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Communication

One-Pot Synthesis of Highly Dispersed VO2 on g-C3N4 Nanomeshes for Advanced Oxidation

by
Yangzhou Deng
1,
Yuqi Zhang
1,
Kunkun Wei
2,
Yue Wang
2,
Shihui Zou
2,* and
Juanjuan Liu
1,*
1
College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310036, China
2
Institute of Catalysis, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
*
Authors to whom correspondence should be addressed.
Catalysts 2024, 14(12), 892; https://doi.org/10.3390/catal14120892
Submission received: 4 November 2024 / Revised: 29 November 2024 / Accepted: 3 December 2024 / Published: 4 December 2024
(This article belongs to the Collection Highly Dispersed Nanocatalysts)
Browse Figures
Figure 1
<p>(<b>a</b>) XRD patterns and (<b>b</b>) N<sub>2</sub> adsorption–desorption isotherms of the g-C<sub>3</sub>N<sub>4</sub>, V-g-C<sub>3</sub>N<sub>4</sub> and V-g-C<sub>3</sub>N<sub>4</sub>-im samples.</p> "> Figure 2
<p>SEM images of the as-prepared (<b>a</b>) g-C<sub>3</sub>N<sub>4</sub>, (<b>b</b>,<b>c</b>) V-g-C<sub>3</sub>N<sub>4</sub>, and (<b>d</b>) V-g-C<sub>3</sub>N<sub>4</sub>-im. (<b>e</b>) HAADF-STEM and elemental mapping of V-g-C<sub>3</sub>N<sub>4</sub>.</p> "> Figure 3
<p>(<b>a</b>) XPS analysis of N1s; (<b>b</b>) the structure of the g-C<sub>3</sub>N<sub>4</sub> and (<b>c</b>) XPS analysis of V2p inV-g-C<sub>3</sub>N<sub>4</sub> and V-g-C<sub>3</sub>N<sub>4</sub>-im samples.</p> "> Figure 4
<p>(<b>a</b>) Removal efficiencies of the MB over various catalysts; (<b>b</b>) kinetic linear simulation curves and (<b>c</b>) the corresponding reaction rate constants for various catalysts. (<b>d</b>) The reusability of V-g-C<sub>3</sub>N<sub>4</sub> for MB removal.</p> "> Figure 5
<p>(<b>a</b>) Scavenger trapping experiments over V-g-C<sub>3</sub>N<sub>4</sub>. (<b>b</b>) EPR spectra using DMPO as the trapping reagent over V-g-C<sub>3</sub>N<sub>4</sub>. (<b>c</b>) A possible reaction mechanism for V-g-C<sub>3</sub>N<sub>4</sub> catalyzed MB removal.</p> "> Scheme 1
<p>Schematic illustration of the one-pot synthetic process for V-g-C<sub>3</sub>N<sub>4</sub> nanostructures.</p> ">
Versions Notes

Abstract

:
Advanced oxidation catalyzed by metal oxides is a promising approach for degrading organic pollutants in wastewater. A critical strategy to enhance the performance of these catalysts is optimizing the dispersion of their active components through innovative synthesis methods. In this study, we report a one-pot synthesis of g-C3N4 nanomeshes supported with highly dispersed VO2 catalysts (V-g-C3N4) for the advanced oxidation of methylene blue (MB). The characterization results reveal that the involvement of VCl3 in the pyrolysis of melamine facilitates the formation of g-C3N4 nanomeshes with abundant amino groups (NH/NH2). The strong interaction between vanadia species and amino groups prevents VO2 particles from agglomerating, resulting in a significantly higher vanadia dispersion than V-g-C3N4-im synthesized via the traditional impregnation method. V-g-C3N4 exhibits a sophisticated microstructure and surface structure, which leads to a rate constant 2.3-fold higher than V-g-C3N4-im in the catalytic degradation of methylene blue using H2O2 as the oxidant. X-ray photoelectron spectroscopy, trapping experiments, and electron paramagnetic resonance measurements reveal that the rapid adsorption and fast diffusion of MB over g-C3N4 nanomeshes, together with the efficient H2O2 activation into ·OH radicals via the V4+/V5+ redox cycle, synergistically contribute to the superior MB removal efficiency of V-g-C3N4. Moreover, V-g-C3N4 demonstrates no significant decrease in activity even after the fourth cycle, indicating its excellent stability during the pollutant removal process.

