TY - JOUR

T1 - Photocatalytic properties of layer-by-layer thin films of hexaniobate nanoscrolls

AU - Nunes, Barbara N.

AU - Haisch, Christoph

AU - Emeline, Alexei V.

AU - Bahnemann, Detlef

AU - Patrocinio, Antonio Octavio T.

N1 - Funding information: In Brazil, this work was supported by Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG, PPM-00220-17), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES). The authors are also thankful to the Grupo de Materiais Inorgânicos do Triângulo (GMIT), a research group supported by FAPEMIG (APQ-00330-14) and to CBMM for the Nb In Brazil, this work was supported by Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG, PPM-00220-17 ), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) . The authors are also thankful to the Grupo de Materiais Inorgânicos do Triângulo (GMIT), a research group supported by FAPEMIG (APQ-00330-14) and to CBMM for the Nb 2 O 5 . A.O.T.P. is thankful to Alexander Von Humboldt Foundation for the fellowship in Germany. Also in Germany, The financial support from the Federal Ministry of Education and Research BMBF (Project “DuaSol” No. 03SF0482C and 03SF0482) is gratefully acknowledged. The present study was performed within the Project Establishment of the Laboratory “Photoactive Nanocomposite Materials ” No. 14.Z50.31.0016 supported by a Mega-grant of the Government of the Russian Federation .

PY - 2019/4/1

Y1 - 2019/4/1

N2 - High efficient photocatalytic surfaces were obtained through the layer-by-layer (LbL) deposition of hexaniobate nanoscrolls on conductive glasses. These films were deposited by alternative immersions of the substrate into exfoliated hexaniobated suspensions (pH = 8) and poly(allylamine hydrochloride) solutions (pH = 4). The organic species were further removed by thermal treatment leading to a fuzzy assembly of hexaniobate nanoscrolls. Pre-adsorption of [Pt(NH 3 ) 4 ] 2+ cations on the niobate layers allows the production of metallic Pt nanoclusters on the film layers. The Pt-modified films exhibited apparent quantum yields of (4.0 ± 0.5) % for H 2 evolution from water/methanol mixtures under UV-A irraditation. The H 2 evolution rates varied linearly with the number of deposited bilayers, indicating that no active sites are lost as the film is grown. The photoelectrochemical properties of the films reveal that the small size of the hole scavenger and its easy diffusion into the hexaniobate layers are key aspects for the photocatalytic activity. In the absence of alcohols as hole scavengers, irradiation of the hexaniobate LbL films in aqueous solutions leads to the production of surface-bound peroxides that limit the photocatalytic water splitting ability of these materials. The results presented here provide evidence for the effectiveness of the LbL technique to deposit thin films of layered materials retaining their interesting adsorption chemistry. This methodology can be further employed for the development of highly active photocatalytic surfaces.

AB - High efficient photocatalytic surfaces were obtained through the layer-by-layer (LbL) deposition of hexaniobate nanoscrolls on conductive glasses. These films were deposited by alternative immersions of the substrate into exfoliated hexaniobated suspensions (pH = 8) and poly(allylamine hydrochloride) solutions (pH = 4). The organic species were further removed by thermal treatment leading to a fuzzy assembly of hexaniobate nanoscrolls. Pre-adsorption of [Pt(NH 3 ) 4 ] 2+ cations on the niobate layers allows the production of metallic Pt nanoclusters on the film layers. The Pt-modified films exhibited apparent quantum yields of (4.0 ± 0.5) % for H 2 evolution from water/methanol mixtures under UV-A irraditation. The H 2 evolution rates varied linearly with the number of deposited bilayers, indicating that no active sites are lost as the film is grown. The photoelectrochemical properties of the films reveal that the small size of the hole scavenger and its easy diffusion into the hexaniobate layers are key aspects for the photocatalytic activity. In the absence of alcohols as hole scavengers, irradiation of the hexaniobate LbL films in aqueous solutions leads to the production of surface-bound peroxides that limit the photocatalytic water splitting ability of these materials. The results presented here provide evidence for the effectiveness of the LbL technique to deposit thin films of layered materials retaining their interesting adsorption chemistry. This methodology can be further employed for the development of highly active photocatalytic surfaces.

KW - Hexaniobate-based photocatalysts

KW - Metal oxide LbL films

KW - Photoactive surface

UR - http://www.scopus.com/inward/record.url?scp=85049330882&partnerID=8YFLogxK

U2 - 10.1016/j.cattod.2018.06.029

DO - 10.1016/j.cattod.2018.06.029

M3 - Article

VL - 326

SP - 60

EP - 67

JO - Catalysis Today

JF - Catalysis Today

SN - 0920-5861

ER -