Nanosized CoWO4 and NiWO4 as efficient oxygen-evolving electrocatalysts

A main challenge to improve the performance of large scale energy technologies based on photo-driven or electricity-driven production of hydrogen from water is the development of efficient and economical water oxidation catalysts. Herein, we, for the first time, report the CoWO4 and NiWO4 nanoparticles as new highly efficient electrode materials for oxygen evolution reaction (OER) in alkaline solutions. The study has shown that both the electrocatalysts efficiently evolve oxygen. At an overpotential (eta) in the OER region, the oxygen evolution current density on CoWO4 was much higher than that on NiWO4. At the current density of 10 mA cm(-2) (per geometrical area) in 1 M KOH, catalytic films of CoWO4 and NiWO4 on GC substrate produced eta approximate to 388 and 507 mV, respectively. When the GC catalyst support was replaced by nickel one, the overpotential required to achieve the current density of 10 mA cm(-2) on CoWO4 (eta approximate to 336 mV) and NiWO4 (eta approximate to 363 mV) electrodes decreased significantly. The OER has a low Tafel slope (approximate to 2 x 2.3 RT/3F) on both catalysts and follows nearly second order kinetics with respect to OH concentration, regardless of the nature of the support material. The catalytic films on Ni exhibited outstanding stability. (C) 2016 Elsevier Ltd. All rights reserved.