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1.
《International Journal of Hydrogen Energy》2022,47(11):7202-7213
The coupling of two-dimensional (2D) layered materials is an effective way to realize photocatalytic hydrogen production. Herein, using first-principles calculations, the photocatalytic properties of GaN/CNs heterojunctions formed by two different graphite-like carbon nitride materials and GaN monolayer are discussed in detail. The results show that the GaN/C2N heterojunction can promote the effective separation of photogenerated electron and hole pairs, which is attributed to its type-II band orientation and high carrier mobility. However, the low overpotential of GaN/C2N for photocatalytic hydrogen production limits the photocatalytic performance. On this basis, we adjust the CBM position of the GaN/C2N heterojunction by applying an electric field to enhance its hydrogen evolution capability. In addition, the GaN/g-C3N4 is a type-I heterojunction, which is suitable for the field of optoelectronic devices. This work broadens the field of vision for the preparation of highly efficient photocatalysts. 相似文献
2.
Xue Zhang Zhiwei Cheng Puhui Deng Linping Zhang Yu Hou 《International Journal of Hydrogen Energy》2021,46(29):15389-15397
A designed type-II heterojunction photocatalyst, NiSe2/Cd0.5Zn0.5S (NiSe2/CZS), was successfully synthesized and it exhibits outstanding photocatalytic hydrogen evolution performance. The optimal loading amount of NiSe2 on Cd0.5Zn0.5S is 13 wt %, and the corresponding hydrogen production rate is approximately 121.01 mmol g?1 h?1 under visible light. The heterojunction structure between Cd0.5Zn0.5S and NiSe2 promoted the separation of photogenerated electron-hole pairs, effectively suppressed the photogenerated carrier recombination and endowed the material with excellent interfacial charge transfer properties, thus improving the photocatalytic performance. 相似文献
3.
《International Journal of Hydrogen Energy》2019,44(10):4821-4831
Construction of semiconductor heterojunctions can effectively accelerate the separation of photo-induced charge carriers and thereby enhance photocatalytic activity. Here, NiSe was used as an effective co-catalyst to construct an active NiSe/TiO2 heterojunction for improving the photocatalytic H2 production of TiO2. The resultant 10%NiSe/TiO2 heterojunction exhibited 11 times higher photocatalytic H2-production activity than that of bare TiO2. The NiSe/TiO2 heterojunction and the photo-reduction of partial Ni2+ to Ni0 notably accelerated the separation and transfer of photo-excited electron-hole pairs, and thus resulted in obvious improvement of H2-evolution activity. This work holds promise for the application of NiSe in photocatalysis as a high-efficiency photocatalytic cocatalyst. 相似文献
4.
《International Journal of Hydrogen Energy》2022,47(1):292-304
ZnCdS/NiAl hydrotalcite S-scheme heterojunction with highly effective photocatalytic hydrogen evolution activity was devised and prepared by a simple solution-based mixing way. Layered double hydroxide (LDH), also called hydrotalcite-like compound, is composed of adjustable metal cations and exchangeable anions between layers. The hydrogen evolution performance of ZnCdS/NiAl LDH is about 7 times that of ZnCdS and 130 times that of NiAl LDH. Because the rod-shaped ZnCdS and the layered NiAl LDH can construct close interface contact. This interface contact helps to accelerate charge transfer, thereby achieving more effective photocatalytic hydrogen evolution. The S-scheme ZnCdS/NiAl LDH heterojunction catalyst shows excellent hydrogen evolution and good stability, which not only gets benefits from the prominent performances of the cob-like ZnCdS and the layered NiAl LDH but also the matching bandgap structure for them. The configuration of the S-scheme ZnCdS/NiAl LDH heterojunction catalyst accelerates the rapid charge movement and inhibits the recombination of charge carriers, thereby greatly enhancing visible-light-driven water splitting, which is corroborated by the PL spectrum, I-T, LSV, EIS, MottSchottky and UV–vis DRS studies, etc. 相似文献
5.
