Recombination Probability Research Articles

Direct Z-scheme FeV2O4/g-C3N4 binary catalyst for highly selective reduction of carbon dioxide

• FeV 2 O 4 /g-C 3 N 4 was prepared by in-situ liquid chemical strategy and CVD. • FeV 2 O 4 /g-C 3 N 4 has exceptional photocatalysis activity, selectivity and stability. • Rapid carrier separation via Z-scheme was achieved for promoted performance. • Direct Z-scheme photocatalytic mechanism is proposed. Spinel oxides have attracted much attention as an excellent light-absorbing material, but they exist fatal problems such as complicated synthesis method and poor carrier separation ability. Herein, a Z-scheme FeV 2 O 4 /g-C 3 N 4 catalyst was designed and prepared via a one-pot hydrothermal ion-exchange method combined with post-treatment encapsulating process without any templates. The graphite phase carbon nitride encapsulated spinel to construct Z-scheme essence not only significantly lessens the recombination probability of photoexcited carriers, but also provides sufficient adsorptive and reactive sites for CO 2 molecules. It also revealed that the resultant composite catalyst exhibited good photocatalytic activity and selectivity with positive inhibition of HER. In this regard, a profound insight is provided to construct high efficiency photocatalyst, which are expected to substitute precious metal catalysts and make progressive contributions for solving CO 2 emissions.

Efficient Photocatalytic Reduction of CO2 to CO Using NiFe2O4@N/C/SnO2 Derived from FeNi Metal-Organic Framework.

Use of light is considered an effective approach to convert CO2 into usable chemical energy. In the present study, an iron- and nickel-containing bimetallic metal-organic framework (MOF) was synthesized via a simple solvothermal route. SnO2 was then composited with the said MOF, and the obtained material was calcined and annealed to fabricate a series of nanophotocatalysts. The annealed sample displayed superior photocatalytic activity to the calcined sample, possibly due to the carbon-nitrogen layer formed after annealing mediating the charge-transfer process. The results of photocatalytic experiments indicated that using [Ru(bpy)3]Cl2·6H2O as a photosensitizer and triethanolamine (TEOA) and acetonitrile (MeCN) as sacrificial agents, the catalyst sample was annealed at 450 °C (NiFe2O4@N/C/SnO2-450) to afford the highest CO yield from CO2 (2057.41 μmol g-1 h-1). The increase in the photocatalytic ability of the nanocomposites is basically attributed to multiple synergistic effects between NiFe2O4 and SnO2, which reduce the recombination probability of the photo-induced electrons and holes. Ultimately, a photocatalytic reaction mechanism is proposed for NiFe2O4@N/C/SnO2 in the reduction of CO2.

A Multifunctional Tyrosine‐Immobilized PAH Molecule as a Universal Cathode Interlayer Enables High‐Efficiency Inverted Polymer Solar Cells

AbstractAmong the various biological components in the photosynthesis reaction, tyrosine (Tyr) is considered crucial for facilitation of charge/proton transfer. However, the practical realization of this capability in recent artificial solar‐energy conversion systems is limited by the required alignment of Tyr molecules with both host materials and themselves. In this work, Tyr−perylene diimide−Tyr (PDI‐Y) is designed for implementation of a molecular‐based artificial photosystem II, where PDI and Tyr act as an antenna and internal mediator, respectively. The experimental and theoretical investigations prove that the presence of covalently immobilized Tyr can enhance the intramolecular charge separation, leading to a significant reduction of the exciton recombination probability. To explore the feasibility of using Tyr‐immobilized PDI in practical applications, PDI‐Y is applied as a universal cathode interlayer in an inverted polymer solar cell (iPSC). The result demonstrates potential multifunctional roles of PDI‐Y as a sub‐photosensitizer and electron transport layer, leading to a superior photovoltaic performance in both fullerene (PC71BM) and nonfullerene (Y6) based iPSCs. Consequently, the simple yet efficient Tyr‐immobilization approach is expected to offer tremendous opportunities for the advancement of electronic and optoelectronic applications.

Genetic Diversity and Population Structure of Vibrio parahaemolyticus Isolated From Clinical and Food Sources.

