Electrochemical　fixation　of　CO2　in　molten　salts　as　carbides　for　catalyzing　the　hydrogen　evolution　reaction　can　contribute　to　carbon　neutrality　and　value-added　conversion　of　CO2　as　well　as　facilitate　the　production　of　sustainable　green　hydrogen　energy.　However,　the　functional　ability　of　the　CO2-derived　carbides　still　needs　to　be　substantially　improved.　Herein,　heterostructuring　the　CO2-derived　Mo2C　layer　with　MoP2　is　realized　via　electro-splitting　of　CO2　in　Ca3(PO4)2-containing　molten　salt.　The　as-designed　Mo2C–MoP2　heterostructure　layer　presents　significantly　improved　HER　performances,　namely　overpotential　being　109　mV　@　100　mA　cm−2　and　stability　for　600　h　@　200　mA　cm−2,　greatly　outperforming　both　the　bare　Mo2C　layer　and　commercial　Pt　candidates.　The　superior　performances　of　the　Mo2C–MoP2　heterostructure　are　in　one　way　attributed　to　the　modified　electronic　structure　that　decrease　the　energy　barrier　of　the　Volmer　rate-determining　step　for　HER.　In　another　way,　the　Mo2C–MoP2　dual-phase　increases　the　hydrophilicity　ability　of　the　catalytic　layer,　accelerating　the　detachment　of　the　H2　bubbles.　The　results　can　provide　new　insights　for　both　value-added　fixation　of　carbon　dioxide　and　preparation　of　high-performance　non-noble　electrocatalyst.　©　2024　Hydrogen　Energy　Publications　LLC