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Kukula mwachangu kwa nanotechnology ndi kuphatikizidwa kwake mu ntchito za tsiku ndi tsiku kungawopseze chilengedwe. Ngakhale njira zobiriwira zowononga zinthu zodetsa zachilengedwe zakhazikitsidwa bwino, kubwezeretsa zinthu zodetsa zopanda organic crystalline ndikofunikira kwambiri chifukwa cha kusakhudzidwa kwawo ndi kusintha kwa zinthu komanso kusamvetsetsa momwe zinthu zimagwirira ntchito pamwamba ndi zamoyo. Pano, tikugwiritsa ntchito chitsanzo cha inorganic 2D MXenes chozikidwa pa Nb chophatikizidwa ndi njira yosavuta yowunikira mawonekedwe kuti titsatire njira yokonzanso zinthu za 2D ceramic nanomaterials ndi green microalgae Raphidocelis subcapitata. Tapeza kuti microalgae imawononga Nb-based MXenes chifukwa cha kuyanjana kwa physico-chemical komwe kumachitika pamwamba. Poyamba, single-layer ndi multilayer MXene nanoflakes zinamangiriridwa pamwamba pa microalgae, zomwe zinachepetsa kukula kwa algae. Komabe, pakakhala nthawi yayitali ndi pamwamba, microalgae inatulutsa MXene nanoflakes ndikuzigawa kukhala NbO ndi Nb2O5. Popeza ma oxide amenewa si oopsa kwa maselo a microalgae, amadya tinthu tating'onoting'ono ta Nb oxide pogwiritsa ntchito njira yoyamwitsa yomwe imabwezeretsa microalgae pambuyo pa maola 72 a chithandizo cha madzi. Zotsatira za michere yokhudzana ndi kuyamwa zimawonekeranso pakuwonjezeka kwa kuchuluka kwa maselo, mawonekedwe awo osalala komanso kusintha kwa kukula. Kutengera zomwe zapezekazi, tatsimikiza kuti kupezeka kwakanthawi kochepa komanso kwa nthawi yayitali kwa ma MXenes okhala ndi Nb m'malo achilengedwe amadzi oyera kungayambitse zotsatira zochepa zachilengedwe. Ndikofunikira kudziwa kuti, pogwiritsa ntchito ma nanomaterials awiriawiri ngati machitidwe achitsanzo, tikuwonetsa kuthekera kotsatira kusintha kwa mawonekedwe ngakhale muzinthu zazing'ono. Ponseponse, kafukufukuyu akuyankha funso lofunika kwambiri lokhudza njira zokhudzana ndi kuyanjana kwa pamwamba zomwe zimayendetsa njira yokonzanso zinthu za 2D nanomaterials ndipo zimapereka maziko a maphunziro ena anthawi yochepa komanso anthawi yayitali okhudza kukhudzidwa kwa chilengedwe kwa zinthu za crystalline nanomaterials zopanda chilengedwe.
Zinthu zopangidwa ndi nanomaterials zapanga chidwi chachikulu kuyambira pomwe zidapezeka, ndipo ma nanotechnologies osiyanasiyana posachedwapa alowa mu gawo lamakono1. Tsoka ilo, kuphatikiza zinthu zopangidwa ndi nanomaterials m'magwiritsidwe ntchito a tsiku ndi tsiku kungayambitse kutulutsidwa mwangozi chifukwa cha kutaya mosayenera, kusasamalira bwino, kapena kusakwanira kwa chitetezo. Chifukwa chake, ndikoyenera kuganiza kuti zinthu zopangidwa ndi nanomaterials, kuphatikiza zinthu zopangidwa ndi ma 2D (2D), zitha kutulutsidwa m'chilengedwe, zomwe machitidwe ndi ntchito zake zamoyo sizikumveka bwino. Chifukwa chake, sizosadabwitsa kuti nkhawa za poizoni wa chilengedwe zayang'ana kwambiri kuthekera kwa zinthu zopangidwa ndi nanomaterials za 2D kulowa m'madzi2,3,4,5,6. M'malo awa achilengedwe, zinthu zina zopangidwa ndi nanomaterials za 2D zimatha kuyanjana ndi zamoyo zosiyanasiyana pamlingo wosiyana wa trophic, kuphatikiza microalgae.
Ma microalgae ndi zamoyo zakale zomwe zimapezeka mwachilengedwe m'malo amadzi abwino komanso m'madzi a m'nyanja zomwe zimapanga mankhwala osiyanasiyana kudzera mu photosynthesis7. Motero, ndi ofunikira kwambiri pa zachilengedwe zam'madzi8,9,10,11,12 koma ndi zizindikiro zodziwika bwino, zotsika mtengo komanso zomwe zimagwiritsidwa ntchito kwambiri za poizoni wa chilengedwe13,14. Popeza maselo a microalgae amachulukana mofulumira komanso mwachangu akapezeka ndi mankhwala osiyanasiyana, akulonjeza kuti padzakhala njira zosamalira chilengedwe zochizira madzi oipitsidwa ndi zinthu zachilengedwe15,16.
Maselo a algae amatha kuchotsa ma ayoni osapangidwa m'madzi kudzera mu biosorption ndi accumulation17,18. Mitundu ina ya algae monga Chlorella, Anabaena invar, Westiellopsis prolica, Stigeoclonium tenue ndi Synechococcus sp. Yapezeka kuti imanyamula komanso kudyetsa ma ayoni achitsulo oopsa monga Fe2+, Cu2+, Zn2+ ndi Mn2+19. Kafukufuku wina wasonyeza kuti ma ayoni a Cu2+, Cd2+, Ni2+, Zn2+ kapena Pb2+ amaletsa kukula kwa Scenedesmus mwa kusintha mawonekedwe a maselo ndikuwononga ma chloroplast awo20,21.
Njira zobiriwira zowola zinthu zodetsa zachilengedwe komanso kuchotsa ma ayoni a zitsulo zolemera zakopa chidwi cha asayansi ndi mainjiniya padziko lonse lapansi. Izi makamaka chifukwa chakuti zinthu zodetsa izi zimakonzedwa mosavuta mu gawo lamadzimadzi. Komabe, zinthu zodetsa zopanda organic zimadziwika ndi kusungunuka kochepa kwa madzi komanso kusakhazikika pang'ono ku kusintha kwa zinthu zosiyanasiyana, zomwe zimayambitsa zovuta zazikulu pakukonzanso, ndipo palibe kupita patsogolo kwakukulu komwe kwachitika m'derali22,23,24,25,26. Chifukwa chake, kufunafuna njira zotetezera chilengedwe zokonzera zinthu za nanomaterials kumakhalabe malo ovuta komanso osafufuzidwa. Chifukwa cha kusatsimikizika kwakukulu pankhani ya zotsatira za kusintha kwa zinthu za nanomaterials za 2D, palibe njira yosavuta yodziwira njira zomwe zingawonongeke panthawi yochepetsa.
Mu phunziroli, tagwiritsa ntchito ma microalgae obiriwira ngati chothandizira chamadzi chobwezeretsa zinthu zadothi zosapangidwa ndi zinthu zadothi, kuphatikiza ndi kuyang'anira momwe MXene imawonongeka ngati choyimira zinthu zosapangidwa ndi zinthu zadothi zosapangidwa ndi zinthu zadothi. Mawu oti "MXene" akuwonetsa stoichiometry ya zinthu za Mn+1XnTx, komwe M ndi chitsulo chosinthira koyambirira, X ndi kaboni ndi/kapena nayitrogeni, Tx ndi chomaliza pamwamba (monga, -OH, -F, -Cl), ndi n = 1, 2, 3 kapena 427.28. Kuyambira pomwe MXenes idapezeka ndi Naguib et al. Sensorics, chithandizo cha khansa ndi kusefa kwa nembanemba 27,29,30. Kuphatikiza apo, MXenes imatha kuonedwa ngati machitidwe a 2D achitsanzo chifukwa cha kukhazikika kwawo kwabwino kwa colloidal komanso kuyanjana kwachilengedwe komwe kungatheke31,32,33,34,35,36.
