Preparation of ternary BiVO4/g-C3N4/diatomite composites for enhanced photodegradation of rhodamine B and formaldehyde

Abstract

Efficient ternary BiVO4/g-C3N4/diatomite (BCNDE) composites were prepared using a strategy combining in situ polymerisation and self-assembly. The photocatalytic degradation efficiencies of BCNDE composites for rhodamine B (RhB) and formaldehyde (CH2O) were investigated. Compared with BiVO4 (BVO), g-C3N4 (CN) and BiVO4/g-C3N4 (BCN), BCNDE showed better photocatalytic performance for RhB and CH2O degradation. Notably, the 20-BCNDE composite demonstrated superior photocatalytic performance, achieved 99 % degradation of RhB under visible light (λ > 400 nm) within 60 min and 81 % degradation of CH2O gas (0.16 mg·L−1) within 40 min. Incorporation of porous microdisc-shaped diatomite (DE) significantly mitigated the agglomeration of the BCNDE composites, as confirmed by scanning electron microscopy (SEM). This structural feature enhanced the separation and migration of photogenerated electron-hole pairs, as evidenced by photoluminescence (PL) spectroscopy and electrochemical impedance spectroscopy (EIS) analyses. Zeta potential analysis at pH 7 revealed a negatively charged surface with a zeta potential of −8.9 mV, facilitating the attraction of photogenerated holes and inhibiting electron-hole recombination. This effectively inhibited the recombination rate of photogenerated electron-hole pairs, thereby significantly improving the photocatalytic performance of the material. These mechanisms were critical in boosting the photocatalytic degradation activities for RhB and CH2O. This study highlights the potential of BCNDE composites for environmental remediation applications, offering a promising approach for the development of efficient mineral-based photocatalytic materials.