Insights into dual-functional catalytic activity of laser-driven CoGaIr-LDH nanosheets in water electrolysis for green hydrogen production via in-situ Raman and theoretical analyses

Abstract

The fabrication of inexpensive dual-functional electrocatalysts with exceptional stability is imperative for clean hydrogen (H2) production via water electrolysis. Herein, we synthesized iridium-doped cobalt gallium-layered double hydroxide (CoGaIr-LDH) nanosheets through a straightforward pulsed laser irradiation in liquid (PLIL) method and investigated their potential as dual-functional electrocatalysts in water electrolysis. The resulting trimetallic CoGaIr-LDH exhibits enhanced activity towards the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) compared to pure CoGa-LDH. Remarkably, the CoGaIr-LDH-20 demonstrates low overpotentials of 190 and 274 mV at 10 mA⋅cm−2 for HER and OER, respectively. Subsequently, CoGaIr-LDH-20 demonstrates exceptional long-term stability for both HER and OER, maintaining its catalytic activity without significant loss after 12 h of continuous operation. Moreover, the in-situ Raman spectroscopy displays active sites at the electrode–electrolyte interface, highlighting the surface growing of effective β-Co(OH)2 and metallic Ir0 intermediates during HER and CoOOH and CoO2 intermediates during OER. Intriguingly, density functional theory (DFT) findings indicate that the Ir dopant is crucial in modifying the electronic structure of CoGa-LDH, increasing charge transfer kinetics of the electrochemical process, and providing additional catalytic sites, thereby boosting both HER and OER performances. Accordingly, the water electrolyzer employing CoGaIr-LDH-20||CoGaIr-LDH-20 achieves a low cell voltage of 1.65 V at 10 mA⋅cm−2 and exhibits excellent stability over 12 h. This study provides a practical and effective strategy for designing cost-efficient, highly stable, and efficient dual-functional electrocatalysts for high-performance water electrolyzers, thus scalable H2 production. © 2024 Elsevier B.V.