Chifukwa chake, njira yomwe yapangidwa m'nkhaniyi ndi malingaliro athu ofufuza akuwonetsedwa mu Chithunzi 1. Malinga ndi lingaliro ili, ma microalgae amawononga ma MXenes okhala ndi Nb kukhala mankhwala osakhala oopsa chifukwa cha kuyanjana kwa physico-chemical komwe kumagwirizana ndi pamwamba, zomwe zimapangitsa kuti algae ibwererenso. Kuti ayesere lingaliro ili, mamembala awiri a banja la ma carbide achitsulo osinthika opangidwa ndi niobium ndi/kapena nitrides (MXenes), omwe ndi Nb2CTx ndi Nb4C3TX, adasankhidwa.
Njira yofufuzira ndi malingaliro ozikidwa pa umboni okhudza kubwezeretsa kwa MXene pogwiritsa ntchito green microalgae Raphidocelis subcapitata. Dziwani kuti ichi ndi chithunzithunzi chabe cha malingaliro ozikidwa pa umboni. Malo okhala nyanja amasiyana malinga ndi michere yomwe imagwiritsidwa ntchito komanso mikhalidwe (monga, kuzungulira kwa tsiku ndi tsiku komanso zoletsa za michere yofunika yomwe ilipo). Yopangidwa ndi BioRender.com.
Chifukwa chake, pogwiritsa ntchito MXene ngati njira yotsanzira, tatsegula chitseko cha kuphunzira za zotsatira zosiyanasiyana za zamoyo zomwe sizingaoneke ndi zinthu zina zachikhalidwe. Makamaka, tikuwonetsa kuthekera kwa bioremediation ya zinthu zamitundu iwiri, monga MXenes zochokera ku niobium, ndi microalgae Raphidocelis subcapitata. Microalgae amatha kuwononga Nb-MXenes kukhala ma oxides osaopsa NbO ndi Nb2O5, omwe amaperekanso michere kudzera mu niobium uptake mechanism. Ponseponse, kafukufukuyu akuyankha funso lofunika kwambiri lokhudza njira zokhudzana ndi kuyanjana kwa physicochemical pamwamba zomwe zimalamulira njira zosinthira bioremediation ya zinthu zamitundu iwiri. Kuphatikiza apo, tikupanga njira yosavuta yokhazikika pamawonekedwe a mawonekedwe kuti titsatire kusintha kochepa mu mawonekedwe a zinthu za 2D. Izi zikulimbikitsa kafukufuku wowonjezereka wa nthawi yochepa komanso wautali pazovuta zosiyanasiyana zachilengedwe za zinthu za crystalline zopanda chilengedwe. Chifukwa chake, kafukufuku wathu akuwonjezera kumvetsetsa kwa kuyanjana pakati pa pamwamba pa zinthu ndi zinthu zamoyo. Tikuperekanso maziko a kafukufuku wowonjezereka wa nthawi yochepa komanso yayitali wa momwe angakhudzire zachilengedwe zamadzi oyera, zomwe tsopano zitha kutsimikiziridwa mosavuta.
Ma MXenes akuyimira gulu losangalatsa la zinthu zomwe zili ndi mawonekedwe apadera komanso okongola a thupi ndi mankhwala ndipo motero amagwiritsidwa ntchito kwambiri. Makhalidwe amenewa amadalira kwambiri stoichiometry yawo ndi chemistry yawo ya pamwamba. Chifukwa chake, mu kafukufuku wathu, tafufuza mitundu iwiri ya ma MXenes okhala ndi Nb-based hierarchical single-layer (SL) MXenes, Nb2CTx ndi Nb4C3TX, popeza zotsatira zosiyana za zamoyo za nanomaterials izi zitha kuwonedwa. Ma MXenes amapangidwa kuchokera kuzinthu zawo zoyambira mwa kuyika pamwamba pa zigawo zoonda za MAX-phase A. Gawo la MAX ndi ceramic ya ternary yopangidwa ndi ma blocks "olumikizidwa" a transition metal carbides ndi zigawo zoonda za zinthu za "A" monga Al, Si, ndi Sn ndi MnAXn-1 stoichiometry. Kapangidwe ka gawo loyambirira la MAX kanawonedwa mwa kusanthula ma electron microscopy (SEM) ndipo kanali kogwirizana ndi maphunziro am'mbuyomu (Onani Zowonjezera, SI, Chithunzi S1). Multilayer (ML) Nb-MXene idapezeka mutachotsa layer ya Al ndi 48% HF (hydrofluoric acid). Kapangidwe ka ML-Nb2CTx ndi ML-Nb4C3TX kanawunikidwa pogwiritsa ntchito scanning electron microscopy (SEM) (Zithunzi S1c ndi S1d motsatana) ndipo kapangidwe ka MXene kokhala ndi zigawo zingapo kanawonedwa, kofanana ndi ma nanoflakes awiri omwe amadutsa m'malo otsetsereka ngati ma pore. Ma Nb-MXene onsewa ali ndi zofanana zambiri ndi magawo a MXene omwe adapangidwa kale ndi acid etching27,38. Titatsimikizira kapangidwe ka MXene, tinayika layer mwa kuphatikizana kwa tetrabutylammonium hydroxide (TBAOH) kutsatiridwa ndi kutsuka ndi sonication, pambuyo pake tinapeza ma nanoflakes a single-layer kapena low-layer (SL) 2D Nb-MXene.
Tinagwiritsa ntchito ma microscopy a ma electron opangidwa ndi resolution yapamwamba (HRTEM) ndi X-ray diffraction (XRD) kuti tiyese kugwira ntchito bwino kwa etching ndi peeling yowonjezera. Zotsatira za HRTEM zomwe zidakonzedwa pogwiritsa ntchito Inverse Fast Fourier Transform (IFFT) ndi Fast Fourier Transform (FFT) zikuwonetsedwa mu Chithunzi 2. Nb-MXene nanoflakes zidayang'aniridwa m'mphepete kuti ziwone kapangidwe ka atomu layer ndikuyesa mtunda wa interplanar. Zithunzi za HRTEM za MXene Nb2CTx ndi Nb4C3TX nanoflakes zidavumbulutsa mtundu wawo woonda wa atomiki (onani Chithunzi 2a1, a2), monga momwe zidanenedwera kale ndi Naguib et al.27 ndi Jastrzębska et al.38. Pa ma monolayers awiri oyandikana a Nb2CTx ndi Nb4C3Tx, tidapeza mtunda wa interlayer wa 0.74 ndi 1.54 nm, motsatana (Zithunzi 2b1,b2), zomwe zikugwirizananso ndi zotsatira zathu zam'mbuyomu38. Izi zinatsimikiziridwanso ndi kusintha kwachangu kwa Fourier (Chithunzi 2c1, c2) ndi kusintha kwachangu kwa Fourier (Chithunzi 2d1, d2) komwe kukuwonetsa mtunda pakati pa ma monolayers a Nb2CTx ndi Nb4C3Tx. Chithunzichi chikuwonetsa kusinthana kwa mikanda yowala ndi yakuda yogwirizana ndi ma atomu a niobium ndi carbon, zomwe zimatsimikizira mtundu wa ma MXenes omwe aphunziridwa. Ndikofunikira kudziwa kuti ma spectra a energy dispersive X-ray spectroscopy (EDX) omwe adapezeka pa Nb2CTx ndi Nb4C3Tx (Zithunzi S2a ndi S2b) sanawonetse zotsalira za gawo loyambirira la MAX, popeza palibe Al peak yomwe idapezeka.
Kufotokozera za ma nanoflakes a SL Nb2CTx ndi Nb4C3Tx MXene, kuphatikizapo (a) kujambula kwa 2D nanoflake ya electron microscopy (HRTEM) ndi ma side-view, (b) intensity mode, (c) inverse fast Fourier transform (IFFT), (d) fast Fourier transform (FFT), (e) Nb-MXenes X-ray patterns. Pa SL 2D Nb2CTx, manambala amafotokozedwa ngati (a1, b1, c1, d1, e1). Pa SL 2D Nb4C3Tx, manambala amafotokozedwa ngati (a2, b2, c2, d2, e1).
