The oxygen evolution reaction (OER) reaction kinetics of nickel-iron (oxy)hydroxides (NiFeOOH) is limited by their weak adsorption of OER intermediates. Herein, a hierarchical NiFeOOH@CeO2−x nanosheets array was in situ grown on a nickel foam by a facile laser direct writing method, which exhibits superior OER activity and durability at high current densities in alkaline electrolytes. The hierarchical nanosheets array exposes abundant catalytic active sites, which greatly promote OER reaction rate. The strong electronic interaction at the NiFeOOH/CeO2−x interface leads to favorable electron transfer from Ni2+/3+ and Fe3+ to Ce3+/4+. The Ni sites with high valences show enhanced OH− adsorption and also promote the formation of *OOH intermediate, thereby greatly improving OER intrinsic activity. The oxygen deficient CeO2−x primary sheets guarantee good electrical conductivity. Such a well-designed catalytic electrode requires overpotentials of only 229 and 287 mV to achieve current densities of 50 and 500 mA·cm−2, respectively, and sustains superior stability at 500 mA·cm−2 and 1 A·cm−2.
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Creating lattice defects and alloying to produce strain effect in Pt-based bimetallic alloys are both effective methods to optimize the crystal and electronic structure and improve the electrocatalytic performance. Unfortunately, the principles that govern the alkaline hydrogen evolution reaction (HER) performance remain unclear, which is detrimental to the rational design of efficient Pt-based electrocatalysts. Herein, PtNi alloys with different Pt/Ni ratios and edge dislocations were synthesized, and the effects of Pt/Ni composition and edge dislocations on the alkaline HER electrocatalytic activity of PtNi alloys were systematically studied. Combined experimental and theoretical investigations reveal that tuning Pt/Ni ratio results in only 1.1 times enhancements in Pt mass activity, whereas edge dislocations-induced extra tensile strain on Ni site and compressive strain on Pt site further boost the alkaline HER intrinsic activity at all Pt/Ni ratios. Impressively, the introduction of edge dislocations in PtNi alloys could break the limit of alloying in boosting Pt mass activity and result in up to 13.7-fold enhancement, in the case that Pt and Ni contents are nearly identical and thus edge dislocation density reaches the maximum. Fundamental mechanism studies demonstrate that the edge dislocation strategy could make a breakthrough in facilitating water dissociation kinetics of PtNi alloys.