Simultaneously Tuning Charge Separation and Oxygen
Reduction Pathway on Graphitic Carbon Nitride by Polyethylenimine
for Boosted Photocatalytic Hydrogen Peroxide Production
posted on 2020-03-05, 17:03authored byXiangkang Zeng, Yue Liu, Yuan Kang, Qinye Li, Yun Xia, Yinlong Zhu, Huilin Hou, Md Hemayet Uddin, Thomas R. Gengenbach, Dehua Xia, Chenghua Sun, David T. Mccarthy, Ana Deletic, Jiaguo Yu, Xiwang Zhang
The
synthesis of hydrogen peroxide (H2O2)
from H2O and O2 by metal-free photocatalysts
(e.g., graphitic carbon nitride, C3N4) is a
potentially promising approach to generate H2O2. However, the photocatalytic H2O2 generation
activity of the pristine C3N4 in pure H2O is poor due to unpropitious rapid charge recombination and
unfavorable selectivity. Herein, we report a facile method to boost
the photocatalytic H2O2 production by grafting
cationic polyethylenimine (PEI) molecules onto C3N4. Experimental results and density functional theory (DFT)
calculations demonstrate PEI can tune the local electronic environment
of C3N4. The unique intermolecular electronic
interaction in PEI/C3N4 not only improves the
electron–hole separation but also promotes the two-electron
O2 reduction to H2O2 via the sequential
two-step single-electron reduction route. With the synergy of improved
charge separation and high selectivity of two-electron O2 reduction, PEI/C3N4 exhibits an unexpectedly
high H2O2 generation activity of 208.1 μmol
g–1 h–1, which is 25-fold higher
than that of pristine C3N4. This study establishes
a paradigm of tuning the electronic property of C3N4 via functional molecules for boosted photocatalysis activity
and selectivity.