Efficient Electrocatalytic Nitrate Reduction to Ammonia Based on DNA-Templated Copper Nanoclusters

In alkaline solutions, the electrocatalytic conversion of nitrates to ammonia (NH 3 ) (NO 3 RR) is hindered by the sluggish hydrogenation step due to the lack of protons on the electrode surface, making it a grand challenge to synthesize NH 3 at a high rate and selectivity. Herein, single-stranded deoxyribonucleic acid (ssDNA)-templated copper nanoclusters (CuNCs) were synthesized for the electrocatalytic production of NH 3 . Because ssDNA was involved in the optimization of the interfacial water distribution and H-bond network connectivity, the water-electrolysis-induced proton generation was enhanced on the electrode surface, which facilitated the NO 3 RR kinetics. The activation energy ( E a ) and in situ spectroscopy studies adequately demonstrated that the NO 3 RR was exothermic until NH 3 desorption, indicating that, in alkaline media, the NO 3 RR catalyzed by ssDNA-templated CuNCs followed the same reaction path as the NO 3 RR in acidic media. Electrocatalytic tests further verified the efficiency of ssDNA-templated CuNCs, which achieved a high NH 3 yield rate of 2.62 mg h –1 cm –2 and a Faraday efficiency of 96.8% at −0.6 V vs reversible hydrogen electrode. The results of this study lay the foundation for engineering catalyst surface ligands for the electrocatalytic NO 3 RR.