Photocatalytic applications of layered niobates and their composites
Ano de defesa: | 2022 |
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Autor(a) principal: | |
Orientador(a): | , |
Banca de defesa: | , , |
Tipo de documento: | Tese |
Tipo de acesso: | Acesso aberto |
Idioma: | eng |
Instituição de defesa: |
Universidade Federal de Uberlândia
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Programa de Pós-Graduação: |
Programa de Pós-graduação em Química
|
Departamento: |
Não Informado pela instituição
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País: |
Brasil
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Palavras-chave em Português: | |
Área do conhecimento CNPq: | |
Link de acesso: | https://repositorio.ufu.br/handle/123456789/34943 http://doi.org/10.14393/ufu.te.2022.217 |
Resumo: | Photocatalytic applications of two-dimensional (2D) materials have called great interest due to several electronic and structural advantages. Among these materials, layered niobates are well-known photocatalysts for H2 evolution with a rich surface chemistry. Taking into account the highly exposed active sites of its 2D structure and the morphological flexibility, the properties of the exfoliated hexaniobate as a heterogeneous photocatalyst has been explored in this work, with particular attention to the electronic and interfacial processes involved in the H2 evolution. Firstly, highly efficient photocatalytic surfaces were obtained through the layer-by-layer (LbL) deposition of hexaniobate nanoscrolls on conductive glasses. These films were deposited by using poly(allylamine hydrochloride) as a polyelectrolyte and further thermal treatment leading to films composed of a fuzzy assembly of hexaniobate nanoscrolls. This configuration favored the diffusion of water and methanol molecules thus facilitating an efficient H2 evolution. Moreover, pre-adsorption of [Pt(NH3)4]2+ cations on the niobate layers allowed the production of metallic Pt nanoclusters within the nanoscrolls. The Pt-modified films exhibited apparent quantum yields of (4.0 ± 0.5) % for H2 evolution from water/methanol mixtures under UV-A irradiation. Then, in order to induce novel electronic processes without changing the bulk properties of the hexaniobate, surface modification was performed by grafting with metallic nanoclusters. Exfoliated hexaniobate (K4−xHxNb6O17) composites with metal ions such as Co2+, Fe3+ and Cu2+ were prepared and their photocatalytic properties were fully investigated. Morphological characterization showed that the grafting ions are attached to the hexaniobate surface forming amorphous clusters. These species induce an additional absorption feature in the UV-A region, which is attributed to an interfacial charge transfer from the niobate valence band to the metal ion centers. In the case of Co2+ and Fe3+, enhanced UV-driven photoactivity in plain water was observed for 0.1 wt.% grafted samples, especially for those modified with Co2+ ions, while smaller H2 evolution rates are observed as the concentration of the grafting ions increased. When Pt was added to the photocatalyst, the H2 evolution rate for the 0.1% Co-grafted sample in plain water was 70% higher than that observed for the nongrafted Pt-hexaniobate. For Cu2+-grafted hexaniobates, Cu2+ clusters provided an expressive improvement in the photocatalytic H2 evolution under UV-vis irradiation from methanolic aqueous solution and promising results for partial water splitting, in comparison to the hexaniobate with photodeposited Pt. These species on the hexaniobate surface present a high redox reversibility, being easily reduced to Cu1+/Cu0 and reoxidized to Cu2+. Cu2+ ions work as electron scavenger following band gap excitation while the resulting reduced species act as active sites to produce H2. Thus, the presence of different ions at different concentrations can directly affect the fate of the photogenerated carriers thus triggering the photocatalytic activity in different ways. Overall, the grafted ions contribute to a more efficient charge separation and to higher photocatalytic performances. |
