Materials that recover dilute metals and convert the recovered species into functional catalysts can link resource circularity with environmental remediation, yet their design is constrained by a trade-off between rapid transport and reactive binding. Here, we report a ZIF−8-derived hollow N-doped porous carbon (HNPC) as a capture-to-catalyst platform for closed-loop gold recovery and nitrate-to-ammonia electrocatalysis. The hollow mesoporous framework shortens diffusion pathways and improves access to internal surfaces, whereas graphitic-N-associated sites promote AuCl₄⁻ adsorption and Au(III)-to-Au(0) reduction. The optimized HNPC exhibits a Langmuir Au(III) capacity of 3245.1 mg·g^-1 and removes >99.9% of Au at trace concentrations under strong ionic competition, corresponding to a distribution coefficient of ~3×10⁹ mL·g⁻¹. Time-resolved microscopy and spectroscopy reveal rapid Au nanoparticle nucleation and progressive conversion to Au(0), while finite−element simulations and density functional theory (DFT) identify the cooperative roles of hollow-structure-enabled transport and graphitic-N-regulated interfacial reactivity. The resulting Au/HNPC is directly reused as a gas-diffusion-electrode catalyst, delivering 96.6% Faradaic efficiency for nitrate-to-ammonia conversion and stable operation for 535 h at 200 mA·cm⁻²_. This work establishes a materials strategy for integrating selective recovery, in situ metal formation, and catalytic reuse in complex aqueous media.

Electrochemical nitric oxide reduction reaction (NORR) to produce ammonia (NH₃) under ambient conditions is a promising alternative to the energy and carbon-intensive Haber–Bosch approach, but its performance is still improved. Herein, molybdenum carbides (MoC) nanocrystals confined by nitrogen-doped carbon nanosheets are first designed as an efficient and durable electrocatalyst for catalyzing the reduction of NO to NH₃ with maximal Faradaic efficiency of 89% ± 2% and a yield rate of 1,350 ± 15 μg·h⁻¹·cm⁻² at the applied potential of −0.8 V vs. reversible hydrogen electrode (RHE) as well as high stable activity with negligible current density and NH₃ yield rate decays over a 30 h continue the test. Moreover, as a proof-of-concept of Zn–NO battery, it achieves a peak power density of 1.8 mW·cm⁻² and a large NH₃ yield rate of 782 ± 10 μg·h⁻¹·cm⁻², which are comparable to the best-reported results. Theoretical calculations reveal that the MoC(111) has a strong electronic interaction with NO molecules and thus lowering the energy barrier of the potential-determining step and suppressing hydrogen evolution kinetics. This work suggests that Mo-based materials are a powerful platform providing great opportunities to explore highly selective and active catalysts for NH₃ production.