Effect of microstructure and surface hydroxyls on the catalytic activity of Au/AlOOH for formaldehyde removal at room temperature

A series of Au/AlOOH catalysts was prepared by impregnating different AlOOH supports with Au precursor followed by NaBH₄-assisted reduction, and examined their activity toward oxidation of indoor formaldehyde (HCHO) pollutant at room temperature. The AlOOH supports used were synthesized by microemulsion, microwave and hydrothermal methods. Among these supports the catalyst obtained by deposition of Au nanoparticles (NPs) on AlOOH prepared by microemulsion method (Au/AlOOH-m) exhibited the highest catalytic activity. Based on the detailed characterization of the catalysts, the microstructure of AlOOH support, dispersion and size of Au NPs, surface hydroxyls, and interactions between Au and the support are important factors controlling the efficient removal of HCHO at room temperature. The superior catalytic performance of Au/AlOOH-m is attributed to its larger specific surface area, small size of Au NP, large amount of reactive surface hydroxyls, and better adsorption properties of this support. This study shows not only the importance of the microstructure and surface hydroxyls on the oxidative degradation of HCHO on Au/AlOOH at room temperature, but also provides a new insight into rational synthesis of high-efficiency catalysts for removal of indoor air pollutants.