Efficient Organic Bonding of Open-Ring Carbonyl-Functionalized g-C3N4
with AQ Molecules for Rapid Hydrogen Peroxide Synthesis
Abstract
Photocatalytic two-electron oxygen reduction for hydrogen peroxide
(H2O2) production represents a cost-effective and sustainable synthetic
approach that has garnered significant attention. Inexpensive
graphite-like carbon nitride (g-C3N4) features a tunable bandgap and
impressive photocatalytic performance in the 2e- oxygen reduction
reaction (ORR), facilitating H2O2 synthesis. This study presents the
design of a defect vacancy ring-opening g-C3N4 that introduces specific
C-OH sites at the edges of the ring openings. The g-C3N4 is covalently
bonded to anthraquinone (AQ) via ester C-O-C=O oxygen bridges, resulting
in a CN-O-AQ catalyst characterized by a silk-like, ordered stacked
layer structure. The incorporation of specialized oxygen bridge bonds
alters charge transport dynamics, establishing rapid charge diffusion
pathways that enhance electron migration to the surface during the
photoactivated oxygen reduction reaction. The synergistic effects of
optimizing the (100) crystal plane crystallinity and introducing dual
O/Cl element doping promote the development of new light absorption
centers and lower oxygen adsorption energy while creating suitable
electron vacancies. This combination significantly boosts the catalyst’s
direct two-electron oxygen reduction capability for H2O2 formation. The
CN-O-AQ catalyst achieved an impressive H2O2 yield of 626 mmol L-1,
which is 14.9 times higher than that of pure CN (42 mmol L-1). This work
elucidates the dual impact of modulating both crystal and electronic
structures on photocatalytic performance, offering valuable insights for
designing defect sites and doping strategies in organic conjugated
structure catalysts.