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2022-04-28T14:47:00Z2022-04-28T14:47:00Z2022-04-12NUNES, Barbara Nascimento. Photocatalytic applications of layered niobates and their composites. 2022. 204 f. Tese (Doutorado em Química) - Universidade Federal de Uberlândia, Uberlândia, 2022. DOI http://doi.org/10.14393/ufu.te.2022.217https://repositorio.ufu.br/handle/123456789/34943http://doi.org/10.14393/ufu.te.2022.217Photocatalytic applications of two-dimensional (2D) materials have called great interest due to several electronic and structural advantages. Among these materials, layered niobates are well-known photocatalysts for H2 evolution with a rich surface chemistry. Taking into account the highly exposed active sites of its 2D structure and the morphological flexibility, the properties of the exfoliated hexaniobate as a heterogeneous photocatalyst has been explored in this work, with particular attention to the electronic and interfacial processes involved in the H2 evolution. Firstly, highly efficient photocatalytic surfaces were obtained through the layer-by-layer (LbL) deposition of hexaniobate nanoscrolls on conductive glasses. These films were deposited by using poly(allylamine hydrochloride) as a polyelectrolyte and further thermal treatment leading to films composed of a fuzzy assembly of hexaniobate nanoscrolls. This configuration favored the diffusion of water and methanol molecules thus facilitating an efficient H2 evolution. Moreover, pre-adsorption of [Pt(NH3)4]2+ cations on the niobate layers allowed the production of metallic Pt nanoclusters within the nanoscrolls. The Pt-modified films exhibited apparent quantum yields of (4.0 ± 0.5) % for H2 evolution from water/methanol mixtures under UV-A irradiation. Then, in order to induce novel electronic processes without changing the bulk properties of the hexaniobate, surface modification was performed by grafting with metallic nanoclusters. Exfoliated hexaniobate (K4−xHxNb6O17) composites with metal ions such as Co2+, Fe3+ and Cu2+ were prepared and their photocatalytic properties were fully investigated. Morphological characterization showed that the grafting ions are attached to the hexaniobate surface forming amorphous clusters. These species induce an additional absorption feature in the UV-A region, which is attributed to an interfacial charge transfer from the niobate valence band to the metal ion centers. In the case of Co2+ and Fe3+, enhanced UV-driven photoactivity in plain water was observed for 0.1 wt.% grafted samples, especially for those modified with Co2+ ions, while smaller H2 evolution rates are observed as the concentration of the grafting ions increased. When Pt was added to the photocatalyst, the H2 evolution rate for the 0.1% Co-grafted sample in plain water was 70% higher than that observed for the nongrafted Pt-hexaniobate. For Cu2+-grafted hexaniobates, Cu2+ clusters provided an expressive improvement in the photocatalytic H2 evolution under UV-vis irradiation from methanolic aqueous solution and promising results for partial water splitting, in comparison to the hexaniobate with photodeposited Pt. These species on the hexaniobate surface present a high redox reversibility, being easily reduced to Cu1+/Cu0 and reoxidized to Cu2+. Cu2+ ions work as electron scavenger following band gap excitation while the resulting reduced species act as active sites to produce H2. Thus, the presence of different ions at different concentrations can directly affect the fate of the photogenerated carriers thus triggering the photocatalytic activity in different ways. Overall, the grafted ions contribute to a more efficient charge separation and to higher photocatalytic performances.Aplicações fotocatalíticas de materiais bidimensionais (2D) têm despertado grande interesse devido às diversas vantagens eletrônicas e estruturais desses materiais. Dentre eles, os niobatos lamelares são fotocatalisadores bem conhecidos para a evolução de H2 com uma rica química de superfície. Levando em consideração os sítios ativos altamente expostos de sua estrutura 2D e sua flexibilidade morfológica, as propriedades do hexaniobato esfoliado como fotocatalisador heterogêneo foram exploradas neste trabalho, com particular atenção aos processos eletrônicos e interfaciais envolvidos na evolução de H2. Primeiramente, superfícies fotocatalíticas de alta eficiência foram obtidas através da deposição camada por camada (LbL) de nanoscrolls de hexaniobato em vidros condutores. Esses filmes foram depositados usando poli(cloridrato de alilamina) como polieletrólito, e o posterior tratamento térmico resultou em filmes compostos por uma montagem difusa de nanoscrolls de hexaniobato. Esta configuração favoreceu a difusão das moléculas de água e metanol, facilitando uma evolução eficiente de H2. Além disso, a pré-adsorção de cátions [Pt(NH3)4]2+ nas camadas