Vibrio parahaemolyticus is a common foodborne pathogen that causes gastroenteritis worldwide. Determining its prevalence and genetic diversity will minimize the risk of infection and the associated economic burden. Multilocus sequence typing (MLST) is an important tool for molecular epidemiology and population genetic studies of bacteria. Here, we analyzed the genetic and evolutionary relationships of 162 V. parahaemolyticus strains isolated in the Guangdong Province, China, using MLST. In the study, 120 strains were isolated from food samples, and 42 strains were isolated from clinical samples. All strains were categorized into 100 sequence types (STs), of which 58 were novel (48 from the food isolates and 10 from the clinical isolates). ST415 was the most prevalent ST among the food isolates, while ST3 was the most prevalent ST among the clinical isolates. Further, 12 clonal complexes, 14 doublets, and 73 singletons were identified in all ST clusters, indicating high genetic diversity of the analyzed strains. At the concatenated sequence level, non-synonymous sites in both, food and clinical isolates, were associated with purifying selection. Of note, the dN/dS ration was greater than 1 for some housekeeping genes in all isolates. This is the first time that some loci under positive selection were identified. These observations confirm frequent recombination events in V. parahaemolyticus. Recombination was much more important than mutation for genetic heterogeneity of the food isolates, but the probabilities of recombination and mutations were almost equal for the clinical isolates. Based on the phylogenetic analysis, the clinical isolates were concentrated in the maximum-likelihood tree, while the food isolates were heterogeneously distributed. In conclusion, the food and clinical isolates of V. parahaemolyticus from the Guangdong Province are similar, but show different evolutionary trends. This may help prevent large-scale spread of highly virulent strains and provides a genetic basis for the discovery of microevolutionary relationships in V. parahaemolyticus populations.

Great Amplification of Circular Polarization Sensitivity via Heterostructure Engineering of a Chiral Two-Dimensional Hybrid Perovskite Crystal with a Three-Dimensional MAPbI3 Crystal.

Chiral hybrid perovskites have brought an unprecedented opportunity for circularly polarized light (CPL) detection. However, the circular polarization sensitivity of such a detector remains extremely low because of the high exciton recombination rate in those single-phase hybrid perovskites. Here, a heterostructure construction strategy is proposed to reduce the electron–hole recombination rate in a chiral hybrid perovskite and achieve CPL detectors with greatly amplified circular polarization sensitivity. A heterostructure crystal, namely, [(R)-MPA]2MAPb2I7/MAPbI3 ((R)-MPA = (R)-methylphenethylamine, MA = methylammonium), has been successfully created by integrating a chiral two-dimensional (2D) perovskite with its three-dimensional counterpart via solution-processed heteroepitaxy. Strikingly, the sharp interface of the as-grown heterostructure crystal facilitates the formation of a built-in electric field, enabling the combined concepts of charge transfer and chirality transfer, which effectively reduces the recombination probability for photogenerated carriers while retaining chiroptical activity of chiral 2D perovskite. Thereby, the resultant CPL detector exhibits significantly amplified circular polarization sensitivity at zero bias with an impressive anisotropy factor up to 0.67, which is about six times higher than that of the single-phase [(R)-MPA]2MAPb2I7 (0.1). As a proof-of-concept, the strategy we presented here enables a novel path to modulate circular polarization sensitivity and will be helpful to design chiral hybrid perovskites for advanced chiroptical devices.

A neutral model for the loss of recombination on sex chromosomes.

The loss of recombination between sex chromosomes has occurred repeatedly throughout nature, with important implications for their subsequent evolution. Explanations for this remarkable convergence have generally invoked only adaptive processes (e.g. sexually antagonistic selection); however, there is still little evidence for these hypotheses. Here we propose a model in which recombination on sex chromosomes is lost due to the neutral accumulation of sequence divergence adjacent to (and thus, in linkage disequilibrium with) the sex determiner. Importantly, we include in our model the fact that sequence divergence, in any form, reduces the probability of recombination between any two sequences. Using simulations, we show that, under certain conditions, a region of suppressed recombination arises and expands outwards from the sex-determining locus, under purely neutral processes. Further, we show that the rate and pattern of recombination loss are sensitive to the pre-existing recombination landscape of the genome and to sex differences in recombination rates, with patterns consistent with evolutionary strata emerging under some conditions. We discuss the applicability of these results to natural systems.This article is part of the theme issue ‘Challenging the paradigm in sex chromosome evolution: empirical and theoretical insights with a focus on vertebrates (Part I)’.

