Among old materials and different approaches to enhance stability and electrochemical activity of Solid Oxide Cells

Perovskite materials are widely studied as cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFC) for their relevant properties regarding electrocatalytic activity or stability. Nevertheless, a material that combines both it is not yet available. Among them, La1-XSrxMnO3 (LSM), La1-xSrxCo1-yFeyO3 (LSCF), Ba1-xSrxCo1-yFeyO3 (BSCF), La1-xSrxFeO3 (LSF), La1-xBaxCoO3 (LBC), were deeply investigated but their properties are not completely exploited or optimized. In this PhD project all the reported electrode materials are investigated using different approaches. The study starts from LSM \u2013 based electrodes, which show a change in kinetic mechanism under particular operating conditions. These results open new horizons about the employment of this material, up today considered not suitable for IT-SOFC temperature range. A first application, with promising results, is proposed here with a LSM infiltration in LSCF and BSCF scaffold. The presence of infiltrated-phase enhance stability and electrochemical activity of electrodes. Promising results are obtained also by mixing BSCF and LSCF powders. Three different BSCF:LSCF ratio are considered to produce three different cathodes. All the new compositions show an improvement of activity for oxygen reduction reaction, with very competitive values of polarization resistance. Moreover, one of these new electrodes has also a lowering of degradation rate compared with reference materials In the last year of this project, other two materials are combined and their interactions investigate. LSF, providing a high stability, is coupled with LBC, which has a really high surface electrocatalytic activity. The two materials are tested in different thin film systems. When they are mixed before the sintering stage react forming a new perovskite phase (Ba0.099Sr0.297La0.594Fe0.8Co0.2O3), with a higher activity. The reaction is avoided producing a bilayer system, and the presence of LBC top layer over a LSF dense thin film drastically reduces polarization resistance, highlighting promising results

Coupling a Boron Doped Diamond Anode with a Solid Polymer Electrolyte to Avoid the Addition of Supporting Electrolyte in Electrochemical Advanced Oxidation Processes

The application of electrochemical technologies to wastewater treatment is limited by solution conductivity. In this paper, a solid polymer electrolyte Nafion\uae membrane has been used sandwiched between a boron doped diamond (BDD) anode and Ti/RuO2 cathode meshes to treat Bismarck Brown Y (BBY) solutions with very low conductivity. BBY has been chosen as model compound to the system, and the influence of several process parameters has been investigated. During the experiments the evolution of chemical oxygen demand (COD), color removal and nitrogen compounds have been monitored. The performances were strongly related with applied current and stirring rate, changed in a range of 0.5\u20132 A and 200 and 850 rpm, respectively. Their increment leads to a decrease of oxidation time required to remove BBY completely. The effect of the presence of Na2SO4 (2 and 7 mM) as supporting electrolyte has been also evaluated. Results were compared with a removal treatment carried out with a conventional batch system, using a flow cell containing liquid supporting electrolyte (Na2SO4). This comparison highlighted that the new cell setup is performing better in removing organic compounds, and thus, can be considered as effective process for the treatment of solutions with a low conductivity

Ammonia as hydrogen carrier for transport application

As the interest in hydrogen to help the decarbonization of the transport sector is growing fast, the interest in new methods for its storage is a key point to improve its diffusion in many contexts, investigating innovative methods. Ammonia is a promising solution, as its hydrogen content per volume unit is higher than hydrogen stored in liquid form; furthermore, ammonia does not require cryogenic temperature nor high amounts of energy for liquefaction. In this study, two different plant layouts have been investigated, considering as a case study an ammonia-to-hydrogen conversion plant to feed a bus station composed of ten hydrogen buses (106 kg H2/day). In the end, a techno-economic analysis is performed to investigate the Levelized Cost of Hydrogen production from ammonia for the two cases and evaluate the most feasible solution. For both the plant layouts, the following results are obtained: (i) the optimal size of the main components; (ii) the global energy efficiency; (iii) the purity of H2 obtained; (iv) the H2 production cost. Finally, the size effect is investigated to evaluate the economic feasibility of the best plant solution for large-scale hydrogen refuelling stations (2000 kg H2/day), which are a more representative case for future implementations

Groundwater treatment using a solid polymer electrolyte cell with mesh electrodes

