Photodegradation behavior and antibacterial activity of light transition metal-based tetranaphthalene porphyrin/C3N5 heterojunction†

In this study, light transition metal-based tetranaphthalene porphyrin/C₃N₅ [(Np)₄MP/CN-x, x is the mass ratio, M = Ni, Cu, Zn] heterojunction composites were prepared and characterized. The photoluminescence spectra, transient photocurrent response and electrochemical impedance shows that the introduction of light transition metal-based tetranaphthalene porphyrin [(Np)₄MP] can effectively improve the serious problem of C₃N₅ photogenerated carrier recombination. Additionally, (Np)₄MP functions as a sensitizer, broadening the visible light absorption range of C₃N₅ and thereby enhancing its photocatalytic activity. Among the synthesized composites, (Np)₄CuP/CN-0.5 exhibited exceptional photocatalytic performance. Within 20 min, it achieved degradation efficiencies of 98.95% for 20 ppm methylene blue (MB) and 97.42% for rhodamine B (RhB). Furthermore, it demonstrated remarkable antibacterial activity, with rates of 97.92% against Escherichia coli and 99.31% against Staphylococcus aureus within just 10 min. The photodegradation efficiency of this catalyst surpasses that of most previously reported catalysts. We also gave an insight into the mechanism of photocatalytic degradation of dyes by (Np)₄MP/CN-0.5 and found that the degradation effect of the catalyst in accordance with the direct Z-scheme heterojunction mechanism was better than that of the type II heterojunction. This study broadens the way for the synthesis of relatively low-cost and multifunctional photocatalysts.