Noble-metal-free hydroxyapatite activated by facile mechanochemical treatment towards highly-efficient catalytic oxidation of volatile organic compound

Controlling of volatile organic compound (VOC) emitted from industrial processes as most abundant and harmful air pollutant, has become one of the most important global environmental issues due to the rapid urbanization and industrialization. As an alternative and new type catalyst instead of conventional noble-metal nanoparticles widely utilized in oxidative decomposition of VOC, here we report the superior catalytic performance with 100% CO2/CO conversion on hydroxyapatite (HAp, Ca-10(PO4)(6)(OH)(2)) with structurally well-controlled active surface tailored via facile one-step mechanochemical treatment in ambient air. With detailed characterizations of particle morphology, crystallinity and chemical structure with respects to surface defect/oxygen vacancy formation, acidity/basicity and VOC affinity on HAps activated through different mechanical stresses when altered ball size is utilized in planetary ball-milling assisted mechanochemical process, it was found that the predominant defect/oxygen vacancy generation in PO43- site and enhanced basic site population established by selective mechanochemical activation of c-plane, facilitates the favorable catalytic oxidation route towards highly-efficient CO2/CO conversion of VOC. Regards to the cost-effectiveness and non-toxic nature of HAp, incorporated with the sustainable mechanochemical surface structure tuning process, the results presented in this work opens new strategy in development of novel noble-metal-free catalyst for VOC elimination and environmental cleaning techniques.

Automated summary

The mechanical chemical treatment of hydroxyapatite (HAp) results in the formation of defect/oxygen vacancies and enhanced basic sites, facilitating efficient catalytic oxidation of VOC for highly-efficient CO2/CO conversion. This opens up a new strategy for the development of novel noble-metal-free catalysts.