Efficient visible-light-driven H2O2 production activity of covalently modified zinc phthalocyanine/g-C3N4 heterostructure

Abstract

Developing efficient heterojunction photocatalysts holds a great promise for advancing solar-to-chemical energy conversion. In this study, tetra-4-carboxyethylenephenoxy-substituted Zinc (II) phthalocyanine (ZnTcPc) was covalently linked to the amine-functionalized graphitic carbon nitride (g-C₃N₄) to create an efficient photocatalyst. The optimized ZnTcPc/g-C₃N₄ composite demonstrated improved photocatalytic activity relative to that of pure g-C₃N₄ and ZnTcPc in the generation of H₂O₂ under 150 W metal halide lamp at ambient temperature. The covalent integration of ZnTcPc into the g-C₃N₄ framework tailored its electronic structure efficiently and highlighted the potential of the ZnTcPc/g-C₃N₄ composite as a visible-light responsive photocatalyst. FT-IR spectroscopy revealed the establishment of novel chemical linkages between ZnTcPc and g-C₃N₄, indicating strong covalent interactions. SEM and TEM analyses provided insight into the morphological transformation, showing a more uniform surface texture and enhanced interface contact between the two materials, facilitating better charge transfer. XRD patterns indicated alterations to the crystalline structure, confirming the successful incorporation of ZnTcPc into the g-C₃N₄ lattice. Additionally, XPS analysis verified the electronic coupling between g-C₃N₄ and ZnTcPc, with shifts in binding energies suggesting strong electronic interaction. These findings underscore the nanocomposite's improved photocatalytic activity and responsiveness to visible light. It achieved the highest H₂O₂ production rate of 27.17 mg/L within 90 min, surpassing the rates of pure g-C₃N₄ and ZnTcPc. This synergistic photocatalytic process provides valuable insights into advancing energy conversion technologies.