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1.
Methods to synthesize crystalline covalent triazine frameworks (CTFs) are limited and little attention has been paid to development of hydrophilic CTFs and photocatalytic overall water splitting. A route to synthesize crystalline and hydrophilic CTF‐HUST‐A1 with a benzylamine‐functionalized monomer is presented. The base reagent used plays an important role in the enhancement of crystallinity and hydrophilicity. CTF‐HUST‐A1 exhibits good crystallinity, excellent hydrophilicity, and excellent photocatalytic activity in sacrificial photocatalytic hydrogen evolution (hydrogen evolution rate up to 9200 μmol g?1 h?1). Photocatalytic overall water splitting is achieved by depositing dual co‐catalysts in CTF‐HUST‐A1, with H2 evolution and O2 evolution rates of 25.4 μmol g?1 h?1 and 12.9 μmol g?1 h?1 in pure water without using sacrificial agent.  相似文献   

2.
The production of green hydrogen through photocatalytic water splitting is crucial for a sustainable hydrogen economy and chemical manufacturing. However, current approaches suffer from slow hydrogen production (<70 μmol ⋅ gcat−1 ⋅ h−1) due to the sluggish four-electrons oxygen evolution reaction (OER) and limited catalyst activity. Herein, we achieve efficient photocatalytic water splitting by exploiting a multifunctional interface between a nano-photocatalyst and metal–organic framework (MOF) layer. The functional interface plays two critical roles: (1) enriching electron density directly on photocatalyst surface to promote catalytic activity, and (2) delocalizing photogenerated holes into MOF to enhance OER. Our photocatalytic ensemble boosts hydrogen evolution by ≈100-fold over pristine photocatalyst and concurrently produces oxygen at ideal stoichiometric ratio, even without using sacrificial agents. Notably, this unique design attains superior hydrogen production (519 μmol ⋅ gcat−1 ⋅ h−1) and apparent quantum efficiency up to 13-fold and 8-fold better than emerging photocatalytic designs utilizing hole scavengers. Comprehensive investigations underscore the vital role of the interfacial design in generating high-energy photoelectrons on surface-degenerate photocatalyst to thermodynamically drive hydrogen evolution, while leveraging the nanoporous MOF scaffold as an effective photohole sink to enhance OER. Our interfacial approach creates vast opportunities for designing next-generation, multifunctional photocatalytic ensembles using reticular chemistry with diverse energy and environmental applications.  相似文献   

3.
Covalent triazine frameworks (CTFs) are normally synthesized by ionothermal methods. The harsh synthetic conditions and associated limited structural diversity do not benefit for further development and practical large‐scale synthesis of CTFs. Herein we report a new strategy to construct CTFs (CTF‐HUSTs) via a polycondensation approach, which allows the synthesis of CTFs under mild conditions from a wide array of building blocks. Interestingly, these CTFs display a layered structure. The CTFs synthesized were also readily scaled up to gram quantities. The CTFs are potential candidates for separations, photocatalysis and for energy storage applications. In particular, CTF‐HUSTs are found to be promising photocatalysts for sacrificial photocatalytic hydrogen evolution with a maximum rate of 2647 μmol h−1 g−1 under visible light. We also applied a pyrolyzed form of CTF‐HUST‐4 as an anode material in a sodium‐ion battery achieving an excellent discharge capacity of 467 mAh g−1.  相似文献   

4.
The solar-driven evolution of hydrogen from water using particulate photocatalysts is considered one of the most economical and promising protocols for achieving a stable supply of renewable energy. However, the efficiency of photocatalytic water splitting is far from satisfactory due to the sluggish electron-hole pair separation kinetics. Herein, isolated Mo atoms in a high oxidation state have been incorporated into the lattice of Cd0.5Zn0.5S (CZS@Mo) nanorods, which exhibit photocatalytic hydrogen evolution rate of 11.32 mmol g−1 h−1 (226.4 μmol h−1; catalyst dosage 20 mg). Experimental and theoretical simulation results imply that the highly oxidized Mo species lead to mobile-charge imbalances in CZS and induce the directional photogenerated electrons transfer, resulting in effectively inhibited electron-hole recombination and greatly enhanced photocatalytic efficiency.  相似文献   

