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1.
Jinwen Shi Botong Zheng Liuhao Mao Cheng Cheng Yuchao Hu Heng Wang Gaosheng Li Dengwei Jing Xianglong Liang 《International Journal of Hydrogen Energy》2021,46(3):2927-2935
A dual-precursors co-pyrolysis strategy was adopted to prepare photocatalysts of MoO3/g-C3N4 composite from MoS2/melamine through a facile one-pot method. By following this strategy, MoS2 was in-situ transformed to MoO3 accompanying with the pyrolysis and polymerization of melamine to g-C3N4 nanosheets. A set of samples about MoO3/g-C3N4 composite containing different MoO3 contents were prepared and the visible-light driven photocatalytic performance of samples were investigated. The photocatalytic activity was notably enhanced and the highest evolution rate for H2 reached 13.9 times and 2.5 times that of the pristine g-C3N4 and the MoO3/g-C3N4 derived from MoO3/melamine, respectively. On the one hand, layered MoS2 used as the precursor of MoO3 contributed to the intimate contact with g-C3N4 nanosheets and the high dispersity of derived MoO3, and on the other hand, the morphology and electronic structure of g-C3N4 were actually changed by the strong interaction between the MoO3 and g-C3N4, thus inducing an efficient Z-scheme (S-scheme) system in the composite. The above-mentioned co-operation effect in the composite resulted in the significant improvement on the activity of photocatalytic H2 evolution. This work presented a valuable reference, by taking MoO3/g-C3N4 as an example, for the construction of composite-photocatalyst system in visible-light-driven H2 evolution. 相似文献
2.
《International Journal of Hydrogen Energy》2021,46(76):37782-37791
Efficient photocatalytic selective conversion of organic under mild condition remains challengeable for green chemistry. In this work, we determined that nitrogen vacancies (NVs) in graphitic carbon nitride (g-C3N4) could enhance photocatalytic selective oxidation of benzyl alcohol to benzaldehyde. The as-prepared N-deficient g-C3N4 samples (CNx) exhibited superior conversion efficiency and excellent product selectivity than pristine g-C3N4 upon visible light irradiation. By combining experimental characterizations and density functional theory calculations, the NVs in g-C3N4 could significantly boost carrier separation and act as specific sites to enhance the adsorption and activation of reactants. Thus, our work could provide insight into the pathways of reaction between defects and reactants, and point out a feasible strategy for green fine chemical production. 相似文献
3.
《International Journal of Hydrogen Energy》2023,48(20):7284-7293
Although graphitic carbon nitride (g-C3N4) is widely used for photocatalytic hydrogen production, its practical application is restricted by the high recombination rate of photoinduced electron-hole pairs and limited active sites. In this work, holey ultrathin g-C3N4 nanosheets (HCN NSs) with rich active sites are prepared, followed by the growth of 1T-MoS2 NSs on their surfaces to construct 2D/2D 1T-MoS2/HCN heterostructure. Due to the high surface area and abundant hydrogen active sites of the hybrid, large and intimate 2D nanointerface between MoS2 and HCN, hydrogen ion adsorption and charge separation/transport ability are greatly enhanced. As a result, 1T-MoS2/HCN-4 with the optimal 1T-MoS2 content of 8 wt% displays the highest H2 production rate of 2724.2 μmol?1 h?1 g?1 under simulated solar light illumination with apparent quantum efficiency of 8.1% (λ = 370 nm). Moreover, the 1T-MoS2/HCN-4 hybrid manifests improved stability after a long-time test. This study opens the door to design highly-efficient g-C3N4 based 2D/2D heterostructures for photocatalytic H2 production. 相似文献
4.
《International Journal of Hydrogen Energy》2019,44(14):7108-7117
Composite of g-C3N4 and poly(3-hexylthiophene) (P3HT) with enhanced photocatalytic H2 production activity was prepared by polymerizing 3-hexylthiophene and g-C3N4, which was treated with thiophene-3-acetic acid (T3A). The morphology, chemical structure, and light absorption properties of samples were characterized by SEM, TEM, BET, XRD, FT-IR, XPS, UV–visible diffuse reflectance spectra (UV–vis). The migration and separation efficiency of charge carriers were characterized by photoluminescence (PL) emission spectra, Time resolved photoluminescence spectra, transient photocurrent responses, and electrochemical impedance spectroscopy (EIS). The photocatalytic activity of the catalysts were tested as the H2 evolution rate from water under visible light irradiation in the presence of triethanolamine as sacrifice agent. The results indicated that g-C3N4-P3HT composite shows significant enhanced migration and separation efficiency of charge carriers, and photocatalytic H2 production activity from water. The intrinsic nature causing the significance enhanced photocatalytic performance was discussed. Our findings here may provide a new strategy to design composite photocatalyst with high photocatalytic activity. 相似文献
5.
