Prominent co-catalytic effect of CoP nanoparticles anchored on high-crystalline g-C3N4 nanosheets for enhanced visible-light photocatalytic degradation of tetracycline in wastewater

Graphitic carbon nitride (g-C3N4) has been regarded as an emerging and promising semiconductor photocatalyst for the solar hydrogen production and organic pollution removal. However, pure g-C3N4 typically exhibits moderate photocatalytic activity. And the amorphous structures and the rapid recombination of the electron-hole pairs are the two main challenges for the improved photocatalytic performance of the single bulk g-C3N4. In this work, we reported the CoP as a co-catalyst modified high-crystalline g-C3N4 (HCCN) to form an stable and highly efficient CoP/HCCN composite via a simple solvothermal method. As expected, the as-prepared composites showed impressive photocatalytic performance toward the tetracycline (TC) degradation. In particular, 5 wt% CoP/HCCN exhibited the optimum photocatalytic efficiency (96.7%, 120 min) and its corresponding degradation rate constant is 10.2 times than HCCN. Additionally, the role of coexisting ions in simulated practical TC wastewater was explored. The enhanced photocatalytic performance mainly derives from two factors: (i) the formation of HCCN to reduce structural defects; (ii) CoP as the cocatalyst on the HCCN surface to accelerate the separation of the photo-generated electrons-hole pairs and strengthen the surface photoreaction of the samples. Our work opens up a new window to the construction of highly effective HCCN-based composite photocatalysts for solar light-driven wastewater treatment.