Modulating Ni d-band center via Ce incorporation for enhanced H2 evolution in seawater electrolysis

Abstract

The main reasons restricting the development of H₂ production through alkaline seawater splitting are the collapse of catalyst structures caused by seawater corrosion and the strong adsorption energy barrier for H* that exists on a nickel surface. In order to boost the activity and stability of catalysts during the alkaline seawater electrolysis process, this research employs a synergistic strategy combining Ce regulation and P coordination to develop a novel Ce,Ni-P@NF material. Herein, addition of the Ce reconfigured the electronic structure around Ni, and the XPS valence band spectroscopy confirmed that the d-band center (ε_d) of nickel shifted downward, thus optimizing the adsorption strength of H*. Density functional theory (DFT) calculations further indicate that the adsorption of H* on the Ce,Ni-P@NF surface have an optimum Gibbs free energy (ΔG_H*). Moreover, the introduction of Ce enhances the hybridization degree of P and Ni, improving the HER catalytic efficiency. Additionally, the in-situ attenuated total reflection surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) indicates that the addition of Ce enhances the ordering of water molecules at the material interface. It facilitates water to be easily adsorbed and dissociated on the surface of Ce,Ni-P@NF, thereby accelerating the generation of H₂. In alkaline seawater, the anion exchange membrane water electrolyzer (AEMWE) with Ce,Ni-P@NF as the cathode can operate stably for more than 120 h without any change in morphology. This paper provides a new idea for designing seawater electrolysis catalysts with resistance to chloride ion corrosion and high activity, which promotes the practical application of green H₂ production on a large scale.