Ce Single Atom‐Engineered Amorphous/Crystalline Nanosheets for Enhanced Alkaline Water Electrolysis

Designing nanocatalysts with fast water dissociation kinetics is key to achieving the industrial current density of the cathodic hydrogen evolution reaction (HER) for green hydrogen production via water electrolysis, which remains a grand challenge. Here, leverage single‐atom engineering,a Ce single‐atom‐doped amorphous RuO x nanosheet featuring abundant amorphous/crystalline nanojunctions, namely, ac‐Ce SA RuO x is successfully developed. When employed as a catalyst for alkaline HER, the ac‐Ce SA RuO x catalyst displays an overpotential of only 8.3 mV at 10 mA cm −2 and Tafel slope as low as 23.1 mV dec −1 , outperforming the Ru‐based catalysts reported in recent studies. Anion exchange‐membrane water electrolyzers (AEMWEs) tests using ac‐Ce SA RuO x as the cathode catalyst exhibit a low cell voltage of 1.71 V at 1000 mA cm −2 , and the performance can be well maintained after 300 h. In situ spectroscopic analyses demonstrate the increased coverage of OH species on ac‐Ce SA RuO x for enhanced water dissociation. Density function theory calculations suggest that the Ce‐doped crystalline nanodomains in the amorphous/nanocrystalline nanojunction could effectively reduce the energy barrier to water dissociation, while the Ce‐doped amorphous constituents regulate the H * adsorption, which collectively boost the HER performance. This work offers a new strategy to create amorphous/nanocrystalline nanojunctions in nanocatalysts for enhanced electrocatalysis.