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.