5.
A few-layer fullerene network possesses several advantageous characteristics, including a large surface area, abundant active sites, high charge mobility, and an appropriate band gap and band edge for solar water splitting. Herein, we report for the first time that the few-layer fullerene network shows interesting photocatalytic performance in pure water splitting into H2 and H2O2 in the absence of any sacrificial reagents. Under optimal conditions, the H2 and H2O2 evolution rates can reach 91 and 116 μmol g−1 h−1, respectively, with good stability. This work demonstrates the novel application of the few-layer fullerene network in the field of energy conversion.  相似文献   

6.
Metal–organic polyhedra (MOPs) are promising candidates for many potential applications; however, their use as photocatalysts for hydrogen production has yet to be developed. Herein, the photocatalytic performance of a water-stable Zr-MOP, ZrT-1-NH2, was evaluated, for the first time, through photocatalytic hydrogen evolution under visible-light irradiation. ZrT-1-NH2 shows clearly enhanced photocatalytic activity (510.42 μmol g−1 h−1) for hydrogen production, in comparison with that of other homogeneous crystalline materials. If platinum nanoparticles were introduced into the photocatalytic system, the hydrogen production efficiency of ZrT-1-NH2 could be further improved. For ZrT-1-NH2, the conspicuous improvement in photocatalysis can be attributed to efficient electron–hole separation, targeted electron transfer, and excellent recombination suppression. Furthermore, ZrT-1-NH2 shows excellent stability during photocatalytic hydrogen evolution over five continuous runs. This work illustrates that MOP-based photocatalysts hold promise for broad applications in the domain of clean energy.  相似文献   

7.
Constructing a powerful photocatalytic system that can achieve the carbon dioxide (CO2) reduction half-reaction and the water (H2O) oxidation half-reaction simultaneously is a very challenging but meaningful task. Herein, a porous material with a crystalline topological network, named viCOF-bpy-Re, was rationally synthesized by incorporating rhenium complexes as reductive sites and triazine ring structures as oxidative sites via robust −C=C− bond linkages. The charge-separation ability of viCOF-bpy-Re is promoted by low polarized π-bridges between rhenium complexes and triazine ring units, and the efficient charge-separation enables the photogenerated electron–hole pairs, followed by an intramolecular charge-transfer process, to form photogenerated electrons involved in CO2 reduction and photogenerated holes that participate in H2O oxidation simultaneously. The viCOF-bpy-Re shows the highest catalytic photocatalytic carbon monoxide (CO) production rate (190.6 μmol g−1 h−1 with about 100 % selectivity) and oxygen (O2) evolution (90.2 μmol g−1 h−1) among all the porous catalysts in CO2 reduction with H2O as sacrificial agents. Therefore, a powerful photocatalytic system was successfully achieved, and this catalytic system exhibited excellent stability in the catalysis process for 50 hours. The structure–function relationship was confirmed by femtosecond transient absorption spectroscopy and density functional theory calculations.  相似文献   

8.
《中国化学快报》2021,32(8):2419-2422
Owing to excellent light absorption and high activity fo r oxygen evolution,monoclinic bismuth vanadate(BiVO_4) is regarded as an ideal candidate for photocatalytic water splitting.However,its application is limited by the large particle size in micrometer scale,as well as the slightly positive conduction band.In this work,we successfully synthesized nano-BiVO_4 with particle size ranged from 27 nm to 57 nm by wet chemical method based on electrostatic spinning method.Unlike bulk BiVO_4,the nano-sized BiVO_4 possesses the ability to generate hydrogen by water splitting,and the activity could reach up to1.66 μmol h~(-1) g~(-1) with the assistance of Pt.The enhanced activity is mainly attributed to the improvements resulted from reduced particle size,which includes elevated conduction band,enlarged specific surface area and promoted charge separation.This work provides a simple method for synthesizing photocatalyst with small particle size and high yield.  相似文献   

