In- situ solid-phase fabrication of Ag/AgX (X=Cl,Br, I)/g-C3N4 composites for enhanced visible-light hydrogen evolution

In this work, a series of Ag/AgX (X = Cl, Br, I)/g-C₃N₄ (Ag/AgX/CN) composites were successfully fabricated by an in-situ solid phase method. The morphology and structure, photoluminescence and photoelectrochemical properties of composites were investigated in detail. The as-prepared Ag/AgX/CN composites were used as H₂ evolution photocatalysts under visible-light irradiation with a sacrificial agent. The experimental results revealed that Ag/AgI/CN-4 composite possesses highest-H₂ evolution rate (up to 59.22 μmol g⁻¹ h⁻¹) which are approximately 31 times higher than that of pure g-C₃N₄ (1.94 μmol g⁻¹ h⁻¹). In addition, Ag/AgCl/CN-4 and Ag/AgBr/CN-4 composites also present high photocatalytic activities yielding, 26.39 and 18.05 μmol_H2 g⁻¹ h⁻¹_, respectively. The enhanced photocatalytic activities of Ag/AgI/CN-4 composite might be attributed to the synergistic effect between Ag/AgI nanoparticles and g-C₃N₄ and the localized surface plasmon resonance effect of metallic Ag. Moreover, Ag/AgI/CN-4 composite showed excellent recyclability and stability after five cycling photocatalytic tests (about 25 h). Furthermore, the possible photocatalytic mechanism of Ag/AgI/CN composites is proposed.     

The charge transfer pathway of g-C3N4 decorated Au/Bi(VO4) composites for highly efficient photocatalytic hydrogen evolution

In this report, a novel g-C₃N₄/Au/BiVO₄ photocatalyst has been prepared successfully by assembling gold nanoparticles on the interface of super-thin porous g-C₃N₄ and BiVO₄, which exhibits outstanding photocatalytic performance toward hydrogen evolution and durable stability in the absence of cocatalyst. FESEM micrograph analysis suggested that the intimate contact between Au, BiVO₄, and g-C₃N₄ in the as-developed photocatalyst allows a smooth migration and separation of photogenerated charge carriers. In addition, the XRD, EDX and XPS analysis further confirmed the successful formation of the as-prepared g-C₃N₄/Au/BiVO₄ photocatalyst. The photocatalytic hydrogen production activity of the developed photocatalyst was evaluated under visible-light irradiation (λ > 420 nm) using methanol as a sacrificial reagent. By optimizing the 5-CN/Au/BiVO₄ composite shows the highest H₂ evolution rate (2986 μmolg⁻¹h⁻¹), which is 15 times higher than that of g-C₃N₄ (199 μmolg⁻¹h⁻¹) and 10 time better than bare BiVO₄ (297 μmolg⁻¹h⁻¹). The enhancement in photocatalytic activity is attributed to efficient separation of the photoexcited charges due to the anisotropic junction in the g-C₃N₄/Au/BiVO₄ system. The enhancement in photocatalytic activity is attributed to efficient separation of the photoexcited charges due to the anisotropic junction in the g-C₃N₄/Au/BiVO₄ system.     

Chloroplast-granum-inspired porous nanorods composed of g-C3N4 ultrathin nanosheets as visible light photocatalysts for highly enhanced hydrogen production

Metal-free photocatalysts have attracted great attention in hydrogen production under visible light due to their low cost and abundance. Inspired by the structure of chloroplast-granum, here we prepare a new porous nanorod composed of F-doped g-C₃N₄ ultrathin nanosheet for photocatalytic hydrogen evolution. The obtained g-C₃N₄ (FCN-PNRs) show layer-by-layer stacked structure for highly efficient light hasting, exhibit F-doping for highly charge separation efficiency, and display porous structure for exposing a large amount of photocatalytic activity sites. These findings have been studied by various characterizations, such as Brunauer-Emmett-Teller, and Photoluminescence. As a result, the hydrogen production performance for the optimized FCN-PNRs photocatalyst reaches 2600 μmol h⁻¹ g⁻¹ under visible light, which is almost 16 times higher than bulk g-C₃N₄. This study not only reports a new chloroplast-granum-inspired g-C₃N₄ photocatalyst, but also provides new views to the fabrication and design of nature-inspired metal-free structures for catalysis applications.     

