Pickering Emulsion Stabilization and Interfacial Catalytic Oxidation by Janus Nano-Au

Structural design and facile synthesis of Janus nanoparticles are crucial to Pickering emulsion interfacial catalysis. By manipulating self-assembly and self-crosslinking activities and weak reducibility of conjugated linoleic acid (CLA), Janus self-crosslinlced admicelle-decorated nano-Fe3O4 (SCA-Fe3O4) was synthesized under protection by Pickering emulsions, and then Janus nano-Au catalyst(Au-SCA-Fe3O4) was prepared by in-situ reduction of Au on the particle surface. Subsequently, Au-SCA-Fe3O4 was investigated to act as both emulsifier and catalyst in the emulsion interfacial catalytic oxidation of benzyl alcohol to henzaldehyde. Experimental results show that Au-SCA-Fe(3)O(4 )is only with 0.66% (mass fraction) of Au content, but shows emulsifying, catalytic activities and magnetic response simultaneously. It creates a Pickering emulsion with appearance stability (uniform size of about 100 mu m) and thermal stability (up to 90 degrees C), and improves the catalytic activity to be two fold of the fully-modified counterpart and three times as high as the coarse dispersion, which is ascribed to significantly increased contact between insoluble reactants and the catalyst. Moreover, the selectivity of benzaldehyde is higher than 99.9%, which depends on the non-rotational property of Au-SCA-Fe3O4 at the benzyl alcohol/water interface avoiding the excessive oxidation of benzaldehyde into benzoic acid. It would offer a new approach for green synthesis and application of Janus nano-catalysts.