N M Ferreira is a PhD in Physics Engineering; currently is a Researcher at i3N, Physics Department at University of Aveiro, Portugal. He had participated in several R&D projects on Material Science. He have experience as researcher in study and development of ceramics-based materials, prepared through conventional methods by melting, solid stated, with particular focus on laser processing (crystal growth – LFZ and surface sintering/modification). Present sample characterization skills include various techniques such as, electrical conductivity and magnetic properties of various oxide materials. Current focus materials are thermoelectrics, ferroelectrics and glass matrices doped with transition metals and rare earth for energy storage and conversion applications. Main expertise is related to structural, magnetic and electrical properties of materials prepared by laser processing.
Traditionally, ceramic companies are completely re-fired with the ceramic pieces in order to correct small defects with few square millimetres, in sanitary ware pieces. This process represents high energy consumption, increasing the cost production. This work presents an attempt to solve this problem using a CO2 laser technology to repair those defects, preventing the extra costs associated with a re-firing. Until now several approaches had been done using laser technology to solve the problem without success. Despite the method shows promising results, all situation led to the development of a circular crack around the defect, due to the elevated thermal gradients caused by laser radiation. A new approach was done using new materials based on sol-gel technique to fill out the cracks after laser treatment. The idea is the use of sol-gel based material and the re-firing post laser processing at lower temperature and time in order to confer the aesthetic aspect required for the commercialization of the pieces.
Roopathy Mohan has pursued her Master’s Degree in Chemistry from National Institute of Technology Tiruchirappalli, India. Currently, she is a Doctoral student in Fuel cell and Electrochemistry group, Ariel University, Israel under the supervision of Prof. Alex Schechter. Her research work mainly focuses on the study of carbon-based oxygen reduction electrocatalysts treated by cold plasma. She has her expertise in designing plasma assisted carbon supported metal free and metal nitrogen and carbon (MNC) catalysts for electrochemical oxygen reduction reaction.
Oxygen reduction reaction (ORR) is pivotal in renewable energy technologies such as in fuel cells and metal-air batteries. ORR is most fundamental and an important cathodic reaction of the electrochemical fuel cell. However, owing to its sluggish nature at the cathode side of proton exchange membrane fuel cell (PEMFC), there is an urgent demand for a cost-effective efficient catalyst with fast ORR kinetics. Though in practice, Pt-based electrodes and N-doped carbon material shows promising ORR activity, the durability, cost and their preparation methods restricts their wide commercialization. To address this issue, we developed metal and nitrogen-free carbon nanotubes (CNTs) through simple and mild plasma treatment. Oxygen plasma treated CNTs were used as a model for comparative study of oxygen reduction on single (SWCNT) and multi-walled nanotubes (MWCNT). Cold oxygen plasma surface modification leads to chemical doping of oxygen functionalities into the sp2 carbon structure of the CNTs, charge redistribution around the doped heteroatom oxygen that promotes ORR activity. The defect sites generated owing to oxygen dopant in CNTs was confirmed by Raman spectra and X-ray photoelectron spectroscopy (XPS) surface composition. Hence, the results indicate that plasma treated SWCNT are more effective ORR catalyst compared to MWCNT due to the inherent structure of SWCNT that can access more defects and surface functional groups than MWCNT. Interestingly, for the first time we explored the comparison of oxygen functional group doped and defect induced SWCNT and MWCNT for ORR activity. Therefore, the catalytic property is dependent on the dopant (oxygenated) concentration at the wall and is related to the increase in defects as well as ORR current. The intriguing wall structure of SWCNT permits high functionality in oxygenated species and reinforce superior stability in ORR than MWCNT.