One−Step Synthesis of Popcorn−Carbon/Co3O4 Composites as High−Performance Supercapacitor Electrodes

In this study, a novel assisted liquid−phase plasma electrolysis was developed to realize one−step synthesis of popcorn biomass−derived porous carbon/cobalt tetroxide (popcorn−carbon/Co3O4) composites, effectively improving the structural stability and conductivity of Co3O4. The phase structure, morphologies, chemical composition, and weight ratio of the as−prepared popcorn−carbon/Co3O4 composites were systematically analyzed. The results of X−ray diffraction (XRD), Raman spectrometer, Fourier infrared spectrometer (FTIR), X−ray photoelectron spectrometer (XPS), and thermogravimetry analyzer (TG) proved the synthesis of the popcorn−carbon/Co3O4 composites. Co3O4 nanoparticles were distributed relatively uniformly on the popcorn−carbon surface. The electrochemical properties of the popcorn−carbon/Co3O4 composite electrode materials were analyzed for exploring the influence of different Co/C ratios on the electrochemical properties of composites. The results showed that the popcorn−carbon/Co3O4 composite electrode materials prepared under 200:1 mass ratio of Co(NO3)2·6H2O and popcorn−carbon possessed a specific capacitance and specific capacity of almost 1264 F/g (594 C/g) at a current density of 1 A/g, exhibiting a better electrochemical property. The efficient, fast, and novel assisted liquid−phase plasma electrolysis provides a new method for the preparation of composite electrode materials on the supercapacitors.

Morphology of metallic foams synthetized by plasma electrolysis deposition

The aim of our work is to understand the mechanism governing the growth of metallic foams synthetized by plasma electrolysis deposition. This paper reports the influence of the applied voltage on the morphology and microstructure of copper and gold foams. The evolution of strands morphology and size is investigated by field emission scanning electronic microscopy (FE-SEM). The role of the voltage in the growth of metallic foams is then discussed. Finally, the crystalline structure of the strands is determined by transmission electronic microscopy (TEM) and selected area electron diffraction.

Cathodic boriding and anodic polishing of medium-carbon steel by plasma electrolysis

The possibility of cathodic plasma electrolytic boriding of medium-carbon steel in an aqueous solution of ammonium chloride and boric acid followed by anodic plasma electrolytic polishing in an ammonium sulfate solution on the same equipment with a change in the operating voltage is shown. The morphology and roughness of the surface, microhardness of the modified layer have been investigated. Wear resistance was studied under dry friction conditions. It has been established that cathodic boriding at 850 °C for 5–30 min leads to the hardening of the surface layer up to 1050 HV with an increase in roughness by 1.5–2.5 times and wear resistance by 3.5 times. Subsequent anodic plasma electrolytic polishing of the boriding surface leads to a decrease in roughness with an increase in wear resistance by 2.3 times.

Cathodic nitriding and anodic polishing of Ti6Al4V alloy by plasma electrolysis

The paper presents the results of studies on modifying the surface of Ti6Al4V titanium alloy by combined exposure to cathodic nitriding and anodic polishing in electrolysis plasma. The morphology and roughness of the surface, microhardness of the modified layer have been investigated. Wear resistance was studied under dry friction conditions. The effect of combined treatment on corrosion resistance of Ti6Al4V alloy was examined by means of potentiodynamic polarization in Ringer’s solution. It has been established that cathodic nitriding at 750 °C for 10 min leads to the hardening of the surface layer up to 820 HV with an increase in roughness by 2 times and wear resistance almost 3 times. Subsequent anodic plasma electrolytic polishing of the nitriding surface in solution of ammonium sulfate leads to a decrease in roughness and friction coefficient with an increase in corrosion resistance.

Plasma generation using dielectric barrier discharge reactor for phenol degradation in batik wastewater

Batik wastewater contains phenolic compounds. Phenolic compounds are hematotoxic, hepatotoxic, and capable of causing mutagenesis and carcinogenesis in humans and other living organisms. Therefore, phenol compounds need to be degraded. This study uses plasma electrolysis method with Dielectric Barrier Discharge (DBD) reactor to degrade phenolic compounds in Batik wastewater. The purpose of this study was to characterize the Dielectric Barrier Discharge (DBD) reactor, to determine the effect of voltage and type of catalyst on phenol concentration, and to determine the interaction between voltage and catalyst type on the response of phenol concentration through analysis of variance (ANOVA). The result obtained from the characterization of the reactor is ignition voltage at 1400 Volt. The best degradation results of phenolic compounds were obtained in the treatment of Batik wastewater with FeSO4 catalyst at 2600 Volt. The phenol reduction in the best conditions reached 88.73%. Based on analysis of variance (ANOVA), voltage and quadratic catalyst variables affect the response of phenol concentrations in batik waste.