Phylogenetic Classification of Global Porcine Deltacoronavirus (PDCoV) Reference Strains and Molecular Characterization of PDCoV in Taiwan.

Porcine deltacoronavirus (PDCoV), a highly transmissible intestinal pathogen, causes mild to severe clinical symptoms, such as anorexia, vomiting and watery diarrhea, in piglets and/or sows. Since the first report of PDCoV infection in Hong Kong in 2012, the virus has readily disseminated to North America and several countries in Asia. However, to date, no unified phylogenetic classification system has been developed. To fill this gap, we classified historical PDCoV reference strains into two major genogroups (G-I and G-II) and three subgroups (G-II-a, G-II-b and G-II-c). In addition, no genetic research on the whole PDCoV genome or spike gene has been conducted on isolates from Taiwan so far. To delineate the genetic characteristics of Taiwanese PDCoV, we performed whole-genome sequencing to decode the viral sequence. The PDCoV/104-553/TW-2015 strain is closely related to the G-II-b group, which is mainly composed of PDCoV variants from China. Additionally, various mutations in the Taiwanese PDCoV (104-553/TW-2015) strain might be linked to the probability of recombination with other genogroups of PDCoVs or other porcine coronaviruses. These results represent a pioneering phylogenetic characterization of the whole genome of a PDCoV strain isolated in Taiwan in 2015 and will potentially facilitate the development of applicable preventive strategies against this problematic virus.

Designing large-sized cocatalysts for fast charge separation towards highly efficient visible-light-driven hydrogen evolution

A key challenge in photocatalysts is their rapid recombination of photo-generated electron-hole pairs. To decrease the recombination probability, significant studies have been devoted to increasing potential active sites of photocatalytic systems for fast charge separation. Here we demonstrate a strategy to boost active sites that is different from conventional approaches, in which large-sized Mxene nanosheets were employed as cocatalysts, while small-sized CdS nanosheets were used as photocatalysts forming effective nanocomposites. Based on our designed strategy, the enrichment of transfer routes guides the fast separation of electrons from CdS nanosheets and transferred onto large-sized Mxene nanosheets. The visible-light-driven hydrogen production of our innovatively designed composites has been improved from 2.8 mmol/g of pure CdS nanosheets to 17.5 mmol/g of the CdS@Mxene optimized composite. The obvious improvement of hydrogen production verifies the feasibility of our design strategy as a unique way to design photocatalytic systems for fast charge separation and highly efficient photocatalytic properties. • A game-changing design of photocatalytic system. • Engineering Low-cost, large-size, and ultra-thin cocatalyst. • Design of ultra-thin and small-sized photocatalyst. • Anchoring small-sized photocatalyst onto large-sized cocatalyst. • Highly improved hydrogen evolution based on the new designed photocatalytic system.

High performance blue and white phosphorescent organic light-emitting diodes obtained by sensitizing both light-emitting and electron transport layers

In this work, novel blue and white organic light-emitting diodes (OLEDs) were designed by utilizing iridium(Ⅲ)bis(4-(tert-butyl)-2,6-diuoro-2,3-bipyridinne)acetylacetonate (FK306) as sensitizer in both light-emitting and electron transport layers. Analysis of device configuration demonstrated that FK306 molecules work as electron trappers in view of their low-lying energy levels and triplet energy, which broaden the width of recombination zone, thus enhancing carriers' recombination probability and suppressing the annihilation of excitons. Consequently, blue and white devices with low turn-on voltages were reported with current efficiencies of 71.95 and 72.23 cd A −1 , external quantum efficiencies of 32.62% and 31.30%, power efficiencies of 74.85 and 70.80 lm W −1 and brightness of 43171 and 37848 cd m −2 , respectively. Within electron transport layer, the optimal doping concentration of FK306 is 2 wt%, which can be easily controlled in device manufacture processes. In addition, it is much more flexible in terms of sensitizer choice for doped electron transport layer compared with light-emitting layer. High performance blue and white organic light-emitting diodes (OLEDs) with slow efficiency roll-off were designed by utilizing iridium(Ⅲ)bis(4-(tert-butyl)-2,6-diuoro-2,3-bipyridinne)acetylacetonate (FK306) as sensitizer in both light-emitting and electron transport layers. • Effective device structure was designed by utilizing iridium(Ⅲ) complex FK306 as sensitizer. • Co-doped sensitizer molecules function as electron trappers, which balanced carriers' distribution and broadened recombination zone. • The sensitized devices displayed higher EL efficiency and slower efficiency roll-off. • It is much more flexible in terms of sensitizer choice within doped electron transport layer.

