Self-supported three-dimensional WP2 (WP) nanosheet arrays for efficient electrocatalytic hydrogen evolution

The development of highly efficient, stable, eco-friendly and low-cost noble-metal-free electrocatalysts is still a great challenge to generate large scale hydrogen fuel from water. In this concern, self-supported WP2 and WP nanosheet (NS) arrays were prepared through an in-situ solid-phase phosphidation of WO3 nanosheet arrays on carbon cloth (CC), whereas, different phosphating temperatures of 650 degrees C, 800 degrees C for 2 h, has been utilized to attain different WP2 NS/CC, WP NS/CC catalysts. Remarkably, the electrocatalysts of WP2 and WP NS arrays exhibit an outstanding hydrogen evolution (HER) performance in acidic environment, with a low overpotential of 140 mV and 175 mV at 10 mA cm(-2), a Tafel slope of 85 mV dec(-1) and 103 mV dec(-1), respectively. Furthermore, Density Functional Theory (DFT) calculations reveal that the enhanced HER activity of WP2 catalyst is attributed to the lowered hydrogen adsorption free energy on WP2 surface, which is much lesser than that on the WP catalyst surface. As a result, WP2 exhibit superior intrinsic catalytic activity than WP. This study offers a valuable way for the synthesis of highly efficient three-dimensional self-supporting catalytic electrodes, and beneficial for realizing the intrinsic electrocatalytic properties of tungsten phosphide for improved water splitting reactions. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.