Inter-plane heterojunctions within 2D/2D FeSe2/g-C3N4 nanosheet semiconductors for photocatalytic hydrogen generation

Abstract Developing and designing a robust hydrogen generation photocatalyst for water splitting remains a huge challenge for realizing highly effective conversion of solar energy into chemical fuel. Herein, two-dimensional FeSe2/g-C3N4 inter-plane heterostructures (2D/2D FeSe2/CNNS) were rationally constructed via the in-situ deposition of FeSe2 nanosheets on the g-C3N4 surface. The resulting 15% FeSe2/CNNS 2D/2D composite exhibited an optimal H2 generation rate of 1655.6 μmol∙h−1 ∙g−1 in Na2S/Na2SO3 solution, being nearly 2.65, 1.73 and 1.19 times higher than that of pristine g-C3N4, FeSe2 and corresponding 0D/2D FeSe2/CNNS nanocrystals, respectively. Such remarkably improved photocatalytic performance could be ascribed to efficient charge carrier mobility, acceleration of H2O2 decomposition via a stepwise two-electron/two-step pathway, and the formed 2D heterojunction interfacial contact between g-C3N4 and FeSe2 nanosheets. This work can provide new insight for designing atomic-level structural and interfacial 2D nanojunctions to steer charge separation and transportation in the nanocomposite.