Bimetallic PtNi alloy modified 2D g-C3N4 nanosheets as an efficient cocatalyst for enhancing photocatalytic hydrogen evolution

Platinum-based alloy materials as effective cocatalysts in improving the performance of photocatalytic H₂ production have raised great interest. Herein, a facile strategy of chemical reduction is established to synthesize bimetallic PtNi nanoparticles on 2D g-C₃N₄ nanosheets with excellent photocatalytic activity. The addition of PtNi nanoparticles can provide new H⁺ reduction sites and increase more active sites of the material. The synergistic effect between PtNi alloy nanoparticles and 2D g-C₃N₄ nanosheets can regulate electronic structure, narrow the band, accelerate charge transfer efficiency and inhabit the recombination of photo-induced electron (e⁻) and hole pairs (h⁺), contributing to the improvement of hydrogen evolution activity. The optimal hydrogen evolution rate of Pt_0.6Ni_0.4/CN shows higher hydrogen evolution rate (9528 μmol·g⁻¹·h⁻¹), which is 13.1 times than that of pure g-C₃N₄ nanosheets. Besides, a possible mechanism of photocatalytic hydrogen generation has been brought up according to a series of physical and chemical characterization. This work also provides a potential idea of developing cocatalysts integrating metal alloys with 2D g-C₃N₄ nanosheets for promoting photocatalytic hydrogen evolution.     

One-pot calcination preparation of graphene/g–C3N4–Co photocatalysts with enhanced visible light photocatalytic activity

Photocatalytic technology for hydrogen evolution from water splitting and pollutant degradation is one of the most sustainable methods. Here, the graphene/g–C₃N₄–Co composite materials have been prepared by one-pot calcination method. The results show that g-C₃N₄ grow on the surface of graphene and form a sandwich structure, meanwhile, the introduction of Co increases the active sites, which promotes the photocatalytic performance. The influences of graphene and Co content on photocatalytic activity were also studied by UV–visible spectrophotometry (DRS), photoluminescence spectroscopy (PL), photocurrent, degradation MB, and hydrogen production. The apparent reaction rate constant k of graphene/g–C₃N₄–Co (3%) is 0.946 h⁻¹, which is 4.90 and 2.18 times faster than g-C₃N₄ and graphene/g-C₃N₄, respectively. And the hydrogen production rate of graphene/g–C₃N₄–Co (3%) (892.3 μmol h⁻¹ g⁻¹) is 3.53 and 1.61 times higher than g-C₃N₄ and graphene/g-C₃N₄, respectively.     

A direct one-step synthesis of ultrathin g-C3N4 nanosheets from thiourea for boosting solar photocatalytic H2 evolution

Two-dimensional (2D) graphitic carbon nitride (g-C₃N₄) nanosheets, as the promising photocatalyst with fascinating properties, have become a “rising star” in the field of photocatalysis. Although g-C₃N₄ nanosheets exfoliated from the bulk g-C₃N₄ powders are extensively emerged, developing a simple synthetic approach is still full of challenge. To this end, here we report a direct polymerization strategy to fabricate the ultrathin g-C₃N₄ nanosheets, that is only heating treatment of thiourea in air without addition of any template. The photocatalytic activities of as-prepared samples were evaluated by photoreduction of water to hydrogen (H₂) using triethanolamine as sacrificial agent and Pt as co-catalyst under visible-light irradiation (λ > 420 nm). As a result, our few-layered g-C₃N₄ nanosheets with an average thickness of 3.5 nm exhibit a superior visible-light photocatalytic H₂ evolution rate (HER) of 1391 μmol g⁻¹ h⁻¹ and a remarkable apparent quantum efficiency of 6.6% at 420 nm. Eventually, the HER of as-fabricated ultrathin g-C₃N₄ nanosheets is not only much higher than the dicyandiamide-derived g-C₃N₄ or melamine-derived g-C₃N₄, but also greater than the thermal-oxidation etched g-C₃N₄ nanosheets under the same condition.     

