Vol 4 No 2 (2022)

• The Activated Carbon with Pyrolle-N from Cotton Stalk for the Electrochemical Performance

  Tiezhen Ren; Meng-Jie Cui; Yan-Mei Zhao, Wen-Long Mo, Zheng Wang

  Porous carbon materials have been applied in many fields for their advanced physical features. Using biomass waste material as the activated carbon (AC) source is of importance to keep the sustainable environment. The CO₂ activation and KOH activation were adopted to create AC with the flexible porous structure and the former caused low surface area but with high nitrogen content of AC. The reversed results were formed with the KOH activation. The differences on specific surface area and nitrogen groups distribution were investigated by nitrogen sorption isotherm and X-ray photoluminescence spectroscopy. Their porous structure and framework were characterized with transmission electron microscope and Raman spectra. Electrochemical performance was evaluated by supercapacitance and oxygen evolution reaction (OER). Comparing to the CO₂ activation, KOH activation improved surface area of AC and more functional groups on the carbon surface, which led to the enhancement of the electroactivity.

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• Oxidative Dehydrogenation of Propane over Nanostructured Mesoporous VOx/CexZr1-xO2 Catalysts

  Bao Agula, Minglei Sun, Shihang Liang, Yongsheng Bao, Meilin Jia, Feng Xu, Zhong-Yong Yuan

  High-surface-area mesoporous Ce_xZr_1-xO₂ materials synthesized through a surfactant-assisted approach of nanocrystalline particle assembly are utilized as a promising support for VO_x-based catalysts. The catalytic properties of the resultant VO_x/Ce_xZr_1-xO₂ nanocatalysts are evaluated by the oxidative dehydrogenation of propane using a microreactor-GC system. It is indicated that the catalyst particles are on a nanoscale, having a mesoporous structure with uniform pore-size distribution and high surface area. The catalytic behavior of these mesoporous nanostructured VO_x/Ce_xZr_1-xO₂ catalysts for the oxidative dehydrogenation of propane reaction relies on the vanadia loading amount, the calcination temperature, the surface area and the Ce/Zr ratio of the supports, the particle size of active compounds, and the additional contribution to the propylene formation derives from the contribution of the catalytic dehydrogenation of propane under oxygen-lean conditions. The catalyst prepared with 8 wt% vanadia loading on Ce_0.2Zr_0.8O₂ exhibits high and stable catalytic performance in the oxidative dehydrogenation of propane reaction. 

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• Build Redox Composite Electrode Materials Based on Polymerized Redox Ionic Liquids

  Yachao Zhu, Jie Deng, Olivier Fontaine

  Electrochemists are racing to develop new organic and inorganic materials for batteries and supercapacitors. As Organic Radical Battery technology approaches, a wide variety of materials are being proposed. However, devising materials with both ionic conductivity and redox storage properties is a strategy to be explored. In this paper, we show a new composite based on mixing carbon nanotubes and redox ionic liquids. The present work's originality is that this composite is realized for the first time and allows a couple of different types of conduction/storage: electronic conduction via carbon nanotubes, ionic conduction via ionic liquids, and redox transport via redox molecules. Flexible composite materials comprised carbon nanotubes and poly(imidazolium) with allyl and redox pendant groups were fabricated and examined. They demonstrated ionic and electrical conductivity and the faradaic response of the redox-polymerized ionic liquid.

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• Self-discharge of Batteries: Causes, Mechanisms and Remedies

  Rudolf Holze

  Self-discharge of batteries is a natural, but nevertheless quite unwelcome phenomenon. Because it is driven in its various forms by the same thermodynamic forces as the discharge during intended operation of the device it can only be slowed down by impeding the reaction kinetics of its various steps, i.e. their respective rates of reaction. This approach should be based on a deeper understanding of the various modes and mechanisms of self-discharge, which in turn depends on the battery chemistry, its mode of operation and environmental conditions. Typical examples from representative battery chemistries are presented and observed effects are reviewed. Similarities between battery chemistries and causes of self-discharge are identified; concepts and ideas obtained this way are outlined. As an outcome of a better understanding of both common and system-independent causes and mechanisms of self-discharge as well as chemistry-specific processes approaches to reduce self-discharge are presented. Achieved progress is highlighted.

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• Recent Advances in Photo-supercapacitor: A Mini Review

  Muraina Abeeb Olalekan, Oluwaseun Adedokun, Ismaila Taiwo Bello , Maroof Ayinde Kareem, Fong Kwong Yam

  Radiant energy (solar energy) plays a vital role due to its continuous power supply and environmentally friendly in meeting the people’s energy demand. The need for an endless supply of energy, majorly through solar energy exploitation has driven the expansion and diversification of a device for proper energy storage. This review summarizes a photo-supercapacitor’s working mechanism. The classification of a supercapacitor was discussed and the advancements of the active components that makeup a photo-supercapacitor and the improvements on photo-supercapacitor in energy storage were highlighted. For the constant generation of electricity, Dye-sensitized solar cells (DSSCs) and Supercapacitor are incorporated. The invention of hybridized dye-sensitized solar cell (DSSC)-capacitors and DSSC-supercapacitors are crucial in energy storage processes, and the advancement in technology has triggered the creation of a photo-supercapacitor for efficient harvesting of energy and proper storage mechanisms. The intent of pairing a DSSC with a supercapacitor for conversion of energy and proper energy storage arose when dye molecules absorb radiant energy and the absorbed energy is transformed to electrical energy. The use of active components of a photo-supercapacitor will determine its conversion efficiency. The performance of active components of photo-supercapacitors such as dye, electrolyte, photoanode, and the counter electrode are the main factors that contribute to efficient conversion of energy to improve the photo-supercapacitor’s storage life.

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• Carbon Supported Catalysts in Fischer-Tropsch Synthesis: Structural Properties of Carbon Supports

  Thaane Hlabathe, Joshua Gorimbo, Mahluli Moyo, Xinying Liu

  The structural properties of some carbon-based supports can prevent the formation of hot spots and improve catalyst stability at Fischer Tropsch Synthesis (FTS) temperature. Special attention and some examples are given to iron-based catalysts and their performance in FTS. The carbon supports’ structural properties such as metal-support interaction, effect of particle size, the confinement effect, graphitization degree of graphene, and interrelationship of catalyst properties, are linked to their function in FTS for supported catalysts. The modification effects of the catalysts with functional groups, promoters and heat treatment are related to FTS performance. The potential research areas and challenges posed by carbon support structural properties’ relationship to FTS performance are identified.

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