lawv tsis tshua muaj rhiab heev rau biotransformation thiab tsis muaj kev nkag siab ntawm cov ntaub ntawv nto kev cuam tshuam nrog cov khoom lom.Ntawm no, peb siv Nb-raws li inorganic 2D MXenes qauv ua ke nrog ib tug yooj yim cov duab parameter tsom xam txoj kev mus taug qab lub bioremediation mechanism ntawm 2D ceramic nanomaterials los ntawm ntsuab microalgae Raphidocelis subcapitata.Peb pom tias microalgae degrade Nb-raws li MXenes vim muaj kev cuam tshuam ntawm physico-tshuaj lom neeg.Thaum pib, ib txheej thiab multilayer MXene nanoflakes tau txuas rau saum npoo ntawm microalgae, uas txo qis kev loj hlob ntawm algae.Txawm li cas los xij, raws li kev cuam tshuam ntev nrog rau saum npoo, microalgae oxidized MXene nanoflakes thiab ntxiv decomposed rau hauv NbO thiab Nb2O5.Vim tias cov oxides no tsis muaj tshuaj lom rau cov kab mob microalgae, lawv haus Nb oxide nanoparticles los ntawm kev nqus cov txheej txheem uas ntxiv cov microalgae tom qab 72 teev ntawm kev kho dej.Cov teebmeem ntawm cov as-ham cuam tshuam nrog kev nqus kuj tseem cuam tshuam txog kev nce hauv cell ntim, lawv cov duab du thiab hloov pauv ntawm kev loj hlob.Raws li cov kev tshawb pom no, peb txiav txim siab tias lub sijhawm luv thiab ntev ntawm Nb-based MXenes nyob rau hauv cov dej tshiab ecosystems yuav ua rau tsuas yog ib puag ncig me me.Nws yog ib qho tseem ceeb uas, siv ob-dimensional nanomaterials raws li cov qauv qauv, peb pom tau hais tias muaj peev xwm taug qab cov duab transformation txawm nyob rau hauv cov ntaub ntawv zoo-grained.Zuag qhia tag nrho, txoj kev tshawb no teb cov lus nug tseem ceeb txog cov txheej txheem cuam tshuam ntawm qhov chaw tsav tsheb bioremediation mechanism ntawm 2D nanomaterials thiab muab lub hauv paus rau kev tshawb fawb luv luv thiab ntev ntev ntawm kev cuam tshuam ib puag ncig ntawm inorganic crystalline nanomaterials.
Nanomaterials tau tsim ntau qhov kev txaus siab txij li thaum lawv qhov kev tshawb pom, thiab ntau yam nanotechnologies tsis ntev los no tau nkag mus rau theem 1 modernization.Hmoov tsis zoo, kev sib koom ua ke ntawm nanomaterials rau hauv cov ntawv thov niaj hnub tuaj yeem ua rau raug tso tawm vim kev pov tseg tsis raug, kev tuav tsis zoo, lossis tsis muaj kev ruaj ntseg infrastructure.Yog li ntawd, nws yog tsim nyog los xav tias nanomaterials, nrog rau ob-dimensional (2D) nanomaterials, tuaj yeem tso tawm rau hauv ib puag ncig ntuj, tus cwj pwm thiab kev ua haujlwm lom neeg uas tseem tsis tau nkag siab tag nrho.Yog li ntawd, nws tsis yog qhov xav tsis thoob tias kev txhawj xeeb ntawm ecotoxicity tau tsom mus rau lub peev xwm ntawm 2D nanomaterials mus rau hauv cov dej hauv dej 2,3,4,5,6.Hauv cov ecosystems no, qee qhov 2D nanomaterials tuaj yeem cuam tshuam nrog ntau yam kab mob ntawm ntau qib trophic, suav nrog microalgae.
Microalgae yog cov kab mob thaum ntxov uas muaj nyob rau hauv cov dej qab zib thiab dej hiav txwv ecosystems uas tsim ntau yam khoom siv tshuaj los ntawm photosynthesis7.Xws li, lawv yog ib qho tseem ceeb rau cov dej ecosystems8,9,10,11,12 tab sis kuj yog rhiab heev, pheej yig thiab dav siv cov cim qhia ntawm ecotoxicity13,14.Txij li thaum microalgae hlwb sib faib sai thiab ceev ceev teb rau lub xub ntiag ntawm ntau lub tebchaw, lawv tau cog lus rau txoj kev loj hlob ntawm ib puag ncig tus phooj ywg txoj kev kho cov dej paug nrog organic tshuaj15,16.
Algae hlwb tuaj yeem tshem tawm inorganic ions los ntawm dej los ntawm biosorption thiab tsub zuj zuj17,18.Qee hom algal xws li Chlorella, Anabaena invar, Westiellopsis prolifica, Stigeoclonium tenue thiab Synechococcus sp.Nws tau pom tias muaj peev xwm nqa tau thiab tseem txhawb nqa cov hlau ions xws li Fe2+, Cu2+, Zn2+ thiab Mn2+19.Lwm cov kev tshawb fawb tau pom tias Cu2+, Cd2+, Ni2+, Zn2+ lossis Pb2+ ions txwv txoj kev loj hlob ntawm Scenedesmus los ntawm kev hloov pauv cell morphology thiab rhuav tshem lawv cov chloroplasts20,21.
Cov txheej txheem ntsuab rau decomposition ntawm cov kuab paug organic thiab tshem tawm cov hlau hnyav ions tau nyiam cov kws tshawb fawb thiab cov kws tshaj lij thoob ntiaj teb.Qhov no feem ntau yog vim qhov tseeb tias cov kab mob no tau yooj yim ua tiav hauv cov kua theem.Txawm li cas los xij, inorganic crystalline pollutants yog tus cwj pwm los ntawm cov dej solubility tsawg thiab tsis tshua muaj kev cuam tshuam rau ntau yam biotransformations, uas ua rau muaj teeb meem loj hauv kev kho, thiab kev nce qib me me tau ua hauv cheeb tsam no 22,23,24,25,26.Yog li, kev tshawb nrhiav cov kev daws teeb meem zoo ib puag ncig rau kev kho cov nanomaterials tseem yog thaj chaw nyuaj thiab tsis tau tshawb nrhiav.Vim tias qhov siab ntawm qhov tsis paub meej txog cov teebmeem biotransformation ntawm 2D nanomaterials, tsis muaj ib txoj hauv kev yooj yim los nrhiav txoj hauv kev ntawm lawv cov degradation thaum txo.
Nyob rau hauv txoj kev tshawb no, peb siv ntsuab microalgae ua ib tug active aqueous bioremediation tus neeg saib xyuas rau inorganic ceramic cov ntaub ntawv, ua ke nrog nyob rau hauv situ saib xyuas cov txheej txheem degradation ntawm MXene ua ib tug neeg sawv cev ntawm inorganic ceramic cov ntaub ntawv.Lub sij hawm "MXene" qhia txog stoichiometry ntawm Mn + 1XnTx cov khoom, qhov twg M yog cov hlau hloov thaum ntxov, X yog carbon thiab / los yog nitrogen, Tx yog lub terminator nto (piv txwv li, -OH, -F, -Cl), thiab n = 1, 2, 3 lossis 427.28.Txij li thaum nrhiav tau ntawm MXenes los ntawm Naguib li al.Sensorics, kho mob qog noj ntshav thiab daim nyias nyias 27,29,30.Tsis tas li ntawd, MXenes tuaj yeem suav tias yog cov qauv 2D vim lawv qhov kev ruaj ntseg zoo colloidal thiab muaj peev xwm ua kom muaj roj ntsha sib cuam tshuam31,32,33,34,35,36.
Yog li ntawd, cov txheej txheem tsim nyob rau hauv tsab xov xwm no thiab peb cov kev tshawb fawb hypotheses tau pom nyob rau hauv daim duab 1. Raws li qhov kev xav no, microalgae degrade Nb-based MXenes rau hauv cov tshuaj tsis muaj tshuaj lom vim yog kev sib cuam tshuam ntawm lub cev, uas tso cai rau cov algae rov qab ntxiv.Txhawm rau ntsuas qhov kev xav no, ob tus tswv cuab ntawm tsev neeg ntawm niobium-raws li kev hloov pauv ntawm cov hlau carbides thiab / lossis nitrides (MXenes), uas yog Nb2CTx thiab Nb4C3TX, raug xaiv.