Kuyeza kwa X-ray diffraction ya SL Nb2CTx ndi Nb4C3Tx MXenes kukuwonetsedwa mu Zithunzi 2e1 ndi e2, motsatana. Ma Peaks (002) pa 4.31 ndi 4.32 akugwirizana ndi MXenes Nb2CTx ndi Nb4C3TX38,39,40,41 omwe adafotokozedwa kale motsatana. Zotsatira za XRD zimasonyezanso kukhalapo kwa mapangidwe ena a ML otsala ndi magawo a MAX, koma makamaka mapangidwe a XRD ogwirizana ndi SL Nb4C3Tx (Chithunzi 2e2). Kupezeka kwa tinthu tating'onoting'ono ta gawo la MAX kungathe kufotokoza peak ya MAX yolimba poyerekeza ndi zigawo za Nb4C3Tx zomwe zasungidwa mosasinthika.
Kafukufuku wina wayang'ana kwambiri pa tizilombo tating'onoting'ono tobiriwira tomwe tili m'gulu la tizilombo ta R. subcapitata. Tinasankha tizilombo tating'onoting'ono chifukwa ndi opanga ofunikira omwe amagwira ntchito mu ma webs akuluakulu a chakudya42. Ndi chimodzi mwa zizindikiro zabwino kwambiri za poizoni chifukwa cha kuthekera kochotsa zinthu zapoizoni zomwe zimanyamulidwa kupita ku unyolo wapamwamba wa chakudya43. Kuphatikiza apo, kafukufuku pa R. subcapitata angathandize kuwunikira poizoni wa SL Nb-MXenes ku tizilombo tating'onoting'ono tomwe timadya madzi amchere. Kuti timvetse izi, ofufuzawo adaganiza kuti tizilombo toyambitsa matenda tonse tili ndi mphamvu yosiyana ndi mankhwala apoizoni omwe ali m'chilengedwe. Kwa zamoyo zambiri, kuchuluka kochepa kwa zinthu sikukhudza kukula kwawo, pomwe kuchuluka kopitilira malire ena kumatha kuwaletsa kapena kubweretsa imfa. Chifukwa chake, pa kafukufuku wathu wa momwe pamwamba pa microalgae ndi MXenes zimagwirira ntchito komanso momwe zimakhalira, tinaganiza zoyesa kuchuluka kosavulaza komanso koopsa kwa Nb-MXenes. Kuti tichite izi, tinayesa kuchuluka kwa 0 (monga chitsanzo), 0.01, 0.1 ndi 10 mg l-1 MXene komanso tizilombo toyambitsa matenda ta microalgae tomwe tili ndi kuchuluka kwakukulu kwa MXene (100 mg l-1 MXene), komwe kungakhale koopsa komanso koopsa. . pa chilengedwe chilichonse cha zamoyo.
Zotsatira za SL Nb-MXenes pa microalgae zikuwonetsedwa mu Chithunzi 3, zomwe zimawonetsedwa ngati kuchuluka kwa kukula (+) kapena kuletsa (-) komwe kumayesedwa pa zitsanzo za 0 mg l-1. Poyerekeza, gawo la Nb-MAX ndi ML Nb-MXenes zinayesedwanso ndipo zotsatira zake zikuwonetsedwa mu SI (onani Chithunzi S3). Zotsatira zomwe zapezeka zatsimikizira kuti SL Nb-MXenes ilibe poizoni konse pamlingo wotsika kuyambira 0.01 mpaka 10 mg/l, monga momwe zasonyezedwera mu Chithunzi 3a,b. Pankhani ya Nb2CTx, sitinawone poizoni woposa 5% pamlingo womwe watchulidwa.
Kulimbikitsa (+) kapena kuletsa (-) kukula kwa ma microalgae pamaso pa SL (a) Nb2CTx ndi (b) Nb4C3TX MXene. Maola 24, 48 ndi 72 a kuyanjana kwa MXene-microalgae adawunikidwa. Deta yofunika kwambiri (t-test, p <0.05) inalembedwa ndi nyenyezi (*). Deta yofunika kwambiri (t-test, p <0.05) inalembedwa ndi nyenyezi (*). Значимые данные (t-критерий, p <0,05) отмечены звездочкой (*). Deta yofunika kwambiri (t-test, p < 0.05) yalembedwa ndi nyenyezi (*).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 (*). Deta yofunika (t-test, p < 0.05) imalembedwa ndi nyenyezi (*).Mivi yofiira imasonyeza kuchotsedwa kwa kusonkhezera koletsa.
Kumbali ina, kuchuluka kochepa kwa Nb4C3TX kunapezeka kuti kunali koopsa pang'ono, koma osati kokwera kuposa 7%. Monga momwe tinkayembekezera, tinaona kuti MXenes inali ndi poizoni wambiri komanso kuletsa kukula kwa ma microalgae pa 100mg L-1. Chochititsa chidwi n'chakuti, palibe chilichonse mwa zinthuzi chomwe chinasonyeza kudalira komweko kwa zotsatira za poizoni/zoopsa poyerekeza ndi zitsanzo za MAX kapena ML (onani SI kuti mudziwe zambiri). Ngakhale kuti pa gawo la MAX (onani Chithunzi S3) poizoni anafika pafupifupi 15-25% ndipo anawonjezeka pakapita nthawi, kusinthaku kunawonedwa pa SL Nb2CTx ndi Nb4C3TX MXene. Kuletsa kukula kwa ma microalgae kunachepa pakapita nthawi. Kunafika pafupifupi 17% patatha maola 24 ndipo kunatsika kufika pa ochepera 5% patatha maola 72 (Chithunzi 3a, b, motsatana).
Chofunika kwambiri, pa SL Nb4C3TX, kuletsa kukula kwa ma microalgae kunafika pafupifupi 27% patatha maola 24, koma patatha maola 72 kunachepa kufika pafupifupi 1%. Chifukwa chake, tinalemba zotsatira zomwe zidawonedwa ngati kuletsa kotsutsana kwa kukondoweza, ndipo zotsatira zake zinali zamphamvu pa SL Nb4C3TX MXene. Kulimbikitsa kukula kwa ma microalgae kunadziwika kale ndi Nb4C3TX (kuyanjana pa 10 mg L-1 kwa maola 24) poyerekeza ndi SL Nb2CTx MXene. Zotsatira zake zoletsa-kulimbikitsa kusintha zinawonetsedwanso bwino mu biomass doubling rate curve (onani Chithunzi S4 kuti mudziwe zambiri). Pakadali pano, poizoni wa Ti3C2TX MXene wokha ndi womwe waphunziridwa m'njira zosiyanasiyana. Si poizoni kwa mazira a zebrafish44 koma ndi poizoni pang'ono kwa zomera za microalgae Desmodesmus quadricauda ndi Sorghum saccharatum45. Zitsanzo zina za zotsatira zake zimaphatikizapo poizoni wambiri ku maselo a khansa kuposa mizere ya maselo wamba46,47. Zingaganizidwe kuti mikhalidwe yoyeserayi ingakhudze kusintha kwa kukula kwa ma microalgae komwe kumawonedwa pamaso pa Nb-MXenes. Mwachitsanzo, pH ya pafupifupi 8 mu chloroplast stroma ndiyo yabwino kwambiri kuti enzyme ya RuBisCO igwire bwino ntchito. Chifukwa chake, kusintha kwa pH kumakhudza kwambiri kuchuluka kwa photosynthesis48,49. Komabe, sitinawone kusintha kwakukulu mu pH panthawi yoyesera (onani SI, Chithunzi S5 kuti mudziwe zambiri). Kawirikawiri, kufalikira kwa ma microalgae okhala ndi Nb-MXenes kunachepetsa pang'ono pH ya yankho pakapita nthawi. Komabe, kuchepa kumeneku kunali kofanana ndi kusintha kwa pH ya medium yoyera. Kuphatikiza apo, mitundu yosiyanasiyana yomwe idapezeka inali yofanana ndi yomwe idayesedwa pa chikhalidwe choyera cha ma microalgae (chitsanzo chowongolera). Chifukwa chake, titha kunena kuti photosynthesis siyikhudzidwa ndi kusintha kwa pH pakapita nthawi.
