Electrochemically co-deposited Pd-CoOx coating for efficient synergistic electrocatalytic reduction of nitrate to ammonia

Abstract

The electrocatalytic reduction of nitrate to ammonia offers a promising method for converting wastewater pollutants into essential chemical feedstocks. Pd-based catalysts exhibit remarkable performance for the NIRR, while their faradaic efficiency is suboptimal due to the challenges associated with nitrite transformation. We fabricated Pd-CoO_x catalysts through electrochemical co-deposition methods to improve the reduction of nitrite, achieving a high ammonia yield (30.3 mg h⁻¹ cm⁻²) and FE (98.7%). In situ Raman spectroscopy demonstrated that CoO_x significantly increased the number of Pd active sites. In situ FTIR reflection spectroscopy further revealed that CoO_x strengthened the desorption of hydroxyl groups, thus facilitating the intermediate reduction. We posit that our synergistic catalytic approach presents an encouraging avenue to promote the efficiency and low-toxicity of electrocatalytic nitrate reduction to ammonia.