Improving Electrocatalytic Nitrogen Reduction Selectivity and Yield by Suppressing Hydrogen Evolution Reaction via Electronic Metal–Support Interaction

摘要

The electrochemical nitrogen reduction reaction (NRR) has the potential to replace the Haber–Bosch process for ammonia synthesis under ambient conditions. However, the selectivity and yield of the NRR are impractical, owing to the preferential binding of the electrocatalyst to H and the consequential coverage of active sites. In this study, VO_2, with N_2 strongly adsorbed over H atoms, is used as a support to provide a N2 source to avoid the hydrogen evolution reaction. Mo, with a high NRR activity, is introduced as the active site to promote the NRR. Meanwhile, the electronic metal–support interaction between the support and Mo creates electron-deficient sites, which weakens H adsorption and lowers the energy barrier of the first step, protonation, thereby kinetically enhancing the NRR activity. The average NH_3 yield of Mo/VO_2 is 190.1 μgNH_3 mgcat.~(?1) h~(?1) and the Faradaic efficiency is 32.4% at ?0.5 V versus reversible hydrogen electrode, which is 10.8 and 2.8 times greater than that of VO_2, respectively.