1. Introduction

Organic dyes are extensively utilized in the textile, printing, and paper industries [1,2]. These dyes, typically complex aromatic compounds with high persistence and visibility, can contaminate water bodies, disrupt aquatic ecosystems, and pose health risks to humans [3,4]. To mitigate the environmental threat, it is essential to neutralize or decompose these dyes from wastewater prior to their final discharge into the environment [5]. Among various water treatment processes, advanced oxidation processes (AOPs) stand out as an effective route for the purification of dye effluents [6,7,8,9]. This effectiveness stems from their ability to generate strongly oxidizing agents, such as •OH radicals [10,11]. The traditional Fenon reaction, which utilizes the efficient reaction between Fe2+ and H2O2 to generate •OH, is one of the most widely studied AOPs for degrading organic pollutants [11,12]. However, this process suffers from several limitations, including a narrow operating pH range, the unrecyclable use of excessive Fe2+, and the generation of a significant volume of iron sludge [3]. To overcome these challenges, researchers have explored the use of heterogeneous Fenton-like catalysts [13,14,15,16], such as supported multivalent metal oxides (e.g., Fe, Mn, Co, Cu, V). For example, Zubir et al. [17] reported that well-dispersed iron oxide nanoparticles supported on graphene oxide sheets can be used as heterogeneous Fenton-like catalysts to rapidly degrade Acid Orange 7 dye. Ling et al. [18] demonstrated activated alumina-supported CoMnAl composite metal oxides as an efficient, stable, and reusable Fenton-like catalyst for the detoxification of pharmaceutical wastewater in neutral condition. In addition, polymers loaded with iron oxide or copper have also been used as cost-effective Fenton catalysts to degrade organic pollutants [19]. Despite the advancements, the activity of these catalysts still has considerable room for improvement, which necessitates the innovation of synthesis methods to optimize their structures.
Metal oxides stabilized on supports are usually synthesized by physical methods (e.g., evaporation, sputtering) or chemical methods (e.g., ion exchange, co-precipitation, sol–gel, wet impregnation) [20,21]. The catalytic performances of metal oxides can be readily modulated by their size, dispersion, surface structures, and the interaction with the support [22]. With the development of nanotechnology, researchers have dedicated considerable effort to optimizing the dispersion of supported metal oxides [23], aiming to maximize the concentration of active sites and enhance their catalytic performance [22,24]. Among various factors, the choice of support and the method of synthesis are particularly important. Graphitic carbon nitride (g-C3N4) is commonly utilized as a two-dimensional (2D) support for metals and metal oxides, owing to its plentiful uncondensed aliphatic amines (NH2 and -NH- groups) that act as anchoring sites for active species [25,26,27,28]. Nevertheless, g-C3N4 synthesized via conventional pyrolysis methods often exhibits a low surface-to-volume ratio and limited active sites, leading to the agglomeration of supported particles. Engineering sophisticated nanostructures for g-C3N4 can increase the surface area and provide more interaction sites to disperse metal oxides. However, traditional strategies of preparing g-C3N4 nanostructures with highly dispersed metal oxides often involve multiple steps, long synthesis times, and even the use of expensive equipment and reagents [28,29]. To meet the demand for time efficiency and sustainability, it is appealing to develop facile and environmentally friendly methods to disperse metal oxides on g-C3N4 under mild conditions. The one-pot protocol, which combines multiple reactions into a single reaction vessel, has significant potential to minimize the number of required steps, reduce complexity, and conserve time and resources. However, the intricate reactions among the reagents in one-pot synthesis pose challenges in achieving a high dispersion of metal oxides.
This study presents a one-pot synthesis method for V-g-C3N4 nanocatalysts, featuring highly dispersed VO2 species on nanomesh-structured g-C3N4. Unlike the traditional method, which directly impregnates as-synthesized g-C3N4 in a VCl3 solution, the one-pot synthesis method involves VCl3 in the transformation of melamine into g-C3N4. The strong interaction between VCl3 and the abundant amine groups in melamine enables the in situ conversion of VCl3 and melamine into highly dispersed VO2 and g-C3N4 nanomeshes with abundant amino groups (NH/NH2) during pyrolysis. Due to its advanced microstructures and surface features, V-g-C3N4 demonstrates enhanced catalytic activity over V-g-C3N4-im in methylene blue degradation with H2O2 as the oxidant.

