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Roughness of abrasive air jet micromachining surface has a significant influence on electro-osmotic flow characteristics, optical properties and adhesion properties. The characterization of surface roughness based on power spectral density approach is studied. The formation mechanisms of surface topography are analyzed. The influence of process parameters on the roughness of abrasive air jet micromachining surface is discussed. The results show that surface profiles with close values of usual roughness parameters can be distinguished by power spectral density curves. The power spectral density curves can be classified into four categories based on the marked knee points on spatial frequency of 0.01 μm−1 and 0.1 μm−1 approximately. Power spectral density curve can be divided into three regions, namely, low frequency region, intermediate frequency region and high frequency region. The roughness of low frequency region and the roughness of intermediate frequency region play dominant roles in the surface roughness, while the contribution of the roughness of high frequency region is negligible. The low frequency region is associated with the overlap of craters. The intermediate frequency region is associated with the indentation removal mechanism and edge cutting mechanism. The high frequency region is associated with micro-dents removal. The roughness of low frequency region increases with an increase in air pressure, while it decreases with an increase in standoff distance. The roughness of low frequency region decreases firstly and then it increases with an increase in nozzle traverse speed. The roughness of intermediate frequency region increases firstly and then it decreases with an increase in air pressure, standoff distance and nozzle traverse speed. The Rq increases with an increase in air pressure, while it decreases with an increase in standoff distance. The Rq decreases firstly and then it increases with an increase in nozzle traverse speed.

In this paper, K-doped ZnO nanocrystalline powders were prepared by the sol-gel method at 500 °C. The effects of potassium (K) doping on the particle size, phase composition, and light absorption properties of zinc oxide nanocrystals were investigated by X-ray diffraction, transmission electron microscopy and ultraviolet–visible spectroscopy. The main crystalline phase of the powders before and after K doping is wurtzite ZnO. With the increased K doping amount, the purple and blue luminescent peaks are enhanced. The band gap of the sample obtained from the light absorption spectra initially increased with the K doping amount, then decreased, and increased again with the K doping amount, which is consistent with the theoretical calculation results. The calculated energy band and density of states results show that when the K doping amount is small, the band gap is reduced because the K doping forms the impurity level and the conduction band moves downward. This decrease is due to the two impurity levels generated at the bottom of the valence band.

In spite of the TiO2 compact layer (TCL) being widely used, it still needs more study. This paper took Ni-doped TCLs as the research target, using an innovative two-step method perfectly prepared Ni-doped TCLs with different thicknesses. And then on the basis of Ni-doped TCLs, the TiO2 nanorod array (TNA) films were successfully prepared. The effects of Ni-doped TCLs with different thicknesses on the morphology, structure, and photoelectric performance of TNA films were investigated. The results indicated that Ni-doped TCLs with appropriate thickness can significantly improve performance of TNA films and obtain satisfactory PCE stability with time. Compared with the TNA films based on Ni:TCL5, Ni:TCL10, and Ni:TCL30, the TNA film with Ni:TCL20 exhibited better comprehensive photoelectric performance, the DSSCs based on this TNA film achieved the highest Jsc (10.191 mA cm−2), Voc (0.574 V), PCE (4.42%), and the most excellent PCE stability with time.

One-dimensional TiO2 nanorod array films (1D TNA films) were prepared by the two-step process. The results show that the density of 1D TNA films is significantly improved with the presence of TiO2 compact layer (TCL) and the hydrothermal reaction time of 15 h. The TiO2 crystallinity is improved. The utilization efficiency of the visible light is increased with the lower concentration of crystal defects. The charge recombination center caused by the defects decreased, while the electrons and holes were effectively separated, thus the charge recombination rate was lowered, and better charge transport performance caused the transient photocurrent to increase significantly.

An innovative two-step method perfectly prepared TCLs with different thicknesses, and then the TNA films based on TCLs were successfully prepared. The effects of different thicknesses of TCLs on the morphology and photoelectrochemical performance of TNA films were investigated. The results indicated that TCLs with appropriate thickness could effectively improve the morphology and photoelectrochemical performance of TNA films. Compared with the TNA films based on TCL5, TCL10 and TCL30, the TNA film based on TCL20 exhibited more ideal and comprehensive photoelectrochemical performance. Moreover, dye-sensitized solar cells (DSSCs) based on this TNA film achieved the highest Jsc (10.2054 mA cm−2), Voc (0.5737 V), PCE (3.3%) and Pout (3.31 mW cm−2).

