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991.
    
Wastewater treatment is essential to shield the environment. The production of H2 is substantial for prospering its applications in diversified sectors; hence the study of wastewater treatment for H2 production is accomplished. Various technologies have been developed and studied considering the potential of wastewater to generate hydrogen-rich gas. These technologies have different mechanisms, diversified setups, and processes. Perhaps these technologies are proven to be exceptional exposures for hydrogen production. Fortunately, a valuable contribution to the environment and the H2 economy is that some technological processes have been promoted to synthesize H2 from lab scale to pilot scale. Contemplating such comprehensive exposure to H2 synthesis from wastewater, the critical information of eight emerging technologies, including their mechanism and reaction parameters influencing the process, pros, cons, and future developmental scopes, are described in this review by classifying them into three different classes, namely light-dependent technologies, light-independent technologies, and other technologies.  相似文献   
992.
    
Since the last two decades, plenty of environmental issues have risen up due to the damage which humans have caused to the planet for the sake of development. The continual ignorance of global climate change and the stalemate approach of major oil producing industries led to the catastrophic melting of glaciers in Arctic and Antarctica and very recently the highest mountain peak of Sweden have become 24 m shorter which is the evident outcome of climatic disturbance. The chaotic unbalancing in the reservoirs of natural resources is leading us to the several crisis which has a potential to affect the livelihood. Among the various techniques used for the development of sustainable energy, photocatalysis is regarded as one of the simplest technique which can yield enormous amount of energy by the utilization of solar energy for meeting the world's demand of an energy requirement and which can be exploited in the degradation of toxic pollutants i.e. organic as well as inorganic pollutants for environment remediation. Transition metal chalcogenides (TMCs) have a potential to get adsorb easily and be utilized for solving the energy-related problems. Large number of photocatalysts has been fabricated, among them Molybdenum (Mo) chalcogenides nanostructures, which also belong to the class of TMCs exhibit exceptional properties such as non-toxicity, low cost and structural flexibility which give them edge over the other materials. Furthermore, the tunable band gap of Mo chalcogenides nanostructures makes them the promising candidates for efficient hydrogen evolution via photocatalytic water splitting in the visible light illumination. This review deals with the photocatalytic applications of Mo based chalcogenides nanostructures in efficient hydrogen production via water splitting and degradation of dyes. It also discusses the recent developments in fabricating Molybdenum chalcogenides nanostructures, their role in the photocatalytic water splitting and discusses the efforts which have been made to improve their photocatalytic activity for extending their applications to the scalable point.  相似文献   
993.
    
Due to the continuous consumption of fossil fuels, natural reserves are depleting and it has been earnest need for developing new sources of energy. Among the several solar energy conversion techniques, photocatalytic hydrogen (H2) generation is regarded as one of the most promising routes. Till date, several metal-based semiconductor materials have been investigated, however, H2 generation is not substantial with the notion of sustainable development. Current research trends show the growing interest in advanced and metal free photocatalyst materials such as covalent organic frameworks (COFs) due to their several benefits such as crystalline porous polymers with pre-designed architectures, large surface area, exceptional stability, and ease of molecular functionalization. By combining COFs with other functional materials, composites may be created that display unique characteristics that exceed those of the separate components. This work provides a comprehensive development on COFs as a photocatalysts and their composites/hybrids for photocatalytic hydrogen generation with a focus on visible-light irradiation. To reduce the dependency on novel metals and overcome the drawbacks of individual material, the creation of composite materials based on covalent-organic frameworks (COFs) are systematically discussed. In addition, advantages in terms of performance, stability, durability of composites/hybrids COFs for photocatalytic hydrogen production in reference to traditional catalysts are investigated. Different composites such as metals loading, morphological development, band engineering, and heterojunctions are systematically discussed. Finally, challenges and opportunities associated with constructing COF-based catalysts as future research prospective for chemistry and materials science are highlighted.  相似文献   
994.
    