Kuphatikiza apo, ma MXene opangidwa ali ndi malekezero pamwamba (omwe amatchulidwa kuti Tx). Awa makamaka ndi magulu ogwira ntchito -O, -F ndi -OH. Komabe, chemistry ya pamwamba imagwirizana mwachindunji ndi njira yopangira. Magulu awa amadziwika kuti amagawidwa mwachisawawa pamwamba, zomwe zimapangitsa kuti zikhale zovuta kulosera momwe amakhudzira katundu wa MXene50. Tikhoza kunena kuti Tx ikhoza kukhala mphamvu yothandizira kuti niobium iwonongeke ndi kuwala. Magulu ogwira ntchito pamwamba amapereka malo ambiri omangira ma photocatalysts awo kuti apange ma heterojunctions51. Komabe, kapangidwe ka growth medium sikanapereke photocatalyst yogwira ntchito ( kapangidwe ka medium katsatanetsatane kangapezeke mu SI Table S6). Kuphatikiza apo, kusintha kulikonse pamwamba ndikofunikira kwambiri, chifukwa ntchito ya MXenes yachilengedwe imatha kusinthidwa chifukwa cha kukonzedwa kwa layer, kusungunuka, kusintha kwa mankhwala pamwamba pa mankhwala a organic ndi inorganic52,53,54,55,56 kapena surface charge engineering38. Chifukwa chake, kuti tiyese ngati niobium oxide ili ndi chochita ndi kusakhazikika kwa zinthu mu sing'anga, tinachita kafukufuku wa zeta (ζ) potential mu sing'anga yokulira ya microalgae ndi madzi oyeretsedwa (kuti tiyerekeze). Zotsatira zathu zikuwonetsa kuti SL Nb-MXenes ndi yokhazikika bwino (onani SI Fig. S6 kuti mupeze zotsatira za MAX ndi ML). Zeta potential ya SL MXenes ndi pafupifupi -10 mV. Pankhani ya SR Nb2CTx, mtengo wa ζ ndi woipa pang'ono kuposa wa Nb4C3Tx. Kusintha kotere kwa ζ value kungasonyeze kuti pamwamba pa MXene nanoflakes zomwe zili ndi negative charge zimayamwa ma ion omwe ali ndi positive charge kuchokera ku sing'anga yokulira. Kuyeza kwakanthawi kwa zeta potential ndi conductivity ya Nb-MXenes mu sing'anga yokulira (onani Zithunzi S7 ndi S8 mu SI kuti mudziwe zambiri) zikuwoneka kuti zikuthandizira lingaliro lathu.
Komabe, ma Nb-MXene SL onse awiri adawonetsa kusintha kochepa kuchokera pa zero. Izi zikuwonetsa bwino kukhazikika kwawo mu microalgae growth medium. Kuphatikiza apo, tidayang'ana ngati kukhalapo kwa microalgae yathu yobiriwira kungakhudze kukhazikika kwa Nb-MXenes mu medium. Zotsatira za zeta potential ndi conductivity ya MXenes pambuyo poyanjana ndi microalgae mu michere ndi chikhalidwe pakapita nthawi zitha kupezeka mu SI (Zithunzi S9 ndi S10). Chosangalatsa ndichakuti, tidawona kuti kukhalapo kwa microalgae kumawoneka kuti kumakhazikitsa kufalikira kwa ma MXenes onse awiri. Pankhani ya Nb2CTx SL, zeta potential idachepa pang'ono pakapita nthawi kufika pa negative values ​​​​​​(-15.8 motsutsana ndi -19.1 mV pambuyo pa maola 72 okhazikika). Zeta potential ya SL Nb4C3TX idakwera pang'ono, koma patatha maola 72 idawonetsabe kukhazikika kwakukulu kuposa nanoflakes popanda kukhalapo kwa microalgae (-18.1 motsutsana ndi -9.1 mV).
Tinapezanso kuti njira za Nb-MXene zotulutsira mpweya zimakhala zochepa kwambiri pamene pali microalgae, zomwe zikusonyeza kuti pali ma ayoni ochepa m'malo osungira michere. Chodziwika bwino n'chakuti, kusakhazikika kwa MXenes m'madzi kumachitika makamaka chifukwa cha kusungunuka kwa madzi pamwamba57. Chifukwa chake, tikukayikira kuti microalgae yobiriwira mwanjira ina inachotsa ma oxides omwe adapangidwa pamwamba pa Nb-MXene ndipo inaletsanso kupezeka kwawo (kusungunuka kwa MXene). Izi zitha kuwoneka pophunzira mitundu ya zinthu zomwe zimayamwa ndi microalgae.
Ngakhale maphunziro athu okhudza poizoni wa chilengedwe adawonetsa kuti ma microalgae adakwanitsa kuthana ndi poizoni wa Nb-MXenes pakapita nthawi komanso kuletsa kosazolowereka kwa kukula kolimbikitsidwa, cholinga cha kafukufuku wathu chinali kufufuza njira zomwe zingagwire ntchito. Zamoyo monga algae zikakumana ndi zinthu zosazolowereka m'chilengedwe chawo, zimatha kuchitapo kanthu m'njira zosiyanasiyana58,59. Popanda ma oxides achitsulo oopsa, ma microalgae amatha kudzidyetsa okha, zomwe zimawalola kukula mosalekeza60. Pambuyo pomeza zinthu zapoizoni, njira zodzitetezera zitha kuyatsidwa, monga kusintha mawonekedwe kapena mawonekedwe. Kuthekera koyamwa kuyeneranso kuganiziridwa58,59. Chofunika kwambiri, chizindikiro chilichonse cha njira yodzitetezera ndi chizindikiro chodziwikiratu cha poizoni wa mankhwala oyesera. Chifukwa chake, pantchito yathu yowonjezera, tidafufuza momwe ma nanoflakes a SL Nb-MXene ndi ma microalgae amatha kugwirira ntchito pamwamba pa MXene yochokera ku SL ndi X-ray fluorescence spectroscopy (XRF) amayamwidwira komanso momwe ma MXene ochokera ku Nb amayamwidwira pogwiritsa ntchito X-ray fluorescence spectroscopy (XRF). Dziwani kuti kusanthula kwa SEM ndi XRF kunachitika kokha pamlingo wapamwamba kwambiri wa MXene kuti athetse mavuto a poizoni wa ntchito.
Zotsatira za SEM zawonetsedwa mu Chithunzi 4. Maselo a microalgae osachiritsidwa (onani Chithunzi 4a, chitsanzo chofotokozera) adawonetsa bwino mawonekedwe a R. subcapitata ndi mawonekedwe ofanana ndi a croissant. Maselo amawoneka osalala komanso osakonzedwa bwino. Maselo ena a microalgae adalumikizana ndikulumikizana, koma izi mwina zidachitika chifukwa cha njira yokonzekera zitsanzo. Kawirikawiri, maselo a microalgae oyera anali ndi malo osalala ndipo sanawonetse kusintha kulikonse kwa mawonekedwe.
Zithunzi za SEM zomwe zikuwonetsa kuyanjana kwa pamwamba pakati pa ma microalgae obiriwira ndi ma nanosheet a MXene pambuyo pa maola 72 a kuyanjana pamlingo waukulu kwambiri (100 mg L-1). (a) Ma microalgae obiriwira osachiritsidwa pambuyo pa kuyanjana ndi SL (b) Nb2CTx ndi (c) Nb4C3TX MXenes. Dziwani kuti ma nanoflakes a Nb-MXene amalembedwa ndi mivi yofiira. Poyerekeza, zithunzi zochokera ku maikulosikopu yowoneka bwino zimawonjezedwanso.
