Construction of perovskite oxide/modified biochar for photothermal synergistic catalytic degradation of VOCs†

Abstract

Photothermal catalytic degradation of volatile organic compounds (VOCs) has been deemed as a promising strategy for air purification. In this work, LaMnO₃/N-doped biochar (NBC) composites with rich oxygen defects and nitrogen-containing functional groups were successfully synthesized by co-pyrolysis of soybean dregs and Mn/La salts, and they were employed for photo-thermal catalytic decomposition of p-xylene. N atoms from soybean dregs were successfully embedded into the biochar framework by the La³⁺ and Mn²⁺ modification. The abundant nitrogen-containing functional groups promoted the adsorption and enrichment of p-xylene on the catalyst surface. The carbon doping from soybean dregs increased oxygen defects of LaMnO₃, which acted as the active center for p-xylene degradation. The p-xylene degradation rate reached as high as 99.6% for the LaMnO₃/NBC-1.5 composite, which was significantly higher than that of pristine LaMnO₃ (65.2%). The biochar introduction enhanced the visible light absorption of LaMnO₃/NBC composites, which then converted light energy into thermal energy, serving as the extra heat source for p-xylene degradation. Moreover, the photogenerated electron–hole pairs of LaMnO₃/NBC composites further generated active radicals such as ˙OH and ˙O₂⁻ with strong oxidative properties on the catalyst surface, which participated in and enhanced the oxidative degradation of p-xylene.