Manipulating Interfacial Water Configuration via Constructing Asymmetric Structure Unit for Hydrogen Production in Alkaline Seawater

Abstract The configuration of interfacial water molecules plays a crucial role in affecting the alkaline hydrogen evolution reaction (HER). Here, a strategy of altering the water molecular configuration through element doping is proposed to enhance HER activity in seawater splitting. By doping the Mo─O group into FeP to construct a Mo─O─FeP asymmetric structure, ab initio molecular dynamics (AIMD) and in situ Raman results demonstrate that Mo─O doping changes the molecular configuration, and more free water on the catalyst surface is dissociated to continuously supply sufficient protons during the HER process, accelerating the HER kinetics and mass transfer process. Density functional theory (DFT) calculations reveal that the Mo─O─FeP catalyst achieves a more balanced H adsorption/desorption. Additionally, asymmetric structure reduces the adsorption energy of Cl ⁻ at the Fe site, preventing Cl ⁻ poisoning in seawater. Benefiting from the above, Mo─O─FeP can reach 1000 mA cm ⁻² with an overpotential of 279 mV in alkaline seawater and has excellent stability. In addition, an AEM electrolyzer assembled from Mo─O─FeP demonstrates outstanding activity and can maintain stable operation for more than 100 h.