Enhanced photocatalytic degradation of formaldehyde via a modified g-C3N4/HKUST-1 diatomite composite

Modified g-C 3 N 4 /HKUST-1/diatomite composite is rationally fabricated. • CN x , HKUST-1 and diatomite synergistically enhance adsorption and photocatalytic oxidation. • Light-induced ·O 2 − and ·OH participate in oxidation of formaldehyde. Effective removal of indoor formaldehyde (HCHO) is critical for improving indoor air quality and protecting human health. In this study, a ternary composite material CN x @DH-4 was constructed by rationally combining K-doped modified carbon nitride (CN x ), diatomite, and HKUST-1. This combination integrates adsorption enrichment with visible light-driven photocatalytic degradation. Structural and surface characterization analyses confirmed the uniform dispersion of CN x and HKUST-1 on the diatomite carrier, while XPS revealed the interface electronic interactions, which regulated the electronic structure. Owing to the optimized CN x loading, extended visible-light absorption, and abundant nitrogen vacancy sites acting as active centers, CN x @DH-4 achieved a HCHO removal efficiency of 83.34%. EPR measurements confirmed the light-induced generation of ·O 2 − and ·OH radicals, suggesting that reactive oxygen species play an important role in HCHO oxidation. CN x @DH-4 maintained its optical and structural stability during 10 cycles and exhibited excellent durability. This study provides a practical strategy for designing multifunctional adsorption-type photocatalysts, where the adsorption sites, defect engineering, and structural stability interact synergistically to achieve continuous and efficient indoor HCHO purification. Download: Download high-res image (184KB) Download: Download full-size image