Carbon　neutrality　has　drawn　increasing　attention　for　realizing　the　carbon　cyclization　and　reducing　the　greenhouse　effect.　Although　the　C1　products,　such　as　CO,　can　be　achieved　with　a　high　Faraday　efficiency,　the　targeted　production　of　C2　fuels　as　well　as　the　mechanism　have　not　been　systematically　investigated.　In　this　work,　we　carry　out　a　first-principles　study　to　screen　dual-atom　catalysts　(DACs)　for　producing　C2　fuels　through　the　electrocatalytic　carbon　monoxide　reduction　reaction　(e-CORR).　We　find　that　methanol,　ethanol　and　ethylene　can　be　produced　on　both　DAC-Co　and　DAC-Cu,　while　acetate　can　be　achieved　on　DAC-Cu　only.　Importantly,　methanol　and　ethylene　are　preferred　on　DAC-Co,　while　acetate　and　ethylene　on　DAC-Cu.　Furthermore,　we　show　that　the　explicit　solvent　can　enhance　the　adsorption　and　influence　the　protonation　steps,　which　subsequently　affects　the　protonation　and　dimerization　behavior　as　well　as　the　performance　and　selectivity　of　e-CORR　on　DACs.　We　further　demonstrate　that　the　C-C　coupling　is　easy　to　be　formed　and　stabilized　if　the　Integrated　Crystal　Orbital　Hamilton　Population　(ICOHP)　is　low　because　of　the　low　energy　barrier.　Our　findings　provide　not　only　guidance　on　the　design　of　novel　catalysts　for　e-CORR,　but　an　insightful　understanding　on　the　reduction　mechanism.