A Copper–Zinc Cyanamide Solid-Solution Catalyst with Tailored Surface Electrostatic Potentials Promotes Asymmetric N-Intermediate Adsorption in Nitrite Electroreduction

Abstract

The electrocatalytic nitrite reduction (NO₂RR) converts nitrogen-containing pollutants to high-value ammonia (NH₃) under ambient conditions. However, its multiple intermediates and multielectron coupled proton transfer process lead to low activity and NH₃ selectivity for the existing electrocatalysts. Herein, we synthesize a solid-solution copper–zinc cyanamide (Cu_0.8Zn_0.2NCN) with localized structure distortion and tailored surface electrostatic potential, allowing for the asymmetric binding of NO₂^–. It exhibits outstanding NO₂RR performance with a Faradaic efficiency of ∼100% and an NH₃ yield of 22 mg h^–1 cm^–2, among the best for such a process. Theoretical calculations and in situ spectroscopic measurements demonstrate that Cu–Zn sites coordinated with linear polarized [NCN]^2– could transform symmetric [Cu–O–N–O–Cu] in CuNCN-NO₂^– to a [Cu–N–O–Zn] asymmetric configuration in Cu_0.8Zn_0.2NCN-NO₂^–, thus enhancing adsorption and bond cleavage. A paired electro-refinery with the Cu_0.8Zn_0.2NCN cathode reaches 2000 mA cm^–2 at 2.36 V and remains fully operational at industrial-level 400 mA cm^–2 for >140 h with a NH₃ production rate of ∼30 mg_NH3 h^–1 cm^–2. Our work opens a new avenue of tailoring surface electrostatic potentials using a solid-solution strategy for advanced electrocatalysis.