Nanocrystalline anatase TiO2/reduced graphene oxide composite films as photoanodes for photoelectrochemical water splitting studies: the role of reduced graphene oxide

Autor(es)

Morais, Andreia ^[1] ; Longo, Claudia ^[1] ; Araujo, Joyce R. ^[2] ; Barroso, Monica ^[3] ; Durrant, James R. ^[4] ; Nogueira, Ana Flavia ^[1]

Afiliação do(s) autor(es)

^[1] Univ Campinas UNICAMP, Inst Chem, POB 6154, BR-13083970 Campinas, SP - Brazil

^[2] Natl Inst Metrol Qual & Technol, Ave Nossa Sra Gracas 50, BR-25250020 Duque De Caxias, RJ - Brazil

^[3] Univ Utrecht, Debye Inst Nanomat Sci, Bolognalaan 10 7, NL-3584 CJ Utrecht - Netherlands

^[4] Univ London Imperial Coll Sci Technol & Med, Dept Chem, South Kensington Campus, London SW7 2AZ - England

• Tipo de documento: Artigo Científico
• Fonte: Physical Chemistry Chemical Physics; v. 18, n. 4, p. 2608-2616, JAN 28 2016.
• Citações Web of Science: 38

Resumo

Nanocrystalline TiO2 and reduced graphene oxide (TiO2/RGO) composite films were prepared by combining a sol-gel method with hydrothermal treatment, employing titanium isopropoxide (Ti((OPr)-Pr-i)(4)) and graphene oxide (GO) as starting materials. Although several reports in the literature have explored the benefits of RGO addition in titania films for photocatalysis and water splitting reactions, the role of RGO in the composite is always described as that of a material that is able to act as an electron acceptor and transport electrons more efficiently. However, in most of these reports, no clear evidence for this ``role'' is presented, and the main focus is deviated to the improved efficiency and not to the reasons for said efficiency. In this study, we employed several techniques to definitively present our understanding of the role of RGO in titania composite films. The TiO2/RGO composite films were characterized by X ray diffraction, Raman spectroscopy, microscopy and electrochemical techniques. In photoelectrochemical water splitting studies, the TiO2/RGO(0.1%) photoelectrodes showed the highest photocurrent density values (0.20 mA cm(-2) at 1.23 V-RHE) compared to other electrodes, with an increase of 78% in relation to pristine TiO2 film (0.11 mA cm(-2) at 1.23 V-RHE). The transient absorption spectroscopy (TAS) results indicated increases in the lifetime and yield of both the photogenerated holes and electrons. Interestingly, the TiO2/RGO(0.1%) film exhibited the best charge generation upon excitation, corroborating the photoelectrochemical data. We proposed that in films with lower concentrations (<0.1 wt%), the RGO sheets are electron acceptors, and a decrease in the charge recombination processes is the immediate consequence. Thus, both holes and electrons live longer and contribute more effectively to the photocurrent density. (AU)

• Processo FAPESP: 11/51593-6 - Celulas solares organicas e hibridas de filmes finos.
• Beneficiário: Ana Flávia Nogueira
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 10/18656-1 - Preparação e caracterização de compósitos de nanopartículas de TiO2 e ZnO contendo materiais carbonáceos e sua aplicação em células solares
• Beneficiário: Andreia de Morais
• Modalidade de apoio: Bolsas no Brasil - Doutorado