Z-scheme g-C₃N₄/Bi₄NbO₈Cl heterojunction for enhanced photocatalytic hydrogen production

Photocatalytic water splitting is promising for sustainable energy development, but it is severely challenged by the low charge separation efficiency and slashing redox potentials requirement. Fabricating a Z-scheme heterojunction as an effective strategy for solving the aforementioned troubles gains enormous efforts. In this work, we develop high-efficiency Z-scheme catalyst g-C₃N₄/Bi₄NbO₈Cl based on a facile high-energy ball-milling method to form an intimate interface between the two phases. It exhibits an enormously promoted photocatalytic activity for H₂ production with visible-light illumination (λ > 420 nm), and the H₂ evolution rate is 6.9 and 67.2 times higher than those of bare g-C₃N₄ and Bi₄NbO₈Cl, respectively. The stronger photoabsorption of g-C₃N₄/Bi₄NbO₈Cl (beyond 500 nm) allows generation of more photons than does g-C₃N₄. More importantly, the separation and transfer of photoexcited charge carriers were greatly improved between g-C₃N₄ and Bi₄NbO₈Cl, as revealed by the photoelectrochemical and time-resolved photoluminescence decay results. The Z-scheme charge transfer mechanism of g-C₃N₄/Bi₄NbO₈Cl was also manifested by electron spin resonance (ESR). The work furnishes a new solution to fabrication of high-efficiency Z-scheme catalysts for countering energy issues.