Cov txheej txheem tshawb fawb thiab pov thawj-raws li kev xav rau MXene rov qab los ntawm ntsuab microalgae Raphidocelis subcapitata.Thov nco ntsoov tias qhov no tsuas yog schematic sawv cev ntawm cov pov thawj-raws li kev xav.Lub pas dej ib puag ncig txawv ntawm cov khoom siv nruab nrab siv thiab cov xwm txheej (piv txwv li, lub voj voog diurnal thiab cov kev txwv hauv cov khoom noj muaj txiaj ntsig tseem ceeb).Tsim nrog BioRender.com.
Yog li ntawd, los ntawm kev siv MXene raws li ib tug qauv system, peb tau qhib lub qhov rooj rau txoj kev tshawb no ntawm ntau yam kev lom neeg cov teebmeem uas yuav tsis raug soj ntsuam nrog rau lwm cov pa nanomaterials.Tshwj xeeb, peb pom tau tias muaj peev xwm ntawm bioremediation ntawm ob-dimensional nanomaterials, xws li niobium-based MXenes, los ntawm microalgae Raphidocelis subcapitata.Microalgae muaj peev xwm degrade Nb-MXenes rau hauv cov tsis muaj tshuaj lom oxides NbO thiab Nb2O5, uas kuj muab cov as-ham los ntawm niobium uptake mechanism.Zuag qhia tag nrho, txoj kev tshawb no teb cov lus nug tseem ceeb ntawm cov txheej txheem cuam tshuam nrog kev sib cuam tshuam ntawm lub cev uas tswj hwm cov txheej txheem ntawm bioremediation ntawm ob-dimensional nanomaterials.Tsis tas li ntawd, peb tab tom tsim ib txoj hauv kev yooj yim-tsis-raws li txoj hauv kev rau kev taug qab hloov maj mam hloov hauv cov duab ntawm 2D nanomaterials.Qhov no txhawb kev tshawb fawb luv luv thiab ntev mus rau ntau yam kev cuam tshuam ib puag ncig ntawm inorganic crystalline nanomaterials.Yog li, peb txoj kev tshawb fawb nce kev nkag siab ntawm kev sib cuam tshuam ntawm cov khoom nto thiab cov khoom siv roj ntsha.Peb tseem tab tom muab lub hauv paus rau kev nthuav dav luv luv thiab mus sij hawm ntev kev tshawb fawb ntawm lawv cov kev cuam tshuam rau cov dej tshiab ecosystems, uas tam sim no tuaj yeem txheeb xyuas tau yooj yim.
MXenes sawv cev rau cov chav kawm nthuav dav ntawm cov ntaub ntawv uas muaj qhov tshwj xeeb thiab ntxim nyiam lub cev thiab tshuaj lom neeg thiab yog li muaj ntau yam kev siv.Cov khoom no feem ntau nyob ntawm lawv cov stoichiometry thiab chemistry nto.Yog li ntawd, hauv peb txoj kev tshawb fawb, peb tau tshawb xyuas ob hom Nb-raws li hierarchical ib txheej txheej (SL) MXenes, Nb2CTx thiab Nb4C3TX, vim muaj kev sib txawv lom ntawm cov nanomaterials no tuaj yeem pom.MXenes yog tsim los ntawm lawv cov khoom pib los ntawm sab saum toj-down xaiv etching ntawm atomically nyias MAX-theem A-txheej.MAX theem yog ternary ceramic tsim los ntawm "bonded" blocks ntawm kev hloov pauv hlau carbides thiab nyias txheej ntawm "A" cov ntsiab lus xws li Al, Si, thiab Sn nrog MnAXn-1 stoichiometry.Lub morphology ntawm thawj theem MAX tau pom los ntawm kev tshuaj ntsuam xyuas electron microscopy (SEM) thiab tau ua raws li cov kev tshawb fawb yav dhau los (Saib Cov Ntaub Ntawv Ntxiv, SI, Daim duab S1).Multilayer (ML) Nb-MXene tau txais tom qab tshem tawm Al txheej nrog 48% HF (hydrofluoric acid).Lub morphology ntawm ML-Nb2CTx thiab ML-Nb4C3TX tau soj ntsuam los ntawm scanning electron microscopy (SEM) (Figures S1c thiab S1d feem) thiab ib tug raug txheej txheej MXene morphology tau pom, zoo ib yam li ob-dimensional nanoflakes dhau los ntawm elongated pore-zoo li.Ob leeg Nb-MXenes muaj ntau yam nrog MXene theem yav dhau los ua ke los ntawm acid etching27,38.Tom qab lees paub cov qauv ntawm MXene, peb muab tso rau nws los ntawm kev sib cuam tshuam ntawm tetrabutylammonium hydroxide (TBAOH) ua raws li kev ntxuav thiab sonication, tom qab ntawd peb tau txais ib txheej txheej lossis txheej qis (SL) 2D Nb-MXene nanoflakes.
Peb siv high-resolution kis tau tus mob electron microscopy (HRTEM) thiab X-ray diffraction (XRD) los ntsuam xyuas cov efficiency ntawm etching thiab ntxiv tev.Cov txiaj ntsig HRTEM tau ua tiav siv Inverse Fast Fourier Transform (IFFT) thiab Fast Fourier Transform (FFT) tau qhia hauv daim duab 2. Nb-MXene nanoflakes tau taw qhia ntug los xyuas cov qauv ntawm cov txheej txheem atomic thiab ntsuas qhov sib txawv ntawm qhov sib txawv.HRTEM cov duab ntawm MXene Nb2CTx thiab Nb4C3TX nanoflakes qhia lawv cov atomically nyias txheej txheej (saib daim duab 2a1, a2), raws li yav dhau los qhia los ntawm Naguib li al.27 thiab Jastrzębska li al.38.Rau ob qhov uas nyob ib sab Nb2CTx thiab Nb4C3Tx monolayers, peb txiav txim siab interlayer nrug ntawm 0.74 thiab 1.54 nm, raws li (Fig. 2b1,b2), uas kuj pom zoo nrog peb cov txiaj ntsig yav dhau los38.Qhov no tau lees paub ntxiv los ntawm kev hloov pauv ceev Fourier (Fig. 2c1, c2) thiab Fourier hloov pauv sai (Fig. 2d1, d2) qhia qhov kev ncua deb ntawm Nb2CTx thiab Nb4C3Tx monolayers.Daim duab qhia txog kev hloov pauv ntawm lub teeb thiab tsaus nti sib txuas rau niobium thiab carbon atoms, uas lees paub qhov txheej txheej ntawm MXenes kawm.Nws yog ib qho tseem ceeb uas yuav tsum nco ntsoov tias lub zog dispersive X-ray spectroscopy (EDX) spectra tau txais rau Nb2CTx thiab Nb4C3Tx (Figures S2a thiab S2b) tsis pom qhov seem ntawm thawj theem MAX, txij li tsis muaj Al peak tau kuaj pom.
Tus cwj pwm ntawm SL Nb2CTx thiab Nb4C3Tx MXene nanoflakes, suav nrog (a) siab daws teeb meem electron microscopy (HRTEM) sab saib 2D nanoflake imaging thiab sib xws, (b) siv hom, (c) thim rov qab ceev Fourier transform (IFFT), (d) ceev Fouriere (FFT) qauv (FFT).Rau SL 2D Nb2CTx, cov lej tau qhia tias yog (a1, b1, c1, d1, e1).Rau SL 2D Nb4C3Tx, cov lej tau qhia tias yog (a2, b2, c2, d2, e1).
X-ray diffraction ntsuas ntawm SL Nb2CTx thiab Nb4C3Tx MXenes tau qhia hauv daim duab.2e1e2 ib.Peaks (002) ntawm 4.31 thiab 4.32 sib haum mus rau yav dhau los piav txheej txheej MXenes Nb2CTx thiab Nb4C3TX38,39,40,41 raws.Cov txiaj ntsig XRD kuj tseem qhia tau tias muaj qee qhov seem ML cov qauv thiab MAX theem, tab sis feem ntau XRD qauv txuam nrog SL Nb4C3Tx (Fig. 2e2).Lub xub ntiag ntawm cov khoom me me ntawm MAX theem tuaj yeem piav qhia qhov muaj zog MAX ncov piv rau cov txheej txheem Nb4C3Tx randomly stacked.
