Selenium vacancy and phosphorus-doping-induced phase transition engineering of cobalt diselenide as bi-functional catalyst for water electrolysis

Abstract

Abstract This study demonstrates a two-step approach for the synthesis of a cobalt phosphoselenide nanobelt (H–CoSe(2−x)Px NB) that has excellent activity for the hydrogen evolution reaction over a wide pH range (0–14), exhibiting low overpotentials of 112, 261, and 391\xa0mV at a current density of 10\xa0mA\xa0cm−2 in 0.5\xa0M\xa0H2SO4, 1\xa0M KOH, and 1\xa0M phosphate-buffered solution, respectively. Conversely, the H–CoSe(2−x)Px NB can be used for the oxygen evolution reaction in basic media, for which its electrochemical performance is superior to that of a platinum catalyst. When a H–CoSe(2−x)Px NB is used on both sides of a single electrolysis cell, almost no degradation occurs at various constant potentials for 12\xa0h period. Its high performance, electrode stability, and easy synthesis suggest that the H–CoSe(2−x)Px NB is an efficient and economic electrocatalyst for water electrolysis.