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Benzophenone derivatives, including benzophenone-1 (C

Herein, Ag3PO4/mixed-valence MIL-88A(Fe) [AMM] Z-scheme heterojunctions with an in-situ-generated photo–Fenton process were successfully constructed. The optimized AMM-20 heterojunctions show the maximum rate of photocatalytic TC degradation, which is 2.5 and 6.6 times of pristine Ag3PO4 and MIL-88A(Fe). The electronic and band structures of Ag3PO4, MIL-88A(Fe), m-MIL-88A(Fe) and AMM heterojunctions were deeply investigated by both experimental and theoretical simulation. The Z-scheme transfer pathway greatly accelerates the transfer rate of charge carriers and effectively inhibits the photocorrosion, leading to the improvement of photocatalytic activity and photostability. Moreover, the adjustment of the FeII/FeIII ratio of mixed-valence MIL-88A(Fe) further enhances the photocatalytic activity of the hybrid photocatalysts, benefiting from the promotion of the efficiency of the in-situ-generated photo-Fenton process. The Z-scheme transfer route coupling with an in-situ-generated photo–Fenton process was verified by the free radical trapping experiment, in-situ XPS measurement, in-situ ESR measurement, and coumarin fluorescence analysis. The degradation pathways of TC were determined through LC-MS analysis and theoretical calculation. Furthermore, the toxicity of intermediates was evaluated by QSAR prediction.

Molybdenum disulfide (MoS2) is considered as one of the most effective materials which can supersede the high cost and scarcity of metal platinum (Pt) for the hydrogen evolution reaction (HER). One road block lying in access to high catalytic performance of MoS2 emanates from the inert basal plane. To enable inert basal plane of flexible MoS2, we demonstrate an effective synthesis strategy via the progressive transformation of MoS2 to MoS2-xOx with O atomically dispersed under actual photo-catalytic hydrogen evolution condition. The rate of hydrogen production of new reconstructed MoS2-xOx nanosheets is improved to be much higher than that of the initial MoS2. Our theoretical calculation results indicate that the appropriate O substitution and strain could modulate the surface electronic state and optimize the Gibbs free energy (ΔGH) of MoS2, thus dramatically accelerating the catalytic efficiency. This work showcases a promising route to achieve tunable photochemical reconstruction by optimizing the electronic structure for low-cost and robust MoS2-based HER catalysts.

The optimized geometrical configuration of muitiple active materials into hierarchical nanoarchitecture is essential for the creation of photocatalytic degradation system that can mimic natural photosynthesis. A bamboo-like architecture, CuO nanosheets and Ag nanoparticles co-decorated TiO2 nanotube arrays (Ag/CuO/TiO2), was fabricated by using simple solution-immersion and electrodeposition process. Under simulated solar light irradiation, the 2,4-dinitrophenol (2,4-DNP) photocatalytic degradation rate over Ag/CuO/TiO2 was about 2.0, 1.5 and 1.2 times that over TiO2 nanotubes, CuO/TiO2 and Ag/TiO2, respectively. The enhanced photocatalytic activity of ternary Ag/CuO/TiO2 photocatalyst was ascribed to improved light absorption, reduced carrier recombination and more exposed active sites. Moreover, the excellent stability and reliability of the Ag/CuO/TiO2 photocatalyst demonstrated a promising application for organic pollutant removal from water.

A new hierarchical nanoarchitecture with integration of multiple active materials has been developed for highly efficient hydrogen evolution reaction (HER), by decorating a perpendicular hybrid of MoS2 and N-doped graphene nanosheets with CdS nanoparticles. The unique architecture promoted light trapping and absorption for highly efficient light harvesting and photocarrier generation, and offered an unblocked electron transport pathway for rapid charge separation/transport to suppress charge recombination. Its high surface area and high density of active sites result in highly efficient utilization of photogenerated carriers for productive HER. Significantly, without using noble metals as co-catalysts, the photocatalysts demonstrated rapid HER rates as high as 5.01 mmol h−1 g−1 under visible-light irradiation, which was approximately 25 times that of pure CdS. The hydrogen production remained stable after a continued test for 30 h, showing an exceedingly high performance and superior stability.