Kev tshawb fawb ntxiv tau tsom mus rau ntsuab microalgae teej tug mus rau hom R. subcapitata.Peb xaiv microalgae vim lawv yog cov tsim khoom tseem ceeb koom nrog hauv cov zaub mov loj webs42.Lawv kuj yog ib qho ntawm cov cim qhia zoo tshaj plaws ntawm toxicity vim muaj peev xwm tshem tawm cov tshuaj lom uas tau nqa mus rau qib siab ntawm cov khoom noj khoom haus43.Tsis tas li ntawd, kev tshawb fawb ntawm R. subcapitata tuaj yeem ua rau pom qhov tshwm sim ntawm SL Nb-MXenes rau cov kab mob hauv dej tshiab.Txhawm rau ua piv txwv li no, cov kws tshawb fawb tau pom tias txhua lub microbe muaj qhov sib txawv rau cov tshuaj lom neeg nyob hauv ib puag ncig.Rau feem ntau cov kab mob, cov ntsiab lus qis ntawm cov tshuaj tsis cuam tshuam rau lawv txoj kev loj hlob, thaum cov ntsiab lus siab tshaj ib qho kev txwv tuaj yeem cuam tshuam lawv lossis ua rau tuag taus.Yog li ntawd, rau peb cov kev tshawb fawb ntawm kev sib cuam tshuam ntawm qhov chaw ntawm microalgae thiab MXenes thiab kev cuam tshuam rov qab los, peb tau txiav txim siab los ntsuas qhov tsis muaj teeb meem thiab tshuaj lom ntawm Nb-MXenes.Txhawm rau ua qhov no, peb tau kuaj cov concentration ntawm 0 (raws li kev siv), 0.01, 0.1 thiab 10 mg l-1 MXene thiab ntxiv rau microalgae nrog cov concentrations siab heev ntawm MXene (100 mg l-1 MXene), uas tuaj yeem ua rau huab cua thiab tuag taus..rau txhua qhov chaw lom neeg.
Cov teebmeem ntawm SL Nb-MXenes ntawm microalgae tau qhia hauv daim duab 3, qhia tias feem pua ​​​​ntawm kev loj hlob nce qib (+) lossis inhibition (-) ntsuas rau 0 mg l-1 cov qauv.Rau kev sib piv, Nb-MAX theem thiab ML Nb-MXenes kuj tau sim thiab cov txiaj ntsig tau pom hauv SI (saib daim duab S3).Cov txiaj ntsig tau lees paub tias SL Nb-MXenes yuav luag tag nrho tsis muaj tshuaj lom nyob rau hauv thaj tsam ntawm qhov qis qis ntawm 0.01 txog 10 mg / l, raws li qhia hauv daim duab 3a,b.Nyob rau hauv cov ntaub ntawv ntawm Nb2CTx, peb pom tsis muaj ntau tshaj 5% ecotoxicity nyob rau hauv lub teev ntau yam.
Stimulation (+) los yog inhibition (-) ntawm microalgae kev loj hlob nyob rau hauv lub xub ntiag ntawm SL (a) Nb2CTx thiab (b) Nb4C3TX MXene.24, 48 thiab 72 teev ntawm MXene-microalgae kev sib cuam tshuam tau txheeb xyuas. Cov ntaub ntawv tseem ceeb (t-test, p < 0.05) tau cim nrog lub hnub qub (*). Cov ntaub ntawv tseem ceeb (t-test, p < 0.05) tau cim nrog lub hnub qub (*). Значимые данные (t-критерий, p < 0,05) отмечены звездочкой (*). Cov ntaub ntawv tseem ceeb (t-test, p < 0.05) yog cim nrog lub hnub qub (*).重要数据（t 检验，p <0.05）用星号(*) 标记.重要数据（t 检验，p <0.05）用星号(*) 标记. Важные данные (t-test, p < 0,05) отмечены звездочкой (*). Cov ntaub ntawv tseem ceeb (t-test, p < 0.05) yog cim nrog lub hnub qub (*).Cov xub liab qhia qhov kev tshem tawm ntawm inhibitory stimulation.
Ntawm qhov tod tes, tsis tshua muaj siab ntawm Nb4C3TX tau dhau los ua cov tshuaj lom me ntsis, tab sis tsis siab dua 7%.Raws li kev cia siab, peb tau pom tias MXenes muaj toxicity ntau dua thiab microalgae loj hlob inhibition ntawm 100mg L-1.Interestingly, tsis muaj ib yam ntawm cov ntaub ntawv qhia tib yam thiab lub sij hawm dependence ntawm atoxic/toxic los piv rau MAX los yog ML cov qauv (saib SI kom paub meej).Thaum lub sijhawm MAX (saib daim duab S3) toxicity mus txog kwv yees li 15-25% thiab nce nrog lub sijhawm, qhov kev hloov pauv tau pom zoo rau SL Nb2CTx thiab Nb4C3TX MXene.Qhov inhibition ntawm microalgae kev loj hlob poob qis dhau sijhawm.Nws mus txog kwv yees li 17% tom qab 24 teev thiab poob qis dua 5% tom qab 72 teev (Fig. 3a, b, raws li).
Qhov tseem ceeb tshaj, rau SL Nb4C3TX, microalgae kev loj hlob inhibition mus txog 27% tom qab 24 teev, tab sis tom qab 72 teev nws txo mus txog 1%.Yog li ntawd, peb tau sau cov txiaj ntsig tau pom raws li kev cuam tshuam ntawm kev txhawb nqa, thiab cov nyhuv muaj zog dua rau SL Nb4C3TX MXene.Kev txhawb nqa ntawm microalgae kev loj hlob tau sau tseg ua ntej nrog Nb4C3TX (kev sib cuam tshuam ntawm 10 mg L-1 rau 24 h) piv nrog SL Nb2CTx MXene.Cov nyhuv inhibition-stimulation thim rov qab kuj tau pom zoo hauv biomass ob npaug ntawm tus nqi nkhaus (saib daim duab S4 kom paub meej).Txog tam sim no, tsuas yog ecotoxicity ntawm Ti3C2TX MXene tau kawm nyob rau hauv ntau txoj kev.Nws tsis yog tshuaj lom rau zebrafish embryos44 tab sis nruab nrab ecotoxic rau microalgae Desmodesmus quadricauda thiab Sorghum saccharatum nroj tsuag45.Lwm cov piv txwv ntawm cov teebmeem tshwj xeeb suav nrog kev ua rau mob qog noj ntshav ntau dua li cov kab cell qub46,47.Nws tuaj yeem xav tias qhov kev sim ntsuas yuav cuam tshuam qhov kev hloov pauv hauv microalgae kev loj hlob pom nyob rau hauv lub xub ntiag ntawm Nb-MXenes.Piv txwv li, pH txog 8 hauv chloroplast stroma yog qhov zoo rau kev ua haujlwm zoo ntawm RuBisCO enzyme.Yog li, pH hloov tsis zoo cuam tshuam tus nqi ntawm photosynthesis48,49.Txawm li cas los xij, peb tsis tau pom qhov hloov pauv tseem ceeb hauv pH thaum lub sijhawm sim (saib SI, Fig. S5 kom paub meej).Feem ntau, kab lis kev cai ntawm microalgae nrog Nb-MXenes txo qis pH ntawm cov tshuaj nyob rau lub sijhawm.Txawm li cas los xij, qhov kev txo qis no zoo ib yam li kev hloov pauv hauv pH ntawm qhov nruab nrab ntshiab.Tsis tas li ntawd, ntau qhov kev hloov pauv pom tau zoo ib yam li qhov ntsuas rau cov kab lis kev cai ntshiab ntawm microalgae (tswj qauv).Yog li, peb xaus lus tias photosynthesis tsis cuam tshuam los ntawm kev hloov pauv hauv pH lub sijhawm.