Optimization of CRISPR-Cas9 through promoter replacement and efficient production of L-homoserine in Corynebacterium glutamicum.

Corynebacterium glutamicum is an important chassis for industrial applications. The low efficiency of commonly used genome editing methods for C. glutamicum limits the rapid multiple engineering of the bacterium. In this study, chromosome-borne expression of cas9 and recET from Escherichia coli K12-MG1655 was achieved to avoid toxicity to the strain, increase the probability of homologous recombination, and reduce loss of viability caused by double-strand breaks. Constitutive strong promoters, such as P45 , Ptrc , and PH36 , were used to replace PglyA and to expand the application of the CRISPR-Cas9 system. By using this system, a C. glutamicum strain producing L-homoserine to 22.1g per L in a 5-L bioreactor after 96 h was obtained. Through the application of visualized fluorescent protein, the process of plasmid curing was optimized, obtain a continuous and rapid CRISPR-Cas9 genome editing system. The method described here could be useful to construct C. glutamicum mutant rapidly.

Construction of Z-scheme g-C3N4 / MnO2 /GO ternary photocatalyst with enhanced photodegradation ability of tetracycline hydrochloride under visible light radiation

A facile wet-chemical method was adopted to synthesize g-C3N4/MnO2/GO heterojunction photocatalyst for visible-light photodegradation of tetracycline hydrochloride (TC). The addition of MnO2 and GO increased the absorption of visible light and the specific surface area of the photocatalyst. The results of photoluminescence, electrochemical impedance spectroscopy, and photocurrent response indicated that CMG-10 had the lowest electron-hole recombination probability, which was beneficial for the photocatalytic reaction. The ternary photocatalyst exhibited enhanced photoelectric performance and superior photocatalytic activity with 91.4% removal of TC (10mg/L) under a mere 60min visible light illumination, which showed enhanced photocatalytic degradation when compared with binary (CM, 77.95%; CG, 78.83%) and single (C3N4, 55.5%; MnO2, 36.41%) photocatalysts. A pH of 6 was optimal for the CMG-10 photocatalytic degradation of TC, and the optimal photocatalyst dosage was 0.5g/L. Common coexisting ions influenced the removal of TC by influencing the production of active species. The catalyst is stable and reusable with only a 10% reduction in removal efficiency after four cycles. According to the active species analysis, the Z-scheme mechanism was a charge transfer behavior in the composite photocatalyst, which could prevent the recombination of photogenerated carriers. This study presents a photocatalytic approach to the effective removal of TC from water bodies, which provides practical implications to advance the use of photocatalytic technology in the restoration of aqueous environmental pollution.

Semiclassical theory of laser-assisted dissociative recombination

We study the process of laser-assisted dissociative recombination of an electron with a molecular cation using a semiclassical approach. In the region outside a reaction sphere the electron motion in the combined laser and Coulomb fields is treated classically. Within the sphere the laser-field effects are neglected, and the recombination probability is obtained from quantum-mechanical cross sections calculated for the laser-free process. Specific calculations are performed for dissociative recombination of ${\mathrm{H}}_{2}^{+}$ in the field of the intensity 2.09 GW/${\mathrm{cm}}^{2}$ and the wavelength $22.8\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{m}$. In the energy region above 1 meV the cross section is significantly enhanced compared with the field-free case due to the Coulomb focusing effect. The influence of the indirect process due to electron capture into Rydberg states is also investigated. Although the Rydberg resonances are washed out due to the field effects, they influence significantly the magnitude of the dissociative recombination cross section.