de niobato permitiu a produção de nanoaglomerados metálicos de Pt nos nanoscrolls. Os filmes modificados com Pt exibiram rendimentos quânticos aparentes de (4,0 ± 0,5)% para a evolução de H2 a partir de misturas de água / metanol sob irraditação UV-A. Em seguência, a fim de induzir novos processos eletrônicos sem alterar as propriedades do hexaniobato, a modificação da superfície foi realizada por grafting com nanoclusters metálicos. Compósitos de hexaniobato esfoliado (K4−xHxNb6O17) com íons metálicos como Co2+, Fe3+ e Cu2+ foram preparados e suas propriedades fotocatalíticas foram extensivamente investigadas. A caracterização morfológica mostrou que os íons adicionados por grafting estão fixados na superfície do hexaniobato formando aglomerados amorfos. Essas espécies induzem uma de absorção adicional característica na região UV-A, que é atribuída a uma transferência de carga interfacial da banda de valência do niobato para os centros de íons metálicos. No caso de Co2+ e Fe3+, a melhor fotoatividade conduzida por UV em água pura foi observada para amostras modificadas a 0,1%, especialmente para aquelas com íons Co2+, enquanto menores taxas de evolução de H2 são observadas conforme a concentração dos íons de grafting aumenta. Quando a Pt foi adicionada ao fotocatalisador, a taxa de evolução de H2 para a amostra modificada a 0,1% em água pura foi 70% maior do que a observada para o Pt-hexaniobato não modificado por grafting. Para hexaniobatos com Cu2+, os clusters de Cu2+ proporcionaram expressiva melhora na evolução fotocatalítica de H2 sob irradiação UV-vis de uma solução aquosa metanólica e resultados promissores para a quebra parcial da água, em comparação ao hexaniobato com Pt fotodepositada. Essas espécies na superfície do hexaniobato apresentam alta reversibilidade redox, que pode ser facilmente reduzida para Cu1+/Cu0 e reoxidada para Cu2+. Os íons Cu2+ funcionam como eliminadores de elétrons após a excitação do bandgap e as espécies reduzidas resultantes atuam como sítio ativo para produzir H2. Assim, a presença de diferentes íons em diferentes concentrações pode afetar diretamente o destino dos portadores fotogerados, desencadeando a atividade fotocatalítica de diferentes maneiras. Os íons adicionados por grafting contribuem para uma separação de carga mais eficiente e desempenhos fotocatalíticos mais elevados.CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorTese (Doutorado)engUniversidade Federal de UberlândiaPrograma de Pós-graduação em QuímicaBrasilCNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA INORGANICA::FOTO-QUIMICA INORGANICAQuímicaCompostos de nióbioÁgua - AnáliseFilmes finos - Propriedades ópticas2D materialsniobium oxideniobatesthin filmsphotoactive surfacephotocatalysishydrogenwater splittingMateriais 2Dóxido de nióbioniobatosfilmes finosfotoativos Superfíciefotocatálisehidrogênioseparação de águaestudos mecanísticosPhotocatalytic applications of layered niobates and their compositesAplicações fotocatalíticas de niobatos lamelares e seus compósitosinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/doctoralThesisPatrocinio, Antonio Otavio de Toledohttp://lattes.cnpq.br/0176020585396338Bahnemann, DetlefBeutel, Saschahttps://www.tci.uni-hannover.de/de/sascha-beutel/Wark, Michaelhttps://uol.de/chemie/prof-dr-michael-warkFeldhoff, Arminhttps://scholar.google.com/citations?user=zyysiuUAAAAJ&hl=dehttp://lattes.cnpq.br/3626047156612933Nunes, Barbara Nascimento2041122500322bb86f18-5c59-4ae8-913a-3cf8e0b8f128info:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFUinstname:Universidade Federal de Uberlândia (UFU)instacron:UFULICENSElicense.txtlicense.txttext/plain; charset=utf-81792https://repositorio.ufu.br/bitstream/123456789/34943/2/license.txt48ded82ce41b8d2426af12aed6b3cbf3MD52TEXTPhotocatalyticApplicationsLayered.pdf.txtPhotocatalyticApplicationsLayered.pdf.txtExtracted texttext/plain380345https://repositorio.ufu.br/bitstream/123456789/34943/3/PhotocatalyticApplicationsLayered.pdf.txt59dad23b41ec0c9e7c36c44f89f616c3MD53THUMBNAILPhotocatalyticApplicationsLayered.pdf.jpgPhotocatalyticApplicationsLayered.pdf.jpgGenerated Thumbnailimage/jpeg1355https://repositorio.ufu.br/bitstream/123456789/34943/4/PhotocatalyticApplicationsLayered.pdf.jpga7c2a3e400b5c961433276ffa5b53bfeMD54ORIGINALPhotocatalyticApplicationsLayered.pdfPhotocatalyticApplicationsLayered.pdfTeseapplication/pdf13965966https://repositorio.ufu.br/bitstream/123456789/34943/5/PhotocatalyticApplicationsLayered.pdfbc59b31780bc0cd72ef1184f43b6e35dMD55123456789/349432022-05-25 09:56:19.723oai:repositorio.ufu.br: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Repositório InstitucionalONGhttp://repositorio.ufu.br/oai/requestdiinf@dirbi.ufu.bropendoar:2022-05-25T12:56:19Repositório Institucional da UFU - Universidade Federal de Uberlândia (UFU)false |
