Insight into the nature of Au-Au2O3 functionalized palygorskite

The Au/palygorskite (Au/Pal) composite was prepared via supporting gold species on the surface of palygorskite. Results indicated that the dehydration of palygorskite showed obvious effect on the Au0/Au3 + molar ratio, and the generated hydroxide radicals (− OH) played a special role in the formation of Au-Au2O3 coexistence system. Au2O3 nanoparticles were formed on the hydrated (010) palygroskite surface, while Au nanoparticles were mainly on the surface of unhydrated (100) palygroskite. The decomposition of Au2O3 to metallic Au was promoted by increasing calcination temperature. However, this process would be hindered by –OH radicals produced at high temperature. The Au0/Au3 + molar ratio changed nonlinearly with the calcination temperature. The dehydration was beneficial to the formation of the chemical bonds between Au species and palygroskite. Au-Au2O3 coexistence expanded the application of gold supported composites. Atomic-level interfaces between Au species and palygorskite surface were also investigated. Realizing Au-Au2O3 coexistence by dehydration of palygorskite could provide a novel method for the synthesis of advanced mineral-based composites.