Rationally designed ternary CdSe/WS2/g-C3N4 hybrid photocatalysts with significantly enhanced hydrogen evolution activity and mechanism insight

Excellent light harvest, efficient charge separation and sufficiently exposed surface active sites are crucial for a given photocatalyst to obtain excellent photocatalytic performances. The construction of two-dimensional/two-dimensional (2D/2D) or zero-dimensional/2D (0D/2D) binary heterojunctions is one of the effective ways to address these crucial issues. Herein, a ternary CdSe/WS₂/g-C₃N₄ composite photocatalyst through decorating WS₂/g-C₃N₄ 2D/2D nanosheets (NSs) with CdSe quantum dots (QDs) was developed to further increase the light harvest and accelerate the separation and migration of photogenerated electron-hole pairs and thus enhance the solar to hydrogen conversion efficiency. As expected, a remarkably enhanced photocatalytic hydrogen evolution rate of 1.29 mmol g⁻¹ h⁻¹ was obtained for such a specially designed CdSe/WS₂/g-C₃N₄ composite photocatalyst, which was about 3.0, 1.7 and 1.3 times greater than those of the pristine g-C₃N₄ NSs (0.43 mmol g⁻¹ h⁻¹), WS₂/g-C₃N₄ 2D/2D NSs (0.74 mmol g⁻¹ h⁻¹) and CdSe/g-C₃N₄ 0D/2D composites (0.96 mmol g⁻¹ h⁻¹), respectively. The superior photocatalytic performance of the prepared ternary CdSe/WS₂/g-C₃N₄ composite could be mainly attributed to the effective charge separation and migration as well as the suppressed photogenerated charge recombination induced by the constructed type-II/type-II heterojunction at the interfaces between g-C₃N₄ NSs, CdSe QDs and WS₂ NSs. Thus, the developed 0D/2D/2D ternary type-II/type-II heterojunction in this work opens up a new insight in designing novel heterogeneous photocatalysts for highly efficient photocatalytic hydrogen evolution.     

Photo-assisted splitting of water into hydrogen using visible-light activated silver doped g-C3N4 & CNTs hybrids

Herein, highly efficient and cost effective solar photocatalytic water splitting for hydrogen (H₂) generation was achieved by modified g-C₃N₄. Visible light absorption of g-C₃N₄ was enhanced by decorating g-C₃N₄ matrix with silver nanoparticles (Ag). Moreover, incorporation of carbon nanotubes (CNTs) in Ag/g-C₃N₄ facilitated photocatalytic performance through efficient separation and transfer of photogenerated e-h pairs (charges) in Ag/g-C₃N₄ that consequently generated very pure and significant H₂. Among several tested ratios (wt. %) of Ag/g-C₃N₄/CNTs, 1.82 (Ag/g-C₃N₄) and 2.00 (and Ag/g-C₃N₄/CNTs) were found to be highly efficient that harvested maximum visible-light and produced H₂ @1.48 mmol h⁻¹ and 1.78 mmol h⁻¹. We witnessed distinctive role of CNTs as an electron collector and carrier to separate photogenerated e-h pairs to facilitate photocatalysis for H₂ generation together with possible utility of Ag and CNTs doped materials with regard to energy transformation.     