2. Results and Discussion

V-g-C3N4 nanostructures were synthesized via a method illustrated in Scheme 1. In this method, melamine and VCl3 were mixed in one pot to fabricate g-C3N4-supported highly dispersed vanadia species. g-C3N4 was synthesized following the same steps as V-g-C3N4, except for the absence of VCl3. V-g-C3N4-im was synthesized using a traditional impregnation method, with g-C3N4 and VCl3 as the starting materials. XRD was used to analyze the chemical composition and crystalline structure of the samples. As shown in Figure 1a, all three samples display a peak at ~27.5°, corresponding to the (002) plane of g-C3N4 (JCPDS: 87–1526) [27,30]. Notably, the peak in V-g-C3N4 is significantly broader than those in g-C3N4 and V-g-C3N4-im, suggesting that the one-pot synthesis method induces a different microstructure for g-C3N4. The N2 adsorption–desorption isotherms further confirm this observation (Figure 1b). All samples display type IV adsorption isotherms with H3 hysteresis loops, signifying the presence of mesopores. The larger hysteresis loop observed for V-g-C3N4 implies the presence of more mesopores compared to the other samples. This eventually leads to a large surfacer area of V-g-C3N4 (43 m2 g−1) than g-C3N4 (10 m2 g−1) and V-g-C3N4-im (27 m2 g−1). Notably, characteristic XRD peaks were also observed in V-g-C3N4-im at 33.0°, 36.2°, 41.2°, 53.9°, and 65.2°, which can be well indexed to the (104), (110), (113), (112), and (300) planes of V2O3 (JCPDS:34-0187) [31,32], respectively. In contrast, no obvious peaks related to vanadium oxides are observed in V-g-C3N4, probably due to the small particle size and good dispersion of vanadia species.
The microstructure and morphology of the synthesized samples were first examined using a SEM (Figure 2). In contrast to g-C3N4 and V-g-C3N4-im, which exhibit irregular bulk structures (Figure 2a,d), V-g-C3N4 displays a nanomesh structure with an interconnected network (Figure 2b,c). This suggests that the introduction of vanadium species during the g-C3N4 fabrication process influences the final framework, which is consistent with the XRD result and N2 sorption isotherms. High-angle annular dark field scanning transmission electron microscopy (HAADF-STEM, Figure 2e) further confirms the nanomeshes structure of V-g-C3N4. Moreover, the EDX elemental mapping of V-g-C3N4 shows uniform distribution of C, N, and V across the sample. The absence of noticeable vanadia aggregation on the g-C3N4 surface indicates a high dispersion of vanadia species in V-g-C3N4, aligning well with the XRD results presented in Figure 1a.
V-g-C3N4 and V-g-C3N4-im not only have distinct microstructures, but also display different surface structures (Figure 3a). The N1s high-resolution XPS spectra for all samples reveal three deconvoluted peaks at 398.5 eV, 399.2 eV, and 400.6 eV, representing sp2-hybridized triazine nitrogen (C-N=C, Na), sp3-hybridized three-coordinate N species (C-N(-C)-H and N-(C)3, Nb), and sp3-hybridized surface nitrogen pending amino groups (e.g., -NH2, Nc in Figure 3b) at the edge of the g-C3N4 framework, respectively [33,34]. Interestingly, the percentages of Na (57.5% vs. 57.1%), Nb (25.6% vs. 25.2%), and Nc (16.9% vs. 17.7%) in V-g-C3N4-im are almost identical to those in g-C3N4, indicating that the impregnation of V2O3 onto g-C3N4 does not significantly alter the structure of g-C3N4. Nevertheless, the relative contents of these N species are significantly different between V-g-C3N4 and V-g-C3N4-im. For V-g-C3N4, the percentage of Na decreases to 48.4% while the percentage of Nb increases to 33.0%, indicating that the presence of vanadium species during the conversion of melamine to g-C3N4 induces structural changes in the surface heterocycles of g-C3N4. More three-coordinated N species are generated, providing anchoring sites for vanadium species and ultimately leading to a high dispersion of vanadia. These observations are consistent with the microstructural characterization shown in Figure 2.
