A facile silicon doping strategy constructing “M–O–Si” bonds in ZnCo-LDH for efficient neutral nitrate reduction to ammonia and Zn–NO3− battery

Abstract

The development of efficient electrocatalysts for the nitrate reduction reaction (NO₃⁻RR) to ammonia in neutral media is often hindered by complex synthesis methods and insufficient catalytic performance. In this study, we report a highly facile and rapid (30 seconds) room-temperature etching method for synthesizing silicon-doped ZnCo layered double hydroxides (Si-ZnCo-LDH/Cu), which facilitates the formation of abundant “M–O–Si” (M = Zn, Co) linkages. This silicon-induced modulation of the electronic structure significantly enhances NO₃⁻RR activity. The Si-ZnCo-LDH/Cu catalyst achieves an ammonia production rate of 25.71 mg h⁻¹ cm⁻² in neutral electrolyte with a Faradaic efficiency of 93.6%, markedly surpassing that of the pristine ZnCo-LDH/Cu (16.03 mg h⁻¹ cm⁻², 58.4%). Comprehensive experimental and theoretical investigations demonstrate that the “M–O–Si” bond acts as a key active site, promoting electron transfer and optimizing the adsorption of critical intermediates, thereby reducing the energy barrier of the rate-determining step (*NO → *NOH) from 0.97 eV to 0.51 eV and effectively suppressing the competing hydrogen evolution reaction. Furthermore, a Zn–nitrate battery assembled with Si-ZnCo-LDH/Cu delivers a maximum power density of 17 mW cm⁻², maintaining stable operation for 60 hours. This work presents a universal and effective doping strategy for the rational design of high-performance layered electrocatalysts.