dc.title.pt_BR.fl_str_mv |
Photocatalytic applications of layered niobates and their composites |
dc.title.alternative.pt_BR.fl_str_mv |
Aplicações fotocatalíticas de niobatos lamelares e seus compósitos |
title |
Photocatalytic applications of layered niobates and their composites |
spellingShingle |
Photocatalytic applications of layered niobates and their composites Nunes, Barbara Nascimento CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA INORGANICA::FOTO-QUIMICA INORGANICA 2D materials niobium oxide niobates thin films photoactive surface photocatalysis hydrogen water splitting Materiais 2D óxido de nióbio niobatos filmes finos fotoativos Superfície fotocatálise hidrogênio separação de água estudos mecanísticos Química Compostos de nióbio Água - Análise Filmes finos - Propriedades ópticas |
title_short |
Photocatalytic applications of layered niobates and their composites |
title_full |
Photocatalytic applications of layered niobates and their composites |
title_fullStr |
Photocatalytic applications of layered niobates and their composites |
title_full_unstemmed |
Photocatalytic applications of layered niobates and their composites |
title_sort |
Photocatalytic applications of layered niobates and their composites |
author |
Nunes, Barbara Nascimento |
author_facet |
Nunes, Barbara Nascimento |
author_role |
author |
dc.contributor.advisor1.fl_str_mv |
Patrocinio, Antonio Otavio de Toledo |
dc.contributor.advisor1Lattes.fl_str_mv |
http://lattes.cnpq.br/0176020585396338 |
dc.contributor.advisor2.fl_str_mv |
Bahnemann, Detlef |
dc.contributor.referee1.fl_str_mv |
Beutel, Sascha |
dc.contributor.referee1Lattes.fl_str_mv |
https://www.tci.uni-hannover.de/de/sascha-beutel/ |
dc.contributor.referee2.fl_str_mv |
Wark, Michael |
dc.contributor.referee2Lattes.fl_str_mv |
https://uol.de/chemie/prof-dr-michael-wark |
dc.contributor.referee3.fl_str_mv |
Feldhoff, Armin |
dc.contributor.referee3Lattes.fl_str_mv |
https://scholar.google.com/citations?user=zyysiuUAAAAJ&hl=de |
dc.contributor.authorLattes.fl_str_mv |
http://lattes.cnpq.br/3626047156612933 |
dc.contributor.author.fl_str_mv |
Nunes, Barbara Nascimento |
contributor_str_mv |
Patrocinio, Antonio Otavio de Toledo Bahnemann, Detlef Beutel, Sascha Wark, Michael Feldhoff, Armin |
dc.subject.cnpq.fl_str_mv |
CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA INORGANICA::FOTO-QUIMICA INORGANICA |
topic |
CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA INORGANICA::FOTO-QUIMICA INORGANICA 2D materials niobium oxide niobates thin films photoactive surface photocatalysis hydrogen water splitting Materiais 2D óxido de nióbio niobatos filmes finos fotoativos Superfície fotocatálise hidrogênio separação de água estudos mecanísticos Química Compostos de nióbio Água - Análise Filmes finos - Propriedades ópticas |
dc.subject.por.fl_str_mv |
2D materials niobium oxide niobates thin films photoactive surface photocatalysis hydrogen water splitting Materiais 2D óxido de nióbio niobatos filmes finos fotoativos Superfície fotocatálise hidrogênio separação de água estudos mecanísticos |
dc.subject.autorizado.pt_BR.fl_str_mv |
Química Compostos de nióbio Água - Análise Filmes finos - Propriedades ópticas |
description |
Photocatalytic applications of two-dimensional (2D) materials have called great interest due to several electronic and structural advantages. Among these materials, layered niobates are well-known photocatalysts for H2 evolution with a rich surface chemistry. Taking into account the highly exposed active sites of its 2D structure and the morphological flexibility, the properties of the exfoliated hexaniobate as a heterogeneous photocatalyst has been explored in this work, with particular attention to the electronic and interfacial processes involved in the H2 evolution. Firstly, highly efficient photocatalytic surfaces were obtained through the layer-by-layer (LbL) deposition of hexaniobate nanoscrolls on conductive glasses. These films were deposited by using poly(allylamine hydrochloride) as a polyelectrolyte and further thermal treatment leading to films composed of a fuzzy assembly of hexaniobate nanoscrolls. This configuration favored the