Electronic and Lattice Modulation of Co_xP Nanosheets by In-Situ Doped Boron to Enhance Activity and *Cl Anti-Poisoning in Alkaline Seawater Electrolysis

Abstract

The high chloride (Cl) concentration in seawater presents a critical challenge for hydrogen production via seawater electrolysis by deactivating catalysts through active site passivation, highlighting the need for catalyst innovation. Herein, in situ boron-doped Co₂P/CoP (B-Co_xP) ultrathin nanosheet arrays are prepared as high-performance bifunctional electrocatalysts for seawater decomposition. Density functional theory (DFT) simulations, comprehensive characterizations, and in-situ analyses reveal that boron doping enhances electron density around Co centers, induces lattice distortions, and significantly elevates catalytic activity and durability. Moreover, boron doping reduces *Cl retention time at active sites—defined as the DFT-derived residence time of adsorbed Cl intermediates based on their adsorption energies—effectively mitigating Cl-induced poisoning. In a three-electrode system, B-Co_xP achieves exceptional bifunctional performance with overpotentials of 11 mV for hydrogen evolution reaction and 196 mV for oxygen evolution reaction to deliver 10 and 50 mA·cm^–2, respectively—a result that showcases its superior bifunctional properties surpassing noble metal-based counterparts. In an alkaline electrolyzer, it delivers 1.56 A·cm^–2 at 2.87 V for seawater electrolysis with outstanding stability over 500 h, preserving active site integrity via boron's robust protective role. This study defines a paradigm for designing advanced seawater electrolysis catalysts through a strategic in-situ doping approach.

Keywords

alkaline electrolyzers / alkaline seawater electrolysis / bifunctional catalyst / in-situ B doping / reduces *Cl retention

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