The scrupulous design and integration of multiple active materials into hierarchical nanoarchitectures is essential for the creation of photocatalytic hydrogen evolution reaction (HER) system that can mimic natural photosynthesis. Here we report the design and preparation of a “cauline leaf”-like structure for highly efficient HER, by decorating TiO2 nanofibers with vertical arrays of atomically-thin MoS2 nanosheets and CdS nanocrystals. The unique integrated “cauline leaf” design can promote light trapping and absorption for highly efficient light harvesting and photocarrier generation, and offer unblocked electron transport pathway for rapid charge separation/transport to suppress charge recombination, as well as high surface area and high density of active sites for highly efficient utilization of photo-generated carriers for productive HER. Structural characterizations by transmission electron microscopy show well-integrated nanoarchitectures. Significantly, photocatalytic studies demonstrate rapid HER rates as high as 12.3 or 6.2 mmol h−1 g−1 under simulated solar light or visible light irradiation, with apparent quantum efficiencies of 70.5% at 365 nm or 57.6% at 420 nm, and excellent long term stability, representing one of the best reported MoS2 hybrid HER photocatalysts. The study could open new opportunities for the rational design of nanoscale architectures for HER or other application.

It is challenging to prepare monolayer MoS2 with activated basal planes in a simple and efficient way. In this study, an interlayer spacing expanded counterpart, ammonia-intercalated MoS2, was obtained by a simple hydrothermal reaction of ammonium molybdate and elemental sulfur in hydrazine monohydrate solution. Then, the ammonia-intercalated MoS2 could be easily exfoliated by ultrasonication to get monolayer MoS2. Importantly, this monolayer MoS2 possessed rich S vacancies. The produced MoS2 demonstrated a proliferated active site density as well as low-loss electrical transport for efficient electrochemical hydrogen production from water. As expected, the monolayer MoS2 with S vacancies exhibited an excellent electrocatalytic hydrogen evolution reaction performance with a low overpotential (at 10 mA cm−2) of 160 mV (V vs. RHE) in acid media and a small Tafel slope of 54.9 mV dec−1. Furthermore, the catalyst displayed a good long-term stability and chemical stability during the electrochemical hydrogen production process. Computational studies prove that the S vacancies enabled the inert basal planes by introducing localized donor states into the bandgap and lowered the hydrogen adsorption free energy. This study could open new opportunities for the rational design and a better understanding of structure–property relationships of MoS2-based catalysts for water splitting or other applications.

Three-dimensional (3D) network-like graphitic carbon nitride nanobelts (g-C3N4 NBs) were facilely achieved by the hydrothermal treatment of bulk g-C3N4 in a medium strong oxalic acid solution (1 M, pH 0.89). The positions of the conduction band (CB) and valence band (VB) were upraised from −0.90 and +1.86 eV for bulk g-C3N4 to −0.92 and +1.92 eV for g-C3N4 NB networks with enhanced redox ability, respectively. With an optimized Pt loading of 3%, the g-C3N4 NB networks showed excellent visible-light photocatalytic H2 production activity (1360 μmol g−1 h−1), which was 10.9 times higher than that of optimized 2% Pt@bulk g-C3N4 (124.7 μmol g−1 h−1) using triethanolamine as a sacrificial agent. Furthermore, Pt@g-C3N4 NBs exhibited a considerable rate of H2 evolution of 33.3 μmol g−1 h−1, much higher than 1.79 μmol g−1 h−1 for Pt@bulk g-C3N4 in distilled water without any sacrificial agents, revealing a great potential for photocatalytic overall water splitting. This outstanding performance not only originates from its unique 3D nanostructure and prolonged electron lifetime, but also from the electronic structure modulation and improved redox capacities of the CB and VB. The pH effect of hydrothermal conditions on the g-C3N4 molecular structure, chemical elements, optical properties and catalytic performance is also expounded. This study demonstrates a facile and environmentally friendly strategy to design highly efficient g-C3N4 catalysts for potential applications in solar energy driven photocatalytic water splitting.

The optimised geometrical configuration between TiO2 nanorods (NRs) arrays and reduced graphene oxide (RGO) is essential for their application in catalysis of photoelectrochemical hydrogen production system. The scrupulous design of hierarchical nanoarchitectures by integration of multiple active materials can reinforce the light harvesting efficiency, enhance photocarrier generation and provide fast electron transport and efficient charge collection. Graphene film formed on the top surface and at the bottom of titanium dioxide nanorod (TiO2 NRs) arrays were scrupulously fabricated in this paper. More importantly, the hydrogen production rate of RGO@TiO2NR@RGO hybrid nanostructures was up to 800 μmol/h−1m2 (radiation intensity: 160 mW/cm2) which is over 2.5 times compared with bare TiO2NR.

