Synopsis of thesis entitled “Electrochemical and Photoelectrochemical Investigations of Co, Mn and Ir-based Catalysts for Water Splitting” by Ahamed Irshad M (SR No: 02-01-02-10-11-11-1-08823) under the supervision of Prof. N. Munichandraiah, Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore (India), for the Ph.D. degree of the Institute under the Faculty of Science. Hydrogen is considered as the fuel for future owing to its high gravimetric energy density and eco-friendly use. In addition, H2 is an important feedstock in Haber process for ammonia synthesis and petroleum refining. Although, it is the most abundant element in the universe, elemental hydrogen is not available in large quantities on the planet. Consequently, H2 must be produced from its various chemical compounds available on earth. Currently, H2 is produced in large scale from methane by a process called steam-methane reforming (SMR). This process releases huge amount of CO2 into atmosphere as the by-product causing serious environmental issues. The development of alternate clean methods to generate H2 is a key challenge for the realization of hydrogen economy. Production of H2 gas by water splitting using electricity or sunlight is known. Low cost, high natural abundance and carbon neutrality make water as the best source of hydrogen. Thermodynamically, splitting of H2O needs 237 kJ mol-1 of energy, which corresponds to 1.23 V according to the equation, ΔG = -nFE. However, commercial electrolyzers usually operate between 1.8 to 2.1 V, due to the need of large overvoltage. The high overvoltage and subsequent energy losses are mainly associated with the sluggish kinetics of oxygen evolution reaction (OER) at the anode and hydrogen evolution reaction (HER) at the cathode. The overvoltage can be considerably reduced using suitable catalysts. Hence, the design and development of stable, robust and highly active catalysts for OER and HER are essential to make water splitting efficient and economical. Attempts in the direction of preparing several novel OER and HER catalysts, physicochemical characterizations and their electrochemical or photoelectrochemical activity are described in the thesis. A comprehensive review of the literature on various types of catalysts, thermodynamics, kinetics and mechanisms of catalysis are provided in the Chapter 1 of the thesis. Chapter 2 furnishes a brief description on various experimental techniques and procedures adopted at different stages of the present studies. Chapter 3 explains the results of the studies on kinetics of deposition and stability of Nocera’s Co-phosphate (Co-Pi) catalyst using electrochemical quartz crystal microbalance (EQCM). The in-situ mass measurements during CV experiments on Au electrode confirm the deposition of Co-Pi at potential above 0.87 V vs. Ag/AgCl, 3 M KCl (Fig.1a and b). The catalyst is found to deposit via a nucleus mediated process at a rate of 1.8 ng s-1 from 0.5 mM Co2+ in 0.1 M neural phosphate solution at 1.0 V. Further studies on the potential and electrolyte dependent stability of the Co-Pi suggest that the catalyst undergoes severe corrosion at high overpotential and in non-buffer electrolytes. Current/ Fig.1 (a) Cyclic voltammograms and (b) mass variations vs. potential of Au-coated quartz crystal in 0.1 M potassium phosphate buffer solution (pH 7.0) containing 0.5 mM Co(NO3)2 Chapter 4 deals with the electrochemical deposition of a novel OER catalyst, namely, Co-acetate (Co-Ac) from a neutral acetate electrolyte containing Co2+ ions. Use of acetate solution instead of phosphate avoids the solubility limitations and helps to get thick layer of the catalyst in a short time from concentrated Co2+ solutions. In addition, the Co-Ac is found to be catalytically superior to Co-Pi (Fig. 2a). It is also observed that the Co-Ac catalyst undergoes ion exchange with electrolyte species during electrolysis in phosphate buffer solution, which results in the formation of a hybrid Co-Ac-Pi catalyst (Fig. 2b). The presence of both acetate and phosphate ions in the catalyst and their synergistic catalytic effect enhance the OER activity. Fig.2. (a) Linear sweep voltammograms of Co-Ac in (i) phosphate and (ii) acetate electrolytes, and that of Co-Pi in (iii) acetate and (iv) phosphate electrolytes. (b) SEM image showing the formation of two layers of the catalysts after electrolysis in phosphate solution. In Chapter 5, high OER activity of an electrodeposited amorphous Ir-phosphate (Ir-Pi) is investigated. The catalyst is prepared by the anodic polarization of a