Electrochemically In Situ Formed Active and Stable Surface Gradient Layer on Amorphous Ni-La-S-O Catalyst for...

The complex corrosive environment and interference from impurity ions in seawater present significant challenges for developing high-performance hydrogen evolution reaction (HER) electrocatalysts. Herein, amorphous Ni-La-S-O materials were developed in conjunction with an in situ electrochemical activation strategy to advance this field. Specifically, through chronopotentiometry at -2500 mA cm^-2 (CP2500), the amorphous Ni-La-S-O catalysts exhibit significantly enhanced HER performance accompanied by surface reconstruction processes, leading to an in situ formed active and stable 5 µm-thick surface gradient layer after CP2500-2 h. Remarkably, the optimal activated Ni-La-S-O (6-1) sample demonstrates superior corrosion-resistant and electrocatalytic performance, requiring overpotentials of only 158 and 226 mV to achieve industrial-level HER current densities of 1000 and 2000 mA cm^-2 in alkaline seawater and sustaining stable operation at 1000 mA cm^-2 for over 120 h, significantly outperforming commercial Pt/C and most other reported representative catalysts. Theoretical calculations further reveal that the activation induced by the CP-processing originates from the optimized d-band centers and reduced water dissociation energy barriers of the Ni-La-S-O catalyst via surface reconstruction. This work not only promotes the large-scale development of seawater electrolysis for hydrogen production but also offers a cutting-edge perspective on optimizing the performance and investigating the working mechanisms of amorphous catalysts.