Tungsten diphosphide nanorods as an efficient catalyst for electrochemical hydrogen evolution

A novel tungsten diphosphide nanorods (WP 2 NRs) material with good crystallinity is synthesized as an efficient hydrogen evolution reaction (HER) electrocatalyst for the first time through phosphidation of (NH 4 ) 0.25 WO 3 NRs precursor. Towards HER the WP 2 NRs exhibit an onset overpotential of 56   mV, a Tafel slope of 52   mV per decade and an exchange current density of 0.013   mA   cm −2 in acidic media. Further, the catalyst only needs overpotentials of 101 and 148   mV to deliver current densities of 2 and 10   mA   cm −2 , respectively. In particular, the catalyst can maintain its catalytic activity for 90 h at least, showing good long term operation stability. It also has excellent activity and stability under both neutral and basic conditions. The catalysis mechanism of WP 2 NRs is explored for the fundamental insights.