Boosting photocatalytic hydrogen evolution of g-C3N4 catalyst via lowering the Fermi level of co-catalyst

Abstract

The photocatalytic performances are highly dependent on the charge separation and surface reaction kinetics of photocatalysts. Aiming at figuring out the effects of co-catalyst with the lower Fermi level on photocatalytic activity, we tuned the Fermi level of Pt nanoparticles on g-C₃N₄(GCN) by introducing Co atom. Experimental results show that lowering the Fermi level of co-catalyst does not alter light absorption of GCN due to the invariable structure. Besides, Pt₃Co with a lower Fermi level contributes less positive influence on charge separation in GCN due to an opposite effect from the stronger electron-trap ability of Pt₃Co and increased band bending in GCN-Pt₃Co. The density functional theory (DFT) calculations indicate that GCN-Pt₃Co has faster surface reaction kinetics than GCN-Pt, owing to easier dissociation of H₂O molecules and faster desorption of H* on Pt₃Co. Consequently, GCN-Pt₃Co exhibits an excellent H₂ evolution rate with 2.91 mmol·g⁻¹·h⁻¹, which 2.67 times that of GCN-Pt.