Abstract:

At the interface of paraffin-water emulsion, a series of Janus g-C₃N₄ were prepared via the one-side modification of nano graphite carbon nitride （g-C₃N₄） using different bromoalkanes. The products were characterized by XRD, UV-vis, FT-IR and SEM. Their emulsification properties were studied by fluorescence microscopy and contact angle test. The photocatalytic oxidation of benzyl alcohol was used as a probe reaction to investigate the catalytic performance. The results showed that, in the case of the alkyl chain lengths of bromoalkanes being C4, C8, C12 and C16, the Janus catalyst grafted with C12 （JCN-12） behaved best in emulsification, contact angle （75°） and photocatalytic performance. In a concentrated emulsion of benzyl alcohol/water （1 mL/1.5 mL）, the conversion of benzyl alcohol reached to 68% （selectivity>99%） with the addition of 20 mg catalyst. It was believed that superoxide radicals （·O^-₂） played a major role in the reaction, being followed by ·OH and hole h⁺. The Janus catalyst could be applied to the oxidation of other substituted benzyl alcohols. The catalyst was easily separated and recovered, showing stable performance after 5 times of recycles.

Key words: graphite carbon nitride, photocatalysis, benzyl alcohol oxidation