This article reports the high performance of a solid polymer electrolyte cell, equipped with a Nafion® N117 membrane packed between a Nb/boron‐doped diamond (Nb/BDD) mesh anode and a Ti/RuO2 mesh cathode, to degrade the insecticide imidacloprid spiked at 1.2-59.2 mg L−1 into low conductivity groundwater by electrochemical oxidation. The natural water matrix was first softened using valorized industrial waste in the form of zeolite as reactive sorbent. Total removal of the insecticide, always obeying pseudo‐first‐order kinetics, and maximum mineralization degrees of 70 %-87 % were achieved, with energy consumption of 26.4±1.6 kWh m−3. Active chlorine in the bulk and .OH at the BDD surface were the main oxidants. Comparative studies using simulated water with analogous anions content revealed that the natural organic matter interfered in the groundwater treatment. Trials carried out in ultrapure water showed the primary conversion of the initial N and Cl atoms of imidacloprid to NO3− and Cl− ions, being the latter anion eventually transformed into ClO3− and ClO4− ions. 6‐Chloro‐nicotinonitrile, 6‐chloro‐pyridine‐3‐carbaldehyde, and tartaric acid were identified as oxidation produc

Hydrogen Carriers: Scientific Limits and Challenges for the Supply Chain, and Key Factors for Techno-Economic Analysis

Hydrogen carriers are one of the keys to the success of using hydrogen as an energy vector. Indeed, sustainable hydrogen production exploits the excess of renewable energy sources, after which temporary storage is required. The conventional approaches to hydrogen storage and transport are compressed hydrogen (CH2) and liquefied hydrogen (LH2), which require severe operating conditions related to pressure (300-700 bar) and temperature (T < -252 ?C), respectively. To overcome these issues, which have hindered market penetration, several alternatives have been proposed in the last few decades. In this review, the most promising hydrogen carriers (ammonia, methanol, liquid organic hydrogen carriers, and metal hydrides) have been considered, and the main stages of their supply chain (production, storage, transportation, H-2 release, and their recyclability) have been described and critically analyzed, focusing on the latest results available in the literature, the highlighting of which is our current concern. The last section reviews recent techno-economic analyses to drive the selection of hydrogen carrier systems and the main constraints that must be considered. The analyzed results show how the selection of H-2 carriers is a multiparametric function, and it depends on technological factors as well as international policies and regulations

Electrochemical technologies for wastewater treatment at pilot plant scale

Process scale-up is a critical, but essential, step in the development of real electrochemical system for oxidation of organic compound. This mini review wants critically analyze the research efforts carried out in the last years about pre-pilot and pilot scale plants, to support the implementation of such technologies in industrial environmental. In the first section are presented the potentiality and the issues related to the anodic oxidation. The second part is dedicated to the electro-Fenton process, while the last is focused on the coupling of the two previous methods. The analysis highlights key factors which are involved in the scaling-up, which are concerning not only the plant size, but involved also their efficiency and economic feasibility

Electrochemical treatment of poorly biodegradable DPC cationic surfactant

The electrochemical oxidation of the cationic surfactant dodecylpyridinium chloride (DPC) was investigated using an electrolytic flow cell operating in batch recycle mode under galvanostatic conditions. The cell was equipped with a boron-doped diamond anode and a stainless steel cathode. The effects of some operating parameters, such as current density, recirculation flow-rate, and DPC concentration were investigated. DPC removal and mineralization were monitored by HPLC analyses and TOC measurements. The results show that DPC can be successfully removed and that degradation is under mass-transport control. The oxidation rate was well described by pseudo-first-order kinetics, and while the apparent rate constant increased with flow-rate, it was unaffected by DPC concentration and current density. Under optimum 5 mA cm-2 and 300 dm3 h-1 conditions, the apparent rate constant was 3.13 7 10-4 s-1. DPC solution with 75 mg dm-3 of surfactant (54 mgdm-3 of initial TOC) was completely mineralized in 330 min, achieving maximum 33% efficiency. Anodic oxidation of the cationic DPC was compared with anionic sodium dodecyl benzene sulfonate (SDBS) degradation and DPC oxidation was demonstrated to be faster and requiring less energy due to the presence of chloride ions in the DPC molecules that are oxidized to active chlorine which acts as redox mediator increasing the removal rate