Synergistic catalysis of Au-Cu/TiO2-NB nanopaper in aerobic oxidation of benzyl alcohol

Au-Cu bimetallic nanoparticles supported on a TiO2-nanobelt (TiO2-NB) have been designed and synthesized by a one-pot photodeposition-galvanic replacement method. TEM observation revealed that small-sized metal nanoparticles (less than 2 nm) were uniformly and finely dispersed on the TiO2 nanobelt. Characterization by XRD coupled with XPS demonstrated that the Au-Cu bimetallic nanoparticles are composed of an Au-rich core/CuOx shell structure. The as-synthesized one-dimensional Au-Cu/TiO2-NB nanostructure can be easily assembled into a paper-like porous monolithic catalyst and applied in heterogeneous catalysis. The formed bimetallic nanopaper catalysts presented synergistically enhanced activity and improved stability for catalyzing the aerobic oxidation of benzyl alcohol compared to their monometallic counterparts. It is likely that the Au-CuOx heterostructure is responsible for the superior catalytic properties of the bimetallic Au-Cu/TiO2-NB catalysts, and the catalytic activity can be significantly affected by the Au/Cu ratio. The uniform and high dispersion of metal nanoparticles on TiO2 nanobelts is also believed to contribute to the stability of Au-Cu/TiO2-NB catalysts, suggesting that the one-dimensional TiO2 nanobelts are a desirable support for the preparation of nanoscale metal catalysts.