Efeitos térmicos durante a foto-eletro-oxidação de glicerol catalisada por CdS

Detalhes bibliográficos
Ano de defesa: 2019
Autor(a) principal: Oliveira, Cristian Hessel de
Orientador(a): Sitta, Elton Fabiano lattes
Banca de defesa: Não Informado pela instituição
Tipo de documento: Dissertação
Tipo de acesso: Acesso aberto
Idioma: por
Instituição de defesa: Universidade Federal de São Carlos
Câmpus São Carlos
Programa de Pós-Graduação: Programa de Pós-Graduação em Química - PPGQ
Departamento: Não Informado pela instituição
País: Não Informado pela instituição
Palavras-chave em Português:
CdS
Palavras-chave em Inglês:
Área do conhecimento CNPq:
Link de acesso: https://repositorio.ufscar.br/handle/20.500.14289/12083
Resumo: Cadmium sulfide (CdS) is one of the most important chalcogenides applied to water splitting, which has a band gap of 2.4 eV that suits very well with the solar spectrum. Moreover, CdS possesses a strong reduction activity for H+ to H2, which makes this material interesting as a cocatalyst with another material for water splitting. Unfortunately, the use of water as electron source (oxygen evolution reaction) is difficulted due to the high overpotential and sluggish kinetic. Thereby organic molecules, as glycerol, oxidation appears as an alternative anodic reaction once it has high power density, renewability and low cost. In this work we focused on the glycerol electro-oxidation reaction (GEOR) catalyzed by FTO/CdS decorated with Platinum above or between FTO/CdS films under visible light irradiation and from 15 to 35°C temperature range. The CdS film was deposited by chemical bath deposition and Pt were deposited from Pt2+ precursor. The films were characterized by Raman and UV spectroscopy, XRD and SEM techniques. Electrochemical experiments were conducted in a quartz window 3 electrodes glass cell, with same solution reversible hydrogen electrode as potential reference and a platinum plate as counter electrode. The measurements were performed in KOH 0.1 mol L-1 and glycerol 1.0 mol L-1 under 100 mW cm-2 light irradiation. The experiments showed that increasing temperature the photocurrent also increases, following the Arrhenius equation and resulting in an apparent activation energy (Ea) of 35, 35 and 26 kJ mol-1 for the FTO/CdS, FTO/CdS/Pt and FTO/Pt/CdS, respectively, for potential under 0.5 V. For potential above 0.6 V the Ea decreases linearly with the potential increasing, tendency which is observed when Pt electrode is used as catalyst and probably linked with GEOR. The above results suggest that glycerol is a candidate to replace water in the anodic process for H2 production, and that increasing the temperature the kinetics of the process is improved.