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TEM image of Au-In 2 O 3 -co-decorated WS2 NSs; Selectivity pattern of Au-IN 2 O 3 -co-decorated WS 2 gas sensor to various gases under fixed 6.2 V applied voltage to 50 ppm. [Display omitted] • Co-decoration of Au and In 2 O 3 NPs on WS 2 nanosheets. • CO gas sensing at different applied voltages in self-heating mode. • Co-decorated gas sensor showed a response of 3.24 to 50 ppm CO gas at 6.2 V. • Explanation of the underlying sensing mechanism. Two-dimensional materials such as WS 2 nanosheets (NSs) have unique merits such as high surface area, good conductivity at low temperatures and good chemo-physical stability. In this study, we co-decorated In 2 O 3 and Au NPs on WS 2 NSs for CO gas sensing studies. The fabricated sensors were used in self-heating mode of operation at 25 °C, which can significantly decrease the power consumption. It was found that co-decorated gas sensor not only operates at a lower applied voltage, but also exhibits a higher sensing performance (sensitivity and selectivity), relative to bare WS 2 NSs. On one hand, generation of In 2 O 3 -WS 2 heterojunctions acted as notable sources of the resistance modulation and on the other hand, Au with its catalytic effect, significantly enhanced the dissociation of oxygen molecules and also offers many favorable adsorption sites for CO molecules. Therefore, we believe that co-decoration of WS 2 is a reliable strategy to enhanced the sensing features in self-heating mode, which is highly demanded for devices with reduced power consumption. [ABSTRACT FROM AUTHOR]

A novel structurally stable 2D-boron nitride material, namely di-BN, is predicted by means of the first-principles simulations. This monolayer BN system is composed of the azo (N N) and diboron (B B) groups. Its in-plane stiffness is close to the monolayer h-BN. Usually, the boron nitride materials are semiconductors with large band gaps. However, the monolayer di-BN possesses a moderate direct band gap of 1.622 eV obtained from our HSE06 calculation. Although the GW correction enlarges the band gap to 2.446 eV, this value is still in the range of the visible light. The detailed investigation of its band arrangement reveals that this material is able to product hydrogen molecules in a photocatalytic water splitting reaction. Furthermore, its charge carrier mobilities are significantly higher than the other popular 2D semiconductors, e.g., MoS 2 and phosphorene. Therefore, this 2D-BN material could have huge application potentials in the electronics and solar energy conversion fields. • A new boron nitride monolayer system, di-BN composed of B B and N N pairs, is proposed. • Unlike the other boron nitride systems with large band gaps, di-BN possesses an optimal direct band gap about 1.622 eV at HSE06 level. • The di-BN is a promising photocatalytic material for hydrogen evolution by water splitting. [ABSTRACT FROM AUTHOR]

[Display omitted] • The fabrication and mechanism of Pb-intercalated graphene (PbG) produced on SiC are investigated by scanning tunneling microscopy (STM) and X-ray Photoelectron Spectroscopy (XPS). • Pb intercalation prefers to happen at the interface between buffer layer and SiC substrate. Pb atoms penetrate into buffer layer through point defects on buffer layer or graphene edges during annealing, making the buffer layer transferred into an additional graphene layer. • PbG regions are mainly exhibited as regular ordered moiré pattern because of the mismatch between Pb atoms and graphene layer. Some irregular PbG regions with scattered moiré pattern are also formed due to the insufficient intercalation of Pb atoms underneath. • The intercalated Pb atoms arrange as two dimensional (2D) ultrathin structure underneath the newly formed PbG, and the thickness of PbG layer will increase by one after Pb intercalation. Revealing the detailed mechanism of metal intercalation on epitaxial graphene on SiC (EG/SiC) is difficult due to the complicacy and randomness of thermal decomposition of SiC substrate. In this context, the fabrication and mechanism of Pb-intercalated graphene (PbG) produced on SiC are investigated by scanning tunneling microscopy (STM) and X-ray Photoelectron Spectroscopy (XPS). It is reported that Pb intercalation prefers to happen at the interface between buffer layer and SiC substrate. Pb atoms penetrate into buffer layer through point defects on buffer layer or graphene edges during annealing, making the buffer layer transferred into an additional graphene layer. PbG regions are mainly exhibited as regular ordered moiré pattern because of the mismatch between Pb atoms and graphene layer. Some irregular PbG regions with scattered moiré pattern are also formed due to the insufficient intercalation of Pb atoms underneath. In addition, the intercalated Pb atoms arrange as two dimensional (2D) ultrathin structure underneath the newly formed PbG, and the thickness of PbG layer will increase by one after Pb intercalation. This study benefits to the modification of electronic properties of graphene on SiC, promoting the development of new 2D materials protected by graphene layer. [ABSTRACT FROM AUTHOR]