Mosiyana ndi zimenezi, maselo a microalgae omwe amakhudzidwa ndi ma nanoflakes a SL Nb-MXene anawonongeka (onani Chithunzi 4b, c, mivi yofiira). Pankhani ya Nb2CTx MXene (Chithunzi 4b), microalgae nthawi zambiri imakula ndi ma nanoscales awiriawiri, zomwe zingasinthe mawonekedwe awo. Chodziwika bwino, tinawonanso kusinthaku pansi pa microscopy yowala (onani Chithunzi SI S11 kuti mudziwe zambiri). Kusintha kwa mawonekedwe kumeneku kuli ndi maziko omveka bwino mu physiology ya microalgae ndi kuthekera kwawo kudziteteza mwa kusintha mawonekedwe a maselo, monga kuwonjezera kuchuluka kwa maselo61. Chifukwa chake, ndikofunikira kuyang'ana kuchuluka kwa maselo a microalgae omwe akukhudzana ndi Nb-MXenes. Kafukufuku wa SEM adawonetsa kuti pafupifupi 52% ya maselo a microalgae adakumana ndi Nb-MXenes, pomwe 48% ya maselo a microalgae awa adapewa kukhudzana. Pa SL Nb4C3Tx MXene, ma microalgae amayesa kupewa kukhudzana ndi MXene, motero amakula kuchokera ku ma nanoscales awiriawiri (Chithunzi 4c). Komabe, sitinaone momwe ma nanoscales amalowera m'maselo a microalgae ndi kuwonongeka kwawo.
Kudzisunga kumadaliranso nthawi yomwe zinthu zimagwirira ntchito poyankha kutsekeka kwa photosynthesis chifukwa cha kuyamwa kwa tinthu tating'onoting'ono pamwamba pa selo ndi chomwe chimatchedwa shading (shading) effect62. N'zoonekeratu kuti chinthu chilichonse (monga Nb-MXene nanoflakes) chomwe chili pakati pa microalgae ndi gwero la kuwala chimachepetsa kuchuluka kwa kuwala komwe kumayamwa ndi ma chloroplast. Komabe, sitikukayikira kuti izi zimakhudza kwambiri zotsatira zomwe zapezeka. Monga momwe tawonera ndi ma microscopic, ma nanoflakes a 2D sanakulungidwe kapena kumamatiridwa kwathunthu pamwamba pa microalgae, ngakhale pamene ma microalgae cell anali kukhudzana ndi Nb-MXenes. M'malo mwake, ma nanoflakes adapezeka kuti akuyang'ana ma microalgae cells popanda kuphimba pamwamba pawo. Gulu la nanoflakes/microalgae lotere silingathe kuchepetsa kwambiri kuchuluka kwa kuwala komwe kumayamwa ndi ma microalgae cells. Komanso, maphunziro ena awonetsa kuti kuwala kumayamwa bwino ndi zamoyo zopangidwa ndi photosynthesis pamene pali zinthu zina zopangidwa ndi ma nanomaterials amitundu iwiri63,64,65,66.
Popeza zithunzi za SEM sizinatsimikizire mwachindunji kuti niobium imatengedwa ndi maselo a microalgae, kafukufuku wathu wowonjezera unatembenukira ku X-ray fluorescence (XRF) ndi X-ray photoelectron spectroscopy (XPS) kusanthula kuti timvetse bwino nkhaniyi. Chifukwa chake, tinayerekeza mphamvu ya Nb peaks ya zitsanzo za microalgae zomwe sizinagwirizane ndi MXenes, MXene nanoflakes yochotsedwa pamwamba pa maselo a microalgae, ndi maselo a microalgal atachotsedwa MXenes yolumikizidwa. Ndikofunikira kudziwa kuti ngati palibe Nb uptake, mtengo wa Nb womwe umapezedwa ndi maselo a microalgae uyenera kukhala zero mutachotsa nanoscales yolumikizidwa. Chifukwa chake, ngati Nb uptake ichitika, zotsatira zonse za XRF ndi XPS ziyenera kuwonetsa Nb peak yomveka bwino.
Pankhani ya ma spectra a XRF, zitsanzo za microalgae zinawonetsa ma Nb peaks a SL Nb2CTx ndi Nb4C3Tx MXene pambuyo poyanjana ndi SL Nb2CTx ndi Nb4C3Tx MXene (onani Chithunzi 5a, onaninso kuti zotsatira za MAX ndi ML MXenes zawonetsedwa mu SI, Zithunzi S12–C17). Chosangalatsa n'chakuti, mphamvu ya Nb peak ndi yofanana m'magawo onse awiri (mipiringidzo yofiira mu Chithunzi 5a). Izi zinasonyeza kuti algae sakanatha kuyamwa Nb yambiri, ndipo mphamvu yayikulu yopezera Nb idapezeka m'maselo, ngakhale kuti Nb4C3Tx MXene yochulukirapo kawiri idalumikizidwa ku maselo a microalgae (mipiringidzo yabuluu mu Chithunzi 5a). Chodziwika bwino n'chakuti, kuthekera kwa microalgae kuyamwa zitsulo kumadalira kuchuluka kwa oxides zachitsulo m'chilengedwe67,68. Shamshada et al.67 adapeza kuti mphamvu yoyamwa ya algae yamadzi oyera imachepa ndi pH yowonjezereka. Raize ndi anzake 68 adawona kuti kuthekera kwa nyanja kuyamwa zitsulo kunali kokwera ndi 25% kuposa kwa Ni2+.
(a) Zotsatira za XRF za kutengedwa kwa basal Nb ndi maselo obiriwira a microalgae omwe amaikidwa pamlingo waukulu wa SL Nb-MXenes (100 mg L-1) kwa maola 72. Zotsatirazi zikuwonetsa kukhalapo kwa α m'maselo oyera a microalgae (chitsanzo chowongolera, mizati imvi), ma nanoflakes a 2D omwe amachotsedwa ku maselo a microalgae apamwamba (mizati yabuluu), ndi maselo a microalgae atapatukana ma nanoflakes a 2D kuchokera pamwamba (mizati yofiira). Kuchuluka kwa elemental Nb, (b) kuchuluka kwa kapangidwe ka mankhwala a microalgae organic components (C=O ndi CHx/C–O) ndi ma Nb oxides omwe amapezeka m'maselo a microalgae atatha kulowetsedwa ndi SL Nb-MXenes, (c–e) Kuyika kwa compositional peak ya XPS SL Nb2CTx spectra ndi (fh) SL Nb4C3Tx MXene internalized ndi maselo a microalgae.
Chifukwa chake, tinkayembekezera kuti Nb ikhoza kuyamwa ndi maselo a algal mu mawonekedwe a ma oxides. Pofuna kuyesa izi, tinachita maphunziro a XPS pa MXenes Nb2CTx ndi Nb4C3TX ndi maselo a algae. Zotsatira za kuyanjana kwa microalgae ndi Nb-MXenes ndi MXenes zolekanitsidwa ndi maselo a algae zikuwonetsedwa mu Zithunzi 5b. Monga momwe tinkayembekezera, tinapeza Nb 3d peaks mu zitsanzo za microalgae titachotsa MXene pamwamba pa microalgae. Kutsimikiza kwa kuchuluka kwa C=O, CHx/CO, ndi Nb oxides kunawerengedwa kutengera ma Nb 3d, O1s, ndi C1s spectra omwe adapezeka ndi Nb2CTx SL (Chithunzi 5c–e) ndi Nb4C3Tx SL (Chithunzi 5c–e). ) omwe adapezeka kuchokera ku microalgae yosungidwa. Chithunzi 5f–h) MXenes. Gome S1-3 likuwonetsa tsatanetsatane wa magawo a peak ndi chemistry yonse yomwe imachokera ku fit. N'zochititsa chidwi kuti madera a Nb 3d a Nb2CTx SL ndi Nb4C3Tx SL (Chithunzi 5c, f) akugwirizana ndi gawo limodzi la Nb2O5. Pano, sitinapeze nsonga zokhudzana ndi MXene mu ma spectra, zomwe zikusonyeza kuti maselo a microalgae amangotenga mawonekedwe a oxide a Nb. Kuphatikiza apo, tinayerekeza C 1 s spectrum ndi zigawo za C–C, CHx/C–O, C=O, ndi –COOH. Tinagawa nsonga za CHx/C–O ndi C=O ku gawo lachilengedwe la maselo a microalgae. Zigawo za organic izi zimakhala ndi 36% ndi 41% ya nsonga za C 1s mu Nb2CTx SL ndi Nb4C3TX SL, motsatana. Kenako tinayika ma spectra a O 1s a SL Nb2CTx ndi SL Nb4C3TX ndi Nb2O5, zigawo za organic za microalgae (CHx/CO), ndi madzi okhudzidwa pamwamba.