Low-density polyethylene (LDPE) was employed to improve the thermal and rheological properties as well as the supercritical CO2 foaming behavior of poly(lactic acid) (PLA) through melt mixing and batch foaming method, due to its long branched chain structure, moderate crystallization capacity and good foamability. The differential scanning calorimetry and polarized optical microscope results showed that the introduction of LDPE had a slight effect for promoting the crystallization of PLA. An important synergistic effect on the rheological properties of PLA/LDPE blends was found through rotational rheometer. With the content of LDPE, the size of spherical LDPE dispersion phase became bigger gradually, which was observed by scanning electron microscope (SEM). A very interesting cellular morphology evolution from flower-like cellular structure to complex cellular structure and then to mono-porous cell structure was found in the SEM images of the PLA/LDPE blending foams with the foaming temperature at 95 °C. The effect of blending ratio and foaming temperature on the cellular morphology and foaming parameters was investigated.

Cobalt disulfide (CoS 2 ) is a promising thermal battery electrode material for its superior thermal stability and discharge performance. However, the low natural resource and poor air stability restrict its application in thermal battery fabrication. In this work, carbon coated CoS 2 composite was prepared by a facile one-pot hydrothermal method with glucose as carbon source. During the growth of CoS 2 , the glucose molecules were in situ adsorbed and carbonized on the surface of the as-synthesized CoS 2 , and the resultant carbon coating provided improved electrical conductivity and discharge performances to the composite. The thermal battery cell, which was fabricated with such a composite cathode and with a Li-Si anode, can output a capacity of 235.8 mAh g −1 and an energy density of 416.9 Wh kg −1 at a cut-off voltage of 1.7 V. This carbon coated CoS 2 composite also presented enhanced air stability. After being stored in dry air for 3 months, the composite can still provide a capacity of 232.4 mAh g −1 to 1.7 V, whereas the capacity of bare CoS 2 stored with the same condition dropped from 202.4 mAh g −1 to 189.7 mAh g −1 .

CoS2/CNTs composites were prepared by a facile and simple hydrothermal growth of CoS2 in the presence of carbon nanotubes (CNTs), as a novel approach of synthesizing cathode composites for thermal battery fabrication. The incorporation of CNTs in the CoS2 cathode materials thus synthesized effectively improved the electrical conductivity and discharge performance of the resultant cathode, without significantly compromising its thermal stability. The thermal battery cell fabricated with such a composite cathode and with a common Li–Si anode showed all functional features of a proper thermal battery cell. The specific discharge capacity at a cut-off voltage of 1.7 V was 219.8 mA h g−1, and the corresponding energy density was 387.2 W h kg−1. With a pulse current density of 500 mA cm−2, the battery delivered a pulse power of 2.45 W, and maintained 64% of this power after 30 pulses. Regarding thermal stability, the CoS2/CNTs cathode was stable at least at 625 °C.

Pure and Ni-doped ZnO nanorod array films were prepared by the hydrothermal method. The effects of Ni doping on the phase composition, microstructure, and optical and electro-chemical properties of ZnO were investigated. The main crystalline phase of the powders before and after Ni doping is wurtzite ZnO. The luminescent peaks are significantly reduced after Ni doping. The light transmission and is the strongest when the doping concentration is 2 %. The light absorption spectrum confirms that the band gap decreased first and then decreased with the increase of Ni2+ doping concentration. According to the M–S (Mott - Schottky) plots, the Ni-doped ZnO is an n-type semiconductor. The current density initially increases with the increased Ni doping amount, and then decreases. First-principles calculation results of nickel-doped zinc oxide show that the energy level of impurities is formed after nickel ions replace zinc ions, which causes the conduction band is shifted down and the band gap is reduced. The impurity energy level causes a slight upward shift in the valence band, which increases the band gap. The calculated results are consistent with the experimental results.