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Abstract Porous In 2 O 3 nanoplates with polycrystalline structure (pp-In 2 O 3 NPs) and single-crystalline structure (ps-In 2 O 3 NPs) were synthesized through a facile solvothermal combined with a post calcination process. The gas sensing performance of the In 2 O 3 nanoplates with different crystallinity and porosity was investigated. Compared with the pp-In 2 O 3 nanoplates, the ps-In 2 O 3 nanoplates exhibited significantly enhanced gas sensitivity and selectivity towards triethylamine (TEA). The enhancement of the gas response of the ps-In 2 O 3 NPs can be attributed to the larger pore size and single-crystalline structure. Larger pore size can facilitate the target gas to diffuse into the inner surface of the sensing materials and increase the contacting chances of target gas and surface adsorbed oxygen species, while single-crystalline structure can decrease a part of grain boundary junction barrier and enhance the conductivity of the sensing film. This work would be important for further understanding the gas sensing mechanism and developing high promising In 2 O 3 gas-sensing materials. Graphical abstract Image 1 Highlights • Porous single-crystalline and polycrystalline In 2 O 3 nanoplates were controllable prepared. • The morphology and structure of the products were analyzed thoroughly. • The ps-In 2 O 3 nanoplates exhibited enhanced gas sensing performance to triethylamine. • The porous and single-crystalline structure contributed to the sensing properties. [ABSTRACT FROM AUTHOR]

A novel translucent TiO 2 porous film was prepared through etched method. The CdS, PbS and CdS/PbS nanoclusters were imbedded on TiO 2 porous film by successive ionic layer adsorption and reaction method. Microstructure, morphology, optical and photoelectron-chemical properties of the as-synthesized thin films were investigated systematically. XRD and morphology analysis showed that PbS or CdS nanoclusters have been attached to the TiO 2 porous films. It was found that the energy band gap of TiO 2 porous film decreased from 3.46 to 3.2 eV after sensitized with nanoclusters. The photocurrent density of ITO/TiO 2 photoelectrode increased from 0.017 to 0.28 mA/cm 2 after co-sensitized with CdS and PbS nanoclusters. Besides, the photoelectrode sensitized with two sorts of nanoclusters showed evident higher photocurrent density than which sensitized just one sort of nanoclusters. The photocurrent density of ITO/TiO 2 /PbS and TO/TiO 2 /CdS photoelectrode was 0.11 mA/cm 2 and 0.22 mA/cm 2 respectively. 0.28 mA/cm 2 can be obtained by ITO/TiO 2 /CdS/PbS photoelectrode. The results showed that the optical and photoelectrochemistry properties and phtotcatalysis performance of TiO 2 porous film were greatly improved by co-sensitized with CdS and PbS nanoclusters. [ABSTRACT FROM AUTHOR]

• Porous Co-doped ZnO nanodiscs with different Co contents have been synthesized. • Co(II) cations were confirmed to enter into ZnO lattice and substitute tetrahedral Zn sites. • The Co-doped ZnO nanodiscs exhibited enhanced TEA gas sensing performances than ZnO. • The CoZnO-3 sensor reached the highest response value of 68–50 ppm TEA and detection limit of 200 ppb. • Both the defects and the porous structure contribute to the sensing properties. Porous Co-doped ZnO nanodiscs were synthesized, exhibiting superior TEA gas-sensing behavior with high gas response, selectivity and low detection limit. [Display omitted] Pure ZnO and a series of Co-doped ZnO nanostructures with different Co doping amount were successfully synthesized by a simple near room-temperature precipitation method combined with subsequent calcination. The products featured a two dimensional (2D) porous nanodisc-like structure, which were composed of nanoparticles of about 30–100 nm in diameter. A series of structural analysis including XRD, Uv-vis adsorption, XPS and elemental mapping revealed that cobalt entered into the crystal lattice of ZnO uniformly in the form of Co(II) and substituted the Zn sites in tetrahedral coordination. The sensing performance of the products was investigated systematically. The Co-doped ZnO sensors especially CoZnO-3 exhibited a superior performance toward triethylamine (TEA) than the pristine ZnO sensor did, including enhanced response, excellent stability, high selectivity and low detection limit. The mechanism of the products was discussed based on the depletion layer model and the work suggested that the enhancement of gas-sensing performance can be mainly attributed to defects induced by Co-doping, the catalytic effect of Co and the porous structure. Thanks to the facile synthesis strategy and high performance, the Co-doped ZnO nanostructures become one of the promising sensing materials in practical applications. [ABSTRACT FROM AUTHOR]

