Construction of ternary alloy Cu-Ni-Co catalysts with highly active sites to enhance the initial adsorption process of nitrate reduction to ammonia

Abstract

Ammonia, an exceptional carbon-free hydrogen source, holds significant promise as a product of electrocatalytic nitrate reduction to ammonia (ENRA) processes. Nonetheless, developing efficient ENRA catalysts remains a formidable challenge due to the intricacies of the eight-electron transfer process that generates a range of complex intermediates, impeding the desired ammonia formation. By offering multiple adsorption sites for various intermediates, multicomponent metal catalysts effectively regulate the processes of proton and electron transfer, providing a viable solution. To address this, CuNiCo alloy catalysts, denoted as CuNiCo/CP, are synthesized via co-deposition, employing salicylic acid as a complexing agent. The CuNiCo/CP alloy catalyst exhibits an ammonia yield of up to 303.49 μmol h–1cm–2 at –0.25 V vs. RHE, Faraday efficiency of up to 96.3 %, and excellent stability. Notably, a battery utilizing Zn-NO3− and CuNiCo/CP as the cathode exhibits an impressive peak power density of 9.678 mW cm–2. Experiment and DFT calculations demonstrate that CuCoNi/CP can provide more active sites and effective modulation of the initial adsorption energy. This work will inspire further Cu-based alloy ENRA catalyst development to optimize the adsorption of multiple intermediates to enhance catalyst activity and selectivity.