carbon paper electrode in neutral phosphate solution containing Ir3+ ions (Fig. 3). The Ir-Pi film deposited on the electrode has Ir and P in an approximate ratio of 1:2 with Ir in an oxidation state higher than +4. Phosphate ions play a major role for both the electrochemical deposition process and its catalytic activity towards OER. The Ir-Pi catalyst is superior to similarly deposited IrO2 and Co-Pi catalysts both in terms of onset potential and current density at any potential in the OER region. Tafel measurements and pH dependence studies identify the formation of a high energy intermediate during oxygen evolution. Fig.3. (a) Cyclic voltammograms during the Ir-Pi deposition and (b) SEM image of Ir-Pi on C. Chapter 6 is on the preparation of a composite of Mn-phosphate (MnOx-Pi) and reduced graphene oxide (rGO) and its utilization as an OER catalyst. The composite is prepared by the simultaneous electrochemical reduction of KMnO4 and graphene oxide (GO) in a phosphate solution (pH 7.0). Various analytical techniques such as TEM, XPS, Raman spectroscopy, etc. confirm the formation of a composite (Fig. 4) and electrochemical studies indicate the favourable role of rGO towards OER. Under identical conditions, MnOx-Pi-rGO gives 6.2 mA cm-2 at 2.05 V vs. RHE whereas it is only 2.9 mA cm-2 for MnOx-Pi alone. However, the catalyst is not very stable during OER which is ascribed to slow oxidation of Mn3+ in the catalyst. Fig.4. (a) Raman spectrum and (b) TEM image of MnOx-Pi-rGO. In Chapter 7, an amorphous Ni-Co-S film is prepared by a potentiodynamic deposition method using thiourea as the sulphur source. The electrodeposit is used as a catalyst for the HER in neutral phosphate solution. The composition of the catalyst and the HER activity are tuned by varying the ratio of concentrations of Ni2+ and Co2+. The bimetallic Ni-Co-S catalyst exhibits better HER activity than both Ni-S and Co-S (Fig. 5a). Under optimized deposition conditions, Ni-Co-S requires just 150 mV for the onset of HER and 10 mA cm-2 is obtained for 280 mV overpotential. The Ni-Co-S shows two different Tafel slopes, indicating two different potential dependent HER mechanisms (Fig. 5b). Presence of two different catalytic sites which contribute selectively in different potential regions is proposed. Fig.5. (a) Linear sweep voltammograms of HER at 1 mV s-1 in 1 M phosphate solutions (pH 7.4) using (i) Ni-S, (ii) Co-S and (c) Ni-Co-S. (b) Tafel plot of Ni-Co-S showing two Tafel slopes. Photoelectrochemical OER using ZnO photoanode and Co-acetate (Co-Ac) cocatalyst is studied in Chapter 8 of the thesis. Randomly oriented crystalline ZnO nanorods are prepared by the electrochemical deposition of Zn(OH)2 followed by heat treatment at 350 ºC in air. Co-Ac is then photochemically deposited onto ZnO nanorods by UV illumination in the presence of neutral acetate buffer solution containing Co2+ ions. The hybrid Co-Ac-ZnO shows higher photoactivity in comparison with bare ZnO towards PEC water oxidation (Fig. 6). Co-Ac acts as a cocatalyst and reduces the charge carrier recombination at the electrode/electrolyte interface. Fig.6. (a) Linear sweep voltammograms of ZnO under (i) dark and (ii) light conditions, and that of Co-Ac-ZnO in (iii) dark and (iv) light in 0.1 M phosphate (pH 7.0) electrolyte. Chapter 9 deals with PEC water oxidation using α-Fe2O3 photoanode and Ir-phosphate (Ir-Pi) cocatalyst. α-Fe2O3 is prepared by direct heating of Fe film in air which in turn is deposited by the electrochemical reduction of Fe2+. Thickness of the film as well as calcination temperature is carefully optimized. In order to further enhance the OER kinetics, Ir-Pi is electrochemically deposited onto α-Fe2O3. Under optimized conditions, Ir-Pi deposited α-Fe2O3 shows around 3 times higher photocurrent than that of bare α-Fe2O3 at 1.23 V vs. RHE (Fig. 7). Ir-Pi acts as a cocatalyst for OER and reduces the photogenerated charge carrier recombination. Fig.7. Photocurrent variation of α-Fe2O3 electrode at 1.23 V vs. RHE for (i) front and (ii) back side illuminations, against Ir-Pi deposition time. The thesis ends with a short summary and future prospectus of studies described in the thesis. The research work presented in the thesis is carried out by the candidate as the part of Ph.D. program. Some of the results have already been published in the literature and some manuscripts are under preparation. A list of publications is included at the end of the thesis. It is anticipated that the studies reported in the thesis will constitute a worthwhile contribution.