The worldwide energy demand is steadily increasing and estimated to be doubled by the year 2050 due to a continuous hike in economies and population. A large part of the global energy requirement procures using traditional energy sources such as fossil fuels, which are non-renewable. Also, their excessive consumption imparts negative impacts on the environment by CO2, and CO emissions, which constantly increase the average global temperature. Therefore, the need for a more reliable, sustainable, inexpensive, renewable and environmentally-friendly form of energy is imperative. From these perspectives, hydrogen energy is emerging as one of the most promising alternatives to overcome rising energy demand with a zero-carbon footprint.Herein, various layered double hydroxides (LDH) nanocomposite owing to their attractive physicochemical properties and synergistic effect with other materials in the field of hydrogen production are reviewed. Why the class of LDHs materials is critical and their ideographic properties which make them promising materials in the field of water splitting via photocatalysis and electrocatalysis are also discussed. The synthetic methods of LDHs based nanocomposites fabrication are summarized. Various challenges and strategies from the viewpoint of a different method of hydrogen production through LDHs are reported. Additionally, multiple techniques like surface plasmon resonance (SPR), heterojunction formation, and doping with co-catalyst to increase the efficiency for photocatalytic hydrogen production are also presented. Hopefully, this review will help the readers explore highly efficient, inexpensive and stable LDH catalysts toward photocatalytic water splitting.  相似文献   
995.
    
Photocatalysts with abundant active sites are essential for photocatalytic H2 evolution from water. Herein, Ni0.85Se-deposited g-C3N4 was obtained by a physical solvent evaporation method. The investigation shows that Ni0.85Se with unsaturated active Se atoms can significantly improve the photocatalytic activity of g-C3N4, and the H2 production rate of Ni0.85Se/g-C3N4 can reach 8780.3 μmol g?1 h?1, which is 3.5 and 92.9 times higher than that of Ni0.85+xSe/g-C3N4 (2497.9 μmol g?1 h?1) and pure g-C3N4 (94.5 μmol g?1 h?1), respectively. This improvement can be attributed to the quick charge transfer between Ni0.85Se and g-C3N4 with S-scheme heterojunction feature based on a series of trapping experiments and photoelectrochemical analysis. Moreover, abundant unsaturated Se atoms could provide more H2 evolution active sites. This work sheds light on the construction of heterojunctions with abundant active sites for H2 production.  相似文献   
996.
    
Photocatalytic Hydrogen production via water splitting is considered a sustainable ecofriendly pathway to replenish the current and future energy demands. In this study, the self-assembly synthesis of Cu nanospheres (～8 nm) surrounded by a thin conductive layer of polyaniline (Cu@PANI) was rationally engineered via in?situ polymerization. Afterward, it was successfully deposited onto the TiO2 surface to improve the photocatalytic activities for hydrogen production. The optimal Cu@PANI/TiO2 ternary photocatalyst produced a substantial hydrogen generation rate (HGR) of 17.7 mmol h?1 g?1, 207-fold higher than that of bare TiO2. The performance was considerably improved compared with (Cu–TiO2)/PANI and (PANI-TiO2)/Cu composites prepared by changing the deposition sequence of Cu and PANI. Such an improved activity was because of multiple transferring paths of photogenerated electrons in the composite. Interestingly, the as-prepared ternary photocatalyst exhibited superior hydrogen evolution compared with the binary hybrids (Cu/TiO2 and PANI/TiO2). The exceptional performance of Cu@PANI/TiO2 could be understood considering the distinctive electrical conductivity of PANI and heterojunction formed between PANI and TiO2, as well as the merits of the Schottky junction constructed between Cu and PANI. These superior features could efficiently suppress the recombination rate of the photogenerated electron–hole pairs and maximize the photocatalytic activity. This study provides new insights for understanding the effect of electron transfer pathways on photocatalytic activities.  相似文献   
997.
    
