In Situ Reconstruction of Partially Hydroxylated Porous Rh Metallene for Ethylene Glycol‐Assisted Seawater Splitting

Abstract Designing efficient and durable electrocatalysts for seawater electrolysis shows a great research prospect, but it remains a significant challenge. Herein, we report the partially hydroxylated Rh metallene (Rh/RhOOH metallene) with porous, ultrathin, defect‐rich and hetero‐phase structure for ethylene glycol (EG)‐assisted seawater electrolysis. In parallel, the unique redox effect of RhOOH species and EG as well as the electroreduction effect riggers the in situ reconstruction for the catalyst during electrocatalysis, which further produces active Rh species to optimize the catalytic activity center and surface catalytic reaction. Benefiting from the unique metallene structure and the Rh/RhOOH heterogeneous structure, the Rh/RhOOH metallene exhibits superior electrocatalytic performance towards hydrogen evolution reaction (HER, overpotential of 29 mV) and EG oxidation reaction (EGOR, specific activity of 1.051 mA cm –2 ). Encouragingly, in the constructed EG‐assisted seawater electrolysis system, the Rh/RhOOH metallene only needs a low cell voltage of 0.678 V to achieve a current density of 10 mA cm –2 for energy‐saving H 2 production, which significantly reduces energy consumption compared to conventional seawater electrolysis.