The pharmaceutical products have becoming ubiquitous in aquatic environment. Photocatalytic degradation is considered as a promising strategy to address this environmental threat. Here we showed new Mo2C/hollow tubular g-C3N4 hybrids (Mo2C/TCN) consisting of well-designed direct Z-scheme heterojunction with favorable charge transfer channels for efficient contaminants degradation. Compare to the traditional Mo2C/g-C3N4 type-I heterojunction reported in the previous literature, the powerful direct Z-scheme heterojunction retains the original redox ability of the component without changing its oxidation and reduction potential. By virtue of the hollow tubular architecture, more incident electrons are expected to be rapid trapped by Mo2C nanoparticles, which contributes to the effective separation of photoinduced hole-electron pairs. As a result, the optimized Z-scheme system exhibits impressive visible-light photocatalytic performance. Especially, the 2 wt% Mo2C/TCN photocatalysts exhibits superior photocatalytic performance for tetracycline degradation with a reaction rate of 0.0391 min−1, which is 3-times and 9-times higher than those of TCN and pristine g-C3N4, respectively. The outstanding performance strongly depends on the synergistic effects among the favorable electrical conductivity of Mo2C and the multitude of charge transfer channels provided by the Z-scheme heterojunction. This work provides a new idea of designing direct Z-scheme material and it sheds novel insight to establish photocatalytic model for environmental amendment.

The construction of a heterojunction structure with close contact and good light absorption capability is crucial to achieve the good photocatalytic H2 evolution performance. The heterostructure of photocatalyst with different orientations has proved to be an efficient strategy for photocatalytic water splitting. Herein, an oriented facet heterojunction (OFH) photocatalyst is reasonably designed with ZnIn2S4 nanosheets (ZIS NSs) and CdS nanowire (NW), in which strained interface between the two materials leads to high separation efficiency of electron-cavity. This heterostructure achieves photocatalytic H2 activity of 3072 μmol h−1 g−1 with excellent long-term stability (>30 h) under simulated solar light. By considering the interactions between atoms and electrons in the interface region, our density functional theory (DFT) calculation reveals the strong interfacial coupling between the ZnIn2S4 tip and the CdS stem. These findings open up a new platform of OFH-engineered nano-catalysts for more powerful and more efficient solar energy utilization and environmental applications.

Silver orthophosphate (Ag3PO4) based semiconductor photocatalysis have been widely investigated for environmental purification due to its strong oxidation ability. Yet, its poor photostability and low photoactivity hamper its extensive applications. Here, an inorganic-organic Z-scheme photocatalytic system for antibiotic degradation demonstrated high photoactivity and stability through the use of Ag3PO4/Perylene diimide organic supermolecule (PDIsm). The apparent rate constant of tetracycline hydrochloride (TC-H) degradation with Ag3PO4/PDIsm was 1.5 times that of Ag3PO4 and 8 times that of PDIsm. The photocatalytic activity of Ag3PO4/PDIsm toward TC-H still kept 65 % after four reuses, while pure Ag3PO4 only kept 22 %. We revealed that this high photoactivity and photostability arisen from the efficient carriers separation and the formation of direct Z-scheme junction. Importantly, this Z-scheme electron transfer pathway was confirmed by thorough experimental study and density functional theory (DFT) calculation. This work demonstrated the significant potential of Ag3PO4-based inorganic-organic Z-scheme photocatalyst in environmental remediation.

Engineering the localized electronic structure is an intriguing way to regulate the charged valence state of materials for various potential applications. Here, we show that electrocatalytic reactions relevant for water splitting can be boosted by the charged excited state generated from tip-induced localized electron. Using intentionally fabricated acicular NiCo2S4-xPx nanowire array, on which charged H2O molecules are driven to metastable excited state to efficiently reduce activation barrier and enhance carrier transfer, the overpotential at 10 mA cm−2 required for hydrogen evolution was decreased to 75 mV and the Tafel slope was lowered to 42.3 mV per decade. This work, distinct from conventional doping and defecting strategy, provides a new insight into the underlying catalytic mechanism and functionalities of material’s catalytic properties via simple structural engineering.

