Hollow doughnut-like ZnO/Au nanocomposites have been synthesized through a fast one-step microwaveassisted hydrothermal route. The formation mechanism of the product is closely connected with the coordination and selective adsorption effect of trisodium citrate (TSC). Other different structures, such as ZnO nanorods/Au nanoparticles, ZnO nanodisks/Au nanoparticles, and ZnO nanospheres/Au nanoparticles have also been obtained in control experiments. The UV−vis and photoluminescence properties of the asprepared hollow structures with different Au concentrations showed tunable UV and visible emission intensity. The hollow ZnO/Au nanocomposites are photostable with a strong resonance Raman signal. The colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays showed that ZnO/Au nanomaterials have low biological cytotoxicity on human colon cancer cells (LOVO cells) at the concentration of 50 μg/mL. The as-prepared ZnO/Au nanocomposites with good biocompatibility may have potential applications in biomedicine and biosensors.

Polypropylene (PP) polymers are used extensively as dielectric layers, packaging films, and separation membranes, etc. Structure, chemistry, and surface features of PP films dominate their performance and durability. Modification of PP films is carried out using atomic layer deposition (ALD) among other techniques to coat uniform layer of nanometer inorganic material on the surface and inside the pores of PP films to serve the purpose of target applications better. Controlling the reaction temperature, precursor pulsing time, and number of cycles during deposition predominate the thickness, morphology, and composition of the coated layer and hence the performance of PP films. Overall, the ALD technique has been proven to be advantageous in advancing PP film properties such as hydrophilicity, UV resistance, membrane separators, dielectric and mechanical strength, etc., primarily through the controllable formation of nanometer coating on PP films. This review discusses the recent advancements and prospective of ALD in the modification and functionalization of PP films for various applications to provide some insights and motivations to design high‐performance novel PP films by well leveraging the ALD technique.

The importance of surface roughness with respect to the bulk properties of dielectric materials is often overlooked. Surface roughness or interfaces between different material layers often significantly affects the external properties of thin films. Surface roughness holds its commonalty and critical impact among many materials properties. This review summarises the recent work on the effect of surface roughness on the mechanical, thermal, physical, and dielectric properties of dielectric films. Appropriate roughness favours adhesion, filtration, biological fouling, tribological properties, and magnetic properties. Nevertheless, lower roughness generally benefits the dielectric properties of dielectric materials, with thicknesses ranging from a few nanometres to up to 50 μm. This review discusses surface roughness control and the techniques of measurement as well. It emphasises the importance and characterisation of sample surface roughness for a better understanding of the dielectric phenomenon, mechanisms, and electrical stress test setup for various dielectric films.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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High voltage electric double layer capacitors with reliable cycling performance are in high demand for energy storage applications. In this research, studies of the process-structureproperty relations of commercial activated carbon electrode modified with atomic layer deposition (ALD) have been performed in terms of coating of various oxide compounds. These investigations have yielded similar enhancements of cycling performance at high voltages (3.5 V) enabled by the ALD coating of oxides on activated carbon surfaces. The commonalities are the phenomenal increase in capacitance retention of coin cell supercapacitors after 1,000 charge/discharge cycles regardless of the electric nature of ALD deposited oxides. Minor differences in coating morphologies and uniformities were observed between the aluminum oxide, titanium oxide, and manganese-cobalt oxide. ALD coating of these oxides of about 20-growth cycle (1-2 nm in thickness) was found to effectively result in reliable cycling performance, lower impedance, and significantly low leakage current. The authors proposed a modified Gouy-Chapman-Stern model to explain the remarkable increase in operating voltage and cycling performance by the increased Stern layer thickness due to the ALD oxide coating. These results demonstrate that the ALD oxide coating has excellent potential for activated carbons for high operating voltage and energy density supercapacitor.

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For twenty years, researchers have investigated nanodielectric composites to advance their dielectric properties toward practical applications in capacitors and electrical insulation. Novel concepts are highly anticipated to enhance dielectric strength...