Bifunctional interfacial engineering for piezo-phototronic enhanced photovoltaic performance of wearable perovskite solar cells

The piezo-phototronic effect can effectively modulate the energy band structure at the interface of p-n or metal-semiconductor junction, manipulating the separation, transport, and recombination of photoinduced charges. While zinc oxide (ZnO) is a good electron transporting layer (ETL), its Lewis's basic nature and presence of surface defects lead to deprotonation of perovskite, resulting in severe degradation of perovskite solar cells (PSC). Herein, the ZnO surface is converted to ZnS, which acts as a bifunctional interfacial layer, passivating the ZnO/perovskite interface by reducing the hydroxyl (‒OH) group on the ZnO surface for improved stability and forming strong coordination with Pb 2+ of perovskite (Zn-S-Pb pathway) and thus adjusting the energy level for efficient electron transport. Consequently, the power conversion efficiency (PCE) of the flexible PSC is remarkably improved from 12.94% to 14.68% under static external strain of 1.5%, ascribed to the strain-induced piezo-polarization charges, which modulate the energy band structure of ZnS/ZnO and ZnS/perovskite interfaces. As a result, spatial separation of photoinduced carriers is facilitated, reducing recombination probability. The energy band diagram is proposed to elucidate the mechanism. This strategy enables effective utilization of the piezo-phototronic effect while enhancing device stability. Power conversion efficiency and current density of flexible perovskite solar cell are enhanced from 12.94% and 21.82 mA cm −2 to 14.68% and 24.40 mA cm −2 , respectively, via a tensile strain of 1.5% due to the piezo-phototronic effect modulating the band structure at ZnO/ZnS and ZnS/perovskite interfaces. • A bifunctional interlayer at ZnO/perovskite interface is introduced for enhancing device stability. • Wearable PSCs with enhanced PCE is developed via the piezo-phototronic effect. • A 14% enhancement in PCE reaching 14.68% with 1.5% tensile strain is achieved. • PCE remains stable (90%) at 25 °C for 50 days and (84.2%) at 80 °C for 30 days. • A piezo-phototronic modulated energy band alignment mechanism for core-shell ETL is proposed.

Enhanced UV photodetectivity in solution driven ZnO nanosheets via piezo-phototronic effect

Here in, we report the fabrication of thin two dimensional (2D) ZnO nanosheets (NSs) flexible piezo-phototronic ultraviolet (UV) photodetector (PD). The morphological and optical properties of the as-synthesized ZnO NSs is characterized in detail. The flexible Ag–ZnO NSs-Ag lateral PDs are fabricated on the polyethylene terephthalate (PET) substrate. A striking photoresponse is observed for 2D-ZnO under UV illumination. Furthermore, by introducing a strain (in the form of bending) the photocurrent and responsivity of this PD can be modulated via piezo-phototronic effect, emerging from the ZnO nanosheets. The photocurrent enhancement under bending could be attributed to the piezo polarization charges produced at ZnO/Ag interface due to strain. This piezo polarization charges result in the modulation of Schottky barrier (SB) height at the semiconductor/metal interface and induce improved photogenerated charge carriers and reduced recombination probability to result enhanced performances from the ZnO NSs photodetector. The physical mechanism involved in the enhancement of photocurrent via piezo-phototronic is proposed to explain change in SB height at semiconductor/metal interface using the band diagrams. This results demonstrates an efficient prototype of the piezo-phototronic PD based on thin ZnO NSs, which provides an effective pathway to enhance the performance of optoelectronic devices.