Tsis tas li ntawd, cov synthesized MXenes muaj qhov xaus ntawm qhov chaw (txhais tau tias yog Tx).Cov no yog cov pab pawg ua haujlwm tseem ceeb -O, -F thiab -OH.Txawm li cas los xij, chemistry nto yog ncaj qha ntsig txog cov txheej txheem ntawm kev sib txuas.Cov pab pawg no tau paub tias yuav tsum tau muab faib ua ntu zus, ua rau nws nyuaj rau kwv yees lawv cov txiaj ntsig ntawm cov khoom ntawm MXene50.Nws tuaj yeem sib cav tias Tx tuaj yeem yog lub zog catalytic rau oxidation ntawm niobium los ntawm lub teeb.Cov pab pawg ua haujlwm ntog tiag tiag muab ntau qhov chaw sib txuas rau lawv cov hauv paus photocatalysts los ua heterojunctions51.Txawm li cas los xij, kev loj hlob nruab nrab muaj pes tsawg leeg tsis tau muab ib qho zoo photocatalyst (cov ntsiab lus nruab nrab muaj nyob hauv SI Table S6).Tsis tas li ntawd, txhua qhov kev hloov kho saum npoo kuj tseem ceeb heev, vim tias kev ua haujlwm lom neeg ntawm MXenes tuaj yeem hloov pauv vim txheej txheej tom qab ua tiav, oxidation, tshuaj lom neeg hloov pauv ntawm cov organic thiab inorganic compounds52,53,54,55,56 lossis nto nqi engineering38.Yog li, txhawm rau ntsuas seb niobium oxide puas muaj dab tsi cuam tshuam nrog cov khoom siv tsis ruaj khov hauv nruab nrab, peb tau tshawb fawb txog zeta (ζ) muaj peev xwm hauv microalgae loj hlob nruab nrab thiab deionized dej (rau kev sib piv).Peb cov txiaj ntsig tau pom tias SL Nb-MXenes ruaj khov (saib SI Fig. S6 rau MAX thiab ML cov txiaj ntsig).Zeta peev xwm ntawm SL MXenes yog hais txog -10 mV.Nyob rau hauv rooj plaub ntawm SR Nb2CTx, tus nqi ntawm ζ yog me ntsis tsis zoo dua li ntawm Nb4C3Tx.Xws li kev hloov pauv hauv ζ tus nqi yuav qhia tau tias qhov chaw tsis zoo ntawm MXene nanoflakes absorbs zoo ions los ntawm kab lis kev cai nruab nrab.Kev ntsuas ib ntus ntawm zeta muaj peev xwm thiab kev coj ua ntawm Nb-MXenes hauv kab lis kev cai nruab nrab (saib daim duab S7 thiab S8 hauv SI kom paub meej ntxiv) zoo li txhawb peb qhov kev xav.
Txawm li cas los xij, ob qho tib si Nb-MXene SLs pom qhov hloov pauv tsawg kawg ntawm xoom.Qhov no qhia meej meej tias lawv cov kev ruaj ntseg hauv microalgae loj hlob nruab nrab.Tsis tas li ntawd, peb tau soj ntsuam seb qhov muaj ntawm peb cov microalgae ntsuab puas yuav cuam tshuam rau kev ruaj ntseg ntawm Nb-MXenes hauv nruab nrab.Cov txiaj ntsig ntawm zeta muaj peev xwm thiab kev coj ua ntawm MXenes tom qab kev cuam tshuam nrog microalgae hauv cov khoom noj khoom haus thiab kab lis kev cai dhau sijhawm tuaj yeem pom hauv SI (Figures S9 thiab S10).Interestingly, peb pom tias muaj microalgae zoo li stabilization ntawm ob qho tib si MXenes.Nyob rau hauv cov ntaub ntawv ntawm Nb2CTx SL, lub zeta muaj peev xwm txawm me ntsis txo lub sij hawm mus rau ntau qhov tsis zoo (-15.8 piv -19.1 mV tom qab 72 h ntawm incubation).Lub zeta muaj peev xwm ntawm SL Nb4C3TX nce me ntsis, tab sis tom qab 72 h nws tseem pom kev ruaj ntseg dua li nanoflakes yam tsis muaj microalgae (-18.1 vs. -9.1 mV).
Peb kuj pom muaj qis conductivity ntawm Nb-MXene cov kev daws teeb meem incubated nyob rau hauv lub xub ntiag ntawm microalgae, qhia ib tug tsawg npaum li cas ntawm ions nyob rau hauv lub nutrient nruab nrab.Qhov tseem ceeb, qhov tsis ruaj khov ntawm MXenes hauv dej yog vim qhov oxidation57.Yog li ntawd, peb xav tias ntsuab microalgae qee yam tshem tawm cov oxides tsim nyob rau saum npoo ntawm Nb-MXene thiab txawm tiv thaiv lawv qhov tshwm sim (oxidation ntawm MXene).Qhov no tuaj yeem pom los ntawm kev kawm txog hom tshuaj absorbed los ntawm microalgae.
Thaum peb cov kev tshawb fawb ecotoxicological tau qhia tias microalgae muaj peev xwm kov yeej cov tshuaj lom ntawm Nb-MXenes nyob rau lub sijhawm thiab qhov txawv txav ntawm kev txhawb nqa kev loj hlob, lub hom phiaj ntawm peb txoj kev tshawb fawb yog los tshawb xyuas cov txheej txheem ua tau.Thaum cov kab mob xws li algae raug rau cov tebchaw lossis cov khoom tsis paub txog lawv cov ecosystems, lawv yuav hnov ​​​​mob ntau yam58,59.Thaum tsis muaj tshuaj lom hlau oxides, microalgae tuaj yeem pub lawv tus kheej, cia lawv loj hlob tsis tu ncua 60.Tom qab noj cov tshuaj lom, cov txheej txheem tiv thaiv yuav raug qhib, xws li hloov cov duab lossis daim ntawv.Qhov ua tau ntawm kev nqus yuav tsum raug xam tias yog 58,59.Qhov tseem ceeb, ib qho kev kos npe ntawm kev tiv thaiv mechanism yog qhov qhia meej ntawm cov tshuaj toxicity ntawm cov tshuaj ntsuam xyuas.Yog li ntawd, hauv peb txoj haujlwm ntxiv, peb tau tshawb xyuas qhov muaj peev xwm ntawm kev sib cuam tshuam ntawm SL Nb-MXene nanoflakes thiab microalgae los ntawm SEM thiab kev nqus tau ntawm Nb-based MXene los ntawm X-ray fluorescence spectroscopy (XRF).Nco ntsoov tias SEM thiab XRF tsom xam tsuas yog ua tiav ntawm qhov siab tshaj plaws ntawm MXene los daws cov teeb meem toxicity.
Cov txiaj ntsig SEM tau pom hauv Fig.4.Tsis kho cov kab mob microalgae (saib daim duab 4a, cov qauv siv) qhia tau meej meej R. subcapitata morphology thiab croissant-zoo li cell zoo li.Cells tshwm flattened thiab me ntsis disorganized.Qee lub hlwb microalgae sib tshooj thiab sib txuas nrog ib leeg, tab sis qhov no yog tshwm sim los ntawm cov qauv kev npaj.Feem ntau, cov cell microalgae ntshiab muaj qhov chaw du thiab tsis pom muaj kev hloov pauv morphological.
SEM cov duab qhia txog kev sib cuam tshuam ntawm ntsuab microalgae thiab MXene nanosheets tom qab 72 teev ntawm kev sib cuam tshuam ntawm huab cua concentration (100 mg L-1).(a) Tsis kho ntsuab microalgae tom qab kev cuam tshuam nrog SL (b) Nb2CTx thiab (c) Nb4C3TX MXenes.Nco ntsoov tias Nb-MXene nanoflakes tau cim nrog cov xub liab.Rau kev sib piv, cov duab los ntawm lub tshuab ntsuas qhov muag kuj tau ntxiv.
