Electrocatalytic Co-Upcycling of Nitrite and Ethylene Glycol over Cobalt–Copper Oxides

Electrocatalytic nitrite (NO₂⁻) reduction reaction (NO₂⁻RR) for ammonia (NH₃) synthesis is a promising alternative for NO₂⁻ resource utilization. Herein, a dual-site copper-cobalt oxide catalyst is reported for the efficient electrocatalytic reduction of NO₂⁻ to NH₃, exhibiting NH₃ Faradaic efficiency that remained above 95% (0.1 m NaNO₂) over a wide potential window (−0.1 to −0.6 V vs reversible hydrogen electrode, vs RHE). More importantly, the high NH₃ Faradaic efficiency maintains an over 85% (−0.1 to −0.3 V vs RHE) at a low concentration of NaNO₂ (0.01 m). Theoretical calculations demonstrate that CuO serves the ^*NO₂ to ^*NO and is subsequently converted to NH₃ on Co₃O₄. Coupled anodic ethylene glycol (EG) oxidation reaction endows low cell voltage (ΔU = 480 mV, 10 mA cm⁻²) and energy consumption saving (>23%) in a two-electrode system. This work provides a reference for a co-upcycling electrolyzer for NO₂⁻ and EG. © 2024 Wiley-VCH GmbH.