diffusion of water and methanol molecules thus facilitating an efficient H2 evolution. Moreover, pre-adsorption of [Pt(NH3)4]2+ cations on the niobate layers allowed the production of metallic Pt nanoclusters within the nanoscrolls. The Pt-modified films exhibited apparent quantum yields of (4.0 ± 0.5) % for H2 evolution from water/methanol mixtures under UV-A irradiation. Then, in order to induce novel electronic processes without changing the bulk properties of the hexaniobate, surface modification was performed by grafting with metallic nanoclusters. Exfoliated hexaniobate (K4−xHxNb6O17) composites with metal ions such as Co2+, Fe3+ and Cu2+ were prepared and their photocatalytic properties were fully investigated. Morphological characterization showed that the grafting ions are attached to the hexaniobate surface forming amorphous clusters. These species induce an additional absorption feature in the UV-A region, which is attributed to an interfacial charge transfer from the niobate valence band to the metal ion centers. In the case of Co2+ and Fe3+, enhanced UV-driven photoactivity in plain water was observed for 0.1 wt.% grafted samples, especially for those modified with Co2+ ions, while smaller H2 evolution rates are observed as the concentration of the grafting ions increased. When Pt was added to the photocatalyst, the H2 evolution rate for the 0.1% Co-grafted sample in plain water was 70% higher than that observed for the nongrafted Pt-hexaniobate. For Cu2+-grafted hexaniobates, Cu2+ clusters provided an expressive improvement in the photocatalytic H2 evolution under UV-vis irradiation from methanolic aqueous solution and promising results for partial water splitting, in comparison to the hexaniobate with photodeposited Pt. These species on the hexaniobate surface present a high redox reversibility, being easily reduced to Cu1+/Cu0 and reoxidized to Cu2+. Cu2+ ions work as electron scavenger following band gap excitation while the resulting reduced species act as active sites to produce H2. Thus, the presence of different ions at different concentrations can directly affect the fate of the photogenerated carriers thus triggering the photocatalytic activity in different ways. Overall, the grafted ions contribute to a more efficient charge separation and to higher photocatalytic performances. |
publishDate |
2022 |
dc.date.accessioned.fl_str_mv |
2022-04-28T14:47:00Z |
dc.date.available.fl_str_mv |
2022-04-28T14:47:00Z |
dc.date.issued.fl_str_mv |
2022-04-12 |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/doctoralThesis |
format |
doctoralThesis |
status_str |
publishedVersion |
dc.identifier.citation.fl_str_mv |
NUNES, Barbara Nascimento. Photocatalytic applications of layered niobates and their composites. 2022. 204 f. Tese (Doutorado em Química) - Universidade Federal de Uberlândia, Uberlândia, 2022. DOI http://doi.org/10.14393/ufu.te.2022.217 |
dc.identifier.uri.fl_str_mv |
https://repositorio.ufu.br/handle/123456789/34943 |
dc.identifier.doi.pt_BR.fl_str_mv |
http://doi.org/10.14393/ufu.te.2022.217 |
identifier_str_mv |
NUNES, Barbara Nascimento. Photocatalytic applications of layered niobates and their composites. 2022. 204 f. Tese (Doutorado em Química) - Universidade Federal de Uberlândia, Uberlândia, 2022. DOI http://doi.org/10.14393/ufu.te.2022.217 |
url |
https://repositorio.ufu.br/handle/123456789/34943 http://doi.org/10.14393/ufu.te.2022.217 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.publisher.none.fl_str_mv |
Universidade Federal de Uberlândia |
dc.publisher.program.fl_str_mv |
Programa de Pós-graduação em Química |
dc.publisher.country.fl_str_mv |
Brasil |
publisher.none.fl_str_mv |
Universidade Federal de Uberlândia |
dc.source.none.fl_str_mv |
reponame:Repositório Institucional da UFU instname:Universidade Federal de Uberlândia (UFU) instacron:UFU |
instname_str |
Universidade Federal de Uberlândia (UFU) |
instacron_str |
UFU |
institution |
UFU |
reponame_str |
Repositório Institucional da UFU |
collection |
Repositório Institucional da UFU |
bitstream.url.fl_str_mv |
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bitstream.checksum.fl_str_mv |
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bitstream.checksumAlgorithm.fl_str_mv |
MD5 MD5 MD5 MD5 |
repository.name.fl_str_mv |
Repositório Institucional da UFU - Universidade Federal de Uberlândia (UFU) |
repository.mail.fl_str_mv |
diinf@dirbi.ufu.br |
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1792331494592610304 |