Amphiphilic confined Pt-based nanocatalysts produced by atomic layer deposition with enhanced catalytic performance for biphasic reactions

Abstract

With the ever-increasing awareness of environmental problems, the use of a green reaction medium in chemical processes has become an urgent research topic for green and sustainable chemistry. Developing excellent catalytic systems to ensure highly efficient molecular transport processes in reaction systems is still a challenge. Here, we introduce a facile template-assisted atomic layer deposition method to assemble amphiphilic confined TiO₂/Pt@CNT and hydrophilic confined TiO₂/Pt@TiO₂/CNT. For TiO₂/Pt@CNT, the void space between the outer TiO₂ nanotube and the inner CNT forms an amphiphilic nanochannel. For TiO₂/Pt@TiO₂/CNT, a TiO₂ layer is additionally deposited on CNTs. Furthermore, amphiphilic confined TiO₂@Pt/CNT and hydrophobic confined C@Pt/CNT with similar tube-in-tube structures are also prepared, and Pt nanoparticles are supported on CNTs. Compared with the hydrophilic/hydrophobic counterparts, amphiphilic confined nanocatalysts exhibit substantially enhanced performance in biphasic benzyl alcohol oxidation and phenol hydrogenation reactions. Detailed analyses reveal that the amphiphilic microenvironment in nanochannels simultaneously promotes the transport of biphasic reactants to Pt sites, and thus improves the catalytic performance. Our assembly strategy can be used to reveal the relationship between the wettability microenvironment and molecular transport in nanochannels, which provides guidance to develop high-performance catalysts for other reactions.