Nyob rau hauv sib piv, microalgae hlwb adsorbed los ntawm SL Nb-MXene nanoflakes puas lawm (saib daim duab 4b, c, liab xub).Nyob rau hauv cov ntaub ntawv ntawm Nb2CTx MXene (Fig. 4b), microalgae yuav loj hlob nrog txuas ob-dimensional nanoscales, uas yuav hloov tau lawv morphology.Qhov tseem ceeb, peb kuj tau pom cov kev hloov pauv no nyob rau hauv lub teeb pom kev zoo (saib SI Figure S11 kom paub meej).Qhov kev hloov morphological no muaj lub hauv paus plausible nyob rau hauv lub cev ntawm microalgae thiab lawv lub peev xwm los tiv thaiv lawv tus kheej los ntawm kev hloov cell morphology, xws li nce cell volume61.Yog li ntawd, nws yog ib qho tseem ceeb uas yuav tsum tau xyuas cov xov tooj ntawm microalgae hlwb uas muaj tiag nyob rau hauv kev sib cuag nrog Nb-MXenes.SEM cov kev tshawb fawb pom tau tias kwv yees li 52% ntawm microalgae hlwb raug Nb-MXenes, thaum 48% ntawm cov microalgae hlwb zam kev sib cuag.Rau SL Nb4C3Tx MXene, microalgae sim zam kev sib cuag nrog MXene, yog li localizing thiab loj hlob los ntawm ob-seem nanoscales (Fig. 4c).Txawm li cas los xij, peb tsis tau soj ntsuam qhov nkag ntawm nanoscales rau hauv microalgae hlwb thiab lawv cov kev puas tsuaj.
Self-preservation kuj yog ib lub sij hawm-raws li tus cwj pwm teb rau lub blockage ntawm photosynthesis vim adsorption ntawm hais nyob rau hauv lub cell nto thiab thiaj li hu ua shading (shading) effect62.Nws yog qhov tseeb tias txhua yam khoom (piv txwv li, Nb-MXene nanoflakes) uas nyob nruab nrab ntawm microalgae thiab lub teeb qhov chaw txwv cov teeb pom kev zoo los ntawm chloroplasts.Txawm li cas los xij, peb tsis muaj qhov tsis ntseeg tias qhov no muaj feem cuam tshuam rau cov txiaj ntsig tau txais.Raws li tau pom los ntawm peb cov kev soj ntsuam microscopic, 2D nanoflakes tsis tau qhwv tag nrho lossis ua raws li qhov chaw ntawm microalgae, txawm tias thaum lub hlwb microalgae tau ntsib nrog Nb-MXenes.Hloov chaw, nanoflakes tau tig mus rau cov kab mob microalgae yam tsis tau npog lawv qhov chaw.Xws li cov txheej txheem ntawm nanoflakes / microalgae tsis tuaj yeem txwv cov teeb pom kev zoo los ntawm microalgae hlwb.Ntxiv mus, qee qhov kev tshawb fawb tau pom tias muaj kev txhim kho hauv lub teeb nqus los ntawm cov kab mob photosynthetic nyob rau hauv lub xub ntiag ntawm ob-dimensional nanomaterials63,64,65,66.
Txij li cov duab SEM tsis tuaj yeem lees paub ncaj qha txog kev nce ntawm niobium los ntawm microalgae hlwb, peb txoj kev tshawb fawb ntxiv tau tig mus rau X-ray fluorescence (XRF) thiab X-ray photoelectron spectroscopy (XPS) tsom xam kom paub meej qhov teeb meem no.Yog li ntawd, peb muab piv rau qhov kev siv ntawm Nb peaks ntawm kev siv cov qauv microalgae uas tsis cuam tshuam nrog MXenes, MXene nanoflakes tshem tawm ntawm lub ntsej muag ntawm microalgae hlwb, thiab microalgal hlwb tom qab tshem tawm ntawm MXenes txuas.Nws yog ib nqi sau cia hais tias yog tsis muaj Nb uptake, tus nqi Nb tau los ntawm cov microalgae hlwb yuav tsum yog xoom tom qab tshem tawm cov txuas nanoscales.Yog li, yog tias Nb uptake tshwm sim, XRF thiab XPS cov txiaj ntsig yuav tsum qhia meej Nb ncov.
Nyob rau hauv rooj plaub ntawm XRF spectra, cov qauv microalgae pom Nb peaks rau SL Nb2CTx thiab Nb4C3Tx MXene tom qab kev cuam tshuam nrog SL Nb2CTx thiab Nb4C3Tx MXene (saib daim duab 5a, kuj tseem nco ntsoov tias cov txiaj ntsig rau MAX thiab ML MXenes tau qhia hauv SI, Figs17 S12–C).Interestingly, qhov kev siv ntawm lub ncov Nb yog tib yam nyob rau hauv ob qho tib si (liab tuav hauv daim duab 5a).Qhov no tau qhia tias cov algae tsis tuaj yeem nqus tau ntau Nb, thiab lub peev xwm siab tshaj plaws rau Nb tsub zuj zuj hauv cov hlwb, txawm hais tias ob zaug ntxiv Nb4C3Tx MXene tau txuas rau microalgae hlwb (xiav bars hauv daim duab 5a).Qhov tseem ceeb, lub peev xwm ntawm microalgae nqus cov hlau nyob ntawm qhov concentration ntawm cov hlau oxides hauv ib puag ncig67,68.Shamshada et al.67 pom tias lub peev xwm nqus dej ntawm algae txo qis nrog nce pH.Raize et al.68 tau sau tseg tias lub peev xwm ntawm seaweed nqus hlau yog li 25% siab dua rau Pb2+ dua li Ni2+.
(a) XRF cov txiaj ntsig ntawm basal Nb uptake los ntawm ntsuab microalgae hlwb incubated ntawm ib tug heev concentration ntawm SL Nb-MXenes (100 mg L-1) rau 72 teev.Cov txiaj ntsig tau pom tias muaj α nyob rau hauv cov ntshiab microalgae hlwb (tswj cov qauv, kab grey), 2D nanoflakes cais tawm ntawm cov kab mob microalgae (xiav kab), thiab microalgae hlwb tom qab sib cais ntawm 2D nanoflakes los ntawm qhov chaw (cov kab liab).Tus nqi ntawm elemental Nb, (b) feem pua ​​​​ntawm cov tshuaj muaj pes tsawg leeg ntawm microalgae organic Cheebtsam (C = O thiab CHx / C–O) thiab Nb oxides tam sim no nyob rau hauv microalgae hlwb tom qab incubation nrog SL Nb-MXenes, (c–e) Fitting ntawm lub compositional ncov ntawm XPS SL Nb2CTx spectra thiab (fhC3e) microalgae (fhC).
Yog li, peb xav tias Nb tuaj yeem nqus tau los ntawm algal hlwb hauv daim ntawv oxides.Txhawm rau kuaj qhov no, peb tau ua XPS cov kev tshawb fawb ntawm MXenes Nb2CTx thiab Nb4C3TX thiab algae hlwb.Cov txiaj ntsig ntawm kev sib cuam tshuam ntawm microalgae nrog Nb-MXenes thiab MXenes cais los ntawm algae hlwb tau pom hauv daim duab.5 ib b.Raws li qhov xav tau, peb tau kuaj pom Nb 3d peaks hauv cov qauv microalgae tom qab tshem tawm MXene los ntawm qhov chaw ntawm microalgae.Kev txiav txim kom muaj nuj nqis ntawm C = O, CHx / CO, thiab Nb oxides raug xam raws li Nb 3d, O 1s, thiab C 1s spectra tau nrog Nb2CTx SL (Fig. 5c–e) thiab Nb4C3Tx SL (Fig. 5c–e).) tau los ntawm incubated microalgae.Daim duab 5f–h) MXenes.Table S1-3 qhia cov ntsiab lus ntawm lub ncov tsis zoo thiab tag nrho chemistry uas tshwm sim los ntawm qhov haum.Nws yog qhov tsim nyog hais tias Nb 3d thaj tsam ntawm Nb2CTx SL thiab Nb4C3Tx SL (Fig. 5c, f) sib raug rau ib qho Nb2O5 tivthaiv.Ntawm no, peb pom tsis muaj MXene-txog cov peaks nyob rau hauv lub spectra, qhia tias microalgae hlwb tsuas yog nqus cov oxide daim ntawv ntawm Nb.Ntxiv rau, peb kwv yees C 1 s spectrum nrog C–C, CHx / C–O, C = O, thiab –COOH Cheebtsam.Peb muab CHx / C–O thiab C = O peaks rau cov organic koom tes ntawm microalgae hlwb.Cov khoom siv organic no suav nrog 36% thiab 41% ntawm C 1s peaks hauv Nb2CTx SL thiab Nb4C3TX SL, raws li.Tom qab ntawd peb haum O 1s spectra ntawm SL Nb2CTx thiab SL Nb4C3TX nrog Nb2O5, organic Cheebtsam ntawm microalgae (CHx / CO), thiab nto adsorbed dej.
