Triggering surface oxygen vacancies on atomic layered molybdenum dioxide for a low energy consumption path toward nitrogen fixation

Facilitating catalyst accessibility to cleavage of N≡N bond and breakage of competition from hydrogen evolution reaction (HER) remain great challenges in catalytic nitrogen reduction reaction (NRR). By fine confining of oxygen vacancies (OVs) in atomic layered molybdenum oxide (MoO2), we herein reported a sustainable strategy to tackle the rigorous requirements, thereby figuring out the deep-seated mechanism underlying the increment mechanism. X-ray absorption near edge structure (XANES) and Electron Paramagnetic Resonance (EPR) results primarily indicated that vast majority of OVs with different concentrations distributed well on layered MoO2. Based on the combined results of chemical N2 adsorption isotherm and DFT calculation, we revealed that OVs favoured chemical adsorption for N2 molecular via electron donation on defective Mo, providing the prerequisite for following activation. Remarkably, the energy change calculation unveiled that suitable confined OVs on MoO2 NRR followed an novel distal/alternating hybrid path, whereby the energy barrier was effectively lowered after directly protonation of N2H2* to HN2H2* (ΔG = 0.36 eV), so that OVs-MoO2 catalyst exhibited a high activity and selectivity with NH3 yield rate of ~12.20 μg h−1 mg−1 and a Faradaic efficiency of 8.2% at a low potential of −0.15 V.