Z-scheme heterojunction of graphitic carbon nitride and calcium ferrite in converter slag for the photocatalytic imidacloprid degradation and hydrogen evolution

[Display omitted] •Co-calcination synthesized graphitic carbon nitride/converter slag composites (gCN/CS).•gCN/artCS and gCN/realCS enhanced hydrogen evolution under UV–vis light irradiation.•The heterojunction between gCN and converter slag prevents electron-hole’s recombination. Graphitic carbon nitride/ converter slag (gCN/CS) composites were fabricated as photocatalysts by a simple co-calcination. The structural, optical, and physicochemical characteristics of graphitic carbon nitride/ artificial converter slag (gCN/artCS) composites were investigated for the photocatalytic degradation of imidacloprid under visible light irradiation to optimize the mixing ratio of converter slag. The optimized gCN/artCS composite containing 11.58 % of artCS exhibited a 2.5 times faster rate of imidacloprid degradation over 120 min compared to pure gCN. The enhanced separation and transportation of photoinduced electrons and holes were revealed for the optimized gCN/artCS composite by the photoluminescence, impedance spectroscopy, and photocurrent densities. Furthermore, the energy-resolved distribution of electron traps (ERDT) pattern for the optimized composite strongly suggested the development of an interfacial Z-scheme heterojunction between gCN and iron oxide included in artCS, leading to reducing electron-hole pair recombination. Finally, the real CS was applied for the fabrication of the composite with gCN, and then the composite (gCN/realCS) was evaluated for H2 evolution. The H2 evolution rate over gCN/realCS did not come up to gCN/artCS but was greater than the pristine gCN. The reason is possibly due to lacking the electron trap states around 2.0–2.6 eV on the ERDT pattern for gCN/realCS. Thus, the present gCN/CS composites can be a potentially effective photocatalyst for hydrogen evolution under light irradiation.