Electrocatalytic　synthesis　of　formamide　(FA)　from　abundant　methanol　and　ammonia　is　a　promising　alternative　to　the　traditional　energy-consumption　thermocatalytic　route.　However,　the　sluggish　electron　transfer　between　catalyst　and　adsorbed　reactants　can　result　in　a　poor　faraday　efficiency　(FE)　and　FA　yield.　Herein,　four　well-defined　α-,　β-,　γ-,　and　δ-MnO2　electrocatalysts　are　achieved　through　a　crystal-phase　engineering　strategy.　The　β-MnO2　is　thermodynamical　in　favor　of　the　Ov　formation　in　comparison　to　the　other　three　crystal　phases　of　MnO2.　The　formed　bridge　Ov　sites　on　β-MnO2　presents　a　positive　electric　field　effect,　which　induces　more　charge　transfer　from　CH3OH　to　β-MnO2　via　Mn-O　bonds　and　promotes　the　CH3OH　oxidation　to　the　*CH2O　key　intermediate.　Subsequently,　the　C–N　coupling　reaction　was　accomplished　via　the　directly　attack　of　*CH2O　intermediates　by　NH3　molecules　without　chemical　adsorption.　Lastly,　the　FA　formation　mechanism　was　clearly　proposed,　in　which　the　conversion　of　*CH2OH　into　*CH2O　is　the　rate　determining　step.　The　reaction　mechanism　contains　two　steps:　(1)　Adsorption　and　oxidation　of　methanol　to　*CH2O　via　Ov　sites　assisted　electron　transfer;　(2)　NH3　attack　and　C–N　coupling　via　the　E-R　reaction　pathway.　Therefore,　Ov　sites　assisted　electron　transfer　via　crystal-phase　engineering　strategy　was　established　to　enhance　the　electrosynthesis　of　formamide.　©　2025