The Zn Vacancy-Mediated De-Accumulation Based Process for Hydrogen Production Performance Promotion of 1D Zn─Cd─S Nanorods.

Due to their anisotropy, 1D semiconductor nanorod-based materials have attracted much attention in the process of hydrogen production by solar energy. Nevertheless, the rational design of 1D heterojunction materials and the modulation of photo-generated electron-hole transfer paths remain a challenge. Herein, a ZnxCd1-xS@ZnS/MoS2 core-shell nanorod heterojunction is precisely constructed via in situ growth of discontinuous ZnS shell and MoS2 NCs on the Zn─Cd─S nanorods. Among them, the Zn vacancy in the ZnS shell builds the defect level, and the nanoroelded MoS2 builds the electron transport site. The optimized photocatalyst shows significant photocatalytic activity without Platinum as an auxiliary catalyst, mainly due to the new interfacial charge transfer channel constructed by the shell vacancy level, the vertical separation and the de-accumulation process of photo-generated electrons and photo-generated holes. At the same time, spectral analysis, and density functional theory (DFT) calculations fully prove that shortening difference of speed between the photogenerated electron and hole movement process is another key factor to enhance the photocatalytic performance. This study provides a new path for the kinetic design of enhanced carrier density by shortening the carrier retention time of 1D heterojunction photocatalysts with improved photocatalytic performance.

Ni(OH)2-derived lamellar MoS2/Ni3S2/NF with Fe-doped heterojunction catalysts for efficient overall water splitting.

Heterostructures formed by combining semiconductor materials with different band structures can provide work functions, d-band positions and electronic properties different from bulk materials and are considered as an effective strategy to improve the catalytic activity through electronic modification. In this study, an efficient MoS2/Fe-Ni3S2/NF heterojunction material was prepared by a two-step hydrothermal method. With the help of flake Ni(OH)2 synthesized in the first step, growth sites were provided for flake Ni3S2. The electronic structure of Ni3S2 was optimized by Fe doping, while the construction of the MoS2/Fe-Ni3S2 heterostructure allowed the catalyst to expose more active sites. MoS2/Fe-Ni3S2/NF exhibited a small charge transfer resistance and excellent electrocatalytic performance. At a current density of 10 mA cm-2, only low overpotentials of 148 mV and 118 mV were required for the oxygen precipitation reaction (OER) and hydrogen precipitation reaction (HER), respectively. Notably, when MoS2/Fe-Ni3S2/NF is used as the anode and cathode for overall hydrolysis, only 1.51 V is required to reach a current density of 10 mA cm-2, demonstrating its great potential for application in hydrolysis. This work provides a feasible idea for the rational construction of non-precious metal bifunctional electrocatalysts with excellent performance.

Improving photocatalytic hydrogen production by switching charge kinetics from type-I to Z-scheme via defective engineering.

By providing the spatial separation of the active sites and retaining high oxidative and reducing capacity, the direct Z-scheme heterostructure is considered the most potential structure for yielding photo-electric response. However, challenges still exist in the directional transfer of charge carriers between two semiconductors in direct Z-scheme structures. In this regard, by constructing the Vzn defect and p-n junction, a direct Z-scheme ZnxCd1-xS@ZnS-NiS heterostructure was obtained for the regulated electronic structure, which ensured high-yield hydrogen properties. The Zn vacancy in the partially-coated ZnS shell led to the Vzn energy level, and the addition of NiS led to the p-n structure, which caused a drastic downshift of the band edge potentials in comparison to that of pristine CdS. This variation gave rise to a staggered band edge alignment between ZnxCd1-xS and NiS, resulting in the variation of charge transfer kinetics from type-I to direct Z-scheme. Through careful characterization, it was found that the optimal photocatalytic hydrogen precipitation activity reached 16 683.6 µmol g-1 h-1, which was 70 times that of CdS, and this improvement was considered to form a spatial barrier, providing a clear direction and path for carrier transmission.

Interfacial Nucleation Mechanism of Water-Soluble Ag-In-S Quantum Dots at Room Temperature and Their Visible Light Catalytic Performance.

A novel interfacial reaction nucleation mechanism for the preparation of water-soluble Ag-In-S quantum dots (AIS QDs) was proposed in which interfacial acid regulates the concentration of hydroxide ions outside the complex and sulfur sources attack cations at the interface of the complex, covalent bonds between cations and sulfur sources are formed at the interface of the complex, and the nucleation and growth of crystals is finished at room temperature. By bypassing the heating process normally necessary for crystal nucleation and growth, AIS QDs can be produced on a large scale under simple, mild conditions. At the same time, the characteristics of this mechanism enable AIS QDs to be directly synthesized in an organic pollutant solution. This study represents a significant advance in the mechanism of crystal synthesis and contributes to the photocatalytic decomposition of organic pollutants from theory to practice.

Controlling microbial activity on walls by a photocatalytic nanocomposite paint: A field study.