《International Journal of Hydrogen Energy》2022,47(65):27961-27972
Designing an efficient heterojunction interface is an effective way to promote the electrons' transfer and improve the photocatalytic H2 evolution performance. In this work, a novel hollow hybrid system of Co@NC/CdS has been fabricated and constructed. CdS nanospheres are anchored on the hollow-structured cobalt incorporated nitrogen-doped carbon (Co@NC) through a one-pot in-situ chemical deposition approach, forming an intimate interface and establishing an excellent channel to improve the electrons transfer and charge carriers separation between CdS and Co@NC cocatalyst, which immensely promotes the photocatalytic activity. The rate of photocatalytic H2 evolution over hollow structured Co@NC/CdS heterojunction can be achieved 8.2 mmol g?1 h?1, which is about 45 times of pristine CdS nanospheres. The photocatalytic H2 evolution mechanism has been investigated by the techniques of photoluminescence (PL) spectra, photocurrent-time (i-t) curves, electrochemical impedance spectroscopy (EIS) etc. This work aims to provide a new way in developing of high-performance advanced 3D heterojunction for photocatalytic hydrogen evolution. 相似文献
6.
《International Journal of Hydrogen Energy》2021,46(68):33809-33822
The construction of p-n type heterojunction is an effective way to enhance the efficiency of photocatalytic hydrogen evolution. In this work, Co3O4/CeO2 p-n heterojunction was construct by a simple hydrothermal method. This heterojunction mainly uses the internal electric field formed and accelerate the separation of electrons and holes in the opposite direction. In addition, according to SEM and TEM characterization, it was found that the granular cobalt oxide nanoparticles prepared by in-situ hydrothermal method were firmly and uniformly dispersed in cerium oxide, which effectively increased the active sites of hydrogen evolution. And combined with the BET results, it shows that the growth of cobalt oxide effectively increases the specific surface area and increases the active sites for hydrogen evolution. By exploring the hydrogen evolution capacity of different ratios of the complex, the test results showed that in all different ratios of the catalyst, CC-0.16 showed the best performance, and the hydrogen production efficiency reached 2298.52 μmol g−1h−1, which was 71 times that of nanobelt CeO2 and 2.72 times that of Co3O4. According to the characterization results, the photocatalytic water splitting mechanism of the p-n heterojunction was proposed, and the charge transfer mechanism in the process was discussed in depth. 相似文献
7.
《International Journal of Hydrogen Energy》2023,48(9):3466-3477
The hydrothermal preparation of NiCo2S4/ZnIn2S4 photocatalysts with different mass ratios is studied. Ni-cobalt bimetallic sulfide nanosheets are grown on zinc-indium bimetallic sulfide to form a compact heterojunction. First, both NiCo2S4 and ZnIn2S4 exhibit N-type semiconductor characteristics, a heterojunction formed by both can reduce the surface reaction energy barrier and use its synergy, strengthening the charge self-diffusion between the two semiconductors, it means the formation of a strong electric field. From the electron transfer path and band structure, NiCo2S4/ZnIn2S4 has S-scheme heterojunction characteristics. NiCo2S4 is a reducing photocatalyst (RP), and ZnIn2S4 is an oxidative photocatalyst (OP). Under the action of built-in electric field (BIEF), strong photogenic electrons and holes exist in CB of RP (NiCo2S4) and VB of OP (ZnIn2S4). Thus, the overall redox capacity of the NiCo2S4/ZnIn2S4 heterojunction is enhanced. Using visible light, the composite material can be used for photocatalytic hydrogen production. It is further shown that the composite material has a good effect in photocatalytic hydrogen production under the sensitizer eosin Y (EY) system. The optimal hydrogen production is about 221.75 μmol when the mass ratios of NiCo2S4/ZnIn2S4 is 20%, and the photocatalytic activity of the composite is about 47 times that of ZnIn2S4. Notably, the stability of the composites is the better. A reasonable photo-catalytic mechanism is proposed based on the band gap and photoelectrochemical properties of heterojunction. 相似文献
8.
《International Journal of Hydrogen Energy》2022,47(21):11190-11202
This study presents a novel approach for synthesizing C–ZnO/CdS graded nanorods derived from metal–organic frameworks (MOFs) that can be applied as a catalyst for photocatalytic hydrogen evolution from pure water. Porous C-doped ZnO was prepared by a self-template method using imidazole-like metal–organic backbone (ZIF-L) as a precursor through a two-step calcination method. CdS nanoparticles were deposited on ZIF-L surface by chemical deposition. The two-step calcination method introduced elemental C, and the unique architecture of ZIF-L played an essential role in forming the hierarchical structure of the porous ZnO nanorods. Compared with other ZnO/CdS catalysts, the C-doped ZnO/CdS graded nanorods exhibited remarkable photocatalytic activity for hydrogen production. The highest hydrogen production rate of 20.25 mmol g?1 h?1 with an apparent quantum yield (AQY) of 24.7% at 365 nm obtained over C–ZnO/CdS with Pt as co-catalyst, which was 24.4 and 65.3 times higher than that over CdS (0.83 mmol g?1 h?1) and ZnO (0.31 mmol g?1 h?1), respectively. This outcome was attributed to (i) the formation of Z-scheme heterojunction that significantly promoted the separation and migration of photogenerated electron–hole pairs; (ii) C doping that reduced the bandgap of ZnO and broadened its spectral response range; and (iii) the ordered arrangement of porous nanorods that effectively reduced the recombination rate of the electron–hole pairs. 相似文献
9.