The preparation method not only alters the structure of g-C3N4, but also influences the surface chemical states of vanadium. Figure 3c shows the V2p3/2 spectra of V-g-C3N4 and V-g-C3N4-im, which can be deconvoluted into two peaks at 515.5 and 516.6 eV, corresponding to V3+ and V4+, respectively [35]. Interestingly, the relative content of V3+/V4+ differs significantly. For V-g-C3N4-im, vanadium mainly exists as V2O3 (Figure 1a). Accordingly, V3+ (59.6%) dominates the surface. In stark contrast, V-g-C3N4 exhibits a V3+/ V4+ ratio of 0.307/0.693, indicating that vanadium mainly exists as highly dispersed VO2.
The distinct microstructures and surface structures between V-g-C3N4 and V-g-C3N4-im likely originate from the different interaction between VCl3 and g-C3N4. Theoretically, strong interactions between precursors and supports facilitate high precursor dispersion, which in turn leads to a high dispersion of supported nanomaterials [33,36]. In terms of VCl3, its interaction with amino groups is usually stronger than that with triazine nitrogen [33]. Therefore, when VCl3 is mixed with melamine in the one-pot synthesis method, the abundant amino groups in melamine strongly bind to VCl3, forming a complex with highly dispersed VCl3. During the subsequent pyrolysis process, VCl3 and melamine undergo in situ conversion to form vanadia and g-C3N4. This in situ conversion facilitates both the high dispersion of vanadium oxide and the formation of a nanomesh structure in g-C3N4 with a high Nb content. In contrast, g-C3N4 synthesized via melamine pyrolysis possesses a limited number of amino groups available for interaction with VCl3 (Figure 3a). During the impregnation process, the weak interaction between VCl3 and g-C3N4 hinders the uniform dispersion of VCl3. Consequently, during the subsequent pyrolysis step, the agglomerated VCl3 tends to form large V2O3 nanoparticles instead of highly dispersed VO2 species. Meanwhile, the structure of g-C3N4 remains largely unaltered during this process. Notably, traditional strategies to prepare g-C3N4 nanostructures with highly dispersed metal oxides often involve multiple steps, long synthesis times, and even the use of expensive equipment and reagents [28,29,37]. In contrast, the one-pot protocol reported in this study minimizes the number of required steps, thereby reducing complexity and conserving both time and resources. This makes it an attractive option for the design and synthesis of new materials. It is crucial to emphasize that the successful implementation of the one-pot synthesis of V-g-C3N4 relies on a strong interaction between VCl3 and melamine. This method may also be applicable to other metal oxide systems, provided that the interactions between the reagents are precisely controlled.
Methylene blue (MB), frequently found in industrial wastewater, presents considerable health hazards if not properly treated [38]. These risks include tissue necrosis, cyanosis, jaundice, vomiting, and shock [39]. Effective removal of MB from wastewater is necessary prior to industrial discharge to mitigate its negative effects. In this study, the catalytic activity of V-g-C3N4 was evaluated via MB removal with H2O2 at room temperature. The adsorption of MB by the catalysts was examined before conducting the catalytic test. Figure 4a demonstrates that different materials show varying adsorption capacities for MB. V-g-C3N4 exhibits a notable adsorption efficiency of 34.9%, surpassing both pristine g-C3N4 (3.3%) and V-g-C3N4-im (19.5%). This enhancement is attributable to the increased surface area of V-g-C3N4. Notably, the catalysts also exhibit different behavior in the following catalysis. As demonstrated in Figure 4a, MB is stable and does not undergo self-degradation within 60 min in the absence