Solar-Driven High-Rate Ammonia Production from Wastewater Coupled with Plastic Waste Reforming

Abstract

Solar-powered electrochemical NH₃ synthesis offers the benefits of sustainability and absence of CO₂ emissions but suffers from a poor solar-to-ammonia yield rate (SAY) due to a low NH₃ selectivity, large bias caused by the sluggish oxygen evolution reaction, and low photocurrent in the corresponding photovoltaics. Herein, a highly efficient photovoltaic–electrocatalytic system enabling high-rate solar-driven NH₃ synthesis was developed. A high-performance Ru-doped Co nanotube catalyst was used to selectively promote the nitrite reduction reaction (NO₂RR), exhibiting a faradaic efficiency of 99.6% and half-cell energy efficiency of 52.3% at 0.15 V vs the reversible hydrogen electrode, delivering a high NO₂RR selectivity even in electrolytes with high NO₃^– and low NO₂^– concentrations. Thus, the promoted NO₂RR was coupled with the ethylene glycol oxidation reaction and a perovskite photovoltaic cell to achieve the highest SAY reported to date (146 ± 1 μmol h^–1 cm^–2) and stable operation.