《International Journal of Hydrogen Energy》2023,48(10):3791-3806
The realization of efficient photocatalytic hydrogen evolution (PHE) significantly depends on the development of durable and effective semiconductor photocatalysts. Copper indium sulfide (CuInS2) is an emerging ternary chalcogenide semiconductor material for solar-to-chemical energy application, because it possesses a suitable bandgap, environment-friendly elements, and a low melting point. CuInS2-based semiconductor photocatalysts have been investigated for PHE via water splitting, but current PHE performance still has difficulty in meeting commercial application requirements and needs to be further improved. In this review, the basic semiconductor properties of CuInS2, including its crystal and band structures, are introduced, and its PHE mechanism is discussed in detail. The PHE performance of CuInS2-based photocatalysts is systematically discussed, with a focus on morphology, engineered structure, and heterojunction construction. Finally, issues and challenges currently encountered in the PHE application of CuInS2-based photocatalysts and their possible solutions are presented. 相似文献
10.
《International Journal of Hydrogen Energy》2019,44(36):19967-19977
A promising biochar/ZnFe2O4 (BZF) composite has been synthesized to improve the efficiency of visible-light-driven H2 evolution via a simple microwave hydrothermal method. The materials were investigated through diverse characterization means including XRD, FTIR, SEM, BET, XPS, VSM, UV–vis/DRS, PL, EIS. Different ratios of BZF composites expressed enhanced photocatalytic H2 evolution performance over pure ZnFe2O4. Especially, biochar/ZnFe2O4 catalysts with 5:1 mass ratio (BZF-5) attained the optimal H2 evolution rate, which is around 6 times higher than that of pure ZnFe2O4. Biochar acts as an electron mediator can effectively promote the separation of electron-hole pairs to enhance the rate of photocatalytic hydrogen evolution. Moreover, Eosin Y, photocatalyst and TEOA have synergistic effects accounted for enhanced photocatalytic performance in reaction system. Three cyclic runs for the photocatalytic H2 evolution on BZF-5 sample illustrated its good stability and sustainable reusability. 相似文献
11.
《International Journal of Hydrogen Energy》2017,42(10):6738-6745
The photocatalytic water splitting for generation of clean hydrogen energy has received increasingly attention in the field of photocatalysis. In this study, the Ta2O5/g-C3N4 heterojunctions were successfully fabricated via a simple one-step heating strategy. The photocatalytic activity of as-prepared photocatalysts were evaluated by water splitting for hydrogen evolution under visible-light irradiation (λ > 420 nm). Compared to the pristine g-C3N4, the obtained heterojunctions exhibited remarkably improved hydrogen production performance. It was found that the 7.5%TO/CN heterojunction presented the best photocatalytic hydrogen evolution efficiency, which was about 4.2 times higher than that of pure g-C3N4. Moreover, the 7.5%TO/CN sample also displayed excellent photochemical stability even after 20 h photocatalytic test. By further experimental study, the enhanced photocatalytic activity is mainly attributed to the significantly improve the interfacial charge separation in the heterojunction between g-C3N4 and Ta2O5. This work provides a facile approach to design g-C3N4-based photocatalyst and develops an efficient visible-light-driven heterojunction for application in solar energy conversion. 相似文献
12.
《International Journal of Hydrogen Energy》2022,47(96):40755-40767
With the shortage of global fossil energy and the increasing crisis of environmental deterioration, hydrogen energy has become an environmentally benign alternative as a clean energy source. In most studies on photocatalytic hydrogen production, novel photocatalytic material has played an important role to enhance the hydrogen production rate. In this study, the optimal conditions for the synthesis of MoS2 were established through series of characterizations with 190 °C calcination temperature and 1 wt% PEG surfactant addition. The best conditions for synthesizing MOF include copper nitrate as the copper precursor, 30% ultrasonic amplitude, and 240 °C calcination temperature. After adding 1 wt% MOF in MOS2, a flower-like structure with small particle size, uniform distribution, regularity, and large surface pores, has been formed, where its unit is modified with many rough, porous, and high specific surface area octahedral structures. In addition, 1MOF/MOS2 has the most negative conduction band edge (?0.135 V), the smallest charge transfer resistance (Rct = 1.78 Ω), the largest photo current (11.1 mA/cm2), the lowest PL spectral peak intensity, and excellent photocatalytic stability. The above morphological features and optical properties can significantly form more active sites, enhance the electron transfer rate, and inhibit the electron-hole recombination, thus making the MOF/MOS2 composite photocatalyst achieve the maximum hydrogen production capacity (626.3 μmol g?1 h?1). 相似文献
13.
