Minimal lanthanum-doping triggered enhancement in bifunctional water splitting activity of molybdenum oxide/sulfide heterostructure through structural evolution

Abstract

Mo-based materials have shown significant promise to be efficient electrocatalysts for hydrogen evolution reaction however; a strategy to induce bifunctional electrocatalytic activity has been left unexplored. A heterostructure containing both sulfide and oxide of Mo would be beneficial in achieving the desired bifunctional activity towards overall water splitting. A unique approach was adopted to design the Mo oxide/sulfide heterostructure with sufficient bifunctional activity. Interestingly, minimal doping of La was able to trigger further structural evolution in it. Elemental doping often caused changes in crystallographic features of materials, however; structural changes with such minimal doping was never achieved previously. La doping accompanied with structural evolution was proven to be beneficial for the heterostructure in achieving superior activity. The doped heterostructure with optimized physicochemical features achieved 10 mA cm−2 for overall water splitting at 1.58 V, which was 100 mV lower than that required for the RuO2-Pt/C couple. This investigation had opened up a new dimension in designing heterostructure-based bifunctional electrocatalyst through minimal-rare-earth-metal-doping-induced structural evolution.