Feδ+-O-Bi atomic pair site with asymmetric charge redistribution tuning non-covalent interaction for ammonia photosynthesis

Precisely designing the atomic coordinate configuration of the reactive center is highly desired to lower the energy barrier and boost photocatalytic ammonia synthesis performance. Here, we describe the isolated asymmetric Fe δ+ -O-Bi (2 <δ<3) atomic pair sites to achieve high-efficiency photosynthesis of ammonia. The difference in work function between Fe and Bi atoms induces local polarization and create asymmetric charge redistribution, enabling carrier lifetime be prolonged from 70.73 ps in Bi 3 O 4 Br to 706.91 ps in Fe-Bi 3 O 4 Br. The delocalization of unpaired electron on Fe d z2 orbital in asymmetric Fe δ+ -O-Bi under excited state can facilitate the adsorption of NO 3 - , donate electrons to continuously activate reaction intermediate states. The asymmetric Fe δ+ -O-Bi atomic pair sites strengthen the non-covalent interaction strength with *H 2 NO and lowering the rate-limiting energy barrier. As a result, the NH 3 generation rate is as high as 5770 μmol g −1 h −1 via NO 3 - photoreduction. The apparent quantum efficiencies can reach 26.9 %, 26.78 %, 14.36 %, 15.47 %, 2.45 % at 380, 400, 450, 500 and 550 nm, respectively. This work provides insights for optimal design of asymmetric atomic pairs for photocatalytic ammonia synthesis . • The isolated asymmetric Fe δ+ -O-Bi atomic pair sites can achieve efficient ammonia photosynthesis. • The local polarization extends carrier lifetime from 70.73 ps in Bi 3 O 4 Br to 706.91 ps in Fe-Bi 3 O 4 Br. • The asymmetric Fe δ+ -O-Bi atomic pair sites strengthen the non-covalent interaction strength with *H 2 NO.