The conversion of nitrate to ammonia can serve two important functions: mitigating nitrate pollution and offering a low energy intensity pathway for ammonia synthesis. Conventional ammonia synthesis from electrocatalytic nitrate reduction reactions (NO3RR) is often impeded by incomplete nitrate conversion, sluggish kinetics, and the competition of hydrogen evolution reactions. Herein, atomic Cu sites anchored on micro-/mesoporous nitrogen-doped carbon (Cu MNC) with fine-tuned hydrophilicity, micro-/mesoporous channels, and abundant Cu­(I) sites were synthesized for selective nitrate reduction to ammonia, achieving ambient temperature and pressure hydrogenation of nitrate. Laboratory experiments demonstrated that the catalyst has an ammonia yield rate per active site of 5466 mmol gCu –1 h–1 and transformed 94.8% nitrate in wastewater containing 100 mg-N L–1 to near drinking water standard (MCL of 5 mg-N L–1) at −0.64 V vs RHE. Extended X-ray absorption fine structure (EXAFS) and theoretical calculations showed that the coordination environment of Cu­(I) sites (Cu­(I)-N3C1) localizes the charge around the central Cu atoms and adsorbs *NO3 and *H onto neighboring Cu and C sites with balanced adsorption energy. The Cu­(I)-N3C1 moieties reduce the activation energy of rate-limiting steps (*HNO3 → *NO2, *NH2 → *NH3) compared with conventional Cu­(II)-N4 and lead to a thermodynamically favorable process to NH3. The as-prepared electrocatalytic cell can run continuously for 84 h (14 cycles) and produce 21.7 mgNH3 with only 5.64 × 10–3 kWh energy consumption, suitable for decentralized nitrate removal and ammonia synthesis from nitrate-containing wastewater.

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Tetracycline (TC) is hard to degrade and is usually present in the aqueous environment due to abuse. It is necessary to find effective treatment methods for TC pollution. In this...

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It is important to further enhance the performance of green and efficient non-homogeneous catalysts for advanced oxidation process of Peroxymonosulfate (PMS-AOP) for green treatment of industrial wastewater. In this paper, nitrogen–sulfur co-doped MOFs-derived carbon material (CoSN@C) was prepared by one-pot synthesis followed by carbonization, and its morphological structure was characterized by XRD and SEM. After pyrolysis, the CoSN@C still maintained the dodecahedral morphology and structure of ZIF-67. The synergistic effects of S and N significantly elevated the activation of PMS. The results show that the CoSN@C + PMS system can effectively activate PMS to degrade Rhodamine B (RhB), with a rate constant (1.85 min−1) four times higher than that of the CoN@C + PMS system (0.44 min−1). The optimal catalytic process parameters of material dosage, PMS concentration, temperature, pH, and other parameters were also investigated for the activation of PMS to remove Rhodamine B. The cyclic experiment shows that the CoSN@C has excellent recyclability and the degradation rate of RhB still reached 88.9% after four cycles. Radical capture experiments and EPR tests showed that the CoSN@C + PMS system generated a large amount of SO4·− and ·OH radicals adsorbed on the catalyst surface and a certain amount of singlet oxygen, and the free radical pathway and non-radical pathway worked together to degrade RhB efficiently and rapidly. While non-radical pathway with singlet oxygen as main reactive oxygen species played a key role in the CoN@C + PMS system. This work provides a new idea for the rational design of non-homogeneous catalysts for PMS-AOP system.