The enhanced electro/photocatalytic activity for nitric oxide reduction to ammonia by B@g-C9N10 monolayer

Selective electro/photocatalytic reduction of nitride oxide (NO) to ammonia (NH3) provides a promising way to remove the pollutant under ambient conditions. The key to NO reduction reaction (NORR) is to develop more economical and efficient electrocatalysts compared to the industrialized Pt-based catalysts. In this work, the boron atom doping g-C9N10 monolayer (B@g-C9N10) is designed and the electro/photocatalytic NORR performance is systematically investigated by means of density functional theory (DFT). Among the N-end, O-end and side-on structures, the N-end NO adsorption is found to be the most stable one, which greatly favors the NO activation by the “σ-donation and π* back-donation” mechanism. Among the N-distal, N-alternating, O-distal, O-alternating, Mixed 1–3 hydrogenation pathways in the electrocatalytic process, the O-alternating and Mixed-2 pathways are the most efficient NORR routes, which have the same limiting potential (UL) of −0.386 V in the step of *NH2→*NH3. However, the NO molecule is more easily activated in *N–OH along O-alternating pathway than Mixed-2 pathway. The energy barrier can be further decreased by considering the implicit and explicit solvation model and the NH3 selectivity of B@g-C9N10 is higher than N2O, N2 and H2. The irradiating energy of 1.094 eV can decrease the reaction energy, resulting in the spontaneous NORR process along Mixed-2 pathway. Our findings uncover a promising approach to design a bifunctional NORR electro/photocatalyst with high NH3 selectivity and activity NO→NH3 conversion.