Ke-Long Chen Jun-Qiu Yan Dan-Dan Sun Shi-Shen Zhang Yan-Ying Zhao Jian-Hua Huang 《International Journal of Hydrogen Energy》2021,46(2):1976-1988
Incorporating aromatics into g-C3N4 is an effective strategy to extend electron delocalization. A novel intramolecular donor-acceptor conjugated g-C3N4 was synthesized via thermal copolymerization of urea and tris(p-fluorophenyl)phosphine (TPP). FTIR and XPS spectra showed that the incorporation of TPP did not destroy the framework of g-C3N4. DFT calculation displayed that the HOMO of TPP-modified g-C3N4 (TPP-CN) came mainly from pz orbital of phosphorus. The change of the electronic property led to a narrowed bandgap, extended delocalization of π-electrons through benzene rings, and accelerated migration of photoexcited electrons via intramolecular charge transfer. The optimal Pt-loaded TPP-CN showed the highest rate of H2 generation of 12.45 mmol h?1 g?1, 5 times of that of pure g-C3N4, and the apparent quantum efficiency of 24.9% at 420 nm. The degradation of p-chlorophenol over the optimal TPP-CN was 4 times of that of pure g-C3N4. The mechanism of photocatalytic p-chlorophenol degradation was proposed based on mass spectrometry analysis. 相似文献
6.
《International Journal of Hydrogen Energy》2020,45(35):17468-17479
The deposition of LaFeO3 at the surface of a graphitic carbon nitride (g-C3N4) film via magnetron sputtering followed by oxidation for photoelectrochemical (PEC) water splitting is reported. The LaFeO3/g-C3N4 film was investigated by various characterization techniques including SEM, XRD, Raman spectroscopy, XPS and photo-electrochemical measurements. Our results show that the hydrogen production rate of a g-C3N4 film covered by a LaFeO3 film, exhibiting both a thickness of ca. 50 nm, is of 10.8 μmol h−1 cm−2 under visible light irradiation. This value is ca. 70% higher than that measured for pure LaFeO3 and g-C3N4 films and confirms the effective separation of electron-hole pairs at the interface of LaFeO3/g-C3N4 films. Moreover, the LaFeO3/g-C3N4 films were demonstrated to be stable and retained a high activity (ca. 70%) after the third reuse. 相似文献
7.
Development of heterostructured photocatalysts which can facilitate spatial separation of photo-generated charge carriers is crucial for achieving improved photocatalytic H2 production. Consequently, herein, we report the synthesis of Zn0.5Cd0.5S/Ni2P heterojunction photocatalysts with varying amount of Ni2P, 0.5 (S1), 1 (S2), 3 (S3), 5 (S4) and 10wt% (S5) for the efficient visible-light-assisted H2 generation by water splitting. The heterostructures were characterized thoroughly by PXRD, FE-SEM, EDS, HR-TEM and XPS studies. FE-SEM and HR-TEM analyses of the samples unveiled the presence of Zn0.5Cd0.5S microspheres composed of smaller nanocrystals with the surface of the microspheres covered with Ni2P nanosheets and the intimate contact between the Zn0.5Cd0.5S and the Ni2P. Further, visible-light-assisted photocatalytic investigation of the samples showed excellent water splitting activity of the heterostructure, Zn0.5Cd0.5S/1wt%Ni2P (S2) with very high H2 generation rate of 21.19 mmol h?1g?1 and the AQY of 21.16% at 450 nm with turnover number (TON) and turnover frequency (TOF) of 251,516 and 62,879 h?1 respectively. Interestingly, H2 generation activity of S2 was found to be about four times higher than that of pure Zn0.5Cd0.5S (5.0 mmol h?1g?1) and about 240 times higher than that of CdS/1wt%Ni2P. The enhanced H2 generation activity of S2 has been attributed to efficient spatial separation of photogenerated charge carriers and the presence of highly reactive Ni2P sites on the surface of Zn0.5Cd0.5S microspheres. A possible mechanism for the enhanced photocatalytic H2 generation activity of Zn0.5Cd0.5S/1wt%Ni2P (S2) has been proposed and is further supported by photoluminescence and photocurrent measurements. Furthermore, the catalyst, S2 can be recycled for several cycles without significant loss of catalytic activity and photostability. Remarkably, the H2 generation activity of S2 was found to be even higher than the reported examples of ZnxCd1-xS doped with noble metal cocatalysts. Hence, the present study highlights the importance of Zn0.5Cd0.5S/Ni2P heterostructures based on non-noble metal co-catalyst for efficient visible-light-driven H2 production from water splitting. 相似文献
8.
