Efficient electrochemical nitrate reduction reaction and a zinc–nitrate battery using atomically thin Cu-modified V2C MXenes

Abstract

The electrocatalytic nitrate reduction reaction (NO₃RR) to ammonia using green electricity presents a solution for a sustainable nitrogen cycle. However, challenges such as low catalytic activity and poor stability hinder its large-scale application. Herein, we developed a novel xCu–V₂C MXene catalyst via the atomic layer deposition (ALD) method for efficient NO₃RR to ammonia conversion. The optimized 15Cu–V₂C MXene catalyst achieves a high ammonia yield rate of 11.25 mol g_cat.⁻¹ h⁻¹ with near-unity faradaic efficiency at −1.0 V versus the reversible hydrogen electrode and retains stability over 30 cycles. The introduction of Cu through ALD enhances catalytic activity by improving mass transfer and intermediate formation. In addition, 15Cu–V₂C MXenes as a cathode enables efficient energy storage in zinc–nitrate batteries, achieving an open-circuit voltage of 1.52 V, a peak power density of 10.3 mW cm⁻² and a stable operation for 457 hours at 2 mA cm⁻².