Electrocatalytic nitrate reduction reaction (eNO₃RR) presents an innovative approach to achieve green NH₃ synthesis and mitigate environmental NO₃⁻ pollution. However, the bottleneck for large-scale application of eNO₃RR is the development of efficient electrocatalysts. Herein, inspired by the structure of nitrogenase and nitrate reductase, a novel Fe-Mo-based electrocatalyst (FeMoS-O) with distinctive bimetallic Fe-O-Mo active centers was developed using FeMo₂S₄ as the precursor via in situ electrochemical activation to induce surface O-doping. Combining comprehensive in situ characterizations and theoretical calculation results reveal that the Fe and Mo sites of the Fe-O-Mo center are responsible for the hydrogenation of NO_x species and the dissociation of H₂O, respectively, which is similar to the working mechanism of nitrate reductase. Meanwhile, O-doping on the Fe-O-Mo surface significantly reduces the energy barriers of the rate-determining steps of these two processes. As feedback, the synergistic effect of Mo and Fe sites endows the resultant FeMoS-O with excellent eNO₃RR performance under neutral conditions, with high faradaic efficiency (> 90%) in a potential window exceeding 0.50 V, large partial current density and yields, as well as quite good stability towards NH₃ production. This work provides new insights into the preparation of more advanced enzyme-mimicking catalysts.

Metal-free carbon catalysts are promising alternatives to noble-metal electrocatalysts for H₂O₂ production through two electron oxygen reduction reaction (2e⁻ ORR). Herein, a novel bioengineering approach is proposed to prepare N-doped hollow carbon nanoboxes from guanine precursor. The optimized NC-HNBs-550 exhibits an exceptional electrocatalytic performance, achieving a high H₂O₂ Faradaic efficiency (FE) of over 90% across a broad potential window exceeding 0.6 V. Remarkably, when tested in a flow cell configuration, NC-HNBs-550 delivers near-unity FE for H₂O₂ production at industrial-grade current densities, demonstrating its practicality for scalable applications. Impressively, the in situ electro-synthesized H₂O₂ is further employed as a green oxidant for rapid degradation of various organic dyes and even tetracyclines, and high-purity benzoyl peroxide (BPO) synthesis, highlighting its versatility in environmental and chemical applications. Combining experimental and theoretical analyses, we reveal that the superior 2e⁻ ORR activity originates from the abundance of pyrrolic-N species in NC-HNBs, which optimize the adsorption energy of *OOH intermediates and promote selective O₂ reduction. This work not only advances the rational design of biomass-derived carbon catalysts for sustainable H₂O₂ production but also provides a versatile platform for environmental remediation and value-added chemical production.