《International Journal of Hydrogen Energy》2022,47(91):38533-38555
Graphitic carbon nitride (g-C3N4), having unique properties, like suitable electronic band structure, ease of functionalization, easy synthesis, and high stability is a polymeric semiconductor. These properties make it suitable to act as a photocatalyst and have attracted researchers to use it for hydrogen evolution reactions (HER). This review provides the recent advances (2019 onwards) in the development of g-C3N4-based photocatalysts to be employed for HER, starting with the fundamentals of g-C3N4, designing and engineering g–C3N4–based photocatalysts categorized as doped-g-C3N4, composites of g-C3N4, and engineered-g-C3N4 are discussed. Analysis of characteristics and advantages of g-C3N4-based heterojunctions is also provided, followed by current challenges and future perspectives, leading to the conclusion. It is expected to offer valuable information for rational design of novel and efficient g-C3N4-based photocatalysts for visible-light-driven HER. 相似文献
9.
《International Journal of Hydrogen Energy》2023,48(37):13827-13842
Despite MoS2 being a promising non-precious-metal cocatalyst, poor electronic conductivity and low activity for hydrogen evolution caused by serious agglomeration have been identified as critical roadblocks to further developing MoS2 cocatalyst for photocatalytic water splitting using solar energy. In this work, the density functional theory calculations reveal that carbon intercalated MoS2 (C-MoS2) has excellent electronic transport properties and could effectively improve catalytic activity. The experiment results show that the prepared tremella-like C-MoS2 nanoparticles have large interlayer spacing along the c-axis direction and high dispersion because of intercalation of the carbon between adjacent MoS2 layers. Furthermore, the heterostructure photocatalyst of C-MoS2@g-C3N4 formed by loading the cocatalyst of C-MoS2 onto g-C3N4 nanosheets exhibits the H2 evolution rate of 157.14 μmolg−1h−1 when containing 5 wt% C-MoS2. The high photocatalytic H2 production activity of the 5 wt% C-MoS2@g-C3N4 can be attributed to the intercalated conductive carbon layers in MoS2, which leads to efficient charge separation and transfer as well as increased activities of the edge S atoms for H2 evolution. We believe that the C-MoS2 will offer great potential as a photocatalytic H2 evolution reaction cocatalyst with high efficiency and low cost. 相似文献
10.
《International Journal of Hydrogen Energy》2019,44(2):778-787
Doping and exfoliation are effective strategies to improve the photocatalytic activity of bulk graphitic carbon nitride (g-C3N4). Therefore, it can be inferred that engineering element-doping and exfoliation into g-C3N4 would further enhance the photocatalytic performance. Herein, we demonstrated a KOH-assisted hydrothermal-reformed melamine strategy for achieving the simultaneous K-doping and exfoliation of g-C3N4. The as-synthesized K-doped g-C3N4 ultrathin nanosheets displayed much enhanced photocatalytic hydrogen evolution rate (HER) of about 13.1 times higher than that of the bulk g-C3N4 under visible-light irradiation, achieving an apparent quantum efficiency of 6.98% at 420 nm. The improved photocatalytic HER can be attributed to the high surface area offering numerous photocatalytic active sites, enlarged conductive band edge optimizing photoreduction potential, and K-doping promoting charge generation and separation as well as the long life-time of photogenerated carriers. This work would provide a promising way to integrate co-doping and exfoliation into new gC3N4based materials. 相似文献
11.
《International Journal of Hydrogen Energy》2022,47(36):16005-16013
Solar-driven photocatalytic H2O2 production is a sustainable and clean technique with respect to the traditional route. Here, the efficient H2O2 generation was accomplished by π?π coupling of AQ onto the few-layered graphitic carbon nitride (g-C3N4) nanoplates through one-step mechanochemical treatment. A H2O2 generation rate of 231 μM h?1 was obtained using AQ-coupled g-C3N4 nanoplates under visible light illumination, exceeding that of the g-C3N4 nanoplates and bulk g-C3N4 by 7-time and 14-time, respectively. Experimental results showed that the high oxygen reduction efficiency could be ascribed to the enhanced surface area, more exposed active sites and the distinct AQ roles of the electrons storage and restraining the charge recombination. This work inspired future work in synthesizing H2O2 through a sustainable and green route. 相似文献
12.