Tungsten trioxide (WO3) has a wide application in environmental remediation due to its stability. Yet, the application of WO3 is severely limited by its wide band gap and weak electron reduction ability. In this work, we intend to enhance the visible light absorption and photocatalytic performance by constructing an organic-inorganic Z-scheme system WO3@Cu@PDI. Apparently, WO3@Cu@PDI has excellent visible light absorption and photocatalytic degradation ability in the degradation of tetracycline hydrochloride (TC). Under visible light irradiation, the degradation rate of composites is 40 times faster than that of sole WO3 and 5 times than PDI. The photocatalytic activity of WO3@Cu@PDI toward TC still kept 85% after three reuses. We revealed that this high photoactivity arisen from the efficient carriers separation and the formation of Z-scheme junction. Importantly, this Z-scheme electron transfer pathway was confirmed by thorough experimental study. This work demonstrated the significant potential of WO3-based inorganic-organic Z-scheme photocatalyst in environmental remediation.

Generally, pristine semiconductor materials are difficult to own excellent photocatalytic performance, and doping is considered an effective strategy to improve their performance. Herein, Co-doped BiOBr (0 1 0) was successfully synthesized. The improved performance could be attributed to the enhanced charge separation efficiency and the expanded light absorption region. Moreover, Co-doped BiOBr (0 1 0) owned relatively rough crystal surface with rich atomic defects and large specific surface area, which leaded to its excellent adsorption performance that contributed to the hole-dominated degradation process. Through density functional theoretical (DFT) calculation, the effect of Co doping on electronic structure of BiOBr was investigated, indicating that an additional energy level inserted into the band gap of Co-doped BiOBr, the band structure of Co-doped BiOBr was more intensive than that of BiOBr, and the CBM and VBM of the Co-doped BiOBr shifted towards lower energy regions. Tetracycline hydrochloride was chosen to further evaluate the photocatalytic performance of as-prepared Co-doped BiOBr (0 1 0), and 83% of tetracycline hydrochloride was degrade within 30 min. Finally, the visible-light driven catalytic mechanism of Co-doped BiOBr (0 1 0) was elucidated. Thus, a feasible strategy was proposed for the fabrication of excellent visible-light-driven photocatalytic materials.

The exploitation of the stable and earth-abundant electrocatalyst with high catalytic activity remains a significant challenge for hydrogen evolution reaction. Being different from complex nanostructuring, this work focuses on a simple and feasible way to improve hydrogen evolution reaction performance via manipulation of intrinsic physical properties of the material. Herein, we present an interesting semiconductor-metal transition in ultrathin troilite FeS nanosheets triggered by near infrared radiation at near room temperature for the first time. The photogenerated metal-phase FeS nanosheets demonstrate intrinsically high catalytic activity and fast carrier transfer for hydrogen evolution reaction, leading to an overpotential of 142 mV at 10 mA cm−2 and a lower Tafel slope of 36.9 mV per decade. Our findings provide new inspirations for the steering of electron transfer and designing new-type catalysts., While earth-abundant materials are promising catalysts for renewable energy conversion, such materials tend to display poor activities. Here, authors show FeS troilite nanosheets to undergo a near-infrared light-triggered transition to a phase that displays improved H2 evolution performances.

Core shell structure, which consists of an inner layer “guest” nanomaterial (nonaparticle or nanosheet) encapsulated inside another protective shell, is the most promising system for protecting the core from the surrounding environment, integrating different functional materials and providing a platform to maximize interface connectivity among the multiple components, which might enhance catalytic performance and materialization stability. Graphitic carbon nitride (g-C3N4), as an intriguing earth-abundant metal-free catalyst with a unique two-dimensional structure, excellent chemical stability, abundant “coordination nest” housing active sites, and tunable electronic structure, is a promising material for the controlled construction of core shell heterojunctions with the largest interface. At present, the applications of g-C3N4 based core shell structured nanomaterials (g-C3N4 CSNs) focus on degradation of contaminants, hydrogen production, reduction of carbon dioxide, fuel cells, as well as water disinfection. This review covers state-of-the-art achievements in g-C3N4 CSNs. The depiction comprises four sections based on g-C3N4 CSNs: the advantages of core shell structure and g-C3N4 CSNs; the design for the construction of g-C3N4 CSNs from both architectures and functions; a comprehensive overview of major advances in the synthesis of g-C3N4 CSNs; the discussion of their applications in photocatalysis, photoelectrocatalysis, and electrocatalysis. Moreover, recent strides in developing synthesis and catalytic applications of g-C3N4 CSNs, as well as an outlook section of offering some insights on the future directions and prospects of g-C3N4 CSNs, will be highlighted with the aim of overcoming the present limitations by exploiting more creative prepared methodologies and exploring other practical applications.

