Ammonia plays a signi cant role in agriculture and the next-generation carbon-free energy supply.Electrocatalytic nitrate reduction to NH 3 is attractive for nitrate removal and NH 3 production under ambient conditions. However, the energy e ciency is limited by the high reaction overpotential. Here, we propose a three-step relay mechanism composed of a spontaneous redox reaction, electrochemical reduction, and electrocatalytic reduction to overcome this issue. Ru x Co y alloys are designed and adopted as model catalysts. Ru 15 Co 85 exhibits an onset potential of +0.4 V versus a reversible hydrogen electrode and an energy e ciency of 41.54 ± 1.72 %, which are both the best records. The high performance results in a low production cost of $0.49 ± 0.02 /kg ammonia ($0.58~1.02/kg ammonia sold in the USA).Electrochemical in situ spectroscopy and theoretical simulations indicate that the three-step relay mechanism leads to excellent catalytic performance on Ru 15 Co 85 and can be extended to Ru x Fe y and Ru x Ni y alloys.

Cyclohexanone oxime, an important nylon-6 precursor, is conventionally synthesized through cyclohexanone-hydroxylamine (NH2OH) and cyclohexanone ammoxidation methodologies. These strategies require complicated procedures, high temperatures, noble metal catalysts, and toxic SO2 or H2O2 usage. Here, we report a one-step electrochemical strategy to synthesize cyclohexanone oxime from nitrite (NO2−) and cyclohexanone under ambient conditions using a low-cost Cu-S catalyst, avoiding complex procedures, noble metal catalysts and H2SO4/H2O2 usage. This strategy produces 92% yield and 99% selectivity of cyclohexanone oxime, comparable to the industrial route. The reaction undergoes a NO2− → NH2OH→oxime reaction pathway. This electrocatalytic strategy is suitable for the production of other oximes, highlighting the methodology universality. The amplified electrolysis experiment and techno-economic analysis confirm its practical potential. This study opens a mild, economical, and sustainable way for the alternative production of cyclohexanone oxime.

Ammonia plays a significant role in agriculture and the next-generation carbon-free energy supply. Electrocatalytic nitrate reduction to NH3 is attractive for nitrate removal and NH3 production under ambient conditions. However, the energy efficiency is limited by the high reaction overpotential. Here, we propose a three-step relay mechanism composed of a spontaneous redox reaction, electrochemical reduction, and electrocatalytic reduction to overcome this issue. RuxCoy alloys are designed and adopted as model catalysts. Ru15Co85 exhibits an onset potential of +0.4 V versus a reversible hydrogen electrode and an energy efficiency of 41.54 ± 1.72 %, which are both the best records. The high performance results in a low production cost of $0.49 ± 0.02 /kgammonia ($0.58~1.02/kgammonia sold in the USA). Electrochemical in situ spectroscopy and theoretical simulations indicate that the three-step relay mechanism leads to excellent catalytic performance on Ru15Co85 and can be extended to RuxFey and RuxNiy alloys.

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