Efficient electrochemical coupling of nitrate and biomass-derived acetone to acetoxime at a high current density over a Zn/Cu hexagonal nanosheet catalyst

Abstract

Acetoxime, as an important type of organic compound containing a CN bond, is commonly employed as a boiler chemical deoxygenation agent and boiler acid pickling passivator due to its low toxicity and high reducibility characteristics. The conventional synthesis of acetoxime involves the initial catalysis of NO_x and H₂ under harsh conditions by noble metal catalysts to generate unstable NH₂OH, which further reacts with acetone to form acetoxime. Herein, we report a Zn/Cu/CF hexagonal ultrathin nanosheet catalyst capable of efficiently catalyzing the coupling reaction between NH₂OH produced in situ from electrocatalytic NO₃⁻ reduction and CH₃COCH₃ to generate an oxime under ambient conditions. The presence of Cu facilitates the conversion of NO₃⁻, while the introduction of Zn is favourable to accelerate the electron transfer rate, enhance the number of active sites, and suppress the reduction hydrogenation of *CH₃COCH₃, thereby significantly improving the activity of oxime. Through catalyst screening and the optimization of electrolysis conditions, a faradaic efficiency of 44.5% with a yield rate of 415.5 μmol cm⁻² h⁻¹ is achieved at an industrially relevant current density of −150 mA cm⁻² in the electrolyte containing 0.2 M NO₃⁻ + 0.2 M CH₃COCH₃ over the Zn/Cu-CF-6 electrocatalyst, corresponding to a C selectivity approaching 100%. A series of control experiments and in situ characterization studies indicate that *NH₂OH and *CH₃COCH₃ are crucial intermediates for the synthesis of acetoxime, proposing a plausible reaction pathway. This work presents a facile synthesis method for Zn/Cu/CF hexagonal nanosheet catalysts and proposes a green strategy for the one-pot efficient electrochemical synthesis of acetoxime from pollutants NO₃⁻ and biomass-derived acetone, offering a green pathway for high-value-added CN product synthesis.