Facet-engineered bismuth oxybromide for enhanced photocatalytic carbon dioxide reduction: From one-dimensional nanobelts to three-dimensional rose-like microstructures

Photocatalytic CO₂ reduction to valuable compounds offers a sustainable route to mitigate atmospheric CO₂ emissions. Herein, we report the synthesis of BiOBr (BOB) with three distinct dimensionalities: one-dimensional nanobelts (1D-BOB), two-dimensional nanosheets (2D-BOB), and three-dimensional rose-like microstructures (3D-BOB). Structural characterization reveals that these samples expose different crystal facets: (010) for 1D-BOB, (001) for 2D-BOB, and (111) for 3D-BOB. The 3D-BOB catalyst exhibits the best CO₂-to-CO yield of 172.44 μmol g^-1, corresponding to 6.12- and 3.42-fold enhancements over 1D-BOB and 2D-BOB, respectively. Experimental results show that 3D-BOB combines more efficient charge separation and a higher relative surface coverage of *COOH species. DFT-optimized surface models further suggest that the (111) surface offers a more favorable free-energy pathway for CO₂ activation. Compared with previous studies, this work provides a systematic comparison of (010)-, (001)-, and (111)-exposed BOB for CO₂ photoreduction, and identifies (111)-exposed 3D-BOB as a superior catalyst. This work demonstrates that facet engineering is a powerful strategy to boost the photocatalytic CO₂ reduction, providing insights for designing efficient bismuth-based photocatalysts.