《International Journal of Hydrogen Energy》2023,48(21):7670-7682
The development of photocatalysts with efficient hydrogen evolution activity has been the goal for sustainable hydrogen production. In this work, heterojunction composite photocatalyst is formed by hydrothermal coupling of ZnO and Mn0.2Cd0.8S. Compared with pure ZnO and Mn0.2Cd0.8S, the composite photocatalyst has the ability to provide more abundant active sites and better photogenerated carriers separation efficiency. The optimized composite photocatalyst shows a 9.36-fold increase in hydrogen evolution activity (4297.99 μmol g?1 h?1) compared to Mn0.2Cd0.8S (459.31 μmol g?1 h?1) and exhibits excellent cycling stability. Density functional theory calculations identifies Type-II charge transfer path in the composite photocatalyst, achieving effective separation in space of photogenerated electrons from holes and suppressing recombination within the semiconductor. The results show that the construction of Type-II heterojunction in this work achieves a significant enhancement of the hydrogen evolution activity of the photocatalyst by constructing carrier transport channels at the contact interface of the heterojunction. 相似文献
14.
《International Journal of Hydrogen Energy》2020,45(51):26733-26745
In this work, p-type semiconductor CoWO4 nanoparticles was successfully anchored on the surface of n-type Mn0.2Cd0.8S nanorods, and p-n type heterostructure photocatalysts with low cost and high efficiency were synthesized. By optimizing the loading of CoWO4 nanoparticles, the hydrogen evolution rate of the compound can reach a maximum, the peak is 408 μmol/5 h. Under visible light irradiation, it is equivalent to 3.61 times pure Mn0.2Cd0.8S. In addition, the composite catalyst has favorable durability and structural stability. In terms of morphology, the combination of nanorods (SBET = 24 m2g-1) and nanoparticles (SBET = 12 m2g-1) increased the specific surface area of the composite catalyst (SBET = 31 m2g-1), thus the composite exposed more active sites. In terms of heterojunction, the conduction bands of two semiconductors were determined by UV–vis diffuse reflection and Mott-Schottky, and the construction of p-n heterojunction was verified. The results of photochemical experiment further indicate that the built-in electric field in the p-n type heterostructure not only accelerates the electron-hole pair transfer, but vastly enhances the carrier average lifetime. In this paper, the morphology of the photocatalyst was modified and p-n heterojunction was constructed. The result is that the performance of Mn0.2Cd0.8S MCS was improved and the possible mechanism of photocatalytic hydrogen evolution was proposed. 相似文献
15.
《International Journal of Hydrogen Energy》2020,45(7):4113-4121
The direct Z-scheme ZnIn2S4/LaNiO3 nanohybrid based on ZnIn2S4 nanosheets and LaNiO3 cubes was synthesized by a facile hydrothermal method. The ZnIn2S4/LaNiO3 nanohybrid showed improved photocatalytic H2 evolution and stability. The photocatalytic H2 evolution activity of ZnIn2S4/LaNiO3 nanohybrid is 3-fold enhanced than that of bare ZnIn2S4. The enhanced performance of ZnIn2S4/LaNiO3 nanohybrid is mainly ascribed to the formation of heterojunction between LaNiO3 and ZnIn2S4. The heterojunction can facilitate charge transport on the interface between LaNiO3 and ZnIn2S4 and suppress the recombination of photo-generated charge carriers over ZnIn2S4/LaNiO3 nanohybrid, which were well demonstrated by photoelectrochemical tests. Moreover, the direct Z-scheme photocatalytic reaction mechanism was proposed to elucidate the improved performance of ZnIn2S4/LaNiO3 nanohybrid photocatalyst. This study may provide some guidance on the construction of direct Z-scheme photocatalytic system for photocatalytic H2 evolution. 相似文献
16.
