Functionalization of metal oxides with thiocyanate groups: A general strategy for boosting oxygen evolution reaction in neutral media

The electrocatalytic splitting of water in neutral solution to produce hydrogen appears highly attractive for the development of hydrogen economy. The corresponding industrial applications, however, have not yet been realized due to the unsatisfactory energy conversion efficiency in the oxygen evolution reaction (OER), with the potential limiting step being the formation of HOO*. In the present work, we report that the functionalization of metal oxide electrocatalysts with thiocyanate groups is a novel, general and effective strategy for improving the catalytic performance of OER. Density Functional Theory (DFT) calculations show that mechanistic origin of such fucntioanlization is that the potenital limiting step of HOO* formation can be promoted via a cyanate assisted water dissociation. As a result, the SCN-Ru-RuO2/C3N4 may achieve the current density of 10 mA cm(-2) in the neutral electrolyte at an overpotential of 342 mV, which is significantly lower than that of commercial RuO2 (545 mV). In addition, the SCN-Ru-RuO2/C3N4 anode is observed to outperform the commercial IrO2-anode-embedded electrolyzer in the PEMWE, indicating significant potential in realistic applications. The generalization of the activity enhancement due to thiocyanate functionalization in neutral medium can be demonstrated SCN-Ir/C3N4 and/or SCN-Co3O4/C3N4.