Outstanding performance of electron-transport-layer-free perovskite solar cells using a novel small-molecule interlayer modified FTO substrate

• An efficient PPPDE interlayer is inserted for the first time in the ETL-free PSCs. • The champion device yields an extraordinary PCE of up to 19.71%. • Ameliorated hysteresis and stability are achieved in PPPDE-based ETL-free PSCs. Organic-inorganic halide perovskites have become promising materials for the next generation of photovoltaic devices on account of the preeminent optoelectronic characteristics and boundless potentialities. Perovskite solar cells (PSCs) normally require a complex structure design with an electron transport layer (ETL) to provide a built-in electric field and depress the probability of carrier recombination. Nonetheless, the construction of a proper ETL is not cost-effective, which precludes the practical commercialization of the PSCs. In this respect, a simplified ETL-free PSC is successfully fabricated by inserting a facile and efficient 1-[N-(2-Hydroxyethyl)-4′-piperidyl]-3-(4′-piperidyl) propane (PPPDE) small-molecule thin interlayer between the FTO substrate and perovskite film. Compared with the bare FTO-based PSCs, this surface engineering can prominently ameliorate the photovoltaic performance parameters, yielding an extraordinary PCE of up to 19.71% with a ca. 31% efficiency enhancement, which can be attributed to the optimized interface energy-level alignment with a barrier-free contact, the elevated charge transfer and collection as well as the suppressed electron-holes recombination at the FTO/perovskite interface. Synchronously, the long-term air stability is also improved with mitigated J – V hysteretic behavior due to the larger grain size of perovskite and the suppressed defect-induced degradation. Furthermore, an augmented performance of 15.87% was achieved for the flexible PPPDE embedded ETL-free PSC fabricated on ITO/PEN substrates via a low-temperature deposition process. The demonstrated PPPDE interlayer presents a brand-new strategy that can simplify the cell configuration and improve the photovoltaic performance of ETL-free PSCs.

Oxygen Recombination Probability Data for Plasma-Assisted Atomic Layer Deposition of SiO2 and TiO2.

Atomic layer deposition (ALD) can provide nanometer-thin films with excellent conformality on demanding three-dimensional (3D) substrates. This also holds for plasma-assisted ALD, provided that the loss of reactive radicals through surface recombination is sufficiently low. In this work, we determine the surface recombination probability r of oxygen radicals during plasma ALD of SiO2 and TiO2 for substrate temperatures from 100 to ∼240 °C and plasma pressures from 12 to 130 mTorr (for SiO2). For both processes, the determined values of r are very low, i.e., ∼10–4 or lower, and decrease with temperature and pressure down to ∼10–5 within the studied ranges. Accordingly, deposition on trench structures with aspect ratios (ARs) of <200 is typically not significantly limited by recombination and obtaining excellent film conformality is relatively facile. For higher AR values, e.g., approaching 1000, the plasma time needed to reach saturation increases exponentially and becomes increasingly dependent on the process conditions and the corresponding value of r. Similar dependence on process conditions can be present for plasma ALD of other materials as well, where, in certain cases, film growth is already recombination-limited for AR values of ∼10. Radical recombination data and trends as provided by this work are valuable for optimizing plasma ALD throughput and feasibility for high-AR applications and can also serve as input for modeling of radical recombination mechanisms.

Efficient hydrogen evolution with ZnO/SrTiO3 S-scheme heterojunction photocatalyst sensitized by Eosin Y

Developing efficient, stable, and cheap photocatalysts for H 2 production has aroused great interest among researchers. Herein, noble-metal-free ZnO/SrTiO 3 composite photocatalysts have been successfully prepared by hydrothermal method. X-ray diffraction, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, ultraviolet–visible diffusion spectroscopy, and photoluminescence spectroscopy are used to characterize the obtained samples. The photocatalytic water splitting for H 2 production by ZnO/SrTiO 3 has been studied under simulated sunlight irradiation by using triethanolamine as a sacrificial agent and Eosin Y (EY) dye as a sensitizer. The orthogonal experiments are designed to optimize the photocatalytic reaction conditions for practical purposes. The influencing extents and trends of the factors have been investigated, including the catalyst composition and dosage, pH value of the solution, triethanolamine, and EY addition. Under the optimum conditions, the H 2 production rate with ZnO/SrTiO 3 is up to 16006.12 μmol g −1 h −1 . The excellent performance of ZnO/SrTiO 3 is attributed to the formation of a step-scheme (S-scheme) heterojunction, which promotes the separation of photocarriers and reduces their recombination probability. • ZnO/SrTiO 3 S-scheme photocatalysts are prepared by hydrothermal method. • The maximum hydrogen production rate of 16006.12 μmol g −1 h −1 is achieved. • Orthogonal experiments are designed to optimize the reaction conditions. • The photocatalytic mechanism of hydrogen production is proposed.

