Defects Promote Ultrafast Charge Separation in Graphitic Carbon Nitride for Enhanced Visible‐Light‐Driven CO₂ Reduction Activity

Abstract

Fundamental photocatalyticl imitations of solar CO 2 reduction remaind ue to low efficiency,s eriousc harge recombination, and short lifetime of catalysts. Herein, twodimensional graphitic carbon nitride nanosheets with nitrogen vacancies (g-C 3 N x )l ocateda tboth three-coordinateN atoms and uncondensed terminal NH x species were prepared by one-step tartaric acid-assistantt hermal polymerization of dicyandiamide. Transient absorption spectra revealed that the defects in g-C 3 N 4 act as trapped states of chargest or esult in prolonged lifetimes of photoexcited charge carriers. Time-resolved photoluminescence spectroscopy revealed that the faster decay of chargesi sd ue to the decreased interlayer stacking distance in g-C 3 N x in favor of hopping transition and mobility of charge carriers to the surface of the material. Owing to the synergic virtues of strong visible-light absorption, large surface area, and efficient charges eparation, the g-C 3 N x nanosheets with negligible loss after 15 ho fp hotocatalysis exhibited aC Oe volution rate of 56.9 mmol g À1 h À1 under visible-light irradiation, which is roughlye ight times higher than that of pristine g-C 3 N 4 . This work presentst he role of defects in modulating light absorption and charge separation, which opens an avenue to robust solar-energyc onversion performance.Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Nanostructured Carbon Nitrides for CO2 Capture and Conversion

“…This is considered as one of the key parameters for the photocatalytic CO 2 reduction reactions (Figure I,J) . The S‐doping and introduction of N‐vacancies in g‐C 3 N 4 could form impurity level under the conduction band edge, which maximizes light absorption for photons of longer wavelengths and minimizes the electron–hole charge recombination . Amine or silica‐functionalized g‐C 3 N 4 presents an enhancement in the conversion of CO 2 due to high CO 2 affinity of the functional groups .…”

Dual-defect-modified graphitic carbon nitride with boosted photocatalytic activity under visible light

“…The formation of nitrogen defects in the g-C 3 N 4 framework is an effective way of reducing the charge-transfer barrier and improving its photocatalytic performance under visible light 46 . As a result, the defect-control methodology has been intensively studied with the aim of increasing the visible-light absorption of g-C 3 N 4 and engender it with superior activity 46–50 . Defects are easily introduced into g-C 3 N 4 by modifying its synthesis conditions, which is ascribable to its metal-free polymer properties and heterogeneous atomic environment; i.e., the various bonding states of its two- and three-coordinated nitrogen atoms.…”

Nitrogen Vacancy‐Induced Deposition of Pd Nanoparticles onto g‐C3N4 with Greatly Improved Photocatalytic Activity in H2 Evolution

“…Notably, with the shortened interlayer distance, it may be in favor of improving the charge transfer between different layers and promoting the photocatalytic activity in H 2 evolution. [ 22 ] Moreover, the intensity of (002) peak for g‐C 3 N 4 was increased after the modifications during preparation. This may be caused by that the interlayer stacking of graphitic structure was partially destroyed with the formation of NVs.…”