The synergistic Cu⁰-Cu^δ+ sites are found as the active sites for NH₃ synthesis through nitrate electroreduction reaction, but still face significant challenges in stabilizing the Cu^δ+ due to its self-reduction. Here we propose an Ohmic contact interface engineering strategy by loading copper nano-islands on indium hydroxide nanocubes. Attributed to the lower work function of Cu than that of In(OH)₃ with n-type semiconductor nature, the electrons in Cu can transfer unimpededly to In(OH)₃ at the interface of Ohmic junction, triggering and stabilizing polarized Cu⁰-Cu^δ+ active sites. Cu@In(OH)₃ sustains both high NH₃ yield rate (4.28 mmol h⁻¹ mg_cat.⁻¹) and Faradaic efficiency (97.35%) at −0.6 V vs. RHE, while maintaining stability for at least 120 h under an Ampere-level of 800 mA cm⁻². Such Ohmic contact interface engineering approach allows for simultaneously constructing and stabilizing the Cu⁰-Cu^δ+ for the electrosynthesis of ammonia, as well as other value-added chemicals relying on above active sites.

A largely unexplored approach for optimizing surface strains on terrace-type catalysts is the break of atomic symmetry to release surface stress. The key challenge lies in how to implement this approach into practical nanocatalysts, in particular the promising high-entropy alloys (HEAs). Herein, we design and synthesize a series of HEA nanorings (NRs) with abundant terrace-type defects for oxygen reduction reaction (ORR) electrocatalysis. The asymmetry-triggered release of surface stress enables the modulation of compressive strain for optimizing the electronic structure. On the optimally-tuned PtPdFeCoNi HEA NRs, we achieve mass and specific activities of 0.99 A mg^-1_{platinum group metal (PGM)} and 1.32 mA cm^-2_PGM at 0.95 V versus reversible hydrogen electrode (vs. RHE), demonstrating a competitive performance. Experimental and theoretical investigations unveil that the stress-released compressive strain lowers the d-band center of Pt sites in HEA NRs, resulting in favorable desorption of oxygenated intermediates and thus accelerated ORR kinetics.