《International Journal of Hydrogen Energy》2022,47(68):29284-29294
Binary heterostructures (named as CN@Re) composed of ReS2 nanospheres and g-C3N4 nanosheets are constructed by electrostatic self-assembly method. The ReS2 nanospheres were prepared by hydrothermal method and the g-C3N4 nanosheets were treated with surface charge modification. Hydrogen production efficiency of modified CN and CN@Re nanostructures was evaluated in a simulated solar environment. To our surprise, CN5@Re5% exhibits the highest H2 production up to 1823 μmol g?1h?1 of CN5@Rey, which is 3.2 times as high as CN. The improvement of the photocatalytic hydrogen production efficiency of modified CN is attributed to its interaction with the hole sacrificing agent lactic acid, while the improvement of the photocatalytic activity of CN@Re nanostructure is attributed to the efficient electron transfer efficiency between CN and ReS2 and the enhanced light absorption capacity brought by ReS2. In addition, the photocatalytic stability of CN5@Re5% has been studied, which can maintain a stable rate of hydrogen production over four cycles. The apparent quantum efficiency is as high as 4.10% at 365 nm and 2.82% at 420 nm. 相似文献
13.
《International Journal of Hydrogen Energy》2019,44(36):20042-20055
Non-metal doping not only optimizes the energy band structure of g-C3N4 to improve the absorption of visible light, but also exacerbates the distortion of lowest and highest unoccupied molecular orbital plane, causing polarization, thereby improving photocatalytic activity. For the first time, S and P are co-introduced into g-C3N4 network to enhance photocatalytic performance and create various tubular morphologies. The ratio of S to P is crucial to control the tubular morphology and property. In the photocatalytic process, the separation of electrons and holes causes by the polarization of the S and P elements and the synergy of the tubular morphology results in new migration paths for photogenerated electrons and holes. Using optimized preparation conditions, g-C3N4 tubes co-doped with S and P (CNSP) reveal very high H2 generation efficiency (163.27 μmol/h), which is two orders of magnitude higher compared to that of pure g-C3N4 and apparent quantum yield is 18.93% at 420 nm. Fast degradation of Rhodamine B by using CNSP occurs within 5 min under visible light irradiation. Because of the reproducible process, the synthetic strategy provides a novel method for controlling the morphology of g-C3N4-based materials with super activity. 相似文献
14.
《International Journal of Hydrogen Energy》2020,45(38):18937-18945
The practical applications of graphitic carbon nitride (g-C3N4) for photocatalytic hydrogen evolution is strictly hindered by the low surface area, poor light harvesting capability and detrimental recombination of photoexcited charge carriers. Herein, using melamine as precursor and metal hydride (i.e., CaH2) as active agent, we facilely incorporate various types of defects (i.e., nitrogen (N) vacancies (VN), cyano groups (CN) and surface absorbed oxygen species(Oabs)) into g-C3N4 within a single step. The as-prepared material (denoted as MM-H) exhibits narrowed bandgap, promoted photoexcited electron-hole separation rate and facilitated charge transfer kinetics with enlarged BET surface area and massive porosity. As a result, a prominently enhanced photocatalytic H2 productivity efficiency (1305.9 μmol h−1g−1) is shown on MM-H. This performance is better than that of g-C3N4 with CaH2 post-treatment (617.3 μmol h−1g−1) and raw bulk-C3N4 (178.2 μmol h−1g−1). This work opens up a new dimension for designing high performance g–C3N4–based catalysts targeting various photocatalytic processes. 相似文献
15.
《International Journal of Hydrogen Energy》2017,42(27):16968-16978
A binary heterostructured CdS/MoS2 flowerlike composite photocatalysts was synthesized via a simple one-pot hydrothermal method. This photocatalyst demonstrated higher photocatalytic hydrogen production activity than pure MoS2. The heterojunction formed between MoS2 and CdS seems to promote interfacial charge transfer (IFCT), suppress the recombination of photogenerated electron–hole pairs, and enhance the hydrogen generation. Based on the good match between the conduction band (CB) edge of CdS and that of MoS2, electrons in the CB of CdS can be transferred to MoS2 easily through the heterojunction between them, which prevents the accumulation of electrons in the CB of CdS, inhibiting photocorrosion itself and greatly enhancing stability of catalyst. Hydrogen evolution reaction (HER) using Na2S/Na2SO3 or glucose as sacrificial agents in aqueous solution was investigated. The ratio between CdS and MoS2 plays an important role in the photocatalytic hydrogen generation. When the ratio between CdS and MoS2 reaches 40 wt%, the photocatalyst showed a superior H2 evolution rate of 55.0 mmol g−1 h−1 with glucose as sacrificial agent under visible light, which is 1.2 times higher than using Na2S/Na2SO3 as sacrificial agent. Our experimental results demonstrate that MoS2-based binary heterostructured composites are promising for photocorrosion inhibition and highly efficient H2 generation. 相似文献
16.