Haoshan Wei Yong Zhang Guoao Zhang Jiewu Cui Yan Wang Yongqiang Qin Xueru Zhang Hark Hoe Tan Jiaqin Liu Yucheng Wu 《International Journal of Hydrogen Energy》2021,46(1):234-246
Heteroatom co-doping has been considered as an effective strategy to simultaneously overcome intrinsic shortcomings of g-C3N4 to achieve enhanced photocatalytic properties, in which the involved dopants could play its role in altering electronic structure, optical absorption and charge separation of the catalyst. Herein, W/O co-doped hollow g-C3N4 tubular structures are successfully obtained for the first time via a one-step thermal decomposition. By W/O co-doping, architecture of g-C3N4 is able to be modulated with enhanced optical absorption towards visible region. In addition, narrowed band gap and restrained charge recombination are conducive for the excitation of electron-hole pairs and transportation. Photocatalytic water splitting tests indicate that the co-doped hollow tubular g-C3N4 structures enable superior activity for generating hydrogen up to 403.57 μmol g?1 h?1 driven by visible light, nearly 2.5 times as high as that of pristine g-C3N4. This work presents a rational strategy to design co-doped g-C3N4 as an efficient visible-light-driven photocatalyst. 相似文献
17.
《International Journal of Hydrogen Energy》2020,45(46):24697-24709
A novel composite has been successfully synthesized in situ via a coprecipitation method about the coupling of Cu2(OH)2CO3 with oxidized carbon nitride (O-g-C3N4) forming Cu2(OH)2CO3/O-g-C3N4 (CuCN) heterojunction structure. The as-prepared composites were characterized by diverse means. The CuCN composite with 3:5 mass ratio of Cu2(OH)2CO3 to O-g-C3N4 (60CuCN) presented an extremely excellent photocatalytic activity. The photocatalytic H2 evolution of 60CuCN was around 23.26 and 44.62 times higher than that of g-C3N4 and Cu2(OH)2CO3, respectively. The photocatalytic degradation malachite green (MG) rate of 60CuCN was up to 91%, which was around 2.2 and 4.8 times as much as that of g-C3N4 and Cu2(OH)2CO3, respectively. These results are mainly attributed to the structure property of O-g-C3N4 and the heterojunction structure of the composite, which could effectively accelerate the separation and transfer rate of photogenerated electrons and holes. The holes (h+) and superoxide radicals (·O2−) played a dominant role in photocatalytic degradation MG reaction. 相似文献
18.
《International Journal of Hydrogen Energy》2022,47(3):1624-1632
Seeking an efficient and non-precious co-catalyst for g-C3N4 (CN) remains a great demanding to achieve high photocatalytic hydrogen generation performance. Herein, a composite photocatalyst with high efficiency was prepared by modifying CN with coral-like NiSe2. The optimal hydrogen evolution rate of 643.16 μmol g?1 h?1 is from NiSe2/CN-5 under visible light. Superior light absorption and interfacial charge transfer properties including suppressed photogenerated carrier recombination and efficient separation of photogenerated electron-hole pairs have been observed, which account for the enhanced photocatalytic performance of CN. 相似文献
19.
20.
《International Journal of Hydrogen Energy》2023,48(69):26707-26717
Promoting the separation of electron and hole plays an important role in photocatalytic hydrogen production. However, single semiconductor materials cannot fully realize their potential due to the rapid recombination of photogenerated carriers. Therefore, in this experiment, a new photocatalyst ZnIn2S4/NiMoO4 was prepared by using an electrostatic self-assembly method, which greatly improved the electron-hole recombination phenomenon. After 5 h reaction under visible light irradiation, ZIS/NMO-3 composite catalyst prepared in ethanol showed the best photocatalytic activity, and the hydrogen evolution capacity reached 173.09 μmol. The hydrogen evolution capacity of ZIS/NMO-3 was 2.47 and 25.83 times that of short rod-like NiMoO4 and microflower-like spherical ZnIn2S4, respectively. Through some physical characterization and electrochemical experiments, it can be seen that NiMoO4 and ZnIn2S4 have good composability. Meanwhile, the composite catalyst ZnIn2S4/NiMoO4-3 has high current response characteristics. It can be seen from the fluorescence emission spectra that the composite catalyst presents the lowest peak value, which indicates that ZIS/NMO-3 can effectively inhibit the recombination of photogenerated electrons and holes. When ZnIn2S4 is loaded on NiMoO4, the separation of photogenerated carrier will be accelerated due to the formation of heterojunction, thus improving the photocatalytic activity. At the same time, the large specific surface area will also provide more abundant active sites for the composite catalyst, which provides a good condition for photocatalytic hydrogen production. This work provides an efficient, uncomplicated and feasible method for the synthesis of ZIS/NMO-3 composite catalyst with excellent properties. 相似文献