Electrocatalytic nitrate reduction to ammonia (ENRA) offers a sustainable strategy for simultaneously mitigating nitrate pollution and producing green ammonia under ambient conditions. However, its efficiency is severely limited by sluggish multi-electron transfer kinetics and the competing hydrogen evolution reaction (HER), particularly due to insufficient regulation of interfacial active hydrogen species (*H). Polyoxometalates (POMs) feature abundant oxygen-rich sites capable of reversible protonation, thereby serving as an effective source of *H. Here, we report a POMs-modulated Cu₂O–Cu catalyts that enables synergistic regulation of interfacial electron distribution and *H availability. X-ray photoelectron spectroscopy confirms pronounced electron transfer between POMs and Cu₂O–Cu, while electrochemical analyses reveal that POMs modification significantly enhances the adsorption and storage capacity of *H, thereby promoting nitrate activation and hydrogenation. Density functional theory (DFT) calculations further reveal that POMs-induced interfacial charge redistribution optimizes nitrate intermediate adsorption and lowers the energy barrier of key proton-coupled electron transfer steps, thereby accelerating the ENRA pathway. As a result, the optimized catalyst delivers a high ammonia yield of 36.5 mg h⁻¹ mg_cat.⁻¹ and excellent Faradaic efficiency of 97.4%. This work provides a general strategy for constructing POMs-based electrocatalysts via interfacial electron and hydrogen regulation, offering new insights into the rational design of selective ENRA systems.

Nanozymes, which possess enzyme-like catalytic activity, are attractive alternatives to natural enzymes. Their activity is largely dependent on the structure of the material. However, challenges remain in optimizing the structure–activity relationship. This work explores the synthesis and utilization of PtCu nanostructures (NSs), focusing on their peroxidase (POD)-like properties and their potential as antibacterial agents. We developed PtCu dendrites that transform into unique dendroframe octahedrons (DFOs) and subsequently stabilize into solid octahedrons with unusual growth behaviour. The intermediate DFO, showed higher POD-like activity in comparison to other shapes of PtCu NSs. The DFOs also have the better ability to consume glutathione, thus enhancing their sterilization effect. Furthermore, we demonstrate the effectiveness of these PtCu DFOs as powerful antibacterial agents. This work provides valuable information on shape dependent activities of PtCu NSs in the field of biomedicine.