9.
Herein, multifunctional N‐doped carbon nanodots (NCNDs) were prepared through the one‐step hydrothermal treatment of yeast. Results show that the NCNDs can be used as a new photocatalyst to drive the water‐splitting reaction under UV light. Moreover, the NCNDs can efficiently catalyze the hydrogen evolution reaction. Under visible‐light irradiation, Eosin Y‐sensitized NCNDs exhibit excellent activity for hydrogen evolution. The hydrogen evolution rate of NCNDs (without any modification and co‐catalyst) reaches 107.1 μmol h?1 (2142 μmol g?1 h?1). When Pt is loaded on the NCNDs, the hydrogen evolution rate reaches 491.2 μmol h?1 (9824 μmol g?1 h?1) under visible‐light irradiation. In addition, the NCNDs show excellent fluorescent properties and can be applied as a fluorescent probe for the sensitive and selective detection of Fe3+.  相似文献   

10.
Z‐scheme water splitting is a promising approach based on high‐performance photocatalysis by harvesting broadband solar energy. Its efficiency depends on the well‐defined interfaces between two semiconductors for the charge kinetics and their exposed surfaces for chemical reactions. Herein, we report a facile cation‐exchange approach to obtain compounds with both properties without the need for noble metals by forming Janus‐like structures consisting of γ‐MnS and Cu7S4 with high‐quality interfaces. The Janus‐like γ‐MnS/Cu7S4 structures displayed dramatically enhanced photocatalytic hydrogen production rates of up to 718 μmol g−1 h−1 under full‐spectrum irradiation. Upon further integration with an MnOx oxygen‐evolution cocatalyst, overall water splitting was accomplished with the Janus structures. This work provides insight into the surface and interface design of hybrid photocatalysts, and offers a noble‐metal‐free approach to broadband photocatalytic hydrogen production.  相似文献   

11.
A photocatalytic system containing a perylene bisimide (PBI) dye as a photosensitizer anchored to titanium dioxide (TiO2) nanoparticles through carboxyl groups was constructed. Under solar-light irradiation in the presence of sacrificial triethanolamine (TEOA) in neutral and basic conditions (pH 8.5), a reaction cascade is initiated in which the PBI molecule first absorbs green light, giving the formation of a stable radical anion (PBI.−), which in a second step absorbs near-infrared light, forming a stable PBI dianion (PBI2−). Finally, the dianion absorbs red light and injects an electron into the TiO2 nanoparticle that is coated with platinum co-catalyst for hydrogen evolution. The hydrogen evolution rates (HERs) are as high as 1216 and 1022 μmol h−1 g−1 with simulated sunlight irradiation in neutral and basic conditions, respectively.  相似文献   

12.
Solar-driven water splitting to produce clean and renewable hydrogen offers a green strategy to address the energy crisis and environmental pollution. Heterostructure catalysts are receiving increasing attention for photocatalytic hydrogen generation. ZnO/ZnS/CdS and ZnO/CdS heterostructures have been successfully designed and prepared according to two different strategies. By introducing a heterointerface layer of ZnS between ZnO and CdS, a Z scheme charge-transfer channel was promoted and achieved superior photocatalytic performance. A highest hydrogen generation rate of 156.7 μmol g−1 h−1 was achieved by precise control of the thickness of the heterointerface layer and of the CdS shell. These findings demonstrated that heterostructures are promising catalysts for solar-driven water splitting, and that heterointerface engineering is an effective way to improve the photocatalytic properties of heterostructures.  相似文献   

