Vanadium nitride based CoFe prussian blue analogues for enhanced electrocatalytic oxygen evolution

The development of efficient and stable nonprecious-metal catalysts remains a challenge for electrochemical water oxidation in practical applications. Prussian blue analogues (MM'-PBAs, A(x)M(y) [M'(CN)(6)], -nH(2)O: A = alkali metal; M/M' = transition metals), as a kind of potential electrocatalyst candidate for oxygen evolution reaction (OER), are rarely studied. Herein, by a facile coprecipitation method, CoFe-PBAs were in-situ grown on the surface of highly conductive vanadium nitride (VN) particles. The hybrid CoFe-PBAs/VN achieves the amelioration of the poor conductivity of bare CoFe-PBAs and the increase in the density of Co2+ active sites due to electron interaction. Compared with bare CoFe-PBAs (over-potential of 398 mV at 10 mA cm(-2) and Tafel slope of 78.35 mV dec(-1)), the CoFe-PBAsNN manifests a remarkably enhanced electrocatalytic activity for OER (lower overpotential of 290 mV at 10 mA cm(-2) and a smaller Tafel slope of 39.72 mV dec(-1)), which is superior among PBAs and PBAs-derived materials reported as electrocatalysts for OER. Besides, this hybrid material behaves an excellent long-term durability. High conductivity of VN and electron interaction between VN and CoFe-PBAs contribute to the promoted catalytic performance. This study provides a novel strategy using VN substrates to support PBAs-based catalysts so as to obtain highly active and stable electrocatalysts towards practical applications. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.