Thaum kawg, XPS cov txiaj ntsig tau qhia meej meej rau daim ntawv ntawm Nb, tsis yog nws lub xub ntiag xwb.Raws li txoj hauj lwm ntawm Nb 3d teeb liab thiab cov txiaj ntsig ntawm deconvolution, peb paub tseeb tias Nb yog absorbed tsuas yog nyob rau hauv daim ntawv ntawm oxides thiab tsis ions los yog MXene nws tus kheej.Tsis tas li ntawd, XPS cov txiaj ntsig tau pom tias cov hlwb microalgae muaj peev xwm ntau dua los txhawb nqa Nb oxides los ntawm SL Nb2CTx piv rau SL Nb4C3TX MXene.
Thaum peb cov txiaj ntsig Nb tau txais txiaj ntsig zoo thiab tso cai rau peb txheeb xyuas MXene degradation, tsis muaj txoj hauv kev los taug qab cov kev hloov pauv hloov pauv hauv 2D nanoflakes.Yog li ntawd, peb kuj tau txiav txim siab los tsim ib txoj kev tsim nyog uas tuaj yeem teb ncaj qha rau txhua qhov kev hloov pauv tshwm sim hauv 2D Nb-MXene nanoflakes thiab microalgae hlwb.Nws yog ib qho tseem ceeb uas yuav tsum nco ntsoov tias peb xav tias yog tias cov tsiaj sib cuam tshuam tau txais kev hloov pauv, decomposition lossis defragmentation, qhov no yuav tsum tshwm sim sai sai rau nws tus kheej raws li kev hloov pauv ntawm cov duab, xws li txoj kab uas hla ntawm thaj tsam sib npaug, roundness, Feret dav, lossis Feret ntev.Txij li thaum cov kev ntsuas no tsim nyog rau kev piav qhia txog cov khoom elongated los yog ob-seem nanoflakes, lawv txoj kev taug qab los ntawm kev txheeb xyuas cov duab zoo nkauj yuav muab cov ntaub ntawv tseem ceeb rau peb txog kev hloov pauv morphological ntawm SL Nb-MXene nanoflakes thaum txo.
Cov txiaj ntsig tau txais yog qhia hauv daim duab 6. Rau kev sib piv, peb kuj tau sim thawj theem MAX thiab ML-MXenes (saib SI Figures S18 thiab S19).Dynamic tsom xam ntawm particle puab pom tias tag nrho cov duab tsis ntawm ob Nb-MXene SLs hloov pauv loj tom qab kev cuam tshuam nrog microalgae.Raws li pom los ntawm qhov sib npaug ntawm qhov sib npaug ntawm lub voj voog txoj kab uas hla (Fig. 6a, b), qhov txo qis qhov siv ntawm cov feem ntawm cov nanoflakes loj qhia tau hais tias lawv yuav lwj mus rau hauv me me fragments.Ntawm daim duab.6c, d qhia tau hais tias qhov txo qis ntawm cov peaks cuam tshuam nrog kev hloov pauv ntawm cov flakes (elongation ntawm nanoflakes), qhia txog kev hloov pauv ntawm 2D nanoflakes rau hauv cov duab zoo li ntau dua.Daim duab 6e-h qhia qhov dav thiab qhov ntev ntawm Feret, feem.Feret dav thiab ntev yog complementary tsis thiab yog li ntawd yuav tsum tau txiav txim siab ua ke.Tom qab incubation ntawm 2D Nb-MXene nanoflakes nyob rau hauv lub xub ntiag ntawm microalgae, lawv Feret correlation peaks hloov thiab lawv siv tsawg.Raws li cov txiaj ntsig no ua ke nrog morphology, XRF thiab XPS, peb tau txiav txim siab tias cov kev hloov pauv tau muaj feem cuam tshuam nrog oxidation vim oxidized MXenes ua ntau wrinkled thiab tawg mus rau hauv cov khoom tawg thiab cov oxide kheej kheej 69,70.
Kev tshuaj xyuas ntawm MXene hloov pauv tom qab kev cuam tshuam nrog ntsuab microalgae.Dynamic particle zoo tsom xam yuav siv sij hawm mus rau hauv tus account xws li tsis xws li (a, b) txoj kab uas hla ntawm qhov sib npaug zos cheeb tsam, (c, d) roundness, (e, f) Feret dav thiab (g, h) Feret ntev.Txog qhov kawg no, ob qho piv txwv microalgae tau txheeb xyuas ua ke nrog thawj SL Nb2CTx thiab SL Nb4C3Tx MXenes, SL Nb2CTx thiab SL Nb4C3Tx MXenes, degraded microalgae, thiab kho microalgae SL Nb2CTx thiab SL Nb4C3Tx MXenes.Cov xub liab qhia qhov kev hloov pauv ntawm cov duab tsis zoo ntawm kev kawm ob sab nanoflakes.
Txij li cov duab parameter tsom xam yog qhov txhim khu kev qha, nws tuaj yeem nthuav tawm cov kev hloov morphological hauv microalgae hlwb.Yog li ntawd, peb txheeb xyuas qhov sib npaug ntawm qhov sib npaug ntawm txoj kab uas hla, roundness, thiab Feret dav / ntev ntawm cov ntshiab microalgae hlwb thiab cov hlwb tom qab kev cuam tshuam nrog 2D Nb nanoflakes.Ntawm daim duab.6a–h qhia txog kev hloov pauv ntawm cov duab tsis zoo ntawm cov algae hlwb, raws li pom los ntawm kev txo qis hauv qhov siab tshaj plaws thiab kev hloov ntawm maxima mus rau qhov tseem ceeb dua.Qhov tshwj xeeb, qhov ntsuas ntawm lub xov tooj ntawm tes tsis pom qhov txo qis hauv cov hlwb elongated thiab nce hauv cov hlwb kheej kheej (Fig. 6a, b).Tsis tas li ntawd, Feret cell dav tau nce los ntawm ob peb micrometers tom qab kev cuam tshuam nrog SL Nb2CTx MXene (Fig. 6e) piv rau SL Nb4C3TX MXene (Fig. 6f).Peb xav tias qhov no yuav yog vim muaj zog ntawm Nb oxides los ntawm microalgae thaum muaj kev cuam tshuam nrog Nb2CTx SR.Tsis tshua muaj kev sib txuas ntawm Nb flakes rau lawv qhov chaw tuaj yeem ua rau kev loj hlob ntawm tes nrog cov nyhuv shading tsawg.
Peb qhov kev soj ntsuam ntawm kev hloov pauv ntawm qhov tsis zoo ntawm cov duab thiab qhov loj ntawm microalgae ntxiv rau lwm cov kev tshawb fawb.Ntsuab microalgae tuaj yeem hloov lawv cov morphology hauv kev teb rau ib puag ncig kev ntxhov siab los ntawm kev hloov cell loj, zoo li qub lossis metabolism61.Piv txwv li, hloov qhov luaj li cas ntawm cov hlwb pab txhawb kev nqus ntawm cov as-ham71.Cov algae me me ua rau pom kev noj zaub mov tsawg dua thiab kev loj hlob tsis zoo.Hloov pauv, cov hlwb loj dua yuav noj ntau cov khoom noj, uas tom qab ntawd tso rau hauv cov cellularly 72,73.Machado thiab Soares pom tias cov fungicide triclosan tuaj yeem ua rau cov cell loj.Lawv kuj pom muaj kev hloov pauv loj hauv cov duab ntawm algae74.Tsis tas li ntawd, Yin et al.9 kuj tau qhia txog kev hloov pauv ntawm morphological hauv algae tom qab raug txo qis graphene oxide nanocomposites.Yog li ntawd, nws yog qhov tseeb tias qhov hloov pauv loj / cov duab tsis zoo ntawm microalgae yog tshwm sim los ntawm muaj MXene.Txij li qhov kev hloov pauv ntawm qhov loj thiab cov duab no yog qhov qhia txog kev hloov pauv ntawm cov khoom noj khoom haus, peb ntseeg tias kev tsom xam ntawm qhov loj thiab cov duab tsis zoo nyob rau lub sijhawm tuaj yeem ua rau pom tias muaj niobium oxide los ntawm microalgae nyob rau hauv lub xub ntiag ntawm Nb-MXenes.
