Automobile exhaust gas purification material based on physical adsorption of tourmaline powder and visible light catalytic decomposition of g-C3N4/BiVO4

Pure g-C3N4, g-C3N4/BiVO4, and g-C3N4/BiVO4/tourmaline powder composite photocatalytic materials were prepared via the methods of one-step calcination and bi-dispersion direct mixing, and their automobile exhaust gas purification efficiencies were tested. Four types of samples (g-C3N4, BiVO4, g-C3N4/BiVO4, and g-C3N4/BiVO4/tourmaline powder) were characterized using various methods, such as X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller analysis, Fourier transform infrared spectroscopy, ultraviolet–visible light-near infrared spectroscopy, and X-ray photoelectron spectroscopy (XPS). The test results showed that the photocatalysis composite exhibited the highest purification efficiency when the mass ratio of g-C3N4/BiVO4 was 2 and the load of tourmaline powder was 25 wt%. The hydrocarbon, CO, and NO purification rates of the g-C3N4/BiVO4/tourmaline powder were 1.73, 1.74, and 2.52 times higher than those of pure g-C3N4, respectively. It was concluded from the XPS patterns that the heterojunction formed by g-C3N4 and BiVO4 promoted the separation of electron-hole pairs and charge migration, which enhanced the photocatalytic degradation of exhaust gas under visible light. Moreover, tourmaline powder increased the physical adsorption capacities of the composite materials for automobile exhaust by releasing several negative ions, thus considerably increasing their decomposition efficiencies. This study is of immense significance to the management of urban automobile exhaust pollution.