The synergistic tandem effect of Cu2+1O and Co3O4 enhances the activity and selectivity of nitrate reduction to ammonia in neutral solution

Construction the electrocatalysts with multiple components is an effective strategy to enhance the activity for NH3 generation in electrocatalytic nitrate reduction reaction (NITRR). Herein, we report a high performance electrocatalyst Co3O4-Cu2+1O/CF. The obtained Co3O4-Cu2+1O/CF nanosheets not only provide large active surface area but also construct the bimetal oxides interface for exerting Cu-Co tandem catalysis. Meanwhile, Co3O4-Cu2+1O/CF exhibits a maximum NH3-Faradaic efficiency of 96.5% and NH3 yield of 0.26 mmol h-1 cm-2 in neutral solution with 10 mM NO3-. The control experiments and Tafel analysis clearly manifest the tandem catalysis mechanism on Co3O4-Cu2+1O/CF, where Cu2+1O favors the NO3- conversion to NO2-, while Co3O4 selectively promotes NO2- conversion to NH3. The DFT calculations reveal that the strengthened NO3- adsorption and the enhanced adsorption of H* on Co3O4-Cu2+1O/CF jointly promote the selective formation of ammonia from NO3- reduction. This work provides the strategy of constructing the efficient transition metal composited electrocatalysts in NITRR.