Ntxiv mus, MXenes tuaj yeem oxidized nyob rau hauv lub xub ntiag ntawm algae.Dalai et al.75 pom tias morphology ntawm ntsuab algae raug nano-TiO2 thiab Al2O376 tsis zoo ib yam.Txawm hais tias peb cov kev soj ntsuam zoo ib yam li qhov kev tshawb fawb tam sim no, nws tsuas yog cuam tshuam rau kev kawm txog cov teebmeem ntawm bioremediation ntawm MXene degradation cov khoom nyob rau hauv lub xub ntiag ntawm 2D nanoflakes thiab tsis nanoparticles.Txij li thaum MXenes tuaj yeem degrade rau hauv cov hlau oxides, 31,32,77,78 nws yog qhov tsim nyog xav tias peb cov Nb nanoflakes tuaj yeem tsim Nb oxides tom qab cuam tshuam nrog microalgae hlwb.
Txhawm rau piav qhia txog qhov txo qis ntawm 2D-Nb nanoflakes los ntawm cov txheej txheem decomposition raws li cov txheej txheem oxidation, peb tau ua cov kev tshawb fawb siv high-resolution transmission electron microscopy (HRTEM) (Fig. 7a, b) thiab X-ray photoelectron spectroscopy (XPS) (Fig. 7).7c-i thiab tables S4-5).Ob txoj hauv kev yog tsim nyog rau kev kawm txog oxidation ntawm 2D cov ntaub ntawv thiab ntxiv rau ib leeg.HRTEM muaj peev xwm txheeb xyuas qhov degradation ntawm ob-seem txheej txheej txheej thiab tom qab zoo li cov hlau oxide nanoparticles, thaum XPS yog rhiab heev rau daim ntawv cog lus nto.Rau lub hom phiaj no, peb tau sim 2D Nb-MXene nanoflakes muab rho tawm los ntawm microalgae cell dispersions, uas yog, lawv cov duab tom qab kev cuam tshuam nrog microalgae hlwb (saib daim duab 7).
HRTEM cov duab uas qhia txog morphology ntawm oxidized (a) SL Nb2CTx thiab (b) SL Nb4C3Tx MXenes, XPS tsom xam cov txiaj ntsig uas qhia (c) cov khoom muaj pes tsawg leeg ntawm oxide tom qab txo qis, (d–f) ncov sib txuam ntawm cov khoom ntawm XPS spectra ntawm SL Nb2CTx thiab (g– i) Nbgae.txal micro kho ntsuab
Cov kev tshawb fawb HRTEM tau lees paub qhov oxidation ntawm ob hom Nb-MXene nanoflakes.Txawm hais tias cov nanoflakes khaws lawv cov morphology ob-dimensional rau qee qhov, oxidation ua rau pom ntau cov nanoparticles npog qhov chaw ntawm MXene nanoflakes (saib daim duab 7a, b).XPS tsom xam ntawm c Nb 3d thiab O 1s cov cim qhia tias Nb oxides tau tsim nyob rau hauv ob qho tib si.Raws li pom hauv daim duab 7c, 2D MXene Nb2CTx thiab Nb4C3TX muaj Nb 3d cov cim qhia tias muaj NbO thiab Nb2O5 oxides, thaum O 1s cov cim qhia txog tus lej ntawm O-Nb daim ntawv cog lus cuam tshuam nrog kev ua haujlwm ntawm 2D nanoflake nto.Peb pom tias Nb oxide pab yog qhov tseem ceeb piv rau Nb-C thiab Nb3 + -O.
Ntawm daim duab.Cov duab 7g–i qhia XPS spectra ntawm Nb 3d, C 1s, thiab O 1s SL Nb2CTx (saib daim duab. 7d–f) thiab SL Nb4C3TX MXene cais tawm ntawm microalgae hlwb.Cov ntsiab lus ntawm Nb-MXenes ncov tsis muaj nyob rau hauv Tables S4-5, raws li.Peb thawj zaug txheeb xyuas qhov muaj pes tsawg leeg ntawm Nb 3d.Nyob rau hauv sib piv rau Nb absorbed los ntawm microalgae hlwb, nyob rau hauv MXene cais los ntawm microalgae hlwb, sib nrug los ntawm Nb2O5, lwm yam Cheebtsam tau pom.Hauv Nb2CTx SL, peb tau pom qhov kev koom tes ntawm Nb3 + -O nyob rau hauv tus nqi ntawm 15%, thaum tus so ntawm Nb 3d spectrum yog dominated los ntawm Nb2O5 (85%).Tsis tas li ntawd, cov qauv SL Nb4C3TX muaj Nb-C (9%) thiab Nb2O5 (91%) cov khoom.Ntawm no Nb-C los ntawm ob sab hauv atomic txheej ntawm hlau carbide hauv Nb4C3Tx SR.Tom qab ntawd peb daim ntawv qhia C 1s spectra rau plaub yam sib txawv, zoo li peb tau ua hauv cov qauv sab hauv.Raws li kev cia siab, C 1s spectrum yog dominated los ntawm graphitic carbon, ua raws li kev koom tes los ntawm cov organic hais (CHx / CO thiab C = O) los ntawm microalgae hlwb.Tsis tas li ntawd, hauv O 1s spectrum, peb tau pom qhov kev koom tes ntawm cov organic cov ntaub ntawv ntawm microalgae hlwb, niobium oxide, thiab cov dej adsorbed.
Tsis tas li ntawd, peb tau tshawb xyuas seb Nb-MXenes cleavage puas cuam tshuam nrog kev muaj cov pa oxygen reactive (ROS) hauv cov khoom nruab nrab thiab / lossis microalgae hlwb.Txog rau qhov kawg no, peb tau soj ntsuam cov qib ntawm singlet oxygen (1O2) nyob rau hauv kab lis kev cai nruab nrab thiab intracellular glutathione, thiol uas ua raws li antioxidant hauv microalgae.Cov txiaj ntsig tau pom hauv SI (Figures S20 thiab S21).Kab lis kev cai nrog SL Nb2CTx thiab Nb4C3TX MXenes tau pom los ntawm qhov txo qis ntawm 1O2 (saib daim duab S20).Nyob rau hauv rooj plaub ntawm SL Nb2CTx, MXene 1O2 raug txo kom txog li 83%.Rau microalgae kab lis kev cai siv SL, Nb4C3TX 1O2 txo qis dua, mus rau 73%.Interestingly, kev hloov pauv hauv 1O2 tau pom zoo ib yam li yav dhau los tau pom tias inhibitory-stimulatory nyhuv (saib daim duab 3).Nws tuaj yeem sib cav tias incubation hauv lub teeb ci tuaj yeem hloov photooxidation.Txawm li cas los xij, cov txiaj ntsig ntawm kev tswj xyuas tau pom yuav luag tas li ntawm 1O2 thaum lub sijhawm sim (Daim duab S22).Nyob rau hauv cov ntaub ntawv ntawm intracellular ROS theem, peb kuj pom ib yam downward trend (saib daim duab S21).Thaum pib, cov theem ntawm ROS nyob rau hauv microalgae hlwb kab lis kev cai nyob rau hauv lub xub ntiag ntawm Nb2CTx thiab Nb4C3Tx SLs tshaj cov theem pom nyob rau hauv ntshiab kab lis kev cai ntawm microalgae.Nws thiaj li, txawm li cas los xij, nws tau tshwm sim tias microalgae tau yoog rau ob qho tib si Nb-MXenes, raws li ROS qib tau txo qis rau 85% thiab 91% ntawm cov qib ntsuas hauv cov kab lis kev cai ntshiab ntawm microalgae inoculated nrog SL Nb2CTx thiab Nb4C3TX, feem.Qhov no yuav qhia tau tias microalgae zoo siab dua lub sij hawm nyob rau hauv lub xub ntiag ntawm Nb-MXene dua li nyob rau hauv nruab nrab nutrient ib leeg.