Pomaliza, zotsatira za XPS zinasonyeza bwino mawonekedwe a Nb, osati kupezeka kwake kokha. Malinga ndi malo a chizindikiro cha Nb 3d ndi zotsatira za deconvolution, tikutsimikizira kuti Nb imayamwa kokha mu mawonekedwe a ma oxide osati ma ion kapena MXene yokha. Kuphatikiza apo, zotsatira za XPS zawonetsa kuti maselo a microalgae ali ndi kuthekera kwakukulu kotenga ma Nb oxides kuchokera ku SL Nb2CTx poyerekeza ndi SL Nb4C3TX MXene.
Ngakhale zotsatira zathu zotengera Nb ndizodabwitsa ndipo zimatilola kuzindikira kuwonongeka kwa MXene, palibe njira yotsatirira kusintha kwa mawonekedwe a 2D nanoflakes. Chifukwa chake, tidaganizanso zopanga njira yoyenera yomwe ingayankhe mwachindunji kusintha kulikonse komwe kumachitika mu 2D Nb-MXene nanoflakes ndi maselo a microalgae. Ndikofunikira kudziwa kuti tikuganiza kuti ngati mitundu yolumikizanayo ikusinthidwa, kuwonongeka kapena kusweka, izi ziyenera kuonekera mwachangu ngati kusintha kwa mawonekedwe, monga m'mimba mwake wa dera lozungulira lofanana, kuzungulira, m'lifupi mwa Feret, kapena kutalika kwa Feret. Popeza magawo awa ndi oyenera kufotokoza tinthu tating'onoting'ono tating'ono kapena ma nanoflakes amitundu iwiri, kuwatsata pogwiritsa ntchito kusanthula kwa mawonekedwe a tinthu tating'onoting'ono kudzatipatsa chidziwitso chofunikira chokhudza kusintha kwa mawonekedwe a SL Nb-MXene nanoflakes panthawi yochepetsa.
Zotsatira zomwe zapezeka zawonetsedwa mu Chithunzi 6. Poyerekeza, tinayesanso gawo loyambirira la MAX ndi ML-MXenes (onani Zithunzi za SI S18 ndi S19). Kusanthula kwamphamvu kwa mawonekedwe a tinthu tating'onoting'ono kunawonetsa kuti magawo onse a mawonekedwe a ma Nb-MXene SL awiri adasintha kwambiri atagwirizana ndi microalgae. Monga momwe zasonyezedwera ndi gawo lofanana la m'mimba mwake wa dera lozungulira (Chithunzi 6a, b), kuchepa kwa mphamvu ya gawo la nanoflakes zazikulu kukuwonetsa kuti nthawi zambiri zimawola kukhala zidutswa zazing'ono. Pa chithunzi 6c, d ikuwonetsa kuchepa kwa nsonga zomwe zimagwirizanitsidwa ndi kukula kopingasa kwa ma flakes (kutalika kwa ma nanoflakes), kusonyeza kusintha kwa ma nanoflakes a 2D kukhala mawonekedwe ofanana ndi tinthu tating'onoting'ono. Chithunzi 6e-h chikuwonetsa m'lifupi ndi kutalika kwa Feret, motsatana. M'lifupi ndi kutalika kwa Feret ndi magawo ogwirizana ndipo chifukwa chake ayenera kuganiziridwa pamodzi. Pambuyo poika ma nanoflakes a 2D Nb-MXene pamaso pa microalgae, nsonga zawo za mgwirizano wa Feret zinasintha ndipo mphamvu zawo zinachepa. Kutengera ndi zotsatira izi pamodzi ndi mawonekedwe, XRF ndi XPS, tinatsimikiza kuti kusintha komwe kwawonedwa kukugwirizana kwambiri ndi okosijeni pamene ma MXenes opangidwa ndi okosijeni amakhala ndi makwinya ambiri ndikusweka kukhala zidutswa ndi tinthu ta oxide tozungulira69,70.
Kusanthula kwa kusintha kwa MXene pambuyo poyanjana ndi microalgae yobiriwira. Kusanthula kwa mawonekedwe a tinthu tating'onoting'ono kumaganizira magawo monga (a, b) m'mimba mwake wa dera lozungulira lofanana, (c, d) kuzungulira, (e, f) m'lifupi mwa Feret ndi (g, h) kutalika kwa Feret. Pachifukwa ichi, zitsanzo ziwiri za microalgae zodziwika bwino zidasanthulidwa pamodzi ndi SL Nb2CTx ndi SL Nb4C3Tx MXenes, SL Nb2CTx ndi SL Nb4C3Tx MXenes, microalgae yoonongeka, ndi microalgae yochiritsidwa SL Nb2CTx ndi SL Nb4C3Tx MXenes. Mivi yofiira ikuwonetsa kusintha kwa magawo a mawonekedwe a nanoflakes ziwiri zomwe zaphunziridwa.
Popeza kusanthula kwa mawonekedwe ndi kodalirika kwambiri, kumathanso kuwonetsa kusintha kwa mawonekedwe a maselo a microalgae. Chifukwa chake, tidasanthula kukula kofanana kwa dera lozungulira, kuzungulira, ndi kutalika kwa Feret kwa maselo oyera a microalgae ndi maselo titalumikizana ndi ma nanoflakes a 2D Nb. Pa chithunzi cha 6a–h tikuwonetsa kusintha kwa mawonekedwe a maselo a algae, monga momwe zasonyezedwera ndi kuchepa kwa mphamvu yayikulu komanso kusintha kwa maxima kupita kuzinthu zapamwamba. Makamaka, magawo ozungulira maselo adawonetsa kuchepa kwa maselo ataliatali komanso kuwonjezeka kwa maselo ozungulira (Chithunzi cha 6a, b). Kuphatikiza apo, kukula kwa maselo a Feret kudakwera ndi ma micrometer angapo titalumikizana ndi SL Nb2CTx MXene (Chithunzi cha 6e) poyerekeza ndi SL Nb4C3TX MXene (Chithunzi cha 6f). Tikuganiza kuti izi zitha kukhala chifukwa cha kutengedwa kwamphamvu kwa ma Nb oxides ndi microalgae ikalumikizana ndi Nb2CTx SR. Kuphatikizika kochepa kwa ma Nb flakes pamwamba pawo kungayambitse kukula kwa maselo ndi zotsatira zochepa za mthunzi.
Kuwona kwathu kusintha kwa mawonekedwe ndi kukula kwa ma microalgae kumathandizira maphunziro ena. Ma microalgae obiriwira amatha kusintha mawonekedwe awo poyankha kupsinjika kwa chilengedwe mwa kusintha kukula kwa maselo, mawonekedwe kapena kagayidwe kachakudya61. Mwachitsanzo, kusintha kukula kwa maselo kumathandiza kuyamwa michere71. Maselo ang'onoang'ono a algae amasonyeza kutsika kwa michere komanso kuchepa kwa kukula. Mosiyana ndi zimenezi, maselo akuluakulu amakonda kudya michere yambiri, yomwe imayikidwa mkati mwa maselo72,73. Machado ndi Soares adapeza kuti fungicide triclosan imatha kuwonjezera kukula kwa maselo. Adapezanso kusintha kwakukulu mu mawonekedwe a algae74. Kuphatikiza apo, Yin et al.9 adawonetsanso kusintha kwa mawonekedwe a algae atakumana ndi ma nanocomposites ochepa a graphene oxide. Chifukwa chake, n'zoonekeratu kuti kusintha kwa kukula/mawonekedwe a microalgae kumachitika chifukwa cha kukhalapo kwa MXene. Popeza kusinthaku kwa kukula ndi mawonekedwe kukuwonetsa kusintha kwa kuyamwa kwa michere, tikukhulupirira kuti kusanthula kwa magawo a kukula ndi mawonekedwe pakapita nthawi kumatha kuwonetsa kuyamwa kwa niobium oxide ndi microalgae pamaso pa Nb-MXenes.