《International Journal of Hydrogen Energy》2021,46(63):32044-32054
Structure and interface control of heterojunction is usually a challenging issue to improve the photocatalytic performance. Herein, a new 3D/2D CoCO3/g-C3N4 heterojunction is assembled by embedding hexahedral CoCO3 on g-C3N4 nanosheets. The unique step-like hierarchical structure of CoCO3, the formed built-in electric field and Z-scheme charge transfer behavior at the interface jointly drive the high-efficient separation of photogenerated carriers to boost the photocatalytic H2 production. It achieves the optimal H2 production rate that is almost 2.6 times than g-C3N4, apparent quantum efficiency (AQE) of 10.1% at 400 nm and continuous running of 60 h over the 3D/2D CoCO3/g-C3N4 heterojunction. This work endows a fresh structural control strategy for the fabrication of 3D/2D Z-scheme heterojunction to improve the photocatalytic H2 production performance. 相似文献
17.
《International Journal of Hydrogen Energy》2022,47(93):39376-39385
Photocatalytic water splitting has become a significant challenge in modern chemistry. In this process, the rate-determining step is the hydrogen evolution reaction (HER). In the present work, a surface modification approach for graphitic carbon nitride (g-C3N4) was applied to improve its photocatalytic HER. 0D ZnS–CuS nanodots were synthesized with the hydrothermal method as a co-catalyst to enhance the capability and stability of water splitting in the presence of visible light irradiation. Also, graphene nanoribbons were synthesized from CNTs unzipping to reduce the energy barrier of HER, improve the HE kinetic, and enhance the catalytic performance of the g-C3N4. By using ZnS–CuS/GNRs(2)/g-C3N4 photocatalyst, a low onset potential of 130 mV, slight Tafel slope of 41 mV dec?1, as well as excellent stability of 2000 s was obtained in acidic media. This efficient performance is attributed to the increased visible light absorption level in the proposed photocatalyst and the high stability in electron-hole pairs. 相似文献
18.
《International Journal of Hydrogen Energy》2022,47(23):11841-11852
Introducing nickel foam as assistant, a novel nonmetal intercalated high crystalline graphitic carbon nitride (g-C3N4) catalyst was successfully fabricated by β-cyclodextrin (β-CD) pretreated melamine with one step thermal polymerization process. The final results show that 0.3-NCCN presented a remarkably visible-light (λ > 400 nm) photocatalytic H2 evolution reaching 9297 μmol g?1 h?1, and the reaction process follows the zero-order kinetic model. The increase in crystallization of 0.3-NCCN implies a higher-ordered arrangement of tris-s-triazine. The nonmetal interlayer formed by oxygen-contained graphitized carbon can extend the π-conjugated system. Both above significantly benefit the rapid migration and separation of charge-carrier. Moreover, the narrowed band gap provides a stronger thermodynamic driving force for improving the photocatalytic water splitting efficiency. Our work paved a new method to construct high performance photocatalyst for water splitting. 相似文献
19.
《International Journal of Hydrogen Energy》2019,44(57):30084-30092
The use of non-noble-metal to replace precious metal as co-catalyst in solar-driven hydrogen evolution reaction (HER) is important for lowering hydrogen production cost. In this work, nickel metal nanoparticles loaded nitrogen-doped graphite carbon nitride (NiNCN3) was prepared, which significantly enhanced the HER activity of nitrogen-doped graphite carbon nitride. The hydrogen evolution rate of NiNCN3 can reach to 1507 μmol g−1 h−1, much higher than that of 3 wt % Pt/NCN (1055 μmol g−1 h−1). The distinguished photocatalytic performance is due to the accelerated electron transfer efficiency and inhibited photogenerated electron-hole recombination. Our study offers an alternative method to achieve the low-cost and effective noble-metal-free photocatalyst for HER. 相似文献
20.
《International Journal of Hydrogen Energy》2023,48(37):13843-13850
Loading co-catalysts are an effective strategy to break the confinement of bulk carbon nitride in photocatalysis. Employing this strategy, N-doped g-C3N4 decorated with CoSx was successfully prepared through a photochemical synthesis route. The optimum hydrogen evolution performance of N-CN-CoSx-4 was 1757 μmol g−1 h−1 under visible light irradiation. Superior interfacial carrier transfer properties and improved light absorption of N-CN-CoSx-4 could elucidate its better photocatalytic activity. This research offers a reference for the construction of high-efficiency, stable and low-priced photocatalysts. 相似文献