Coating a protective agent or promoter on the surface of the photocatalyst is a proven good strategy to realize photocatalytic hydrogen production from pure water, but remains still a considerable challenge. Herein, a novel CdS@Mg(OH)2 core/shell composite nanorods photocatalyst was synthesized by coating Mg(OH)2 on CdS surface by hydrothermal and precipitation processes. The coated-Mg(OH)2 layer did not change the structure of CdS, and the photocatalytic overall water splitting performance of the CdS@Mg(OH)2 under visible light irradiation was improved obviously. After loading nano-Pt via the photodeposited method, the hydrogen production rate and stability of Pt/CdS@Mg(OH)2 were 3.3 and 2.4 times that of the Pt/CdS under the visible light irradiation, respectively. The surface Mg(OH)2 layer improved the hydrophilicity and stability of the core/shell composites and increased the amount of active sites, thus improving the photocatalytic properties. It is believed that Mg(OH)2 can be used as a new co-catalyst to enhance the performance of photocatalytic overall water splitting.  相似文献   
998.
    
Z-scheme photocatalysis provides a promising solution to photocatalytic solar water splitting, yet restricted by inferior interfacial charge transfer. Here, we demonstrate a Z-scheme composite photocatalyst made of Fe2O3, a carbon layer, and g-C3N4 that can achieve efficient hydrogen generation from solar water decomposition. The success relies on in-situ preparation of core-shell Fe2O3@C structure at the surface of g-C3N4. Carbon as an intermediate layer thus acts as a bridge that significantly accelerates the migration of photogenerated electrons from Fe2O3 conduction band to g-C3N4 valence band. As a result, the highest rate of H2 generation reaches 5.26 mmol h−1g−1. This activity is approximately 33-time greater than that achieved over pristine g-C3N4 and about 4-time larger than that obtained over a Fe2O3/g-C3N4 heterojunction without internal carbon layer. This work explicates the potential insight of the composite and paves a promising way to engineer the charge transfer behavior.  相似文献   
999.
    
They are sometimes identified as zero-dimensional (0D) nanoparticles. These particles have gained much attention in water splitting into hydrogen and oxygen through photocatalytic conversion. CQDs act as semiconductor few nm sizes, due to very small size; their optical and electronic properties differ from larger particles. CQDs particle has high stability, mild toxicity besides conductivity. These particles are environmentally friendly due to low toxicity and also have excellent luminescence. Therefore they can be utilized as a potential source for the splitting of water photocatalytically. The parting of water into H2 and O2 will enable us to produce or collect hydrogen to be used as a future fuel. The review summarizes the efforts made by various researchers in the field of utilizing carbon quantum dabs for water splitting which may be further followed by future researchers for commercial-scale hydrogen production. Thus, the study concludes the methods for the production of CQDs and their utilization under sunlight by catalytically hydrogen gas production from water.  相似文献   
1000.
Converting hydrocarbons into aldehydes in a green and environmentally benign way is of great signif-icance in fine chemistry.In this work,all-inorganic Cs3Bi2Br9 perovskite nanoparticles were uniformly loaded on BiOBr nanosheets via an in-situ growth method,which can selectivity photoactivate aromatic C(sp3)-H bond of toluene to generate benzaldehyde.According to the in-situ X-ray photoelectron spec-troscopy characterization,the photogenerated electrons of BiOBr transfer to Cs3Bi2Br9 enforced by the in-ternal electric field under light irradiation,resulting in S-scheme heterojunction.Furthermore,theoretical calculations indicate that toluene molecules are inclined to adsorb on the BiOBr surface,subsequently in-volving the oxidation reaction to generate benzyl radical(PhCH2·)by using the energetic holes of BiOBr,while the remaining photoinduced electrons in the conduction band(CB)of Cs3Bi2Br9 with powerful reduction ability reduce O2 into·O2-,which is the vital oxidative active species working on toluene selective oxidation process.Such an unexceptionable charge carrier utilization mode and tendentious ad-sorption behavior of reactants contribute to the optimized Cs3Bi2Br9/BiOBr heterojunction with excellent photocatalytic performance,achieving a maximum of 22.5％toluene conversion and 96.2％selectivity to-wards benzaldehyde formation.This work provides a rational photocatalyst heterojunction construction protocol for the selective oxidation of saturated aromatic C-H bonds.  相似文献   
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