Recent developments and prospects for engineering first-row transition metal-based catalysts for electrocatalytic NOx− reduction to ammonia

Abstract

Immense interest in the electrocatalytic reduction of nitrate (NO₃⁻)/nitrite (NO₂⁻) to ammonia has been driven by promising prospects as an eco-friendly and energy-efficient approach for wastewater treatment and ammonia synthesis. Currently, a variety of transition metal-based catalysts have been developed, but these still suffer from inferior selectivity and low energy conversion efficiency. Among diverse transition metal-based catalysts, first-row transition metal-based catalysts exhibit the advantages of suitable adsorption energies for NO_x⁻ species and high abundance. As a consequence, this review firstly discusses the reaction mechanisms and hurdles for reaching high-efficiency NH₃ production and analyses the principles for constructing superior NO_x⁻ reduction catalysts. Then, the focus of this review is placed on recent advances in first-row transition metal-based electrocatalysts, including Cu, Fe, Co, Ni, Ti-based electrocatalysts, for electrochemical NO₃⁻/NO₂⁻ reduction. Finally, the challenges and opportunities are highlighted for future studies and applications. This review provides novel perspectives and ideas for developing first-row transition metal-based NO_x⁻ reduction electrocatalysts.