Enhanced electron density of the π-conjugated structure and in-plane charge transport to boost photocatalytic H2 evolution of g-C3N4

Abstract

Graphite carbon nitride (g-C 3 N 4 ) has become an emerging metal-free photocatalyst and attracted the attention of researchers. However, pure g-C 3 N 4 (PCN) prepared by traditional thermal condensation polymerization has a low polymerization of heptazine ring chains and a large number of charge recombination centers, which hinder in-plane charge transport, leading to undesirable photocatalytic performance. Herein, PCN fabrication by thermal treatment with ammonium oxalate monohydrate was performed to produce highly dispersed porous g-C 3 N 4 nanosheets, and the integrity of their in-plane heptazine ring chains was successfully improved without introducing heteroatoms. Electron paramagnetic resonance and 13 C nuclear magnetic resonance analyses revealed significantly increased electron density and delocalization of the π-conjugated structure. The obtained samples exhibited acceptable stability and photocatalytic activity, and the hydrogen reduction rates without and with the Pt co-catalyst were 11.2 and 5.3 times that of PCN.

Novel Asymmetric Aggregation Strategy to Boost Charge Separation in Carbon Nitride Polymers for High-Performance Hydrogen Photosynthesis

“…Peaks in the 1200−1650 cm −1 region correspond to the typical modes of CN heterocycles. 42 X-ray photoelectron spectroscopy (XPS) survey spectra confirm the existence of C and N atoms of CNP and SS-CNP (Figure S2).…”

“…Typically, the sharp peak around 810 cm –1 was assigned to the out-of-plane bending vibration of heptazine ring units. Peaks in the 1200–1650 cm –1 region correspond to the typical stretching modes of CN heterocycles . X-ray photoelectron spectroscopy (XPS) survey spectra confirm the existence of C and N atoms of CNP and SS-CNP (Figure S2).…”

Synthesis of lamellar O-doped ZnIn2S4 on layered g-C3N4 for boosted charge transfer and photocatalytic performances

“…The strong peak at 27.41 is corresponding to the interlayer-stacking peak of the conjugated aromatic rings and corresponds to the (002) crystal plane. 30,31 For O-doped ZIS, the diffraction peaks at 21.581, 27.691, 47.171, 47.781, and 27.691 can be ascribed to the (006), ( 102), ( 110), (1012), and (202) planes of hexagonal ZnIn 2 S 4 (JCPDS 72-0773), 22,32 showing that the as-prepared O-doped ZIS maintained its primitive crystal structure. After coupling with CN, the CN/O-doped ZIS samples were similar to the O-doped ZIS, certifying that the formation of the composites did not affect the crystal structure of the O-doped ZIS.…”

Effective inter-chain charge transfer and high charge mobility in polymeric carbon nitride arising from controllable molecular structures for enhanced photocatalytic H2O2 and H2 production

“…Compared to that of traditional BCN, the evidently decreased radii of all the cross-linked carbon nitrides (PTI, CN-70%, CN-80%, CN-90%, and CN-100%) demonstrate the reduced charge transfer resistance. 39,40 This could be due to the existence of cross-linking in these samples. Note that BCN is composed of 1D chains, not allowing inter-chain charge transfer.…”