Exploring and designing an efficient and robust photocatalyst toward the degradation of organic pollutants under nature sunlight irradiation is a challenging research topic. The ability to maintain the photocatalytic activity in the entire daytime will be the ultimate goal for further widespread application of solar energy-driven semiconductor photocatalysis. Here, an all-day-active Z-scheme photocatalytic system is reported by employing Ag@AgI nanoparticles decorated Ag

"Memory catalysis" (MC) studies have received appreciable attention recently because of the unique talent to retain the catalytic performance in the dark condition. However, the MC activity is still low owing to the relatively limited electron storage capacity of the present materials. Here, a TiO

Potassium ion-batteries (PIBs) have attracted tremendous attention recently due to the abundance of potassium resources and the low standard electrode potential of potassium. Particularly, the solid-electrolyte interphase (SEI) in the anode of PIBs plays a vital role in battery security and battery cycling performance due to the highly reactive potassium. However, the SEI in the anode for PIBs with traditional electrolytes is mainly composed of organic compositions, which are highly reactive with air and water, resulting in inferior cycle performance and safety hazards. Herein, a highly stable and effective inorganic SEI layer in the anode is formed with optimized electrolyte. As expected, the PIBs exhibit an ultralong cycle performance over 14 000 cycles at 2000 mA g-1 and an ultrahigh average coulombic efficiency over 99.9%.

Fig S1. The cross profile SEM image of the prepared vertical 1T-WS2 nanosheets on Ti substrate. Fig S2. Whole-energy spectra of vertical 1T-WS2 nanosheets. Fig S3. (a) and (b) are false-color images responding to vertical 1T-WS2 nanosheets transform into 2H-WS2 nanosheets after 300 °C annealing treatment, respectively. Fig S4. Raman spectrum of vertical 1T-WS2 nanosheets (bottom) transform into 2H-WS2 nanosheets (up) after 300 °C annealing treatment. Fig S5. Polarization curves of vertical 1T-WS2 nanosheets after annealing at 300 °C in 0.5 M H2SO4 at a scan rate of 5 mV/s. Fig S6. Variation of current density versus the potential as a function of the pH for the vertical 1T-WS2 nanosheets. The highest current density is obtained for the lowest pH, consistent with the solution having the highest proton concentration. Table S1. Element analyses of the vertical 1T-WS2 nanosheets. Table S2. Summary of literature catalytic parameters of various MoS2 or MoS2-based catalysts, recently. (DOCX 1570 kb).

The catalytic activity of molybdenum sulfide (MoS 2 ) for hydrogen evolution reaction (HER) strongly depends on the number of exposed active edges of MoS 2 nanosheets. Making single or few-layer MoS 2 nanosheets vertically stand on a substrate is a very effective way to maximally expose the edge sites of MoS 2 nanosheets. Vertically standing single or few-layer MoS 2 nanosheets on porous TiO 2 nanofibers (TiO 2 @MoS 2 ) are successfully prepared via a simple hydrothermal reaction. Due to plenty of pores in the electrospun TiO 2 nanofibers, the MoS 2 nanosheets vertically grow from the inside to the outside, and the growth mode of the MoS 2 nanosheets rooting into the TiO 2 nanofibers endows not only intimate contact between TiO 2 and MoS 2 for fast electrons transfer but also high structural stability of TiO 2 @MoS 2 heterostructure. The vertical orientation of MoS 2 nanosheets enables the active edge sites of MoS 2 to be maximally exposed. Without using Pt cocatalyst, the TiO 2 @MoS 2 heterostructure achieves high photocatalytic hydrogen production rates of 1.68 or 0.49 mmol h −1 g −1 under UV–vis or visible light illumination, respectively. This high photocatalytic activity arises from the positive synergetic effect between the MoS 2 and TiO 2 components in this novel heterostructure. In addition, the TiO 2 @MoS 2 heterostructure exhibits a high durability as evidenced by the invariable hydrogen production rate after continuous illumination over 30 h. The work advances the development of highly efficient molybdenum sulfide-based HER catalysts.

