Heterostructured NiMo-sulfide micro-pillar arrays for advanced alkaline electrocatalytic clean hydrogen production via overall water splitting

Abstract

Transition metals doped molybdenum sulfide/oxide present themselves as capable for hydrogen evolution reaction (HER), because of their exceptional chemical and physical properties. In this study, we introduce a strategy for synthesizing molybdenum-based binary sulfide/oxide heterostructures using a hydrothermal method. An electrochemical investigation revealed the pivotal role of NiMo-sulfide in achieving remarkable bifunctional electrocatalytic activity, resulting in a current density of −50 mA cm−2 at an overpotential of 174 mV for HER. The excellent reaction kinetics were evident from the low Tafel slope of 116.8 mVdec−1. The electrolyzer showcased outstanding performance, with the best-performing NiMo-sulfide and benchmark RuO2 at the anode. It achieved a low cell potential of 1.60 V to reach 10 mA cm−2, exhibited remarkable durability for 100 h, and demonstrated promise for water splitting with a Faradaic efficiency of 94 and 89 % for O2 and H2 evolution respectively. Furthermore, the electrolyzer displayed potential for large-scale hydrogen production by attaining an industrially appropriate current density of 800 mA cm−2 at a cell potential of 2.24 V. This study also highlights the latest advancements in electrodialysis to enhance the catalytic activity of electrode materials. © 2024 Elsevier B.V.