Nanostructured defects-rich black-ZnO/biowaste-derived carbon composites for efficient visible light-driven hydrogen generation: A study on the role of C–Zn@C–O–Zn interface

The use of a highly efficient and noble-metal-free cocatalyst, which is being pursued to create hydrogen (H₂) via photocatalysis, has been the subject of many studies. In this work, a unique ultrasonication-assisted laser beam irradiation process is employed to synthesize a new carbon material generated from pineapple peel biowaste (ppC) and mix it with oxygen-deficient black zinc oxide (b-ZnO_vac) nanoparticles. In the ppC_x@b-ZnO_vac nanostructures, the XPS analysis verified the presence of surface oxygen (O₂) defects and vacancies as well as chemical interactions between carbon and zinc via carbon-zinc (C–Zn) and carbon-oxygen-zinc (C–O–Zn) connection interfaces. Following optimization, the visible light active photocatalytic H₂ production rate of the ppC₁₀@b-ZnO_vac nanostructures reached 215.92 μmol h⁻¹ g⁻¹, which was the highest. The positive synergistic interaction between b-ZnO_vac and ppC is responsible for the significant increase in the rate of H₂ generation. Furthermore, the significant chemical bond between ppC and b-ZnO_vac via the C–Zn/C–O–Zn interface, as well as the development of surface O₂ vacancy defects in b-ZnO_vac, improve the efficient transfer of energetic electrons and make visible active photocatalytic H₂ production from methanol in the ppC_x@b-ZnO_vac nanostructures easier. Our work presents a new strategy for chemically generating affordable carbon materials through the use of metal oxide-based photocatalysts with surface O₂ vacancy defects and bio-waste. Applications such as water splitting, energy production, and environmental remediation show promise for these advanced materials for large-scale field applications.