Engineering Amorphous/Crystalline Ni/NiO Electrocatalysts for Highly Efficient Hydrogen Peroxide Production.

Abstract

Enhanced O2 adsorption and favorable oxygen-intermediate desorption are essential for efficient electrochemical hydrogen peroxide production (EHPP) via the two-electron oxygen reduction reaction (2e- ORR). Here, we report an amorphous/crystalline Ni-NiO electrocatalyst synthesized via a partial reduction strategy. By engineering the amorphous/crystalline interfacial strain through varying the reduction time, the optimized Ni/NiO catalyst achieves a hydrogen peroxide selectivity of 91.78% with a Faradaic efficiency of 97.47%. It maintains a high H2O2 yield of 949.5 mM/g-1cat h-1 across three electrode systems, outperforming most Ni-based benchmarks. Density functional theory calculations and in situ characterizations reveal that strain at unsaturated Ni sites promotes electron redistribution and Ni-O bond lengthening, thereby shifting the d-p band center difference to favor O2 adsorption while weakening *OOH binding. The enhanced O2 adsorption and accelerated *OOH desorption direct the ORR pathway toward the two-electron route for H2O2 generation. Furthermore, the in situ generated H2O2 effectively degrades organic pollutants, indicating its practical utility in water remediation. This work presents the strain engineering approach in amorphous/crystalline Ni/NiO heterostructures for high-performance EHPP and selective two-electron ORR.