Fabrication and photosensitivity of ZnO/CdS/silica nanopillars based photoresistor

A kind of Zinc oxide (ZnO)/Cadmium sulfide (CdS)/Silica nanopillars structure is fabricated to photoresistor for the first time. The silica wafer with countless nanopillars is used as the substrate for photoresistor. CdS and ZnO film are deposited by frequency (RF) magnetron sputtering onto the silica nanopillars surface to form ZnO/CdS/Silica nanopillars structure. The ZnO nanowires also can grow on the CdS surface by the hydrothermal reaction to ZnO nanowires/CdS/Silica nanopillars structures. The X-ray diffraction curves show that the ZnO and CdS film both on the planar silica and nanopillar silica surface are well-crystallized. The ZnO film deposition can reduce the reflection and increase the absorption of the incoming light, especially for the light with a wavelength less than 350 nm. And the ZnO/CdS heterojunction structure can retard the recombination probability of the photon-generated carries and prolong the lifetime of the photon-generated carriers, which lending to a remarkable photocurrent improvement. The photosensitivity property testing results show that the ZnO nanowires/CdS/Silica nanopillars structure has the best photosensitivity response of 135 for the white light with 10 mW/cm2 illumination.

Ultrathin 2D/2D ZnIn2S4/g‐C3N4 Nanosheet Heterojunction with Atomic‐Level Intimate Interface for Photocatalytic Hydrogen Evolution under Visible Light

AbstractDesignation of high‐efficiency water splitting photocatalyst is still a challenge in converting solar energy into chemical fuels. Heterojunction can inhibit recombination of carriers which is considered to be a reliable strategy to improve photocatalytic performance on water splitting. In this work, a “face‐to‐face” 2D tight heterostructure is constructed by growing ZnIn2S4 nanosheets on g‐C3N4 nanosheets. Due to the ultrathin 2D structure and large amounts of NS bonds forming at the interface of heterojunction affording charge transferring tunnel, the synthesized 2D heterojunction photocatalysts successfully accelerate the carrier migration rate and decrease recombination probability of photogenerated electrons and holes. As a result, the optimized ZISCN‐50 sample has excellent photocatalytic H2 production activity (10.92 mmol h−1 g−1) under visible light, which is ≈5.2 times of ZnIn2S4 (2.09 mmol h−1 g−1) and 136.5 times of pure g‐C3N4 nanosheets (0.08 mmol h−1 g−1). Cycle experiments show that the composite material has excellent stability and recyclability. This work provides fresh insights into atomic‐level structure and interface design in order to synthesize high‐efficiency 2D/2D heterojunction photocatalysts.

Fabrication of magnetically recyclable yolk-shell Fe3O4@TiO2 nanosheet/Ag/g-C3N4 microspheres for enhanced photocatalytic degradation of organic pollutants

Herein, we report the fabrication of Fe3O4@TiO2 nanosheet/Ag/g-C3N4 (Fe3O4@ns-TiO2/Ag/g-C3N4) composite photocatalysts with well-designed hierarchical yolk-shell structure. To endow the composites with fascinating features, multiple functional components are perfectly integrated into the definite structure. The photodegradation experiments of organic pollutants revealed a significant enhancement in photocatalytic activity of developed composites as compared to P25, which is mainly due to the synergetic interaction of the tailored three-dimensional (3D) yolk-shell porous nanostructure, extended sunlight response range, and retarded the recombination probability of photogenerated electrons-holes. More importantly, the hybrid samples exhibited superior magnetic properties due to the magnetic component. The excellent magnetic recyclability and reusability of the photocatalysts are verified by the magnetic hysteresis loop and cyclic photocatalytic degradation experiments, which is significant for the green and sustainable applications of photocatalysts. Considering its remarkable photocatalytic performance and expectant magnetic recyclability, the composite photocatalysts are expected to be a promising candidate to dispose of future environmental issues.