of either H2O2 or catalyst. Upon adding 2 mL of H2O2 into the mixture, V-g-C3N4 demonstrates enhanced degradation activity relative to g-C3N4 and V-g-C3N4-im. Specifically, V-g-C3N4 demonstrated ~91% degradation of MB within 30 min, outperforming g-C3N4 and V-g-C3N4-im, which achieved only ~39.3% and ~65.7% removal efficiency, respectively, within the same time frame. The kinetic plots of the degradation results were well-fitted by the pseudo-first-order model. As shown in Figure 4b, the degradation rate constant on V-g-C3N4 was 0.056 min−1 (Figure 4c), which is 48.3, 4.3, and 2.3 times higher than that of the blank, pristine g-C3N4, and V-g-C3N4-im, respectively. These results clearly indicate that V-g-C3N4 with highly dispersed VO2, exhibits better catalytic activity. The superior activity of V-g-C3N4 is likely attributed to the highly dispersed VO2 nanoparticles in the framework of the g-C3N4 nanomeshes, in contrast to the aggregated V2O3 particles supported on the bulk g-C3N4. Furthermore, recycling experiments were conducted to evaluate the stability of V-g-C3N4 in removing MB. As displayed in Figure 4d, there is no significant decrease in activity even after the fourth cycle, indicating that the V-g-C3N4 composites are quite stable during the pollutant removal process.
Notably, the absence of either H2O2 or catalysts results in no MB degradation, indicating that MB is broken down by reactive oxygen species (ROS), such as ·OH or O2−, produced via a Fenton-like reaction between the H2O2 and the catalysts. To determine the dominant ROS involved in the V-g-C3N4 catalyzed MB removal process, trapping experiments were conducted using p-benzoquinone to trap O2− and tert-butanol to trap ·OH radicals [40] (Figure 5a). Interestingly, the addition of p-benzoquinone after the mixture reached adsorption equilibrium has little effect on the degradation efficiency, implying that O2− radicals are not the primary ROS. In contrast, the degradation efficiency is significantly reduced upon the addition of tert-butanol, suggesting the essential role of ·OH radicals in the catalytic removal of MB. Electron paramagnetic resonance (EPR) measurements with 5,5-Dimethyl-1-Pyrroline-N-oxide (DMPO) as the trapping reagent further validated these findings. When V-g-C3N4 is mixed with H2O2 and DMPO, four antisymmetric peaks with an intensity ratio of 1:2:2:1 are observed (Figure 5b), characteristic of DMPO-·OH signals [40]. In stark contrast, no such signals are observed in the case of H2O2 + DMPO and H2O2+g-C3N4+DMPO. These results suggest that the primary ROS, ·OH, are produced via the reaction between H2O2 and the highly dispersed VO2 species. According to the literature [41,42,43], both V4+ (VO2+ + H2O2 → VO2+ + ·OH + H+) and V3+ (V3+ + H2O2 → VO2+ + ·OH + H+) can react with H2O2 to generate ·OH. In addition, the produced VO2+ species can be reduced to VO2+ to complete the V4+/V5+ cycle (Figure 5c). To this end, supported vanadia with abundant V4+ species are widely used as Fenton-like catalysts for various applications, such as benzene hydroxylation and advanced oxidation of organic pollutants [33].
Taking all the above results together, we propose the following mechanism for V-g-C3N4-catalyzed MB removal (Figure 5c). The one-pot synthesized V-g-C3N4 consists of highly dispersed VO2 species supported on g-C3N4 nanomeshes. When V-g-C3N4 is added into the solution, MB will rapidly adsorb onto the g-C3N4 nanomeshes due to its high surface area and three-dimensional interconnected structure. Once H2O2 is added, the Fenton-like reaction between H2O2 and VO2 will produce ·OH and V5+, both of which can oxidize the adsorbed MB (Figure 5c). The rapid adsorption and fast diffusion of MB over g-C3N4 nanomeshes, together with the efficient H2O2 activation involved in the V4+/V5+ redox cycle, synergistically contribute to the superior MB removal efficiency of V-g-C3N4.