A unique hierarchical architecture of ZnS–In 2 S 3 solid solution nanostructures onto TiO 2 nanofibers (TiO 2 @ZnS–In 2 S 3 ) has been successfully fabricated by simple hydrothermal method. The ZnS–In 2 S 3 solid solution nanostructures exhibit a diversity of morphologies: nanosheet, nanorod and nanoparticle. The porous TiO 2 nanofiber templates effectively inhibit the aggregation growth of ZnS–In 2 S 3 solid solution. The formation of ZnS–In 2 S 3 solid solution is proved by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) and the intimate contact between TiO 2 nanofibers and ZnS–In 2 S 3 solid solution favors fast transfer of photogenerated electrons. The trinary TiO 2 @ZnS–In 2 S 3 heterostructures exhibit high adsorption capacity and visible light photocatalytic activity for the degradation of rhodamine B dye (RhB), remarkably superior to pure TiO 2 nanofibers or binary structures (ZnS/TiO 2 nanofibers, In 2 S 3 /TiO 2 nanofibers and ZnS–In 2 S 3 solid solution). Under visible light irradiation the RhB photocatalytic degradation rate over TiO 2 @ZnS–In 2 S 3 heterostructures is about 16.7, 12.5, 6.3, 5.9, and 2.2 times that over pure TiO 2 nanofibers, ZnS nanoparticles, In 2 S 3 /TiO 2 nanofibers, ZnS/TiO 2 nanofibers, and ZnS-In 2 S 3 solid solution, respectively. Furthermore, the TiO 2 @ZnS–In 2 S 3 heterostructures show highly stable recycling performance.

We present a four-band and polarization-insensitive terahertz metamaterial absorber formed by four square metallic rings and a metallic ground plane separated by a dielectric layer. It is found that the structure has four distinctive absorption bands whose peaks are over 97% on average. The mechanism of the four-band absorber is attributed to the overlapping of four resonance frequencies, and the mechanism of the absorption is investigated by the distributions of the electric field. In particular, the frequency of each absorption peak can be flexibly controlled by varying the size of the corresponding metallic ring. The proposed concept is applicable to other types of absorber structures and can be readily scaled up to the structures that are working in the microwave frequency range. Moreover, the characteristic of the design can be used to design a five-band metamaterial absorber by adding one more metallic ring. The proposed absorber has potential applications in detection, imaging, and stealth technology.

Heterogeneous Fenton-like system has been proved to be an promising alternative to Fenton system due to its easy separation. However, it's a challenge to design heterogeneous Fenton-like catalysts with high activity and great durability. Here, ternary solid solution Fe

The rational design and preparation of hierarchical nanoarchitectures are critical for enhanced photocatalytic hydrogen evolution reaction (HER). Herein, well-integrated hollow ZnO@TiO2 heterojunctions were obtained by a simple hydrothermal method. This unique hierarchical heterostructure not only caused multiple reflections which enhances the light absorption but also improved the lifetime and transfer of photogenerated charge carriers due to the potential difference generated on the ZnO–TiO2 interface. As a result, compared to bare ZnO and TiO2, the ZnO@TiO2 composite photocatalyst exhibited higher hydrogen production rated up to 0.152 mmol h−1 g−1 under simulated solar light. In addition, highly repeated photostability was also observed on the ZnO@TiO2 composite photocatalyst even after a continuous test for 30 h. It is expected that this low-cost, nontoxic, and readily available ZnO@TiO2 catalyst could exhibit promising potential in photocatalytic H2 to meet the future fuel needs.

To realize the sustainable employment of solar energy in contaminant degradation and environmental recovery, design and development of an efficient photocatalyst is urgently needed. Herein, a novel direct Z-scheme composite photocatalysts consist of phosphorous-doped ultrathin g-C3N4 nanosheets (PCNS) and bismuth vanadate (BiVO4) are developed via a one-pot impregnated precipitation method. The as-prepared hybrid nanocomposite was utilized for the degradation tetracycline (TC) under visible light irradiation. Among the composites with various PCNS/BiVO4 ratios, the prepared PCNS/BVO-400 photocatalyst presents the best performance, showing a TC (10mg/L) removal efficiency of 96.95% within 60min, more than double that of pristine BiVO4 (41.45%) and higher than that of pure PCNS (71.78%) under the same conditions. The effects of initial TC concentration, catalyst dosage, pH value and different water sources have been studied in detail. The improved photocatalytic performance of the as-prepared PCNS/BiVO4 nanocomposites could be attributed to the promoted separation efficiency of the photogenerated electrons and the enhanced charge carrier lifetime (1.65ns) owing to the synergistic effect between the PCNS and BiVO4. The degradation intermediates and decomposition pathway of TC were also analyzed and proposed. Additionally, radical trapping experiments and ESR measurement indicated that the photogenerated holes (h+), superoxide radical (O2-) and hydroxyl radical (OH) all participated in the TC removal procedure in the reaction system. The high performance of PCNS/BVO-400 in real wastewater indicated the potential of the prepared composite in practical application. This work provides an efficient and promising approach for the formation of high performance Z-scheme photocatalyst and study the possibility for real wastewater treatment.

