Free-standing and flexible Cu/Cu2O/CuO heterojunction net: A novel material as cost-effective and easily recycled visible-light photocatalyst

Facing the worldwide deepening water-shortage and water-contamination crises, developing visible-light photocatalysts for water purification is an urgent need. However, the present photocatalysts are mostly in form of powders and nanoparticles, which make the recovery inevitably depend on expansive separation processes. The great challenge of photocatalyst recovery severely limits their industry applications. Herein, a new kind of free-standing and flexible visible-light photocatalyst that can be easily recycled is developed for the first time. Cu/Cu2O/CuO heterojunction net is successfully fabricated by one-step calcination in air using low-cost Cu net as the matrix. The mixing narrow band gaps of the Cu/Cu2O/CuO heterojunction ensure its wide absorption band in visible region and effective electron/hole separation, and consequently lead to markedly photocatalytic activity under visible light irradiation. In addition, a large number of CuO nanowires growing on the heterojunction surface provide high specific surface area, expose abundant active sites for photocatalysis, and thus guarantee its high photocatalytic efficiency. More importantly, the Cu/Cu2O/CuO photocatalyst possesses flexible property for recovery, which is a significant advance in comparison with the previously reported photocatalysts. With a marvelous combination of low cost, facile fabrication, visible-light response, and easy recycling characteristic, this newly developed photocatalyst is expected to have great potential applications in water crises.