Oxygen Vacancies and Interface Engineering on Amorphous/Crystalline CrOx -Ni3 N Heterostructures toward High-Durability and Kinetically Accelerated Water Splitting.

Manipulating catalytic active sites and reaction kinetics in alkaline media is crucial for rationally designing mighty water-splitting electrocatalysts with high efficiency. Herein, the coupling between oxygen vacancies and interface engineering is highlighted to fabricate a novel amorphous/crystalline CrOx -Ni3 N heterostructure grown on Ni foam for accelerating the alkaline hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Density functional theory (DFT) calculations reveal that the electron transfer from amorphous CrOx to Ni3 N at the interfaces, and the optimized Gibbs free energies of H2 O dissociation (ΔGH-OH ) and H adsorption (ΔGH ) in the amorphous/crystalline CrOx -Ni3 N heterostructure are conducive to the superior and stable HER activity. Experimental data confirm that numerous oxygen vacancies and amorphous/crystalline interfaces in the CrOx -Ni3 N catalysts are favorable for abundant accessible active sites and enhanced intrinsic activity, resulting in excellent catalytic performances for HER and OER. Additionally, the in situ reconstruction of CrOx -Ni3 N into highly active Ni3 N/Ni(OH)2 is responsible for the optimized OER performance in a long-term stability test. Eventually, an alkaline electrolyzer using CrOx -Ni3 N as both cathode and anode has a low cell voltage of 1.53 V at 10 mA cm-2 , together with extraordinary durability for 500 h, revealing its potential in industrial applications.

Boosting the zinc ion storage capacity and cycling stability of interlayer-expanded vanadium disulfide through in-situ electrochemical oxidation strategy.

Metallic vanadium dichalcogenides with high conductivity and large layer spacing are fantastically potential to be cathode candidates for aqueous zinc ion batteries. However, simply reliance on the reversible Zn2+ intercalation/deintercalation process in the layer structure of vanadium dichalcogenides makes it suffer from low specific capacity and limited cycling number. Here we report a facile in-situ electrochemical oxidation strategy to boost the zinc ion storage capacity of interlayer-expanded vanadium disulfide (VS2·NH3) hollow spheres with satisfying cyclic stability. The hydrated vanadium oxide (V2O5·nH2O) generated from oxidized VS2·NH3, are endowed with reduced nanosheet size and subordinated porous structure, which provides abundant accessible sites and accelerates the zinc ion diffusion process. As a result, the VS2·NH3 derived cathode after the electrochemical oxidation process delivers a high reversible capacity of 392 mA h g-1 at 0.1 A g-1 and long cyclic stability (110% capacity retention at 3 A g-1 after 2000 cycles). The efficient oxidation process of VS2·NH3 cathode and the storage mechanism in the subsequent cycles are schematically investigated. This work not only reveals the zinc ion storage mechanism of the oxidized VS2·NH3 but also sheds light on advanced design for high-performance Zn ion cathode materials.

Magnetic recyclable CoFe2O4@PPy prepared by in situ Fenton oxidization polymerization with advanced photo-Fenton performance.

Here we present a magnetic recyclable photo-Fenton catalyst CoFe2O4@PPy with uniform morphology and excellent dispersibility prepared via simple in situ Fenton oxidization polymerization. The CoFe2O4 core provides good magnetic recyclability for the catalysts as well as the ion source for catalyzed decomposition of H2O2 in PPy coating. The optimal catalytic effect can be obtained by adjusting the ratio of CoFe2O4 and PPy. Methylene blue, Methyl orange and Rhodamine B (RhB) employed as model pollutants certificated that the catalyst exhibits a wide range of photodegradability. The decoloration rates reach nearly 100% in the photodegradation of 10 mg L-1 RhB after 2 h visible-light irradiation and only low toxicity small molecules are detected by LC-MS. Moreover, the catalytic activity remains after 5 cycles with decoloration rates up to 90%. The degradation measurement in the presence of scavengers of reactive species reveals that the positive holes (h+) and hydroxyl radical (·OH) are the main reactive oxygen species in the CoFe2O4@PPy system. The performance enhancement may be attributed to the combination of improved Fenton activity by coordinated Fe2+ and PPy redox pairs and photo-catalytic activity by broaden adsorption and photo-generated charge separation.

HfS2/MoTe2 vdW heterostructure: bandstructure and strain engineering based on first-principles calculation.

In this study, a multilayered van der Waals (vdW) heterostructure, HfS2/MoTe2, was modeled and simulated using density functional theory (DFT). It was found that the multilayers (up to 7 layers) are typical indirect bandgap semiconductors with an indirect band gap varying from 0.35 eV to 0.51 eV. The maximum energy value of the valence band (VBM) and the minimum energy value of the conduction band (CBM) of the heterostructure were found to be dominated by the MoTe2 layer and the HfS2 layer, respectively, characterized as type-II band alignment, leading to potential photovoltaic applications. Optical spectra analysis also revealed that the materials have strong absorption coefficients in the visible and ultraviolet regions, which can be used in the detection of visible and ultraviolet light. Under an external strain perpendicular to the layer plane, the heterostructure exhibits a general transition from semiconductor to metal at a critical interlayer-distance of 2.54 Å. The carrier effective mass and optical properties of the heterostructures can also be modulated under external strain, indicating a good piezoelectric effect in the heterostructure.

Study of zwitterionic sulfopropylbetaine containing reactive siloxanes for application in antibacterial materials.

Antibacterial agents receive a great deal of attention around the world due to the interesting academic problems of how to combat bacteria and of the beneficial health, social and economic effects of successful agents. Scientists are actively developing new antibacterial agents for biomaterial applications. This paper reports the novel antibacterial agent siloxane sulfopropylbetaine (SSPB), which contains reactive alkoxysilane groups. The structure and properties of SSPB were systematically investigated, with the results showing that SSPB contains both quaternary ammonium compounds and reactive siloxane groups. SSPB has good antibacterial activity against both Escherichia coli (E. coli, 8099) and Staphylococcus aureus (S. aureus, ATCC 6538). The minimal inhibition concentration is 70 µmol/ml SSPB against both E. coli and S. aureus. In addition, the SSPB antibacterial agent can be used in both weak acid and weak alkaline environments, functioning within the wide pH range of 4.0-9.0. The SSPB-modified glass surface killed 99.96% of both S. aureus and E. coli organisms within 24 h. No significant decrease was observed in this antibacterial activity after 20 washes. Moreover, SSPB does not induce a skin reaction and is nontoxic to animals. Thus, SSPB is an ideal candidate for future applications as a safe, environmentally friendly antibacterial agent.

Environmentally friendly antibacterial cotton textiles finished with siloxane sulfopropylbetaine.

This paper reports a novel environmentally friendly antibacterial cotton textile finished with reactive siloxane sulfopropylbetaine(SSPB). The results show that SSPB can be covalently bound onto the cotton textile surface, imparting perdurable antibacterial activity. The textiles finished with SSPB have been investigated systematically from the mechanical properties, thermal stability, hydrophilic properties and antibacterial properties. It is found that the hydrophilicity and breaking strength are improved greatly after the cotton textiles are finished with SSPB. Additionally, the cotton textiles finished with SSPB exhibit good antibacterial activities against gram-positive bacteria Staphylococcus aureus (S.aureus, ATCC 6538), gram-negative bacteria Escherichia coli (E.coli, 8099) and fungi Candida albicans (C.albicans, ATCC 10231). Moreover, SSPB is nonleachable from the textiles, and it does not induce skin stimulation and is nontoxic to animals. Thus, SSPB is ideal candidate for environmentally friendly antibacterial textile applications.