Co3W intermetallic compound as an efficient hydrogen evolution electrocatalyst for water splitting and electrocoagulation in non-acidic media.

• Co 3 W intermetallic compound is transformed from CoWO 4 by thermal reduction. • Co 3 W presents high performance for HER in non-acidic media. • H 2 production and wastewater treatment are achieved at the same time. The hydrogen evolution reaction (HER) is the cathodic reaction of water electrolysis and electrocoagulation. The development of precious metal-free HER catalyst with high performance is important to decrease the energy consumption and capital cost. Due to the adjustable electronic structure and composition, intermetallic compounds are promising candidates to act as efficient HER catalysts. Herein, Co 3 W intermetallic compound is synthesized by reducing CoWO 4 with H 2 , during which CoWO 4 is transformed into a composite in the form of Co 3 W interconnected with W. The Co 3 W/W composite requires a low overpotential of 78 mV to reach the current density of 10 mA cm−2 in 1 M KOH. Moreover, the electrocoagulation device assembled by Co 3 W/W composite and iron plate only needs 0.2 V to initiate H 2 production in 0.5 M Na 2 SO 4 ; meanwhile, high removal ability for multiple water pollutants is also achieved. As the active species, Co 3 W presents low water dissociation energy barrier and proper adsorption strength of hydrogen atom, both of which are beneficial to HER kinetics. This work demonstrates a promising HER electrocatalyst that can be applied in non-acidic media for water splitting and electrocoagulation. [ABSTRACT FROM AUTHOR]