13.
The development of high-performance photocatalytic systems for CO2 reduction is appealing to address energy and environmental issues, while it is challenging to avoid using toxic metals and organic sacrificial reagents. We here immobilize a family of cobalt phthalocyanine catalysts on Pb-free halide perovskite Cs2AgBiBr6 nanosheets with delicate control on the anchors of the cobalt catalysts. Among them, the molecular hybrid photocatalyst assembled by carboxyl anchors achieves the optimal performance with an electron consumption rate of 300±13 μmol g−1 h−1 for visible-light-driven CO2-to-CO conversion coupled with water oxidation to O2, over 8 times of the unmodified Cs2AgBiBr6 (36±8 μmol g−1 h−1), also far surpassing the documented systems (<150 μmol g−1 h−1). Besides the improved intrinsic activity, electrochemical, computational, ex-/in situ X-ray photoelectron and X-ray absorption spectroscopic results indicate that the electrons photogenerated at the Bi atoms of Cs2AgBiBr6 can be directionally transferred to the cobalt catalyst via the carboxyl anchors which strongly bind to the Bi atoms, substantially facilitating the interfacial electron transfer kinetics and thereby the photocatalysis.  相似文献   

14.
An active and stable photocatalyst to directly split water is desirable for solar‐energy conversion. However, it is difficult to accomplish overall water splitting without sacrificial electron donors. Herein, we demonstrate a strategy via constructing a single site to simultaneously promote charge separation and catalytic activity for robust overall water splitting. A single Co1‐P4 site confined on g‐C3N4 nanosheets was prepared by a facile phosphidation method, and identified by electron microscopy and X‐ray absorption spectroscopy. This coordinatively unsaturated Co site can effectively suppress charge recombination and prolong carrier lifetime by about 20 times relative to pristine g‐C3N4, and boost water molecular adsorption and activation for oxygen evolution. This single‐site photocatalyst exhibits steady and high water splitting activity with H2 evolution rate up to 410.3 μmol h−1 g−1, and quantum efficiency as high as 2.2 % at 500 nm.  相似文献   

15.
Covalent triazine frameworks (CTFs) with two-dimensional structures have exhibited promising visible-light-induced H2 evolution performance. However, it is still a challenge to improve their activity. Herein, we report π-conjugation-linked CTF-1/GO for boosting photocatalytic H2 evolution. The CTF-1/GO hybrid material was obtained by a facile low-temperature condensation of 1,4-dicyanobenzene in the presence of GO. The results of photocatalytic H2 evolution indicate that the optimum hybrid, CTF-1/GO-3.0, exhibited an H2 evolution rate of 2262.4 μmol ⋅ g−1 ⋅ h−1 under visible light irradiation, which was 9 times that of pure CTF-1. The enhanced photocatalytic performance could be attributed to the fact that GO in CTF-1/GO hybrids not only acts as an electron collector and transporter like a “bridge” to facilitate the separation and transfer of photogenerated charges but also shortens the electron migration path due to its thin sheet layer uniformly distribution over CTF-1. This work could help future development of novel conjugated CTF-based composite materials as high-efficiency photocatalyst for photocatalysis.  相似文献   

16.
H2O2 is a significant chemical widely utilized in the environmental and industrial fields, with growing global demand. Without sacrificial agents, simultaneous photocatalyzed H2O2 synthesis through the oxygen reduction reaction (ORR) and water oxidation reaction (WOR) dual channels from seawater is green and sustainable but still challenging. Herein, two novel thiophene-containing covalent organic frameworks (TD-COF and TT-COF) were first constructed and served as catalysts for H2O2 synthesis via indirect 2e ORR and direct 2e WOR channels. The photocatalytic H2O2 production performance can be regulated by adjusting the N-heterocycle modules (pyridine and triazine) in COFs. Notably, with no sacrificial agents, just using air and water as raw materials, TD-COF exhibited high H2O2 production yields of 4060 μmol h−1 g−1 and 3364 μmol h−1 g−1 in deionized water and natural seawater, respectively. Further computational mechanism studies revealed that the thiophene was the primary photoreduction unit for ORR, while the benzene ring (linked to the thiophene by the imine bond) was the central photooxidation unit for WOR. The current work exploits thiophene-containing COFs for overall photocatalytic H2O2 synthesis via ORR and WOR dual channels and provides fresh insight into creating innovative catalysts for photocatalyzing H2O2 synthesis.  相似文献   

