Proton-dependent photocatalytic dehalogenation activities caused by oxygen vacancies of In2O3

Increasing number of evidences has proved that the oxygen vacancies played a key role in the photocatalytic reactions. However, traditional theories for oxygen vacancies to participate in the reactions mainly focused on its accompanying enhanced trapping capability of photo-induced electrons. In this work, by turning the amounts of oxygen vacancies in In2O3 photocatalysts, it was found that the photocatalytic dehalogenation of decabromodiphenyl ether and hexabromobenzene by In2O3 was also strongly dependent on the enhanced trapping of protons caused by the oxygen vacancies. Through a series of characterizations and measurements, the photo-induced electrons and protons were proved to be simultaneously trapped and confirmed to be determined by the concentration of oxygen vacancies. Moreover, the kinetic isotope studies investigated the proton coupled electron transfer (PCET) pathway in the photocatalytic dehalogenation reactions of In2O3. Protons transfer was demonstrated to be existed in the rate-determining step of the whole photocatalytic reaction. The enhanced concentration of oxygen vacancies resulted in the superior trapping capability of photo-induced electrons and protons, simultaneously promoted the transfer efficiency of protons and electrons, accelerated the separation of photo-reduced carriers and finally improved the photocatalytic activities of In2O3 in the PCET reactions.

Automated summary

This study found that oxygen vacancies play a key role in the photocatalytic reactions of In2O3, with the trapping of protons caused by oxygen vacancies being crucial for the photocatalytic dehalogenation. By controlling the concentration of oxygen vacancies, simultaneous trapping of protons and electrons was achieved, revealing the proton-coupled electron transfer pathway.