Hydroxyapatite-Supported Low-Content Pt Catalysts for Efficient Removal of Formaldehyde at Room Temperature

Indoor environmental quality directly affects the life quality and health of human beings, and therefore, it is highly vital to eliminate the volatile organic compounds especially formaldehyde (HCHO), which is regarded as one of the most common harmful pollutants in indoor air. Hydroxyapatite (HAP)-supported Pt (Pt/HAP) catalysts with a low content of Pt (0.2 wt %) obtained via hydrothermal and chemical reduction processes could effectively remove gaseous HCHO from the indoor environment at room temperature. The influence of modifier in the preparation on the catalyst activity was investigated. The HAP and HAP modified by sodium citrate and hexamethylenetetramine-supported 0.2 wt % Pt could completely decompose HCHO into CO₂ and water, while HAP modified by sodium dodecyl-sulfate-supported Pt removed HCHO primarily via adsorption. The HAP modified by the sodium citrate catalyst exhibited superior catalytic performance of HCHO compared to the HAP and HAP modified by hexamethylenetetramine and sodium dodecyl-sulfate-supported Pt catalysts, which was mainly because of its higher surface Ca/P ratio providing more Lewis acidic sites (Ca²⁺) for co-operational capture of HCHO molecules and a larger amount of active oxygen species. Our results indicate that an optimized combination of functional supports and low-content noble metal nanoparticles could be a route to fabricate effective room-temperature catalysts for potential application in indoor air purification.