Rational Engineering on Copper-Silver-Ruthenium Heterostructures for the Electrocatalytic Conversion of Nitrate and Glycerol.

Coupling nitrate reduction reaction (NORR) with glycerol oxidation reaction (GOR) establishes a sustainable "C─N co-conversion" electrolysis system to generate ammonium formate. Unfortunately, the rational design of high-performance bifunctional electrocatalysts remains challenging. Herein, we developed a 3D Ag/Ru-decorated CuO/Cu(OH) heterostructures supported by copper foams via interface engineering. The optimal catalyst exhibited outstanding NORR and GOR performance, achieving Faradaic efficiency (FE) of 97.3% and yield of 9.85 mg h cm at -0.5 V vs. RHE for NH synthesis, and FE of 82.6% and yield of 90.31 mg h cm at 1.55 V vs. RHE for formate production. Mechanistic studies revealed that the decoration of Ag and Ru atoms led to electron redistribution around the copper sites, promoting proton-coupled electron transfer and optimizing the adsorption of the reactants/intermediates. Notably, on the basis of the as-prepared bifunctional electrode, a "NORR || GOR" electrolyzer was constructed, which achieved simultaneous output of NH and formate with a current density of 100 mA cm at only 1.48 V. The performance of the electrolyzer was further demonstrated using simulated nitrate pollutants and crude glycerol as feedstock, yielding 20.9 g of ammonium formate via a 4-h electrolysis. This work demonstrates a sustainable pathway for the synthesis of high-value-added ammonium formate by constructing an efficient bifunctional electrocatalyst through rational interfacial engineering.