Strategies for the enhancement of the catalytic performance of cutinase in nonaqueous media

Dissertação para obtenção do Grau de Doutor em Engenharia Química e Bioquímic

Proton Exchange Membrane Fuel Cells (PEMFCs): Advances and Challenges

The study of the electrochemical catalyst conversion of renewable electricity and carbon oxides into chemical fuels attracts a great deal of attention by different researchers. The main role of this process is in mitigating the worldwide energy crisis through a closed technological carbon cycle, where chemical fuels, such as hydrogen, are stored and reconverted to electricity via electrochemical reaction processes in fuel cells. The scientific community focuses its efforts on the development of high-performance polymeric membranes together with nanomaterials with high catalytic activity and stability in order to reduce the platinum group metal applied as a cathode to build stacks of proton exchange membrane fuel cells (PEMFCs) to work at low and moderate temperatures. The design of new conductive membranes and nanoparticles (NPs) whose morphology directly affects their catalytic properties is of utmost importance. Nanoparticle morphologies, like cubes, octahedrons, icosahedrons, bipyramids, plates, and polyhedrons, among others, are widely studied for catalysis applications. The recent progress around the high catalytic activity has focused on the stabilizing agents and their potential impact on nanomaterial synthesis to induce changes in the morphology of NPs

Newly designed single-ion conducting polymer electrolytes enabling advanced Li-metal solid-state batteries

L'abstract è presente nell'allegato / the abstract is in the attachmen

The influence of ion-ion correlations on conductivity in concentrated ionic systems

This study delves into the fascinating realm of concentrated ionic systems, such as ionic liquids, superionic materials, organic ionic plastic crystals, and polyelectrolytes, which hold immense potential for energy storage applications. The focus is on understanding the intricate role of ionic correlations in shaping their ionic conductivity behavior. These correlations can either boost or impede conductivity, yet their underlying mechanisms remain elusive. Through extensive investigation of various materials, including ionic liquids with differing anionic masses, pure organic ionic plastic crystals, and doped systems, this research employs advanced techniques like dielectric spectroscopy and innovative momentum conservation models to quantify these correlations. Additionally, the study explores the impact of Li+ doping on the conductivity of organic ionic plastic crystals, providing valuable insights into ways to enhance their conductivity. Ultimately, this research not only contributes to the development of high-conductivity electrolytes for innovative technologies like solid-state batteries but also advances our fundamental understanding of ion transport in concentrated ionic systems

Theories and models of supercapacitors with recent advancements: Impact and interpretations

none8siSupercapacitors provide remarkable eco-friendly advancement in energy conversion and storage with a huge potential to control the future economy of the entire world. Currently, industries focus on the design and engineering aspects of supercapacitors with high performance (high energy), flexibility (by the use of composite polymer based electrolytes), high voltage (ionic liquid) and low cost. The paper reviews the modelling techniques like Empirical modelling, Dissipation transmission line models, Continuum models, Atomistic models, Quantum models, Simplified analytical models etc. proposed for the theoretical study of Supercapacitors and discusses their limitations in studying all the aspects of Supercapacitors. It also reviews the various software packages available for Supercapacitor(SC) modelling and discusses their advantages and disadvantages. The paper also reviews the Experimental advancements in the field of electric double layer capacitors(EDLCs), pseudo capacitors and hybrid/ asymmetric supercapacitors and discusses the commercial progress of supercapacitors as well.openBharti Baniwal; Ashwani Kumar; Gulzar Ahmad; Meenal Gupta; Patrizia Bocchetta; Ravikant Adalati; Ramesh Chandra; Yogesh KumarBaniwal, Bharti; Kumar, Ashwani; Ahmad, Gulzar; Gupta, Meenal; Bocchetta, Patrizia; Adalati, Ravikant; Chandra, Ramesh; Kumar, Yoges

Computational studies of ion transport in polymer electrolytes

Improving ionic conductivity and lithium mobility in polymer electrolytes is important for their practical use for battery electrolytes. In this study, a combination of molecular dynamics and Monte Carlo simulations was used to bring insight into lithium ion transport in poly(ethylene oxide) (PEO) with plasticizers and also next to alumina solid surface doped with lithium salt. The simulations were performed using a moderately high molecular weight polymer (Mn = 10,000 g/mol) at an EO:Li ratio of 15. For the plasticized system, the PEO with LiN(CF3SO 2)2 (LiTFSI) was mixed with 10 wt% plasticizers that included either cyclic ethylene carbonate (EC) or propylene carbonate (PC). Comparisons with an array of experiments showed a slight underestimation of the compared ionic conductivity, but within a factor of two, at most. With the addition of EC and PC plasticizers, the ionic conductivity increased a moderate degree with most of the increase due to faster TFSI anion motion, but not lithium cation. It was found that propylene carbonate formed complexes with the TFSI anion, in which lithium was an intermediary, creating moderate sized clusters. This formation allowed enhanced diffusion of lithium ions bound with TFSI ions, but this formation was offset by slower diffusion for lithium ions bound with ethylene oxide oxygens. Ethylene carbonate, on the other hand, showed no significant complexing with TFSI anion. The formation of this cluster, therefore, may be an avenue for increasing lithium diffusion but would likely require a plasticizer with stronger interactions with lithium than the carbonates studied. We also examined the influence of both acidic and basic alumina surfaces on the structure and lithium mobility in PEO with LiClO4 salts. The results showed the surface interacted with lithium salt anion in the acidic case via hydrogen bonding, which essentially freezes the lithium salt anion movement at the surface, yet a modest enhancement in lithium ion mobility was observed at low temperature

Computational modelling of the effect of side chain chemistry on the micro-structure and electrolyte interactions of mixed transport polymers

As we scale up our use of energy storage facilities to meet the demands of the future, the prob- lems associated with current energy storage technologies will grow to unacceptable levels. In this work I explore how we can develop high performing polymers for use as cathode materials in energy storage devices operating with aqueous electrolytes. Energy storage devices using these materials have the potential for low cost production and safe operation. Through a combination of atomistic simulation methods, this thesis relates aspects of the polymer chemistry to their microstructural properties, and subsequently to their ability to operate successfully as electrodes.Open Acces

Roadmap on semiconductor-cell biointerfaces.

This roadmap outlines the role semiconductor-based materials play in understanding the complex biophysical dynamics at multiple length scales, as well as the design and implementation of next-generation electronic, optoelectronic, and mechanical devices for biointerfaces. The roadmap emphasizes the advantages of semiconductor building blocks in interfacing, monitoring, and manipulating the activity of biological components, and discusses the possibility of using active semiconductor-cell interfaces for discovering new signaling processes in the biological world