The　weak　internal　electric　field　over　antiferromagnetic　materials　makes　it　difficult　to　facilitate　charge　migration　to　the　surface,　leading　to　low　performance　for　CO2　photoreduction.　The　asymmetry　and　polarization　refinement　structure　can　induce　an　intensive　internal　electric　field.　Herein,　n-type　NiO　is　synthesized　with　highly　dispersed　erbium　atoms　doping　(Er/NiO1−x)　via　a　molten　salt　method　to　accelerate　charge　separation　and　transfer.　The　doping　of　Er　atoms　can　distort　the　unit　cell　of　NiO　to　alter　the　symmetry　and　enhance　the　polarization　and　internal　electric　field,　in　favor　of　efficient　separation　of　charges.　In　addition,　the　highly　dispersed　erbium-doped　n-type　NiO　can　largely　boost　the　adsorption　and　activation　of　CO2,　and　weaken　the　energy　barrier　for　CO2　photoreduction　reaction.　Benefiting　from　the　unique　features,　an　optimal　doping　ratio　(≈2%)　with　erbium　atoms　achieves　a　remarkable　elevation　in　carrier　separation　efficiency　and　excellent　CO2　photoreduction　performance　with　a　CO　yield　of　368　µmol g−1 h−1　in　the　Ru(byp)32+/ethanolamine　electron-agent　generating　system,　which　is　26.3-fold　and　3.9-fold　relative　to　traditional　NiO　and　n-type　NiO,　respectively.　The　obtained　Er/NiO1−x　photocatalyst　and　the　unit　cell　dipole　governing　the　internal　electric　field　opens　a　new　window　for　CO2　photoreduction　in　antiferromagnetic　materials.　©　2022　Wiley-VCH　GmbH.