Carboxylated cellulose-derived carbon mediated flower-like bismuth oxyhalides for efficient Cr(VI) reduction under visible light

Exquisitely tailoring the morphologies of photocatalysts could achieve high activities. In this study, the morphological transformation of bismuth oxyhalide (BiOX, X = Br, I and Cl) from disordered lamellae to regular flowers was facilely achieved via the use of carboxylated cellulose-derived carbon (CDC). The sphere-like structure and abundant surface functional groups of CDC induce the formation of such flower-like morphologies of BiOX/CDC, and this morphology results in a pronounced increase in surface area (e.g., the surface area of BiOBr increases from 3 to 106 m2 g-1) and porosity. Combined with the good light absorption and conductivity of CDC, the flower-like BiOX/CDC exhibited impressive photocatalytic activity under visible light. Regarding the probing Cr(VI) reduction reaction, the representative BiOBr/CDC is capable of reducing 98% of Cr(VI) within 30 min of visible-light illumination, which is markedly greater than those of pure BiOBr (6%) and CDC (16%). Likewise, BiOI/CDC and BiOCl/CDC also have decent photocatalytic Cr(VI) reduction capacities (89% for BiOI/CDC and 69% for BiOCl/CDC) under visible light in comparison with pristine BiOI (13%) and BiOCl (1.5%). This work furnishes a novel and facile approach to tune photocatalyst morphologies and sheds light on the great potential of biomass-derived carbon, which may enlighten the judicious design of photocatalysts with high efficiency.