Despite numerous studies on peroxydisulfate (PS) activation with catalysts, the PS activation by organic contaminants themselves has been rarely reported. Here, we found that PS can be activated by dyes such as rhodamine B (RhB), eosin Y (EY) and methylene blue (MB) under visible light (Vis) irradiation, achieving simultaneous degradation of dye and antibiotics (e.g., tetracycline hydrochloride) via both radical and nonradical pathways. Experimental results demonstrated that the radical reaction was the major route, which was caused by the reduction of PS by photogenerated electrons of the dye. Dye-mediated electron transfer from pollutants to the oxidized dye (dye*+) was responsible for the nonradical reaction. Compared with EY and MB, the most negative LUMO (lowest unoccupied molecular orbital) level of RhB facilitated rapid electron transfer from RhB to PS, resulting in the highest activation efficiency. Interestingly, post-processing with base can further increase the mineralization efficiency due to the PS activation by generated phenolic intermediates of RhB degradation. This work elucidated a new pathway of PS activation and provide a new “using waste to treat waste” strategy for the disposal of dye wastewater and complex wastewater containing dye.

Phase transition through local strain engineering is an exciting yet complex phenomenon in nanoscience for enhancing electronic, magnetic, and catalytic properties of nanomaterials. Here we report a topotactic transformation in 2H-WS2 nanobelts into 1T-WS2 nanohelices, which is mediated via an aqueous electrochemical activation method. The resulting nanohelices exhibited superior catalytic properties for HER with a low overpotential of 170 mV for an electrocatalytic current density of 10 mA/cm2. Notably, the electrochemical stability of WS2 nanohelices increased after 20,000 cycles, where the stability of the Pt benchmark catalyst is known to decrease, thus implying WS2 nanohelices as ideal catalysts for long-term electrochemical processes. The emergence of such enhanced properties is attributed to the strain induced decrease in charge transfer resistance, enhanced per site activity and increased number of active edge sites in 1T-WS2 nanohelices. This study points the way for creating topological motifs in 2D materials with novel properties.

Hydroxyalkylation of phenol with formaldehyde to bisphenol F over heteropolyacid impregnated on clay was investigated. These catalysts displayed excellent catalytic performance for this reaction, especially that the effects of acid sites on the isomer distribution are obvious. Various solid catalysts were prepared by impregnating heteropolyacid on different kind of clay matrices, and their chemical compositions, textural properties, and acid strength of the heteropolyacid catalysts were characterized by EDX, BET, NH 3 -TPD, XRD, and FT-IR. Moreover, the effects of acid sites and reaction temperature on the yield and 4,4′-isomer distribution were launched by comparing the data obtained from the two kinds of catalysts. Furthermore, the kinetics of the hydroxyalkylation of phenol to BPF was established.

The 2p3/2 core-level binding energy (BE) shifts of Fe surface and Fe nanoparticles have been analyzed by considering the bond order-length-strength (BOLS) correlation mechanism [6] in decomposition of the X-ray photoelectron spectrum (XPS). It turns out that the Fe 2p3/2 BE shifts positively by 2.17 eV from the atomic value of 704.52 eV to the bulk value of 706.69 eV and that a further 0.32 and 0.16 eV positive shift occurs, respectively, to the top and the second atomic layers. Consistency between BOLS predictions and the measured size dependence of BE shift clarifies the dominance of the broken-bond-induced local strain and quantum trapping in perturbing the Hamiltonian and hence the positive shift of the 2p3/2 BE of Fe surface and Fe nanostructures.

We have investigated the joint effect of size- and composition-induced band-gap change of semiconductive nanocompounds from the recently developed bond-order-length-strength (BOLS) correlation mechanism using the approach of local bond average (LBA). An analytical solution has been developed to connect the band-gap energy with the bonding identities of the nanocompounds. Agreement between the model predictions with the available experimental measurements of band-gap change of II–VI semiconductor nanocompounds showed that both the particle size and the composition with alloying effect can be used as factors tuning the band-gap energy, suggesting an effective way to realize the desirable properties of semiconductive nanocompounds.

