Influence of the electronic structures on the heterogeneous photoelectrocatalytic performance of Ti/RuxSn1-xO2 electrodes

DSA-type Ti/RuxSn1-xO2 electrodes were prepared by thermal decomposition method as photoelectrocatalysts (PECs) and extensively characterized by various sophisticated techniques. First-principles calculations was employed to study the effects of Ru content on the electronic structures of the RuxSn1-xO2 coatings. The photoelectric-synergistic catalytic activity of the Ti/RuxSn1-xO2 electrodes was evaluated for the degradation of methyl orange (MO) in aqueous solution. The results show that the RuO2−SnO2 solid solution could be formed. The band gaps of the RuxSn1-xO2 coatings gradually decreased and eventually turned into metallic conductivity with the increase of ruthenium content. As a PEC electrode, reducing band gap is helpful to improve electronic conductivity and the electrocatalytic activity, but not always advantageous to increase the photocatalytic activity. Because too narrow band gap will sacrifice the photogenerated charge carriers and thus reduce photocatalytic activity of the electrode. In our experiments, the rate constant of Ti/Ru0.05Sn0.95O2 electrode increased with increasing Ru content and exhibited the maximum rate for 5% Ru loading. The stability test showed the photoelectrocatalytic activity of the Ti/Ru0.05Sn0.95O2 electrode almost had no attenuation after 100 h photoelectrolysis, revealing that this electrode has good long-term stability.