Construction of La decorated CoMoP composite and its highly efficient electrocatalytic activity for overall water splitting in alkaline media

A series of ultra-evenly La-decorated CoMoP composites have been fabricated by a selective corrosion and sequential in situ phosphorization strategy using La-doped Co-ZIF-67 as precursors. The electrochemical performance showed that introducing La ions within transition metal phosphides' structure could effectively optimize the electronic configuration and result in an excellent bifunctional electrocatalyst for overall water splitting. Along with the increased La doping content to 10 %, the catalytic activities of the composites for hydrogen evolution reaction (HER), and oxygen evolution reaction (OER) all tended to increase initially and then decrease. Among all the synthesized La-decorated CoMoP materials, the 5 % La-doped composite presented the most excellent HER and OER performance in 1 M KOH. The overpotential could reach 49 mV for HER and 250 mV for OER at 10 mA·cm−2, respectively. In addition, when employed as both anode and cathode to assemble an alkaline electrolyzer, it only required a cell voltage of 1.56 V to achieve a current density of 10 mA·cm−2, which is superior to the most reported precious-metal-free bifunctional catalysts. More importantly, the electrolyzer could maintain a stable water-splitting current density of 10 mA·cm−2 for at least 24 h without any deviation, highlighting its potential for practical applications.