Revealing the role of kapok fibre as bio-template for In-situ construction of C-doped g-C₃N₄@C, N co-doped TiO₂ core-shell heterojunction photocatalyst and its photocatalytic hydrogen production performance

For the first time, C-doped g-C₃N₄@C, N co-doped TiO₂ core-shell heterojunction photocatalyst was successfully prepared by an in-situ one-pot hydrothermal bio-template approach, assisted by calcination treatment at 500 °C. Kapok fibre was used as a bio-templates and in-situ C doping in g-C₃N₄ and TiO₂ during the formation of core-shell heterojunction photocatalyst. Moreover, the used of urea as g-C₃N₄-precursor also contribute to band-gap narrowing by an in-situ carbon and nitrogen doping in TiO₂. Various characterisation techniques were employed to understand the effect TiO₂ precursor concentration on the evolution of core-shell nanostructure heterojunction photocatalyst that can affect and boost the catalytic activity. The detailed understanding of the concurrent growth of C-doped g-C₃N₄ (CCN) and C, N co-doped TiO₂ mechanism, as well as the formation of core-shell nanostructures heterojunction formation, are also proposed in this study. Our finding indicated that the bio-template core-shell nanostructure heterojunction photocatalysts showed a dramatic increase in photoinduced electron-hole separation efficiency as demonstrated by the photoelectrochemical and photoluminescence analyses. The enhancement in photogenerated charge carrier separation and narrower band gap resulted in superior photocatalytic activities with the highest rate of hydrogen production was recorded by CCN/T-1.5 sample (625.5 μmol h⁻¹ g⁻¹) in methanol aqueous solution. The well-developed interconnected heterojunction formation with appropriate CCN and TiO₂ contents in core-shell nanoarchitectures system is a prime factor for the future design of a highly efficient visible-light-driven photocatalyst.