[Display omitted] • Porous cPTA/CN nanorod was prepared by using PTA as both template and adhesive. • In such a nanocomposite, the CN nanolayer forms on the surface of cPTA nanorods. • cPTA/CN degrades 97% RhB in 80 min and 78% tetracycline in 3 h under visible light. • cPTA facilitates the photoinduced carrier separation and afford more active sites. • This study offers a generic method for making nanorod photocatalysts. Solar energy-driven photocatalysis has become a promising green technology to degrade organic pollutants discharged into water environment in recent years. In this study, a kind of novel cPTA/CN nanorod photocatalysts were prepared by using poly(tannic acid) as both template and adhesive, in which the g-C 3 N 4 (CN) nanolayer formed on the surface of carbonized poly(tannic acid) (cPTA) nanorods, similar to the adhesion of marine mussel foot silk protein on the solid surface. The porous cPTA/CN nanorods with about 400 nm in width and 2–4 μm in length can degrade 97% Rhodamine B within 80 min and 78% tetracycline within 3 h under visible light irradiation. Porous cPTA nanorods play an important role for promoting the photocatalytic activity, which can not only accelerate the separation of photogenerated carriers, but also afford more active sites and molecule diffusion channels. This kind of nanocomposite photocatalysts may find broad application potential in the treatment of organic pollutants in aqueous solution. [ABSTRACT FROM AUTHOR]

[Display omitted] • Low-cost FVC photocatalysts were successfully prepared using two-step hydrothermal method. • The prepared FVC photocatalysts exhibited a narrow bandgap of 2.0 eV and a wide light absorption range of 400 ∼ 700 nm. • Rapid transfer of photogenerated electrons through carbon media in FVC photocatalysts. • CSB, FV, and PMS had synergistic effect on promoting OFX degradation under visible light. • Gradual decrease in the toxicity of OFX intermediates. Biochar is recognized as a good medium for promoting photogenerated charge separation in photocatalysts. In this study, the FeVO 4 /coconut shell biochar (CSB) composites (FVC) were prepared through a cost-effective hydrothermal approach to activate peroxymonosulfate (PMS) for the degradation of ofloxacin (OFX). Incorporated CSB expanded the light absorption range of FVC by approximately 100 nm, and the band gap energy of FVC was reduced to 2.00 eV. Measurements through linear scanning voltammetry (LSV) and current–time (IT) chronoamperometric further confirmed that the accelerated electron transmission rate boosted PMS oxidation, which was attributed to the role of CSB acting as a mediator. Importantly, OFX degradation was significantly boosted by CSB, FV, and PMS synergistically. FVC had a significant OFX degradation efficiency under visible light irradiation (95.2 %) compared to FV (70.9 %), CSB (57.8 %) and PMS (30.5 %). Moreover, the h+, 1O 2 , ·O2–, ·OH, and SO 4 ·− were the main active species, whose degradation pathways were explored and the toxicity of the intermediates was assessed. Furthermore, the as-obtained FVC exhibited a remarkable stability and reusability. This work provides new insights into the mechanism of biochar-mediated charge transfer for antibiotic degradation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three ZnAl 2 O 4 surfaces and their activities were theoretically studied. • The stability of ZnAl 2 O 4 decreases in the trend of (1 0 0) > (1 1 1) > (1 1 0). • ZnAl 2 O 4 (1 1 1) is the active surface for syngas to methanol conversion. • Stepwise pathway involving formate moiety dominates initial CO activation. • Activity plot with CO conversion and temperature was revealed. Identifying active site structure and unveiling corresponding reaction pathways are crucial issues to construct compatible reactive components in bifunctional catalysts for direct syngas conversion. Herein, the active surface structure and the reaction mechanism of syngas conversion to bridging intermediate methanol on ZnAl 2 O 4 spinel oxide are systematically investigated by combining density functional theory calculations and microkinetic simulations. The hydroxylated oxygen-rich surfaces of ZnAl 2 O 4 are demonstrated and their stabilities decreases as (1 0 0)-B-1/4H > (1 1 1)-B-3/8H > (1 1 0)-B-1/4H. Four reaction pathways differentiating in the adsorption site of CO and the participation style of H 2 on these surfaces are kinetically compared. We reveal that ZnAl 2 O 4 (1 1 1) is the active surface for syngas conversion; CO bonding on O site is activated more readily in a stepwise way to CH 2 O and the concerted pathway is then followed for CH 2 O to methanol. On ZnAl 2 O 4 (1 0 0) and ZnAl 2 O 4 (1 1 0) surfaces, the Non-Horiuti-Polanyi pathway in which gaseous H 2 reacting directly with CO or CH 2 O becomes kinetically more important. The Zn-O site of ZnAl 2 O 4 (1 1 1) is essential to dissociate H 2 heterolytically and stabilize key intermediate CHO. We show that the reaction rate decreases with the CO conversion, and the simulated reaction rate (~13 s−1) at 8% conversion agrees quite well with the experimental one (~20 s−1) under the typical reaction conditions. The predicted activity plots with temperature and CO conversion highlight the driving essentiality of zeolite component in bifunctional catalysts for syngas conversion. [ABSTRACT FROM AUTHOR]

