Comparisons of WO3 reduction to HxWO3 under thermochemical and electrochemical control

Abstract

The use of renewable electricity as an energy source for the chemical industry is attractive from the standpoint of improved environmental sustainability. The development of such electrification strategies would greatly benefit from improved understanding of the relationships between thermochemical and electrochemical redox processes. We have used time-resolved optical microscopy to study H_xWO₃ bronze formation from WO₃via thermochemical H-spillover and electrochemical H-intercalation reactions. The rates of hydrogen uptake in these films were found to be similar in each case, and too fast to be limited by proton diffusion in the solid state. These results point to a single predominant reaction mechanism that is primarily gated by interfacial electron-transfer rather than proton or hydrogen-atom diffusion.