17.
The polarity of a semiconducting molecule affects its intrinsic photophysical properties, which can be tuned by varying the molecular geometry. Herein, we developed a D3h-symmetric tricyanomesitylene as a new monomer which could be reticulated into a vinylene-linked covalent organic framework (g-C54N6-COF) via Knoevenagel condensation with another D3h-symmetric monomer 2,4,6-tris(4′-formyl-biphenyl-4-yl)-1,3,5-triazine. Replacing tricyanomesitylene with a C2v-symmetric 3,5-dicyano-2,4,6-trimethylpyridine gave a less-symmetric vinylene-linked COF (g-C52N6-COF). The octupolar conjugated characters of g-C54N6-COF were reflected in its scarce solvatochromic effects either in ground or excited states, and endowed it with more promising semiconducting behavior as compared with g-C52N6-COF, such as enhanced light-harvesting and excellent photo-induced charge generation and separation. Along with the matched energy level, g-C54N6-COF enabled the two-half reactions of photocatalytic water splitting with an average O2 evolution rate of 51.0 μmol h−1 g−1 and H2 evolution rate of 2518.9 μmol h−1 g−1. Such values are among the highest of state-of-the-art COF photocatalysts.  相似文献   

18.
Develop a photocatalyst system for solar energy conversion to electric energy or chemical energy is a topic of great interest for fundamental and practical importance. In this study, nitrogen-doped TiO2 with high hydrogen production by photocatalytic water splitting were prepared by microwave-assisted hydrothermal method using titanium sulfate as precursor in the presence of urea. The nitrogen doped TiO2 prepared in this study was pure anatase phase with a high surface area (372?m2?g?1) and showed a very high hydrogen evolution rate of water splitting reaction under UV light irradiation (4,386?μmol?g?1?h?1) and visible light irradiation (185?μmol?g?1?h?1) which was about 15?times higher than commercial TiO2 (Degussa P25).  相似文献   

19.
Solar-driven CO2 reduction reaction (CO2RR) is largely constrained by the sluggish mass transfer and fast combination of photogenerated charge carriers. Herein, we find that the photocatalytic CO2RR efficiency at the abundant gas-liquid interface provided by microdroplets is two orders of magnitude higher than that of the corresponding bulk phase reaction. Even in the absence of sacrificial agents, the production rates of HCOOH over WO3 ⋅ 0.33H2O mediated by microdroplets reaches 2536 μmol h−1 g−1 (vs. 13 μmol h−1 g−1 in bulk phase), which is significantly superior to the previously reported photocatalytic CO2RR in bulk phase reaction condition. Beyond the efficient delivery of CO2 to photocatalyst surfaces within microdroplets, we reveal that the strong electric field at the gas-liquid interface of microdroplets essentially promotes the separation of photogenerated electron-hole pairs. This study provides a deep understanding of ultrafast reaction kinetics promoted by the gas-liquid interface of microdroplets and a novel way of addressing the low efficiency of photocatalytic CO2 reduction to fuel.  相似文献   

20.
As one of the most efficient systems for photocatalytic hydrogen evolution, the Z-Scheme system, consisting of different semiconductors with a reversible donor–acceptor pair, has attracted great attention. Considering the non-toxicity and low cost of photocatalysts, a series of g-C3N4/α-Fe2O3 hybrids were rationally constructed based on the Z-Scheme mechanism for the first time, using a metal-organic framework template approach that can fine tune the compositions and properties of the hybrids. An optimized hybrid, g-C3N4/α-Fe2O3-2, exhibited prominent photocatalytic water splitting performance with a visible light response. Under irradiation of visible light (λ>420 nm), the hybrid shows a high durability and superior hydrogen production rate of 2066.2 μmol g−1 h−1 from water splitting, which is approximately three times greater than that of bulk g-C3N4 because of the effective separation of photo-excited charge carriers by two narrow band gap semiconductors, tightly coupled with the Z-Scheme structural feature.  相似文献   

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