Ag2CO3-derived Ag/g-C3N4 composite with enhanced visible-light photocatalytic activity for hydrogen production from water splitting

In this paper, Ag-based g-C₃N₄ composites have been successfully fabricated through two deferent synthetic methods: (i) a facile and efficient precipitation-calcination strategy (denoted as D–CN–xAg, x represents the dosage of Ag₂CO₃, the same below), (ii) a calcination method (denoted as Z–CN–xAg). All Ag-based g-C₃N₄ composites exhibit the enhanced photocatalytic activities under visible-light irradiation. Moreover, the optimal dosage of Ag₂CO₃ in the D–CN–xAg composite is found to be 5%, the corresponding hydrogen production capacity is 153.33 μmol g⁻¹ h⁻¹, which is 4.6 times higher than that of Z–CN–5%Ag composite. This might be attributed to appropriate content of metallic Ag and more active sites exposed on the surface of D–CN–5%Ag composite. Meanwhile, combining with photoelectrochemical results, it could be inferred that LSPR effect and the intimate interfacial between metallic Ag and g-C₃N₄ in the system play also important role for the improvement of photocatalytic activity. These results demonstrate that the appropriate loading of metallic Ag originated from Ag₂CO₃ into g-C₃N₄ could accelerate the separation and transfer of photogenerated electron-hole pairs, leading to the improvement of photocatalytic activity for hydrogen production from water splitting. Finally, a possible photocatalytic mechanism is proposed.     

Fabrication of hollow g-C3N4@α-Fe2O3/Co-Pi heterojunction spheres with enhanced visible-light photocatalytic water splitting activity

For the first time, g-C₃N₄@α-Fe₂O₃/Co-Pi heterojunctional hollow spheres were successfully fabricated via thermal condensation method followed by solvothermal and photo-deposition treatment, which showed excellent photocatalytical property. Except for the Z-scheme charge transfer between α-Fe₂O₃ and g-C₃N₄, the Co-Pi could further reduce the combination of photogenerated electrons and holes as a hole storage agent, resulting in remarkably enhanced visible-light photocatalytic water splitting activity with the H₂ production rate of 450 μmol h⁻¹g⁻¹, which is 15.7 times higher than that of g-C₃N₄. Moreover, the photocatalytic activity of the prepared ternary hollow photocatalysts showed almost no significant weakness after five cycles, which indicated their good performance stability. The as-prepared g-C₃N₄@α-Fe₂O₃/Co-Pi also possessed good activity for overall water splitting with the hydrogen production rate reaching 9.8 μmol h⁻¹g⁻¹. This synthesized g-C₃N₄@α-Fe₂O₃/Co-Pi composite is expected to be a promising candidate for water splitting.     

The synergistic effect of potassium ions and nitrogen defects on carbon nitride for enhanced photocatalytic hydrogen evolution

Ion doping is an effective method to improve the photocatalytic activity of graphitic carbon nitride (g-C₃N₄) by providing a photocarriers transfer channel. But limited by the bonds in heptazine rings, photoelectrons are still trapped in the structure. Therefore, both potassium ions and nitrogen defects were successfully introduced into g-C₃N₄ by high temperature calcination to accelerate the charges transfer between both interlayers and intralayer of g-C₃N₄. The results showed that the hydrogen production rate of g-C₃N₄ modified simultaneously by nitrogen defects and potassium ions reaches 1722.4 μmol·g⁻¹·h⁻¹, which is 8 times that of pristine g-C₃N₄. Based on various characterization techniques and DFT calculations, we attributed the enhanced photocatalytic hydrogen evolution to the improved light adsorption, more delocalized HOMO-LUMO, and stronger interlayer interactions. This work will provide a promising way to enhance photocatalytic hydrogen evolution of g-C₃N₄ and a possible mechanism was proposed.     

