Strong Metal–Support Interactions between Gold Nanoparticles and Nonoxides

The strong metal-support interaction (SMSI) is of great importance for supported catalysts in heterogeneous catalysis. We report the first example of SMSI between Au nanoparticles (NPs) and hydroxyapatite (HAP), a nonoxide. The reversible encapsulation of Au NPs by HAP support, electron transfer, and changes in CO adsorption are identical to the classic SMSI except that the SMSI of Au/HAP occurred under oxidative condition; the opposite condition for the classical SMSI. The SMSI of Au/HAP not only enhanced the sintering resistance of Au NPs upon calcination but also improved their selectivity and reusability in liquid-phase reaction. It was found that the SMSI between Au and HAP is general and could be extended to other phosphate-supported Au systems such as Au/LaPO4. This new discovery may open a new way to design and develop highly stable supported Au catalysts with controllable activity and selectivity.