Komanso, MXenes imatha kusungunuka ngati pali algae. Dalai ndi anzake 75 adawona kuti mawonekedwe a algae wobiriwira omwe amapezeka ku nano-TiO2 ndi Al2O376 sanali ofanana. Ngakhale kuti zomwe tawona zikufanana ndi kafukufukuyu, ndizofunikira kwambiri pakuphunzira za zotsatira za bioremediation pankhani ya zinthu za MXene zomwe zimawonongeka ngati pali 2D nanoflakes osati nanoparticles. Popeza MXenes imatha kusungunuka kukhala metal oxides,31,32,77,78 ndizomveka kuganiza kuti Nb nanoflakes zathu zimathanso kupanga Nb oxides pambuyo polumikizana ndi maselo a microalgae.
Pofuna kufotokoza kuchepa kwa ma nanoflakes a 2D-Nb kudzera mu njira yowola kutengera njira yowola, tinachita maphunziro pogwiritsa ntchito ma microscopy a ma electron opangidwa ndi ma high-resolution transmission (HRTEM) (Chithunzi 7a,b) ndi X-ray photoelectron spectroscopy (XPS) (Chithunzi 7). 7c-i ndi matebulo S4-5). Njira zonsezi ndizoyenera kuphunzira za okosijeni wa zinthu za 2D ndikugwirizana. HRTEM imatha kusanthula kuwonongeka kwa kapangidwe ka magawo awiri ndi mawonekedwe a nanoparticles a oxide achitsulo, pomwe XPS imazindikira zomangira za pamwamba. Pachifukwa ichi, tinayesa ma nanoflakes a 2D Nb-MXene otengedwa kuchokera ku ma microalgae cell dispersions, kutanthauza mawonekedwe awo atatha kuyanjana ndi ma microalgae cell (onani Chithunzi 7).
Zithunzi za HRTEM zomwe zikuwonetsa mawonekedwe a oxidized (a) SL Nb2CTx ndi (b) SL Nb4C3Tx MXenes, zotsatira za kusanthula kwa XPS zomwe zikuwonetsa (c) kapangidwe ka zinthu za oxide pambuyo pochepetsedwa, (d–f) kufanana kwa zigawo za XPS spectra ya SL Nb2CTx ndi (g– i) Nb4C3Tx SL yokonzedwa ndi microalgae yobiriwira.
Kafukufuku wa HRTEM adatsimikizira kukhuthala kwa mitundu iwiri ya ma nanoflakes a Nb-MXene. Ngakhale kuti ma nanoflakes adasunga mawonekedwe awo amitundu iwiri mpaka pamlingo wina, kukhuthala kunapangitsa kuti pakhale ma nanoparticles ambiri omwe amaphimba pamwamba pa ma nanoflakes a MXene (onani Chithunzi 7a,b). Kusanthula kwa XPS kwa zizindikiro za c Nb 3d ndi O 1s kunawonetsa kuti ma Nb oxides adapangidwa m'zochitika zonse ziwiri. Monga momwe zasonyezedwera pa Chithunzi 7c, 2D MXene Nb2CTx ndi Nb4C3TX ali ndi zizindikiro za Nb 3d zomwe zikusonyeza kukhalapo kwa ma NbO ndi ma Nb2O5 oxides, pomwe zizindikiro za O 1s zikuwonetsa kuchuluka kwa ma bond a O–Nb omwe amagwirizana ndi magwiridwe antchito a pamwamba pa 2D nanoflake. Tawona kuti gawo la Nb oxide ndilofunika kwambiri poyerekeza ndi Nb-C ndi Nb3+-O.
Pa chithunzi 7g–i zikuwonetsa ma XPS spectra a Nb 3d, C 1s, ndi O 1s SL Nb2CTx (onani Zithunzi 7d–f) ndi SL Nb4C3TX MXene zochotsedwa ku maselo a microalgae. Tsatanetsatane wa magawo akuluakulu a Nb-MXenes aperekedwa mu Matebulo S4–5, motsatana. Choyamba tinasanthula kapangidwe ka Nb 3d. Mosiyana ndi Nb yomwe imayamwa ndi maselo a microalgae, mu MXene yochotsedwa ku maselo a microalgae, kupatula Nb2O5, zigawo zina zidapezeka. Mu Nb2CTx SL, tinawona gawo la Nb3+-O mu kuchuluka kwa 15%, pomwe zina zonse za Nb 3d spectrum zinali zolamulidwa ndi Nb2O5 (85%). Kuphatikiza apo, chitsanzo cha SL Nb4C3TX chili ndi zigawo za Nb-C (9%) ndi Nb2O5 (91%). Apa Nb-C imachokera ku zigawo ziwiri zamkati mwa atomiki za carbide yachitsulo mu Nb4C3Tx SR. Kenako timayika ma spectra a C1s ku zigawo zinayi zosiyana, monga momwe tinachitira mu zitsanzo zamkati. Monga momwe timayembekezera, ma spectra a C1s amalamulidwa ndi graphitic carbon, kutsatiridwa ndi zopereka kuchokera ku tinthu tachilengedwe (CHx/CO ndi C=O) kuchokera ku maselo a microalgae. Kuphatikiza apo, mu ma spectra a O1s, tinawona zopereka za mitundu yachilengedwe ya maselo a microalgae, niobium oxide, ndi madzi okhudzidwa.
Kuphatikiza apo, tafufuza ngati kugawanika kwa Nb-MXenes kumagwirizana ndi kukhalapo kwa mitundu ya okosijeni yogwira ntchito (ROS) mu michere ndi/kapena maselo a microalgae. Pachifukwa ichi, tayesa kuchuluka kwa mpweya wa singlet (1O2) mu culture medium ndi intracellular glutathione, thiol yomwe imagwira ntchito ngati antioxidant mu microalgae. Zotsatira zake zawonetsedwa mu SI (Zithunzi S20 ndi S21). Cultures yokhala ndi SL Nb2CTx ndi Nb4C3TX MXenes idadziwika ndi kuchepa kwa 1O2 (onani Chithunzi S20). Pankhani ya SL Nb2CTx, MXene 1O2 imachepetsedwa kufika pafupifupi 83%. Pa cultures ya microalgae pogwiritsa ntchito SL, Nb4C3TX 1O2 idachepa kwambiri, kufika pa 73%. Chosangalatsa n'chakuti, kusintha kwa 1O2 kunawonetsa momwe zinthu zinalili kale monga momwe zinalili kale (onani Chithunzi 3). Tikhoza kunena kuti kupangika kwa kuwala kowala kumatha kusintha kuwala kowala. Komabe, zotsatira za kusanthula kowongolera zinawonetsa milingo yofanana ya 1O2 panthawi yoyesera (Chithunzi S22). Pankhani ya milingo ya ROS yamkati mwa maselo, tinawonanso kutsika komweko (onani Chithunzi S21). Poyamba, milingo ya ROS m'maselo a microalgae omwe amakula pamaso pa Nb2CTx ndi Nb4C3Tx SLs inapitirira milingo yomwe imapezeka m'makolo oyera a microalgae. Komabe, pamapeto pake, zinaoneka kuti microalgae inazolowera kukhalapo kwa Nb-MXenes onse awiri, pamene milingo ya ROS inachepa kufika pa 85% ndi 91% ya milingo yomwe imayesedwa m'makolo oyera a microalgae omwe amaikidwa SL Nb2CTx ndi Nb4C3TX, motsatana. Izi zitha kusonyeza kuti microalgae imamva bwino pakapita nthawi pamaso pa Nb-MXene kuposa m'malo osungira zakudya okha.