[Display omitted] • Coble's densification model has been adopted to investigate the densification behavior of a freeze-casted Al 2 O 3 sample. • A shift of the densification mechanism from grain boundary to lattice diffusion has been elucidated at 1500 °C. • Glassy phases at grain boundary would facilitate densification when grain boundary diffusion dominates below 1500 °C. • Densification also would be facilitated by oxygen vacancies formed at grain boundary due to segregation of impurities. • Proper selection of dopants is important for densification to obtain beneficial grain boundary characteristics. Coble's densification theory has been adopted to investigate the densification behavior of a freeze-casted Al 2 O 3 sample. The successful adoption of bulk theory determined the dominant densification mechanisms of the porous structure. We noted a shift of the densification mechanism from grain boundary to lattice diffusion at 1500 °C. Interestingly, a very low activation energy value of 72.17 kJ/mol was measured for grain boundary diffusion while a general value of 455.83 kJ/mol for lattice diffusion. This outcome was accompanied by the presence of glassy phases at the grain boundary that would facilitate densification when grain boundary diffusion dominates the overall densification kinetics. Otherwise, the concentration of oxygen vacancies was high at the grain boundaries without the glassy phases. Both resulted from the segregation of intrinsic impurities, emphasizing the need for the proper selection of dopants to determine the grain boundary characteristics and hence potential densification strategies based on sintering science. [ABSTRACT FROM AUTHOR]

[Display omitted] • The incorporation of rGO induced PPy to be continuously and densely coated on the surface of PLA/rGO nanofibers. • The incorporation of rGO can increase and stabilize the conductivity, i.e., PLA/rGO3.5/PPy shows the highest conductivity. • The growth, proliferation, and neurite growth of PC-12 exhibit the highest level with 400 mV/cm. • The protein adsorption is affected by electrical stimulation, which in turn regulates cell behavior. The synergistic effect of endogenous electric field and electrical stimulation (ES) has promising application in the repair and regeneration of injured peripheral nerve. Conducting polymers-based (especially polypyrrole (PPy)) nanofibers have received more attention due to the promotive effects on cell behaviors under ES. However, the conductivity of PPy is unstable and the inferior hydrophilicity hinders its broad applications. Herein, the stable conductive polylactic acid/reduced graphene oxide/polypyrrole (PLA/rGO/PPy) composite nanofibers were prepared by incorporating rGO into PLA, by the following in-situ PPy polymerized on the surface of the PLA/rGO nanofibers. The results show that PPy on the surface of composite nanofibers are dense and continuous, the wettability is significantly improved. With the presence of PPy and rGO, the conductivity and stability of PLA/rGO/PPy composite nanofibers increase, and the conductivity of PLA/rGO 3.5/PPy composite nanofibers was the highest conductivity (1.46 × 10−1 S/cm). The proliferation and differentiation of PC-12 cells seeded on the surface of PLA/rGO3.5/PPy composite nanofibers reach the highest level under 400 mV/cm. These results are beneficial for improving biomaterial properties and provide guidance to ES application in peripheral nerve repair. [ABSTRACT FROM AUTHOR]