First insight on Mo(II) as electrocatalytically active species for oxygen evolution reaction

The replacement of noble metals with earth-abundant metals is still a big challenge for the practical application of electrocatalysis. In this work, we have developed the MoxC-modified alloy@nitrogen-doped carbon hybrid electrocatalysts (MoxC-alloy@NC, alloy: FeCo, NiCo) for oxygen evolution reaction (OER) by a simple thermolysis method. Compared with FeCo@NC and NiCo@NC, the OER performances of MoxC-FeCo@NC and MoC-NiCo@NC are greatly enhanced, mainly due to the improved electrical conductivity by the introduce of MoxC. Moreover, MoxC-FeCo@NC exhibits a smaller Tafel slope (80 mV/dec) and a lower overpotential (318 mV) at 10 mA cm(-2) in 1 M KOH solution, compared with MoC-NiCo@NC (186 mV/dec, 352 mV). In consideration of a lower BET area (6.6 m(2) g(-1)) of MoxC-FeCo@NC than those of MoC-NiCo@NC (25.4 m(2) g(-2)), the remarkable electrocatalytic activity of MoxC-FeCo@NC is mainly attributed to the presence of Mo(II) acting as the OER active species. Although Mo as hydrogen evolution reaction (HER) active species is well known, Mo(II) as the OER active species has not been reported before. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.