g-C₃N₄/TiO₂ Mesocrystals Composite for H₂ Evolution under Visible-Light Irradiation and Its Charge Carrier Dynamics

Abstract

The photocatalytic performance of graphitic carbon nitride (g-CN) has been limited to low efficiency due to fast charge recombination. Here, we constructed g-CN nanosheets/TiO mesocrystals metal-free composite (g-CN NS/TMC) to promote the efficiency of charge separation. The photocatalytic H evolution experiments indicate that coupling g-CN NS with TMC increases photogenerated charge carriers in g-CN NS/TMC composite due to efficient charge separation. g-CN NS (31 wt %)/TMC shows the highest photocatalytic activity and the corresponding H evolution rate is 3.6 μ mol h. This value is 20 times larger than that of g-CN NS without any noble metal cocatalyst under visible-light irradiation (λ > 420 nm). The photocatalytic activity of g-CN NS/TMC (3.6 μmol h) is 7 times higher than that of g-CN NS/P25 (0.5 μ mol h), confirming the importance of strong interface interaction between two-dimensional g-CN NS and plate-shape TMC. Femtosecond time-resolved diffuse reflectance (fs-TDR) was employed to study the fundamental photophysical processes of bulk g-CN, g-CN NS, and g-CN/TMC composite which are essential to explain the photocatalytic activity. Using fs-TDR, we demonstrate that the photocatalytic activity depends on the increased driving force for photoinduced electron transfer and a higher percentage of photogenerated charges.

Engineering oxygen vacancy on rutile TiO2 for efficient electron-hole separation and high solar-driven photocatalytic hydrogen evolution

“…Hence, photocatalytic hydrogen production attracts much more attention recently [2][3][4]. Since Fujishima and Honda [5][6][7] discovered hydrogen production from water splitting on TiO 2 for the first time, it is considered as the most promising photocatalyst candidate due to nontoxicity, high stability and low-cost [8][9][10]. Therefore, TiO 2 is widely used in photocatalytic degradation of pollutants, photocatalytic hydrogen production, solar cells, photoelectrochemical devices, and so on [11][12][13][14].…”

Defective Anatase TiO2−x Mesocrystal Growth In Situ on g‐C3N4 Nanosheets: Construction of 3D/2D Z‐Scheme Heterostructures for Highly Efficient Visible‐Light Photocatalysis

“…The good matching of the band positions between g‐C 3 N 4 and TiO 2 endows the constructed TiO 2 /g‐C 3 N 4 heterostructures with a greater driving force for charge transfer across the heterointerface, thereby promoting the spatial separation of photogenerated electron/hole pairs and leading to the enhancement of the overall photoconversion efficiency . Generally, the properties and operational performance of TiO 2 /g‐C 3 N 4 heterostructures are largely dependent on the morphology, mesostructure, contact area, and interface properties of the two components . Considering the novel structural characteristics of defective TiO 2− x mesocrystals, the good dispersion of well‐defined defective TiO 2− x mesocrystals on g‐C 3 N 4 nanosheets (NSs) to achieve a high contact area and tightly chemical‐bonded interface is highly anticipated to optimize the photocatalytic activity, but has rarely been reported.…”

“…[52][53][54][55] Generally,the properties and operational performance of TiO 2 /g-C 3 N 4 heterostructures are largely dependento nt he morphology, mesostructure, contacta rea, and interface properties of the two components. [56][57][58][59][60][61][62][63][64] Considering the novel structural characteristics of defective TiO 2Àx mesocrystals, the good dispersion of well-defined defective TiO 2Àx mesocrystals on g-C 3 N 4 nanosheets (NSs) to achieve ah igh contact area andt ightly chemical-bonded interface is highly anticipatedt oo ptimize the photocatalytica ctivity,b ut has rarely been reported. Only one example of ad efective TiO 2Àx mesocrystal/g-C 3 N 4 NS heterostructure has been reportedi nw hich micrometer-sized urchin-like Ti 3 + -dopedT iO 2 mesocrystals constructed of radially aligned anatase nanowires were successfully utilized to form ah ybrid with g-C 3 N 4 NSs.…”

Kohlenstoffnitridmaterialien für photochemische Zellen zur Wasserspaltung

“…Eine der ersten erfolgreichen Abscheidungen erfolgte durch ein Gasphasenverfahren:d ie chemische Gasphasenabscheidung (CVD). [67][68][69] Zhang et al haben gezeigt, dass die Protonierung von CN unter Verwendung einer starken Säure zu einem Sol führt, das die Abscheidung auf Filmen unter Verwendung von Tauchbeschichten erlaubt. [59] Die Flüssigphasen-Alternative beinhaltet Polymerisation und Kondensation auf der Oberfläche des leitfähigen Substrats.…”

“…[66] Einige Gusstechniken liefern gute Ergebnisse auf kleinen Substraten, beispielsweise das Fallgießen einer Lçsung von dispergiertem CN auf glasartigen Kohlenstoff zur elektrochemischen Charakterisierung. [67][68][69] Zhang et al haben gezeigt, dass die Protonierung von CN unter Verwendung einer starken Säure zu einem Sol führt, das die Abscheidung auf Filmen unter Verwendung von Tauchbeschichten erlaubt. Aufd iese Weise konnten sie die Schwierigkeit der Anwendung der Sol-Gel-Techniken fürC Nüberwinden, die sich in den meisten organischen Lçsungsmitteln nicht lçsen.…”