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 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. Moreover, the in-situ/operando 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 with excellent stability. The present study delivers a favorable method for engineering low-cost and efficient dual-functional electrocatalysts for large-scale H₂ production.

Keywords: Pulse laser technology; CoGaIr-LDH nanosheets; Dual-functional electrocatalyst; Green H₂ fuel production; In-situ/operando Raman spectroscopy; Theoretical DFT analysis