Dangling bonds and asymmetric charge redistribution triggered by grain boundary for improved photocatalytic CO2 reduction and ammonia synthesis

Abstract

The role of grain boundaries in photocatalysis is still an open question. In this work, a generic crystal-induced re-growth strategy is developed to engineer grain boundaries into various 2D atomic layers to boost the photocatalytic activity. Take BOB as an example, the engineered grain boundaries will lead to the generation of asymmetric charge redistributed interface, and work as quantum well to promote the oriented charge separation. Meantime, the grain boundaries will provide active electronic states with abundant dangling bonds to strengthen molecular interaction, and further optimize intermediate conversion. Benefiting from these advantages, the grain boundaries-rich BOB (BOB-GB) display a good CO₂ photoreduction rate to yield CO (61.34 μmol g⁻¹h⁻¹), 5.4 and 95.9 times higher than BOB and bulk BOB, respectively. Moreover, it delivers an excellent NH₃ generation rate of 13620 μmol g⁻¹h⁻¹, with apparent quantum efficiencies of 43.0 %, 30.7 % at 380, 400 nm, respectively.