Valorization systems of electrocatalytic nitrate/nitrite conversion for energy supply and valuable product synthesis

Abstract

The excessive accumulation of nitrate/nitrite (NOx-) in surface and groundwater has severely disrupted global nitrogen cycle and jeopardized public health. The electrochemical conversion of NOx- to ammonia (NH3) not only holds promise for ecofriendly NOx- removal, but also provides a green alternate to the energy-intensive Haber–Bosch process for NH3 production. Recently, in addition to electrocatalyst design explosion in this field, many innovative valorization systems based on NOx--to-NH3 conversion have been developed for generating energy and expanding the range of value-added products. Collective knowledge of advanced conversion systems is indispensable for restoring global nitrogen cycle and promoting N-based economy. Herein, a timely and comprehensive review is provided on the important progresses of valorization systems based on NOx- conversion, including waste treating system, novel electrolytic systems, and energy conversion and storage systems. Some mechanism explorations, device designs, key electrode developments and feasibility analyses are involved to gain deeper understanding of various systems and facilitate implementing these cleaning systems in industry. Finally, challenges and future perspectives are outlined in the NOx- conversion field with an aim to promote large-scale electrocatalytic system development and prosperous N-based electrochemistry.