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

Abstract

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.