Photo-reduced Cu/CuO nanoclusters on TiO₂ nanotube arrays as highly efficient and reusable catalyst

Non-noble metal nanoparticles are becoming more and more important in catalysis recently. Cu/CuO nanoclusters on highly ordered TiO₂ nanotube arrays are successfully developed by a surfactant-free photoreduction method. This non-noble metal Cu/CuO-TiO₂ catalyst exhibits excellent catalytic activity and stability for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with the presence of sodium borohydride (NaBH₄). The rate constant of this low-cost Cu/CuO based catalyst is even higher than that of the noble metal nanoparticles decorated on the same TiO₂ substrate. The conversion efficiency remains almost unchanged after 7 cycles of recycling. The recycle process of this Cu/CuO-TiO₂ catalyst supported by Ti foil is very simple and convenient compared with that of the common powder catalysts. This catalyst also exhibited great catalytic activity to other organic dyes, such as methylene blue (MB), rhodamine B (RhB) and methyl orange (MO). This highly efficient, low-cost and easily reusable Cu/CuO-TiO₂ catalyst is expected to be of great potential in catalysis in the future.