Facile synthesis of CeO2/g-C3N4 nanocomposites with significantly improved visible-light photocatalytic activity for hydrogen evolution

Ceria dioxide supported on graphitic carbon nitride (CeO₂/g-C₃N₄) composites were facilely synthesized to be application for photocatalytic hydrogen (H₂) generation in this present work. The physical and chemical properties of CeO₂/g-C₃N₄ nanocomposites were determined via a series of characterizations. The CeO₂/g-C₃N₄ composites prepared by facile thermal annealing and rotation-evaporation method exhibit excellent photocatalytic H₂ evolution with visible-light illumination. The best hydrogen generation rate of CeO₂/g-C₃N₄ composite with 1.5 wt% Pt is 0.83 mmol h⁻¹ g⁻¹, which is almost same as that of composite with 3 wt% Pt prepared by simple physical mixing method. The significantly developed photocatalytic activity of CeO₂/g-C₃N₄ composite is majorly ascribed to the stronger interfacial effects with the more visible-light absorbance and faster electron transfer. This work reveals that construction of the CeO₂/g-C₃N₄ composite with high disperse and close knit by the facile thermal annealing and rotation-evaporation method could be an effective method to achieve excellent photocatalytic hydrogen evolution performance.     

Investigation of Photo(electro)catalytic water splitting to evolve H2 on Pt-g-C3N4 nanosheets

g-C₃N₄ has shown great potentials in photocatalytic water splitting to produce hydrogen. Herein, we successfully synthesized g-C₃N₄ nanosheets via exfoliating bulk g-C₃N₄. And different metal nanoparticles were photo-deposited onto the surface of g-C₃N₄ nanosheets. The photocatalytic H₂ production activity of g-C₃N₄ nanosheets increased from 0 to 11.2 μmol/h/g_cat. The Pt loaded g-C₃N₄ nanosheets manifested the highest H₂ production activity with a rate of 589.4 μmol/h/g_cat. In addition, the hydrogen evolution rate was further enhanced with addition of external bias to fabricate a photoelectrocatalytic (PEC) system. And the maximum hydrogen production rate (23.1 mmol/h/m²) was obtained at a voltage of 0.6 V (vs. Ag/AgCl). The enhancement in H₂ production may be due to the following reasons: (1) Two-dimensional atomic flakes is beneficial to increase the specific surface area of g-C₃N₄, enhance the mobility of carriers, and improve the energy band structure, (2) Pt nanoparticles play an important role in g-C₃N₄ electron transport, (3) the g-C₃N₄ nanosheets loaded with Pt nanoparticles exhibited significant enhancement in photoelectrocatalytic performance, which may be attributed to its enhanced electronic conductivity and photoelectrochemical surface area, (4) Pt inhibited the recombination of photogenerated carriers and significantly improved the photocatalytic performance. The enhancement mechanism was deeply discussed and explained in this work.     

Enhancement of visible light photocatalytic hydrogen evolution by bio-mimetic C-doped graphitic carbon nitride

Bio-mimetic C-doped graphitic carbon nitride (g-C₃N₄) with mesoporous microtubular structure has been prepared by a simple chemical wet bio-template impregnation approach (direct impregnation and hydrothermal impregnation) using urea as a precursor and kapok fibre as bio-template and in-situ carbon dopant. Our finding indicated that the hydrothermal impregnation had induced more in-situ C-doping in g-C₃N₄ as compared to the direct impregnation approach. The introduction of in-situ C doping in the g-C₃N₄ and the mesoporous microtubular structure remarkably enhanced light-harvesting capability up to near infrared regions. The photocurrent measurement and electrochemical impedance spectroscopy (EIS) analysis suggested that the bio-template C-doped g-C₃N₄ exhibits a superior photoinduced electron-hole pairs separation efficiency due to C doping and mesoporous microtubular structure significantly promotes excellent conductivity and electron redistribution in the sample. C-doped graphitic carbon nitride sample prepared by the hydrothermal (HB/g-C₃N₄) approach exhibits excellent photocatalytic hydrogen production with an H₂ production rate of 216.8 μmol h⁻¹ g⁻¹ which was a 1.3 and 2.9 improvement over C-doped graphitic carbon nitride prepared by direct impregnation (DB/g-C₃N₄) and pristine g-C₃N_4, respectively. This study provides new insights into the development of low-cost and sustainable photocatalysts for photocatalytic hydrogen production.     