In this paper, the surface state of the single-crystalline AlN template's impact on the epitaxial growth of gallium nitride (GaN) was studied. Subsequently, Schottky barrier devices were fabricated and analyzed. The results indicate that surface states subjected to different treatments exhibit varying epitaxial growth modes at the initial nucleation stage, which have a correlated effect on surface topography, crystalline quality, strain and other material characteristics of the epitaxial GaN. Higher surface energy leads to a reduction in screw dislocation of GaN material, but has less influence on edge dislocation. Single-crystalline AlN templates with higher surface energy are more likely to exhibit Stranski-Krastanow and Frank-van der Merwe growth model and achieve high-quality epitaxial materials. Schottky devices prepared using GaN material with lower screw dislocation density exhibit lower reverse leakage current. First-principles simulation analysis revealed that the migration barrier of gallium and nitrogen atoms on the surface can be overcome with the larger surface energy of single-crystalline AlN template. This facilitates their migration on the surface, resulting in higher quality material epitaxy. The conclusions of this work provide insights for quality control of epitaxial GaN materials on single-crystalline AlN templates, as well as for studying device leakage in the backend of the device fabrication process, or similar homogeneous compound semiconductor heteroepitaxy studies. • The correlation between surface energy, epitaxy and device was established for GaN epitaxial on single-crystalline AlN. • Surface energy prefers to driving Stranski-Krastanow growth mode and reducing screw dislocation density during GaN epitaxy. • The results confirm that reverse leakage of GaN SBD is more sensitive to screw dislocation rather than edge dislocation. [ABSTRACT FROM AUTHOR]

The exploitation of efficient and low-cost electrocatalysts for the oxygen evolution reaction (OER) is the key to the industrialization of the hydrogen production technology from water splitting. Herein, Ni 1 Fe 2 @Fe 2 O 3 composites with core-shell structure embedded in Metaplexis japonica fluff-derived carbon microtube matrix (Ni 1 Fe 2 @Fe 2 O 3 @C) are prepared by nitrate soaking and subsequent high-temperature calcination, which are used to catalyze the OER. The existence of carbon matrix greatly prevents the agglomeration of metal particles and creates an efficient electron transfer path for OER. The synergy among the carbon matrix, Ni 1 Fe 2 core and Fe 2 O 3 shell together enhances the OER performance, thus endowing Ni 1 Fe 2 @Fe 2 O 3 @C with the considerable catalytic activity with the overpotential of 271 mV at 10 mA cm−2 and a Tafel slope of 78 mV dec−1. Ni 1 Fe 2 @Fe 2 O 3 @C also shows good stability due to the double protection of metal particles by biomass carbon matrix and ultrathin Fe 2 O 3 shell. The water splitting device composed of Pt/C as the cathode and Ni 1 Fe 2 @Fe 2 O 3 @C as the anode exhibits water splitting activity close to that of Pt/C || RuO 2 system in alkaline medium, and the stability retention rate of the system reaches to 93 % after 30 h electrolysis. [Display omitted] • Ni 1 Fe 2 @Fe 2 O 3 composites with core-shell structure embedded in Metaplexis japonica fluff-derived carbon microtube matrix were prepared. • The existence of carbon matrix greatly prevents the agglomeration of metal particles and creates an efficient electron transfer path for OER. • Ni 1 Fe 2 @Fe 2 O 3 @C exhibits considerable catalytic activity with the low overpotential for OER. [ABSTRACT FROM AUTHOR]