Tailoring metal-support interaction over faceted TiO₂ and copper nanoparticles for electrocatalytic nitrate reduction to ammonia

The electrocatalytic nitrate reduction reaction (NO3-RR) provides a sustainable route for ammonia production while mitigating nitrate pollutants in the environment. Metal-support interaction has a significant influence on this electrocatalytic process. However, the mechanism of the facet-dependent metal-support interaction in the NO3-RR is still unknown. Herein, we report the modulation of the metal-support interaction by depositing copper nanoparticles on anatase TiO2 with different facet exposures, i.e., (001) and (101) facets. The result of copper nanoparticles being deposited on TiO2 with dominant (101) facet exposure is an enhanced ammonia yield rate of 447.5 mu g mg(cat)(-1) h(-1) at -0.9 V vs. reversible hydrogen electrode (RHE), which is 4.2 times higher than the pristine TiO2 counterpart. The strong interaction between copper nanoparticles and TiO2 with dominant (101) facet exposure contributes to a greater increase in catalytic performance than TiO2 with dominant (001) facet exposure. The strong interaction leads to electron-deficient copper nanoparticles, efficient electron transfer, and stronger binding of the *NO2 intermediate, promoting the hydrogenation process in the NO3- reduction reaction for selective NH3 synthesis.