The application of thermoeconomic optimization design in an air-conditioning system is important in achieving economical life cycle cost. Previous work on thermoeconomic optimization mainly focused on directly calculating exergy input into the system. However, it is usually difficult to do so because of the uncertainty of input power of fan on the air side of the heat-exchanger and that of pump in the system. This paper introduces a new concept that exergy input into the system can be substituted for the sum of exergy destruction and exergy output from the system according to conservation of exergy. Although it is also difficult for a large-scale system to calculate exergy destruction, it is feasible to do so for a small-scale system, for instance, villa air conditioner (VAC). In order to perform thermoeconomic optimization, a program is firstly developed to evaluate the thermodynamic property of HFC134a on the basis of Martin–Hou state equation. Authors develop thermodynamic and thermoeconomic objective functions based on second law and thermoeconomic analysis of VAC system. Two optimization results are obtained. The design of VAC only aimed at decreasing the energy consumption is not comprehensive. Life cycle cost at thermoeconomic optimization is lower than that at thermodynamic optimization.

A unique hollow microsphere TiO2/ZnO p–n heterojuction was successfully fabricated via a one-step hydrothermal method for degradation of 2,4-Dinitrophenol. The enhancement of mineralization of 2,4-dinitrophenol (2,4-DNP) via photocatalytic degradation of TiO2/ZnO p–n heterojuction was investigated. The 2,4-DNP was degraded completely by TiO2/ZnO, and 78% of the total organic carbon (TOC) was removed which is greatly superior to that on the controlled TiO2, ZnO with 53%, 45%, respectively. A schematic diagram of photocatalytic oxidation mechanism of 2,4-DNP was also presented by [Formula: see text]OH radical detection. The oxidation of 2,4-DNP and the intermediate productions was based on the hydroxyl (OH) with a high oxidation potential of 2.8[Formula: see text]V. Moreover, the excellent stability and reliability of the TiO2/ZnO composite hollow microsphere photocatalyst demonstrated its promising application for removal of organic pollutant from water.

The development of an electron cloud in the vacuum chambers of high intensity positron and proton storage rings may limit machine performance. The suppression of electrons in a magnet is a challenge for the positron damping ring of the International Linear Collider (ILC) as well as the Large Hadron Collider. Simulation show that grooved surfaces can significantly reduce the electron yield in a magnet. Some of the secondary electrons emitted from the grooved surface return to the surface within a few gyrations, resulting in a low effective secondary electron yield (SEY) of below 1.0 A triangular surface is an effective, technologically attractive mitigation with a low SEY and a weak dependence on the scale of the corrugations and the external magnetic field. A chamber with triangular grooved surface is proposed for the dipole and wiggler sections of the ILC and will be tested in KEKB in 2007. The strategy of electron cloud control in ILC and the optimization of the grooved chamber such as the SEY, impedance as well as the manufacturing of the chamber, are also discussed.

Possible remedies for the electron cloud in positron damping ring (DR) of the International Linear Collider (ILC) includes thin-film coatings, surface conditioning, photon antechamber, clearing electrodes and chamber with grooves or slots. We installed chambers in the PEP-II Low Energy Ring (LER) to monitor the secondary electron yield (SEY) of TiN, TiZrV (NEC) and technical accelerator materials under the effect of electron and photon conditioning in situ. We have also installed chambers with rectangular grooves in straight sections to test this possible mitigation technique. In this paper, we describe the ILC R&D ongoing effort at SLAC to reduce the electron cloud effect in the damping ring, the chambers installation in the PEP-II and latest results.

Electron cloud due to beam-induced multipacting can generate transverse instabilities and beam size blow-up in both positron and proton accelerators. A solenoid satisfactorily suppresses multipacting in the drift region by confining the electrons close to the walls’ surface. There is a long drift region in the KEKB LER, wherein a solenoid occupies most of the beam’s pipe. We investigated the solenoid’s effects on the build-up of the electron cloud, the wake field and transverse coupled instabilities induced by electron cloud.

An analysis of the electromagnetic field based on an adaptive finite element method is presented in this paper. The performance of the adaptive algorithms, based on an element-element h-refinement technique, is assessed. The features of the refinement indictors, adaptation criteria and error estimation parameters are discussed. The strategy of the adaptive mesh refinement method applied to the eigenvalue problem is studied to improve the accuracy of the eigenvector. Numerical results for a pill-box cavity and a disc-loaded structure are shown.

A 3-dimensional particle simulation code is developed to study the photoelectron cloud in positron rings. The effects of the various magnetic fields in the KEKB LER are presented. The distribution and evolution of the electron-cloud are simulated.