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Designing a novel photocatalytic composite for the efficient degradation of organic dyes remains a serious challenge. Herein, the multi-layered Co3O4@NP−CuO photocatalyst with unique features, i.e., the self-supporting, hierarchical porous network as well as the construction of heterojunction between Co3O4 and CuO, are synthesized by dealloying-electrodeposition and subsequent thermal treatment techniques. It is found that the interwoven ultrathin Co3O4 nanopetals evenly grow on the nanoporous CuO network (Co3O4@NP−CuO). The three-dimensional (3D) hierarchical porous structure for the catalyst provides more surface area to act as active sites and facilitates the absorption of visible light in the photodegradation reaction. Compared with the commercial CuO and Co3O4 powders, the newly designed Co3O4@NP−CuO composite exhibits superior photodegradation performance for RhB. The enhanced performance is mainly due to the construction of heterojunction of Co3O4/CuO, greatly promoting the efficient carrier separation for photocatalysis. Furthermore, the possible photocatalytic mechanism is analyzed in detail. This work provides a promising strategy for the fabrication of a new controllable heterojunction to improve photocatalytic activity.

Today, the development of new self-supporting electrode materials with high porosity and excellent degradation properties is of great importance for the removal of dye pollutants. Herein, this work synthesized nanoporous nickel@nickel oxide (np-Ni@NiO) electrode containing an amorphous alloy in the middle interlayer. The nanoporous structure endowed the electrode with more active sites and facilitated the ion/electron transport. The electrochemical active surface area was about 185.5 cm2. The electrochemical degradation of rhodamine B (RhB) using a np-Ni@NiO electrode was systematically investigated. The effects of technology paraments (NaCl concentration, the applied potential and pH) on electro-catalytic degradation were explored. An RhB removal rate of 99.68% was achieved in 30 s at optimized conditions, which was attributed to the unique bicontinuous ligament/pore structure and more active sites on the surface, as well as lower charge transfer resistance. In addition, the degradation mechanism of RhB in electrochemical oxidation was proposed, according to active species capture tests and EPR measurements.