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

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.