BACKGROUND: Bacteria and fungi that grow on the walls can cause allergic reactions and infectious diseases in human. We proposed a low-cost and easy-to-operate testing protocol for large scale field studies to evaluate the long-term antimicrobial performance of a novel WOx paint in 2 primary schools. METHODS: In Tun Mun and Tin Shui Wai schools, WOx paints were painted on semi-outdoor and indoor walls and daily chlorine disinfection was applied after class in TSW School. A guidance was proposed for the protocol using the ATP biofluorescence method for large-scale field studies. ATP swab samples were taken at locations with and without the WOx paint on a control basis with a sampling frequency once a week for three months. The ATP values were then processed and presented in box plots. RESULTS: In both schools, the median log-scale ATP values of walls with WOx paint were at least 0.5-log lower than those without WOx paint. The WOx paint also performed better than daily chlorine disinfection in reducing microbial activities in long-term. CONCLUSIONS: The proposed testing protocol is suitable to evaluate long-term performance of an antimicrobial paint by analyzing its microbial activity in large-scale field tests. The WOx paint shows long-term effectiveness in reducing microbial activities on wall surfaces in both indoor and semi-outdoor environments.

Preparation of a Water-Soluble ZnX Cd1-X S Quantum Dot Photocatalyst at Room Temperature Assisted by 3-Mercaptopropionic Acid.

An effective path to synthesize Znx Cd1-x S quantum dots (ZCS QDs) in aqueous phase at room temperature has remained relatively unexplored. Here, we developed a room-temperature, aqueous-phase approach to ZCS QDs, using 3-mercaptopropionic acid (MPA) to adjust the pH of the reaction precursor solution to regulate the competition between sulfur source and hydroxyl group, and realize the large-scale preparation of water-soluble ZCS QDs photocatalyst at room temperature. Without recombination with other materials, and only by regulating the ratio of pH, excess sulfur sources and Zn/Cd, the photocatalytic degradation of rhodamine B (RhB) can reach 98% within 1 min, showing high photocatalytic activity. ZCS QDs show high stability and recoverability, and are expected to be able to deal with organic pollutants on a large scale. This study provides a new idea for the preparation of other QDs at room temperature.

Molecular mechanisms mediating asymmetric subcellular localisation of the core planar polarity pathway proteins.

Planar polarity refers to cellular polarity in an orthogonal plane to apicobasal polarity, and is seen across scales from molecular distributions of proteins to tissue patterning. In many contexts it is regulated by the evolutionarily conserved 'core' planar polarity pathway that is essential for normal organismal development. Core planar polarity pathway components form asymmetric intercellular complexes that communicate polarity between neighbouring cells and direct polarised cell behaviours and the formation of polarised structures. The core planar polarity pathway consists of six structurally different proteins. In the fruitfly Drosophila melanogaster, where the pathway is best characterised, an intercellular homodimer of the seven-pass transmembrane protein Flamingo interacts on one side of the cell junction with the seven-pass transmembrane protein Frizzled, and on the other side with the four-pass transmembrane protein Strabismus. The cytoplasmic proteins Diego and Dishevelled are co-localised with Frizzled, and Prickle co-localises with Strabismus. Between these six components there are myriad possible molecular interactions, which could stabilise or destabilise the intercellular complexes and lead to their sorting into polarised distributions within cells. Post-translational modifications are key regulators of molecular interactions between proteins. Several post-translational modifications of core proteins have been reported to be of functional significance, in particular phosphorylation and ubiquitination. In this review, we discuss the molecular control of planar polarity and the molecular ecology of the core planar polarity intercellular complexes. Furthermore, we highlight the importance of understanding the spatial control of post-translational modifications in the establishment of planar polarity.

[To evaluate the changes in body composition in male human immunodeficiency virus-related lipodystrophy after different treatment regimens by dual-energy X-ray absorptiometry].

OBJECTIVE: To evaluate the changes of body composition in male patients with human immunodeficiency (HIV)-related lipodystrophy (LD) syndrome (HIV-LD) switching from stavudine (d4T) to zidovudine (AZT) or tenofovir (TDF) by Dual-energy X-ray absorptiometry (DXA). METHODS: A total of 47 men with HIV-LD who had been exposed to stavudine (d4T) were enrolled in our study from May 2007 to September 2013 in Peking Union Medical College Hospital. Twice DXA assessments were administrated with interval of at least 12 months. All patients were divided into two different treatment regimens, either AZT group switching from d4T to zidovudine (AZT) or TDF group switching from d4T to TDF. Parameters of body composition in two groups were evaluated by DXA. RESULTS: Compared with baseline level, lower limb lean mass increased significantly after treatment [(15.4 ± 1.7) kg vs (16.0 ± 1.7) kg, t = 2.781, P < 0.01] and lower limb fat mass had a small decrease(P = 0.05) in AZT group. In TDF group, there were significant increases both in upper limb fat mass [(0.6 ± 0.3) kg vs (1.0 ± 0.7) kg, t = 2.422, P < 0.05] and lower limb fat mass [(1.8 ± 0.8) kg vs (2.6 ± 1.7) kg, t = 2.369, P < 0.05]. In AZT group, change of lower limb fat mass was generally small (median -0.04 kg, -4.55%). In TDF group, increase of lower limb fat mass and percentage of lower limb fat gain were even greater (median 0.46 kg, 27.41%). In a visual comparison of DXA results between AZT and TDF recipients, more fat gain of leg fat mass was seen in patients who switched from d4T to TDF (U = 2.954, P < 0.01). CONCLUSIONS: Compared with AZT group, TDF group led to a more increase in leg fat mass. Replacing d4T with TDF translates into an improvement of lipodystrophy. Although fat mass did not show a significant increase in AZT group, lean mass had improved after switching treatment, indicating AZT as a possible alternative agent of d4T. Body composition in men patients with HIV-LD can help to adjust the treatment regimen.