Ma microalgae ndi gulu losiyanasiyana la zamoyo zomwe zimapanga photosynthesis. Panthawi ya photosynthesis, amasintha mpweya wa carbon dioxide (CO2) kukhala organic carbon. Zopangidwa ndi photosynthesis ndi shuga ndi mpweya79. Tikuganiza kuti mpweya womwe umapangidwa umagwira ntchito yofunika kwambiri pakusungunuka kwa Nb-MXenes. Chifukwa chimodzi chomwe chingakhalepo ndichakuti gawo losiyana la mpweya limapangidwa pamavuto otsika komanso apamwamba a mpweya kunja ndi mkati mwa ma nanoflakes a Nb-MXene. Izi zikutanthauza kuti kulikonse komwe kuli madera okhala ndi mavuto osiyanasiyana a mpweya, dera lomwe lili ndi mulingo wotsika kwambiri limapanga anode 80, 81, 82. Apa, ma microalgae amathandizira kupanga maselo opumira mpweya osiyanasiyana pamwamba pa ma flakes a MXene, omwe amapanga mpweya chifukwa cha mphamvu zawo zopangira photosynthesis. Zotsatira zake, zinthu za biocorrosion (pankhaniyi, niobium oxides) zimapangidwa. Mbali ina ndi yakuti ma microalgae amatha kupanga ma organic acid omwe amatulutsidwa m'madzi83,84. Chifukwa chake, malo owopsa amapangidwa, motero amasintha ma Nb-MXenes. Kuphatikiza apo, ma microalgae amatha kusintha pH ya chilengedwe kukhala ya alkaline chifukwa cha kuyamwa kwa carbon dioxide, komwe kungayambitsenso dzimbiri79.
Chofunika kwambiri, nthawi yamdima/yowala yomwe yagwiritsidwa ntchito mu kafukufuku wathu ndi yofunika kwambiri kuti timvetsetse zotsatira zomwe zapezeka. Mbali iyi yafotokozedwa mwatsatanetsatane mu Djemai-Zoghlache et al. 85 Adagwiritsa ntchito mwadala nthawi ya 12/12 ya photoperiod kuwonetsa biocorrosion yogwirizana ndi biofouling ndi red microalgae Porphyridium purpureum. Amasonyeza kuti nthawi ya photoperiod ikugwirizana ndi kusintha kwa mphamvu popanda biocorrosion, zomwe zimadziwonetsera ngati pseudoperiodic oscillations pafupifupi 24:00. Zomwe zawonedwazi zidatsimikiziridwa ndi Dowling et al. 86 Adawonetsa photosynthetic biofilms ya cyanobacteria Anabaena. Mpweya wosungunuka umapangidwa pansi pa kuwala, komwe kumalumikizidwa ndi kusintha kapena kusinthasintha kwa mphamvu ya free biocorrosion. Kufunika kwa nthawi ya photoperiod kumagogomezedwa ndi mfundo yakuti mphamvu yaulere ya biocorrosion imawonjezeka mu gawo la kuwala ndikuchepa mu gawo lamdima. Izi zimachitika chifukwa cha mpweya wopangidwa ndi photosynthetic microalgae, womwe umakhudza cathodic reaction kudzera mu kupanikizika pang'ono komwe kumapangidwa pafupi ndi ma electrodes87.
Kuphatikiza apo, Fourier transform infrared spectroscopy (FTIR) idachitika kuti idziwe ngati pali kusintha kulikonse komwe kunachitika mu kapangidwe ka mankhwala a maselo a microalgae pambuyo polumikizana ndi Nb-MXenes. Zotsatirazi zomwe zapezeka ndi zovuta ndipo timaziwonetsa mu SI (Zithunzi S23-S25, kuphatikiza zotsatira za gawo la MAX ndi ML MXenes). Mwachidule, ma reference spectra omwe apezeka a microalgae amatipatsa chidziwitso chofunikira chokhudza mawonekedwe a mankhwala a zamoyozi. Kugwedezeka komwe kungakhalepo kwambiri kumeneku kuli pamafupipafupi a 1060 cm-1 (CO), 1540 cm-1, 1640 cm-1 (C=C), 1730 cm-1 (C=O), 2850 cm-1, 2920 cm-1. imodzi. 1 1 (C–H) ndi 3280 cm–1 (O–H). Kwa SL Nb-MXenes, tapeza siginecha yotambasula ya CH-bond yomwe ikugwirizana ndi kafukufuku wathu wakale38. Komabe, tinaona kuti ma peak ena owonjezera okhudzana ndi ma bond a C=C ndi CH adasowa. Izi zikusonyeza kuti kapangidwe ka mankhwala ka microalgae kangasinthe pang'ono chifukwa cha kuyanjana ndi SL Nb-MXenes.
Poganizira kusintha komwe kungachitike mu biochemistry ya microalgae, kuchulukana kwa ma inorganic oxides, monga niobium oxide, kuyenera kuganiziridwanso59. Kumakhudzidwa ndi kutenga zitsulo ndi pamwamba pa selo, kunyamula kwawo kupita ku cytoplasm, kugwirizana kwawo ndi magulu a carboxyl amkati mwa maselo, komanso kuchulukana kwawo mu microalgae polyphosphosomes20,88,89,90. Kuphatikiza apo, ubale pakati pa microalgae ndi zitsulo umasungidwa ndi magulu ogwira ntchito a maselo. Pachifukwa ichi, kuyamwa kumadaliranso ndi microalgae surface chemistry, yomwe ndi yovuta kwambiri9,91. Kawirikawiri, monga momwe timayembekezera, kapangidwe ka mankhwala a microalgae wobiriwira kanasintha pang'ono chifukwa cha kuyamwa kwa Nb oxide.
Chochititsa chidwi n'chakuti, kuletsa koyamba kwa ma microalgae kunasinthidwa pakapita nthawi. Monga momwe tinaonera, ma microalgae anagonjetsa kusintha koyamba kwa chilengedwe ndipo pamapeto pake anabwerera ku kukula kwabwinobwino komanso anawonjezeka. Kafukufuku wa zeta potential akuwonetsa kukhazikika kwakukulu akalowetsedwa m'maselo a michere. Motero, kuyanjana kwa pamwamba pakati pa maselo a microalgae ndi ma Nb-MXene nanoflakes kunasungidwa panthawi yonse yoyesera kuchepetsa. Mu kusanthula kwathu kwina, tikufotokozera mwachidule njira zazikulu zogwirira ntchito zomwe zimayambitsa khalidwe lodabwitsa la ma microalgae.
Zomwe zapezeka mu SEM zasonyeza kuti ma microalgae amakonda kugwirizana ndi Nb-MXenes. Pogwiritsa ntchito kusanthula kwazithunzi, tikutsimikizira kuti izi zimapangitsa kuti ma nanoflakes a Nb-MXene akhale tinthu tating'onoting'ono tozungulira, zomwe zikusonyeza kuti kuwonongeka kwa ma nanoflakes kumalumikizidwa ndi okosijeni awo. Kuti tiyese lingaliro lathu, tinachita kafukufuku wosiyanasiyana wa zinthu ndi zamankhwala. Titayesa, ma nanoflakes pang'onopang'ono adasungunuka ndikuwola kukhala zinthu za NbO ndi Nb2O5, zomwe sizinali zoopsa ku ma microalgae obiriwira. Pogwiritsa ntchito kuwunika kwa FTIR, sitinapeze kusintha kwakukulu mu kapangidwe ka mankhwala a ma microalgae omwe amasungidwa pamaso pa ma nanoflakes a 2D Nb-MXene. Poganizira kuthekera kwa kuyamwa kwa niobium oxide ndi ma microalgae, tinachita kusanthula kwa X-ray fluorescence. Zotsatirazi zikuwonetsa momveka bwino kuti ma microalgae omwe aphunziridwa amadya ma niobium oxides (NbO ndi Nb2O5), omwe si oopsa ku ma microalgae omwe aphunziridwa.