Photocatalytic　CO2　conversion　to　industrial　fuels　is　considered　an　effective　measure　to　solve　energy　and　environmental　problems.　Presently,　Catalysts　for　CO2　reduction　reaction　(CO2RR)　are　mostly　confined　to　metal-based　materials,　but　non-metal　materials　are　less　explored.　We　decorate　the　highly　crystalline　carbon　nitride,　i.e.,　poly　(triazine)　imides　(PTI),　with　non-metallic　boron　(B)　to　obtain　two　B/PTI　catalysts:　Bi/PTI　with　B　being　deposited　into　the　six-fold　cavity　of　the　PTI,　and　Bs/PTI　with　B　substituting　for　C　in　PTI.　For　CO2RR,　Bi/PTI　follows　a　quasi　Mars-van　Krevelen　process,　but　the　high　exposure　of　Bi　results　in　an　overly　strong　interaction　with　intermediates,　inhibiting　the　reactivity.　In　contrast,　Bs/PTI　enhances　the　binding　with　intermediates　by　introducing　Lewis　acidbase　pairs　(B-N),　which　reduce　the　ring　conjugation　effect　and　induce　the　enrichment　of　electrons　at　the　pyridine　N.　Hence,　CO2　reduction　with　the　adsorbed　H*　(Ha)　hydrogenation　mechanism　in　Bs/PTI　has　a　significant　reactivity.