Low-temperature low-power PECVD synthesis of vertically aligned graphene.

The need for 2D vertical graphene nanosheets (VGNs) is driven by its great potential in diverse energy, electronics, and sensor applications, wherein many cases a low-temperature synthesis is preferred due to requirements of the manufacturing process. Unfortunately, most of today's known methods, including plasma, require either relatively high temperatures or high plasma powers. Herein, we report on a controllable synthesis of VGNs at a pushed down low-temperature boundary for synthesis, the low temperatures (450 °C) and low plasma powers (30 W) using capacitively coupled plasma (CCP) driven by radio-frequency power at 13.56 MHz. The strategies implemented also include unrevealing the role of Nickel (Ni) catalyst thin film on the substrates (Si/Al). It was found that the Ni catalyst on Si/Al initiates the nucleation/growth of VGNs at 450 °C in comparison to the substrates without Ni catalyst. With increasing temperature, the graphene nanosheets become bigger in size, well-structured and well separated. The role of Ni catalysts is hence to boost the growth rate, density, and quality of the growing VGNs. Furthermore, this CCP method can be used to synthesize VGNs at the lowest temperatures possible so far on a variety of substrates and provide new opportunities in the practical application of VGNs.

Superomniphobic and Photoactive Surface Presents Antimicrobial Properties by Repelling and Killing Pathogens.

Healthcare-acquired infections place a significant burden on the cost and quality of patient care in hospitals. Reducing contamination on surfaces within healthcare environments is critical for halting the spread of these infections. Herein, we report a bifunctional─repel and kill─surface developed using photoactive TiO2 nanoparticles integrated into a hierarchical scaffold (OmniKill). To quantify the repellency of OmniKill, we developed a touch-based assay, capable of simulating the transfer of individual pathogens, multiple pathogens, or pathogen-latent fecal matter from hands to surfaces. OmniKill repels bacterial pathogens by at least 2.77-log (99.8%). The photoactive material within OmniKill further reduces the viability of transferred pathogens on the surface by an additional 2.43-log (99.6%) after 1 h of light exposure. The antipathogenic effects─repel and kill─remain robust under complex biological contaminates such as feces. These findings show the potential use of OmniKill in reducing the physical transmission of bacterial pathogens in healthcare settings.

Formation and behavior of negative ions in low pressure aniline-containing RF plasmas.

This paper is focused on the formation mechanisms and the general behavior of negative ions in low pressure radio-frequency (RF) plasmas operated in a mixture of argon and aniline vapor. This type of plasma is mostly used for the synthesis of polyaniline, one of the most studied conductive polymers. Experiments based on mass spectroscopy measurements reveal the necessity to have a thin layer of plasma synthesized polyaniline on the electrodes to produce negative ions through complex surface reactions. In addition, thin-films deposited using this type of discharge are analyzed by means of Near Edge X-ray Absorption Fine Structure spectroscopy (NEXAFS). The material analysis gives a first indication about the possible contribution of negative ions to polyaniline deposition.