The in situ decoration of Ti3C2 quantum dots on Cu nanowires for highly efficient electrocatalytic reduction of nitric oxide to ammonia

Abstract

In order to solve the environmental problems caused by the ever-growing NO emission from the combustion of fossil fuels, an electrocatalytic reduction technique has been developed to convert NO into NH₃ under ambient conditions, which is also regarded as a promising alternative for the traditional Haber–Bosch process. Catalysts with excellent activity and selectivity are necessary for the efficient NO reduction to NH₃. Herein, we decorated Ti₃C₂ quantum dots (Ti₃C₂ QDs) on Cu nanowires (Cu NWs) as an efficient and stable electrocatalyst (Ti₃C₂ QDs/Cu NWs) with greatly improved NO conversion performances. The Ti₃C₂ QDs/Cu NWs affords a significantly enhanced NH₃ yield of 5346.3 μg h⁻¹ mg⁻¹ and high faradaic efficiency (FE) of 95.5% compared to the Cu NWs (3313.11 μg h⁻¹ mg⁻¹, 89.51%) at −0.4 V vs. RHE in 0.1 M K₂SO₄ electrolyte. We further assembled a Zn–NO battery using Ti₃C₂ QDs/Cu NWs as the cathode and a Zn plate as the anode, which shows a power density of 3.03 mW cm⁻² and an NH₃ yield of 925.2 μg h⁻¹ mg⁻¹. The improved NORR activity can be attributed to the role of the Ti₃C₂ QDs converter. The density functional theory calculation results reveal the catalytic mechanism, indicating the reaction pathway of *NO → *HNO → *N → *NH → *NH₂ → *NH₃ and the potential determination step of *N → *NH.