3. Materials and Methods

Chemicals and reagents. VCl3 (≥99.0%) was purchased from Aladdin, Inc. (Shanghai, China). Melamine, hydrogen peroxide (H2O2, 30%), nitric acid (HNO3, ~68%), and anhydrous ethanol were obtained from Sinopharm Chemical Reagents Co., Ltd. (Shanghai, China). Methylene blue (MB) was purchased from Yuanye Bio., Inc. (Shanghai, China).
Synthesis of V-g-C3N4. The one-pot synthesis of V-g-C3N4 is schematically illustrated in Scheme 1. A mixture was prepared by dispersing 3.0 g of melamine into 40 mL of ethanol, followed by the addition of 1.11 g of HNO3 to achieve a concentration of 0.3 M in the entire reaction system. Subsequently, 355.5 mg of VCl3 was added into the mixture. After vigorous stirring at room temperature for 60 min to ensure thorough mixing, the mixture was heated to 80 °C to fully evaporate the solvent. The solid was calcined in a covered crucible at 550 °C for 2 h under a nitrogen atmosphere. The final product was labeled as V-g-C3N4. Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analysis verified that the vanadium mass loading was approximately 5.0 wt%.
For comparison, g-C3N4 was fabricated following similar steps to V-g-C3N4, but without the introduction of VCl3.
Synthesis of V-g-C3N4-im. Typically, 0.3 g of g-C3N4 was added into 40 mL of ethanol containing 48.69 mg of VCl3. After vigorous stirring for 60 min, the mixture was heated at ~80 °C to evaporate the solvent completely. The resulting product was calcined at 550 °C for 2 h under N2 atmosphere. ICP-AES analysis confirmed that the mass loading of vanadium was ~5.0 wt%.
Characterizations. A transmission electron microscope (TEM, JEOL JEM-1230, Tokyo, Japan) with an energy dispersive X-ray (EDX) spectroscope was used to examine the microstructure and chemical composition distribution. Morphological analysis was conducted using a Hitachi S4800 (Hitachi, Ltd. Tokyo, Japan) scanning electron microscope (SEM). The crystalline phase was analyzed using a Rigaku Ultimate IV (Rigaku Corporation, Tokyo, Japan) X-ray diffractometer (XRD) with Cu Kα radiation. A VG Scientific ESCALAB Mark II X-ray photoelectron spectrometer (XPS) was used to determine the chemical states and environment of the catalysts. Nitrogen sorption isotherms were obtained using a Micromeritics ASAP 2020 adsorption analyzer (Micromeritics Corporation, Norcross, GA, USA). The V species content was accurately verified using ICP-AES with a Profile Spec instrument. Electron paramagnetic resonance (EPR) experiments were conducted using a Bruker model A300 spectrometer (Bruker Corporation, Billerica, MA, USA) operating at 100 kHz modulation frequency at room temperature.
Catalytic activity test. Catalyst activity was assessed through a model reaction involving pollutant removal. Briefly, 10 mg of the synthesized catalyst was added to 30 mL of a methylene blue (MB) solution (15 ppm) in a 50 mL glass tube. The mixture was stirred at 25 °C for 60 min to reach the adsorption/desorption equilibrium. Afterwards, 2 mL of hydrogen peroxide (H2O2, 30 wt%) was rapidly added to the mixture. At predetermined time intervals, 1 mL of the suspension was extracted and centrifuged. The Shimadzu UV-3600 spectrometer was used to measure the residual MB concentration in the supernatant.

4. Conclusions

We report a one-pot synthesis of V-g-C3N4 nanostructures for the advanced oxidation of MB. The incorporation of vanadia species during g-C3N4 synthesis modifies the microstructure and surface structure of g-C3N4, creating a nanomesh structure with abundant amino groups (NH/NH2). These amino groups act as anchoring sites for vanadia species, promoting high VO2 dispersion in V-g-C3N4. The rapid adsorption and fast diffusion of MB over g-C3N4 nanomeshes, together with the efficient H2O2 activation into ·OH radicals via the V4+/V5+ redox cycle, synergistically contribute to the superior MB removal efficiency of V-g-C3N4. Under the optimal experimental conditions, ~91% of MB was degraded by V-g-C3N4 within 30 min. The catalytic rate constant of V-g-C3N4 is 2.3-fold higher than that of V-g-C3N4-im. Moreover, V-g-C3N4 demonstrates no significant decrease in activity even after the fourth cycle, indicating its excellent stability during the pollutant removal process. Given the efficiency, cost-effectiveness, and environmentally friendly nature of the proposed one-pot synthesis, future research will investigate the scalability of this method and its applications to other dyes and pollutants.

Author Contributions

Conceptualization, J.L. and S.Z.; methodology, J.L. and K.W.; validation, Y.D. and Y.Z.; investigation, Y.D., Y.Z., K.W. and Y.W.; writing—original draft preparation, J.L.; writing—review and editing, S.Z.; visualization, J.L.; supervision, J.L. and S.Z.; project administration, J.L. and S.Z.; funding acquisition, J.L. and S.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This research received financial support from the National Natural Science Foundation of China (Grant No. 22372051) and the Zhejiang Province Natural Science Foundation (Grant No. LY22B030010).