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This work concentrates on the study of mathematical models of human behaviour in dynamic games; in particular games with aspects of cooperation, implementation of a model and experimentation with the model. The game DarkElf was chosen for this project. It is a strategic, turn based game with economic and military features, where the decisions made by players are simultaneously implemented at a predetermined time.

In recent decades, it was shown that belowground competition for some plants may take form of the tragedy of the commons (TOC). In these plants, the competing neighbours invest more in root systems than would be appropriate for optimal nutrient uptake for the group and also more than they do when grown alone. However, there is also strong evidence that other species do not follow TOC, and tailor their root system to best nutrient exploitation irrespectively of competitor presence. The root investment strategy of these plants should correspond to the ideal free distribution (IFD). In my thesis I focus on two aspects:  I use game theoretical models to explore, whether those strategies can coexist within species and also whether different species can coexist if they have different strategy. From this model I draw predictions, which I test by meta-analysis.  Using Agrostis stolonifera as a model, I test assumptions on nutrient and neighbour perception, which underlie TOC and IFD models. I show that according to mathematical models, those two strategies can coexist in different species in a community, but cannot coexist within a species. Within a species, the TOC strategy should always dominate, once it appears. This can be extrapolated to macroevolutionary scale - once TOC occurs in certain clade, it should...

The topic of this diploma thesis is devoted to the issue of a children enrolment to the first form of a basic school as an important milestone in their life. The theoretical part deals with the topic of the enrolment in its full scale. The author presents an overview concerning the issue of school maturity, school preparedness and their diagnostics. Further she deals with the topic of a postponement of school attendance and legislation. The main chapter of the theoretical part is the topic of competencies which a teacher of primary education should have at disposal during enrolments. In the practical part of this diploma thesis the author gives space to teachers, who, by means of a questionnaire and an unstructured interview, reflect their opinions and feelings concerning their role during enrolments. The author deals with their pedagogical competency. The teachers have an opportunity to present their opinions about the current form of the enrolment procedure. The outcome of this thesis is a discussion about usefulness of the current enrolment procedure and concrete suggestions for a change.

The South African Revenue Service has in the past had difficulty in applying debt forgiveness in cases of corporate and business rescues. Taxation legislation was drafted to counter innovative section 311 schemes of arrangements where the sole purpose was to obtain maximum taxations benefits in relation to entities in financial difficulties. This approach was only concerned with the interests of the Revenue authorities. The central theme of this study focuses of the procedures now available to tax authorities and debtors alike when compromises were and are considered in South Africa in terms of income tax and company legislation. The South Africa Revenue Service’s approach the corporate rehabilitation is examined which is vital for investors, creditors and debtors alike. A comparative study with similar procedures in England is undertaken to establish how valid the procedures are in establishing a viable corporate rescue environment in South Africa in the future. / Dissertation (LLM)--University of Pretoria, 2012. / Procedural Law / unrestricted

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The work deals with the relationship between game mechanics and user experience. Identifies the basic gameplay mechanics and elements that have the most important influence on the quality of user experience. Research is realized on the example of a specific game using the concept of game design patterns. Part of the work deals with the introduction of this concept. Furthermore, the work deals with the general theories of games, models of classification and history of computer games. Part of the work is a description of the author's practical experience in creating games as a school project.

This thesis talks about different ways of dealing with people who find themselves in unfavourable social situations. It shows, based on casuistic cases and examples, the importance of a loving approach to the client. It describes particular ways of work with people who seem to be optimal from theoretical and practical point of view. It examines a conversation with a client in more detail. It tries to find an internal source of positive adjustment of the helping worker towards people. This adjustment is found not in set rules and instrumental method, but in a Christian approach to the person. A person, as an image of God is my fellowman and I am responsible for him/her. The source of a loving and optimistic approach to people comes from Christian culture, solidarity and respect for people, which is included in the Gospels. Christian approach to people is very much needed and should be part of social work within the middle of Europe.

