TiO2/carbon composites from waste sawdust for methylene blue photodegradation

Titanium dioxide/carbon (TiO2/C) composites are generally prepared from fossil resources, which contradicts carbon neutrality science and economics. This study used sawdust as the feedstock to make TiO2/C binary composites that were further used to photodegrade methylene blue (MB) under simulated sunlight irradiation. The composites were characterized by SEM, FT-IR, XRD, XPS, TG-DT G, UV-vis, and N2 adsorption-desorption. Carbon primarily existed in the outer layer of the composite, significantly enhancing sensitization. The direct band gap of the TiO2/C-550 composite was 2.7 eV. As a result, the visible light absorption of TiO2 widened, and the charge recombination rate decreased. The degradation ratio of MB aqueous solution reached nearly 100% within 30 min in the presence of TiO2/C-550 composites. Moreover, TiO2/C-550 still maintained about 95% photodegradation efficiency after 5 cycles. Meanwhile, the dominant role of center dot O2-produced in the reaction has been confirmed through free radical capture experiments. Compared with pure TiO2, the photodegradation performance of MB was significantly improved under visible light irradiation. In addition, the material prepa-ration is green, simple, and low-cost. We can confirm that the TiO2/C composites prepared from waste sawdust had sustainable and efficient advantages, reducing the consumption of fossil resources.