Electronic Transfer-Driven Optimization of Ni_0.7Cu_0.3Mn₂O₄ for Electrocatalytic Nitrate Reduction and Polyethylene...

Electrochemical recycling of waste pollutant nitrate (NO₃ ^-) into high-value fuels or chemicals is regarded as a green and sustainable approach to addressing global resource utilization issues. Despite considerable efforts, advancements in this area are significantly impeded by the scarcity of high-performance electrocatalysts. This study introduced a robust Ni-doped optimized CuMn₂O₄ spinel oxide electrocatalyst (Ni_0.7Cu_0.3Mn₂O₄) that effectively facilitated the reduction of nitrate to ammonia (NH₃) (NO₃RR), achieving a high NH₃ Faradaic efficiency (FE) (90.8%) and yield (551.3 mmol h^-1 g^-1) at a suitable potential. Experimental analysis and theoretical calculations indicated that the in situ incorporation of Ni induced electron transfer from Ni and Cu toward Mn atoms, which changed the electronic microenvironment of the Ni_0.7Cu_0.3Mn₂O₄, thus reduced the reaction barrier for the formation of active hydrogen (^*H), subsequently promoted the production and use of ^*H for NO₃RR. The change of electronic microenvironment also optimized the d-band center of Ni_0.7Cu_0.3Mn₂O₄, thus improved the electron transfer energy of the catalyst to NO₃ ^-, finally improved the adsorption of NO₃ ^-. Moreover, Ni_0.7Cu_0.3Mn₂O₄ exhibited excellent catalytic performance for the oxidation of polyethylene terephthalate (PETOR), can selectively generated high-value-added formate (FA). NO₃RR is coupled with PETOR instead of oxygen evolution reaction, which further improved the resource utilization.