Data Availability Statement

The data presented in this study are available on request from the corresponding author.

Conflicts of Interest

The authors declare no conflicts of interest.

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Catalysts 14 00892 sch001
Scheme 1. Schematic illustration of the one-pot synthetic process for V-g-C3N4 nanostructures.
Scheme 1. Schematic illustration of the one-pot synthetic process for V-g-C3N4 nanostructures.
Catalysts 14 00892 sch001
Catalysts 14 00892 g001
Figure 1. (a) XRD patterns and (b) N2 adsorption–desorption isotherms of the g-C3N4, V-g-C3N4 and V-g-C3N4-im samples.
Figure 1. (a) XRD patterns and (b) N2 adsorption–desorption isotherms of the g-C3N4, V-g-C3N4 and V-g-C3N4-im samples.
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Figure 2. SEM images of the as-prepared (a) g-C3N4, (b,c) V-g-C3N4, and (d) V-g-C3N4-im. (e) HAADF-STEM and elemental mapping of V-g-C3N4.
Figure 2. SEM images of the as-prepared (a) g-C3N4, (b,c) V-g-C3N4, and (d) V-g-C3N4-im. (e) HAADF-STEM and elemental mapping of V-g-C3N4.
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Figure 3. (a) XPS analysis of N1s; (b) the structure of the g-C3N4 and (c) XPS analysis of V2p inV-g-C3N4 and V-g-C3N4-im samples.
Figure 3. (a) XPS analysis of N1s; (b) the structure of the g-C3N4 and (c) XPS analysis of V2p inV-g-C3N4 and V-g-C3N4-im samples.
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Figure 4. (a) Removal efficiencies of the MB over various catalysts; (b) kinetic linear simulation curves and (c) the corresponding reaction rate constants for various catalysts. (d) The reusability of V-g-C3N4 for MB removal.
Figure 4. (a) Removal efficiencies of the MB over various catalysts; (b) kinetic linear simulation curves and (c) the corresponding reaction rate constants for various catalysts. (d) The reusability of V-g-C3N4 for MB removal.
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Catalysts 14 00892 g005
Figure 5. (a) Scavenger trapping experiments over V-g-C3N4. (b) EPR spectra using DMPO as the trapping reagent over V-g-C3N4. (c) A possible reaction mechanism for V-g-C3N4 catalyzed MB removal.
Figure 5. (a) Scavenger trapping experiments over V-g-C3N4. (b) EPR spectra using DMPO as the trapping reagent over V-g-C3N4. (c) A possible reaction mechanism for V-g-C3N4 catalyzed MB removal.
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MDPI and ACS Style

Deng, Y.; Zhang, Y.; Wei, K.; Wang, Y.; Zou, S.; Liu, J. One-Pot Synthesis of Highly Dispersed VO2 on g-C3N4 Nanomeshes for Advanced Oxidation. Catalysts 2024, 14, 892. https://doi.org/10.3390/catal14120892

AMA Style

Deng Y, Zhang Y, Wei K, Wang Y, Zou S, Liu J. One-Pot Synthesis of Highly Dispersed VO2 on g-C3N4 Nanomeshes for Advanced Oxidation. Catalysts. 2024; 14(12):892. https://doi.org/10.3390/catal14120892

Chicago/Turabian Style

Deng, Yangzhou, Yuqi Zhang, Kunkun Wei, Yue Wang, Shihui Zou, and Juanjuan Liu. 2024. "One-Pot Synthesis of Highly Dispersed VO2 on g-C3N4 Nanomeshes for Advanced Oxidation" Catalysts 14, no. 12: 892. https://doi.org/10.3390/catal14120892

APA Style

Deng, Y., Zhang, Y., Wei, K., Wang, Y., Zou, S., & Liu, J. (2024). One-Pot Synthesis of Highly Dispersed VO2 on g-C3N4 Nanomeshes for Advanced Oxidation. Catalysts, 14(12), 892. https://doi.org/10.3390/catal14120892

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