Tungsten doped manganese silicate films as stable and efficient oxygen evolution catalysts in near-neutral media

Efficient, stable and cost-effective oxygen evolution catalysts (OECs) operating in near-neutral or weak acid media have highly practical applications in electrochemical (EC) and photoelectrochemical (PEC) fields. However, conventional catalysts are mostly based on precious metals, while those based on earth-abundant elements that are efficient in alkaline solution generally suffer from dissolution in such media. Herein, we show that novel manganese silicate-based film materials prepared from thermal vapor deposition and a subsequent microwave reaction can act as potential oxygen evolution reaction (OER) catalysts in near-neutral media. Pristine manganese silicate displays excellent intrinsic catalytic activity. With W doping, the catalysts exhibit remarkably better apparent catalytic activity as it leads to the exposure of more active sites without impairing the bulk conductivity. W doping also serves to significantly adjust the elementary valence states of Mn and enrich the surface hydroxyl groups, resulting in much improved stability. DFT calculations reveal that the theoretical overpotential of manganese silicate is comparable to that of other reported manganese oxide OER catalysts. These results demonstrate manganese silicates as a new class of OECs for stable water splitting in near-neutral media. They also illustrate a new pathway of improving stability in near-neutral media by introducing high-valency metal elements for the design of nonprecious OEC.