Optical and electrochemical properties of 3D nanoporous Cu2O-Cu inverse opal structures tuned by electrodeposition

Three-dimensional (3D), ordered nanoporous Cu2O and Cu inverse opal structures are attractive for various applications in photonics and catalysis. Here, we demonstrate an approach to fabricate 3D nanoporous inverse opals by electroplating through a uniform polystyrene (PS) opal template. The material composition of the inverse opals can be controlled to consist of pure Cu, Cu2O or Cu2O-Cu composites on Cu foils. Good agreement between experiment and simulation for reflectance spectra exhibits a low-angle-dependent photonic band for Cu2O inverse opals when compared with PS opals. Moreover, 3D nanoporous Cu2O with different layers obtain a large charge capacitance of up to 1.8 mF/cm(2) (geometry), 25 times that of Cu foil. The hybrid Cu2O-Cu inverse opals exhibit higher separation efficiency of photogenerated carriers (optical properties) and double layer capacitance (electrochemical properties) than pure Cu or pure Cu2O inverse opals, which indicates a promising application in photoelectrochemistry.