Montmorillonite-hybridized g-C3N4 composite modified by NiCoP cocatalyst for efficient visible-light-driven photocatalytic hydrogen evolution by dye-sensitization

The photocatalytic hydrogen evolution performance of g-C₃N₄ was enhanced via the hybridization with montmorillonite (MMT) and using NiCoP as cocatalyst. The highest hydrogen-evolution rate from water splitting under visible-light irradiation observed over MMT/g-C₃N₄/15%NiCoP was 12.50 mmol g⁻¹ h⁻¹ under 1.0 mmol L⁻¹ of Eosin Y-sensitization at pH of 11, which was ∼26.0 and 1.6 times higher than that of MMT/g-C₃N₄ (0.48 mmol g⁻¹ h⁻¹) and g-C₃N₄/15%NiCoP (7.69 mmol g⁻¹ h⁻¹). The apparent quantum yield at 420 nm reached 40.3%. The remarkably improved photocatalytic activity can be ascribed to the increased dispersion of g-C₃N₄ layers, staggered conduction band potentials between g-C₃N₄ and NiCoP, as well as the electrostatic repulsion originated from negatively charged MMT. This work demonstrates that MMT can be an outstanding support for the deposition of catalytically active components for photocatalytic hydrogen production.     

Construction of heterostructured g-C3N4@TiATA/Pt composites for efficacious photocatalytic hydrogen evolution

Construction of heterostructured photocatalysts is a feasible method for improving hydrogen production from water splitting because of its good charge transport efficiency. Herein, we coupled the Ti-MOFs (TiATA) with metal-free graphitic carbon nitride (g-C₃N₄) to synthesize composites, g-C₃N₄@TiATA, in which a heterostructure was formed between g-C₃N₄ and TiATA. The establishment of heterojunctions not only broadens the light absorption range of g-C₃N₄@TiATA (490 nm) by contrast with g-C₃N₄ (456 nm), but also greatly accelerates charge migration. Photocatalytic studies present that the construction of heterostructure steering the charges flow from g-C₃N₄ to TiATA and then delivery to the cocatalyst of Pt nanoparticles, exhibiting an impressively photocatalytic hydrogen production rate (265.8 μmol·h⁻¹) in assistance of 300 W Xenon lamp, which is about 3.4 times as much as g-C₃N₄/Pt.     

Sustainable hydrogen production by CdO/exfoliated g-C3N4 via photoreforming of formaldehyde containing wastewater

Graphitic carbon nitride (g-C₃N₄) has been well-known as an appealing semiconducting material for photocatalytic hydrogen production despite its restricted active sites and poor electronic properties. In this work, exfoliated g-C₃N₄ nanosheets were synthesised by chemical treatment of the bulk graphitic carbon nitride (gCN) and the nanosheets were further doped with CdO. The photocatalysts produced were extensively characterized by diverse analysis including XRD, BET, XPS, TEM, FESEM, UV-Vis spectroscopy and PL analysis. The BET surface area of CdO/exfoliated g-C₃N₄, 40.1 m² g⁻¹ was doubled in comparison to the exfoliated g-C₃N₄. Numerous electrochemical analyses such as Mott-Schottky, linear weep voltammetry and chronoamperometry were also performed in a standard photoelectrochemical system with three-electrode cell. The hydrothermally synthesised CdO/exfoliated g-C₃N₄ resulted higher amount of hydrogen evolution (145 μmol/g) for the photoreforming of aqueous formaldehyde than the CdO (20 μmol/g), bulk gCN (58 μmol/g) and exfoliated g-C₃N₄ (87 μmol/g). The excellent hydrogen production rate using CdO/exfoliated g-C₃N₄ nanocomposite could be ascribed by higher number of active sites as well as shorter path of the charge carries to the reaction surface. The anticipated Z-Scheme mechanism has demonstrated a synergistic impact between the CdO and exfoliated g-C₃N₄ where the organic compounds acting as hole scavenger as well as contribute protons, H⁺ for the effective hydrogen production. Thus, it is clearly confirmed that the newly formulated CdO/exfoliated g-C₃N₄ has an outstanding potentiality for environmental remediation and conversion sectors.     

