Modulating Defect Concentration of Boron Nitride Flowers for CO₂ Photoreduction

The efficient conversion of carbon dioxide into high-value chemicals presents a promising strategy for achieving carbon neutrality. Defects play a critical role in numerous catalytic reactions. However, an excessive number of defects can lead to electron trapping, deactivating the catalyst surface. Optimizing the defect concentration is crucial for significantly enhancing catalytic performance. In this work, two types of flower-like BN-based photocatalysts composed of nanofibers were synthesized by in situ self-assembly and high-temperature calcination. The BN-based photocatalyst with fewer defects (V_poor-BNF) achieved a CO₂ reduction rate 2 times higher than that of the BN-based photocatalyst with more defects (V_rich-BNF), with a CO yield of 32 μmol g^-1 h^-1 with 86.9% selectivity. Importantly, the mechanism of enhanced CO₂ reduction activity over BN-like photocatalysts was investigated in combination with various advanced characterization. The results show that excessive C doping causes carbon deposition, creating more defects that trap photogenerated electrons and affect the photocatalytic activity. In contrast, the V_poor-BNF has longer photogenerated carrier lifetime and better photoelectric properties, which are beneficial for the CO₂ photoreduction reaction. In addition, the good stability of the catalyst was confirmed by the cyclic experiment. This study presents an effective approach for synthesizing defect-controlled catalysts, which is beneficial for the development of advanced photocatalysts.