Microalgae yog ntau pawg ntawm cov kab mob photosynthetic.Thaum lub sij hawm photosynthesis, lawv hloov atmospheric carbon dioxide (CO2) rau hauv cov organic carbon.Cov khoom ntawm photosynthesis yog qabzib thiab oxygen79.Peb xav tias cov pa oxygen tsim ua lub luag haujlwm tseem ceeb hauv oxidation ntawm Nb-MXenes.Ib qho ua tau piav qhia rau qhov no yog tias qhov sib txawv aeration parameter yog tsim los ntawm qhov qis thiab siab ib feem ntawm cov pa oxygen sab nraud thiab sab hauv Nb-MXene nanoflakes.Qhov no txhais tau hais tias txhua qhov chaw muaj qhov sib txawv ntawm qhov sib txawv ntawm cov pa oxygen, thaj chaw qis tshaj plaws yuav tsim cov anode 80, 81, 82. Ntawm no, cov microalgae pab txhawb kev tsim cov hlwb sib txawv ntawm cov MXene flakes, uas tsim cov pa oxygen vim lawv cov khoom siv photosynthetic.Yog li ntawd, biocorrosion khoom (qhov no, niobium oxides) yog tsim.Lwm qhov yog tias microalgae tuaj yeem tsim cov organic acids uas tso rau hauv dej 83,84.Yog li ntawd, ib puag ncig nruj tsim, yog li hloov Nb-MXenes.Tsis tas li ntawd, microalgae tuaj yeem hloov pH ntawm ib puag ncig rau alkaline vim qhov nqus ntawm carbon dioxide, uas tuaj yeem ua rau corrosion79.
Qhov tseem ceeb tshaj, qhov tsaus ntuj / lub teeb photoperiod siv hauv peb txoj kev tshawb fawb yog qhov tseem ceeb rau kev nkag siab txog cov txiaj ntsig tau txais.Qhov nam no tau piav qhia meej hauv Djemai-Zoghlache li al.85 Lawv txhob txwm siv 12/12 teev photoperiod los qhia txog biocorrosion txuam nrog biofouling los ntawm liab microalgae Porphyridium purpureum.Lawv qhia tias lub photoperiod yog txuam nrog evolution ntawm lub peev xwm tsis muaj biocorrosion, manifesting nws tus kheej li pseudoperiodic oscillations nyob ib ncig ntawm 24:00.Cov kev soj ntsuam no tau lees paub los ntawm Dowling li al.86 Lawv tau pom cov duab hluavtaws biofilms ntawm cyanobacteria Anabaena.Cov pa oxygen dissolved yog tsim nyob rau hauv qhov kev txiav txim ntawm lub teeb, uas yog txuam nrog kev hloov lossis hloov pauv hauv qhov muaj peev xwm biocorrosion dawb.Qhov tseem ceeb ntawm photoperiod yog hais txog qhov tseeb tias lub peev xwm dawb rau biocorrosion nce hauv lub teeb theem thiab txo qis hauv qhov tsaus ntuj.Qhov no yog vim cov pa oxygen uas tsim los ntawm photosynthetic microalgae, uas cuam tshuam cov cathodic cov tshuaj tiv thaiv los ntawm ib nrab siab generated nyob ze ntawm lub electrodes87.
Tsis tas li ntawd, Fourier transform infrared spectroscopy (FTIR) tau ua los xyuas seb puas muaj kev hloov pauv hauv cov tshuaj muaj pes tsawg leeg ntawm microalgae hlwb tom qab kev cuam tshuam nrog Nb-MXenes.Cov txiaj ntsig tau txais no yog qhov nyuaj thiab peb nthuav tawm lawv hauv SI (Cov duab S23-S25, suav nrog cov txiaj ntsig ntawm MAX theem thiab ML MXenes).Hauv luv luv, qhov tau txais kev siv spectra ntawm microalgae muab peb cov ntaub ntawv tseem ceeb txog cov yam ntxwv ntawm cov kab mob no.Cov kev vibrations feem ntau yog nyob ntawm zaus ntawm 1060 cm-1 (CO), 1540 cm-1, 1640 cm-1 (C = C), 1730 cm-1 (C = O), 2850 cm-1, 2920 cm-1.ib.1 1 (C–H) thiab 3280 cm–1 (O–H).Rau SL Nb-MXenes, peb pom CH-daim ntawv cog lus kos npe uas zoo ib yam nrog peb txoj kev kawm dhau los38.Txawm li cas los xij, peb tau pom tias qee qhov nce ntxiv cuam tshuam nrog C = C thiab CH daim ntawv cog lus ploj lawm.Qhov no qhia tau hais tias cov tshuaj muaj pes tsawg leeg ntawm microalgae tuaj yeem hloov pauv me ntsis vim muaj kev cuam tshuam nrog SL Nb-MXenes.
Thaum xav txog cov kev hloov pauv hauv biochemistry ntawm microalgae, qhov sib xyaw ntawm inorganic oxides, xws li niobium oxide, yuav tsum tau rov xav dua59.Nws yog koom nrog hauv kev txhawb nqa ntawm cov hlau los ntawm lub xov tooj ntawm tes, lawv thauj mus rau hauv cytoplasm, lawv cov koom haum nrog intracellular carboxyl pawg, thiab lawv tsub zuj zuj hauv microalgae polyphosphosomes20,88,89,90.Tsis tas li ntawd, kev sib raug zoo ntawm microalgae thiab hlau yog tswj los ntawm cov pab pawg ua haujlwm ntawm cov hlwb.Vim li no, kev nqus kuj yog nyob ntawm microalgae nto chemistry, uas yog complex9,91.Feem ntau, raws li xav tau, cov tshuaj muaj pes tsawg leeg ntawm ntsuab microalgae hloov me ntsis vim qhov nqus ntawm Nb oxide.
Interestingly, qhov pom thawj zaug inhibition ntawm microalgae yog thim rov qab lub sijhawm.Raws li peb tau pom, microalgae tau kov yeej qhov kev hloov pauv ib puag ncig thawj zaug thiab nws thiaj li rov qab mus rau qhov kev loj hlob zoo li qub thiab tseem nce ntxiv.Kev tshawb fawb ntawm zeta muaj peev xwm qhia tau tias muaj kev ruaj ntseg thaum nkag mus rau hauv cov khoom noj khoom haus.Yog li, kev sib cuam tshuam saum npoo ntawm microalgae hlwb thiab Nb-MXene nanoflakes tau khaws cia thoob plaws qhov kev sim txo qis.Hauv peb qhov kev tshuaj xyuas ntxiv, peb sau cov txheej txheem tseem ceeb ntawm kev ua hauv qab no tus cwj pwm zoo kawg nkaus ntawm microalgae.
Kev soj ntsuam SEM tau pom tias microalgae nyiam txuas rau Nb-MXenes.Siv cov duab dynamic tsom xam, peb paub meej tias cov nyhuv no ua rau kev hloov pauv ntawm ob-dimensional Nb-MXene nanoflakes mus rau hauv ntau cov duab kheej kheej, yog li qhia tau hais tias decomposition ntawm nanoflakes yog txuam nrog lawv oxidation.Txhawm rau kuaj peb qhov kev xav, peb tau ua cov kev tshawb fawb ntawm cov khoom siv thiab biochemical.Tom qab kev sim, nanoflakes maj mam oxidized thiab decomposed rau hauv NbO thiab Nb2O5 cov khoom, uas tsis ua phem rau ntsuab microalgae.Siv FTIR kev soj ntsuam, peb pom tsis muaj kev hloov pauv tseem ceeb hauv cov tshuaj muaj pes tsawg leeg ntawm microalgae incubated nyob rau hauv lub xub ntiag ntawm 2D Nb-MXene nanoflakes.Nrog rau qhov ua tau ntawm kev nqus ntawm niobium oxide los ntawm microalgae, peb tau ua X-ray fluorescence tsom xam.Cov txiaj ntsig no qhia meej meej tias qhov kev kawm microalgae pub rau niobium oxides (NbO thiab Nb2O5), uas tsis muaj tshuaj lom rau cov microalgae kawm.