Construction of Cu7.2S4/g-C3N4 photocatalyst for efficient NIR photocatalysis of H2 production

Graphite-like carbon nitride (g-C₃N₄) has been regarded as a promising photocatalyst for solar-to-chemical conversion. Nevertheless, the narrow absorption of light extremely limited its photocatalytic performance under near-infrared (NIR) irradiation. Herein, the Cu₇.₂S₄ with outstanding NIR absorption was successfully introduced to g-C₃N₄ nanosheets through a simple in-situ growth procedure. As expected, the constructed Cu_7.2S₄/g-C₃N₄ (CSCN) photocatalysts exhibit superior H₂ production activity of 82 μmol g⁻¹ h⁻¹ under NIR light irradiation (λ > 800 nm), which outperforms currently reported g–C₃N₄–based NIR-driven H₂ production systems. Especially, the optimal sample CSCN-5 displays a robust activity of 66 μmol g⁻¹ h⁻¹ at λ = 850 nm monochromatic light irradiation. The excellent photocatalytic performance is linked to the extended optical absorption as well as the efficient separation efficiency of photoinduced carriers, which are evidenced by the UV-visible absorption spectroscopy and photoelectrochemical test. This work provides an effective approach for constructing a Cu_7.2S₄/g-C₃N₄ photocatalytic system for the transformation of NIR solar energy into hydrogen.     

Surface defect and rational design of TiO2−x nanobelts/ g-C3N4 nanosheets/ CdS quantum dots hierarchical structure for enhanced visible-light-driven photocatalysis

TiO_2-x/g-C₃N₄/CdS ternary heterojunctions are fabricated through thermal polymerization-chemical bath deposition combined with in-situ solid-state chemical reduction approach. The prepared materials are characterized by X-ray diffraction, Fourier transform infrared spectra, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption, and X-ray photoelectron spectroscopy. The results show that the ternary heterojunctions are formed successfully and CdS quantum dots (QDs) and TiO₂ are anchored on surface of g-C₃N₄ nanosheets simultaneously. The visible-light-driven photocatalytic degradation ratio of Bisphenol A and hydrogen production rate are up to 95% and ∼254.8 μmol h⁻¹, respectively, which are several times higher than that of pristine TiO₂. The excellent visible-light-driven photocatalytic activity can be ascribed to the synergistic effect of TiO_2−x, g-C₃N₄ and CdS QDs which extend the photoresponse to visible light region and favor the spatial separation of photogenerated charge carriers.     

Synthesis of solar-light responsive Pt/g-C3N4/SrTiO3 composite for improved hydrogen production: Investigation of Pt/g-C3N4/SrTiO3 synthetic sequences

Solar-light responsive platinum/graphite-like carbon nitride/strontium titanate (Pt/g-C₃N₄/SrTiO₃) with excellent charge separation was synthesized via thermal treatment process. A photocatalytic hydrogen production rate of 552 μmol/h/g was achieved under simulated sunlight irradiation for the Pt/(g-C₃N₄/SrTiO₃) catalyst with 5 v/v% triethanolamine (TEOA) as a sacrificial agent. The hydrogen production rate of Pt/g-C₃N₄/SrTiO₃ prepared via different synthetic sequences decreased in the following order: Pt/(g-C₃N₄/SrTiO₃) > (Pt/g-C₃N₄)/SrTiO₃ > g-C₃N₄/(Pt/SrTiO₃). The mechanisms of electron transfer in the different synthetic sequences of Pt/g-C₃N₄/SrTiO₃ were investigated. The electron transfer pathway of Pt/(g-C₃N₄/SrTiO₃) was as follows: (1) g-C₃N₄→SrTiO₃→Pt, (2) g-C₃N₄→Pt, (3) SrTiO₃→Pt, and (4) g-C₃N₄→SrTiO₃, leading to optimal charge separation and H⁺ ion reduction.