Effect of pyrolysis temperature on structure and photocatalytic properties of biochar-coupled BiVO₄

A series of biochar with pyrolysis temperature of 300, 500, 700, 800 coupled BiVO4 (CBi-300, CBi-500, CBi-700, CBi-800) photocatalysts were successfully fabricated via a pyrolysis-hydrothermal approach, which were well characterized with the aid of various analytical methods by BET, XRD, FTIR, SEM, EDS, XPS, UV-Vis-DRS, PL, EIS, I-t and SPS. Photocatalytic activity was evaluated by the degradation of sulfanilamide (4-aminobenzene sulfonamide, SA) under simulated solar light irradiation. The results indicated that the photocatalyst CBi-700 possessed the best degradation rate for SA (97%) under the synergy with H2O2, and primary active species were center dot OH and h(+). The improved catalytic efficiency of CBi with a certain biochar pyrolysis temperature could be attributed to the excellent texture properties, the enhanced chemical interaction between biochar and BiVO4, the advanced electron transfer ability as well as improved the production of center dot OH. The HPLC, TOC and ion chromatography revealed the degradation of SA, the formation of inorganic products (CO2, H2O, SO42-, NH4+) and organic intermediates of small molecule, which provides us with a new perspective to analyze the decomposition of SA and other sulfonamides under simulation light irradiation.