Boosting photocatalytic hydrogen evolution of g-C3N4 catalyst via lowering the Fermi level of co-catalyst
Hairui Cai, Bin Wang, Laifei Xiong, Jinglei Bi, Hanjing Hao, Xiaojing Yu, Chao Li, Jiamei Liu, Shengchun Yang
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.