Electronic configuration regulation of single-atomic Mn sites mediated by Mo/Mn clusters for an efficient hydrogen evolution reaction

Tuning the electron distribution of metal single-atom active sites via bimetallic clusters is an effective way to enhance their hydrogen evolution reaction (HER) activity, but remains a great challenge. A biochar-based electrocatalyst (BCMoMn800-2) with both MnN4 active sites and Mo2C/Mn7C3 clusters was synthesized using in situ enriched Mo/Mn biomass as a precursor to trigger the HER. Various characterization and density functional theory (DFT) calculation results indicated that the presence of Mo2C/Mn7C3 clusters in BCMoMn800-2 effectively induced the redistribution of charges at MnN4 sites, reducing the energy of H* activation during the HER. In 0.5 M H2SO4, the overpotential was 27.4 mV at a current density of 10 mA cm-2 and the Tafel slope was 31 mV dec-1, and its electrocatalytic performance was close to that of Pt/C. The electrocatalyst also exhibited excellent electrocatalytic stability and durability. This work might provide a new strategy for solid waste recycling and constructing efficient HER electrocatalysts. Tuning the electron distribution of metal single-atom active sites via bimetallic clusters is an effective way to enhance their hydrogen evolution reaction (HER) activity.