Tesis por compendio / [ES] El efecto invernadero, causado por el consumo masivo de combustibles fósiles en los últimos 100 años, ha exacerbado la tendencia del calentamiento global y también ha tenido un impacto severo en la salud humana y el medio ambiente ecológico. Las tecnologías de generación de energía renovable son cruciales para abordar el cambio climático y lograr la sostenibilidad energética, pero estas tecnologías también enfrentan algunos problemas y desafíos comunes, como la intermitencia y la imprevisibilidad, la integración y estabilidad de la red, problemas de almacenamiento de energía, etc. Por lo tanto, investigar dispositivos eficientes de almacenamiento de energía electroquímica y desarrollar tecnologías avanzadas de conversión de energía eléctrica renovable en energía química se vuelve particularmente crucial. El supercondensador es un nuevo tipo de dispositivo de almacenamiento de energía electroquímica que permite el rápido ciclo de descarga y carga. Su mayor densidad de potencia, capacidades de carga y descarga rápidas, amplio rango de temperatura de operación y seguridad permiten aplicaciones generalizadas en fuentes de alimentación de respaldo industriales, vehículos eléctricos, el sector militar y otros campos. Por lo tanto, en la tesis doctoral actual, se han utilizado materiales de óxido de metal y fosfuro de metal como electrodos de supercondensador para el estudio de los mecanismos de almacenamiento de energía y explorar el potencial para aplicaciones prácticas. Por otro lado, convertir la energía eléctrica sostenible en energía química para almacenamiento y utilización también es una forma efectiva, en la que la energía eléctrica se utiliza para impulsar reacciones químicas no espontáneas. La tesis doctoral actual desarrolló un catalizador de fosfuro de metal utilizando un método de síntesis verde y libre de contaminación y lo aplicó a reacciones electrocatalíticas de división de agua. Los resultados experimentales muestran que el material puede operar de manera estable durante mucho tiempo a alta densidad de corriente. Además, la conversión electrocatalítica de nitrato a amoníaco se considera una ruta eficiente para el tratamiento de aguas residuales de nitrato y la producción de combustible de amoníaco rico en hidrógeno. Preparamos con éxito un catalizador de carburo bimetálico utilizando un método sonoquímico, que muestra excelentes propiedades de reducción de nitrato de baja sobretensión y alta eficiencia de rendimiento de amoníaco. / [CA] L'efecte hivernacle, causat pel consum massiu de combustibles fòssils en els últims 100 anys, ha exacerbà la tendència del escalfament global i també ha tingut un impacte sever en la salut humana i el medi ambient ecològic. Les tecnologies de generació d'energia renovable són crucials per a abordar el canvi climàtic i aconseguir la sostenibilitat energètica, però aquestes tecnologies també enfronten alguns problemes i desafiaments comuns, com la intermitència i la imprevisibilitat, la integració i estabilitat de la xarxa, problemes d'emmagatzematge d'energia, etc. Per tant, investigar dispositius eficients d'emmagatzematge d'energia electroquímica i desenvolupar tecnologies avançades de conversió d'energia elèctrica renovable en energia química es torna particularment crucial. El supercondensador és un nou tipus de dispositiu d'emmagatzematge d'energia electroquímica que permet el ràpid cicle de descàrrega i càrrega. La seua major densitat de potència, capacitats de càrrega i descàrrega ràpides, ampli rang de temperatura d'operació i seguretat permeten aplicacions generalitzades en fonts d'alimentació de reserva industrials, vehicles elèctrics, el sector militar i altres camps. Per tant, en la tesi doctoral actual, s'han utilitzat materials d'òxid de metall i fosfurs de metall com a electrodos de supercondensador per a l'estudi dels mecanismes d'emmagatzematge d'energia i explorar el potencial per a aplicacions pràctiques. D'altra banda, convertir l'energia elèctrica sostenible en energia química per a emmagatzematge i utilització també és una forma efectiva, en la qual l'energia elèctrica s'utilitza per a impulsar reaccions químiques no espontànies. La tesi doctoral actual va desenvolupar un catalitzador de fosfurs de metall utilitzant un mètode de síntesi verd i lliure de contaminació i l'aplicà a reaccions electrocatalítiques de divisió d'aigua. Els resultats experimentals mostren que el material pot operar de manera estable durant molt temps a alta densitat de corrent. A més, la conversió electrocatalítica de nitrats a amoníac es considera una ruta eficient per al tractament d'aigües residuals de nitrats i la producció de combustible d'amoníac ric en hidrogen. Vam preparar amb èxit un catalitzador de carburs bimetàlics utilitzant un mètode sonoquímic, que mostra excel·lents propietats de reducció de nitrats de baixa sobretensió i alta eficiència de rendiment d'amoníac. / [EN] The greenhouse effect, caused by the massive consumption of fossil fuels over the past 100 years, has exacerbated the trend of global climate warming and has also severe impact on human health and the ecological environment. Renewable energy power generation technologies are crucial for addressing climate change and achieving energy sustainability, but these technologies also face some common problems and challenges, such as intermittency and unpredictability, grid integration and stability, energy storage issues, etc. Therefore, researching efficient electrochemical energy storage devices and developing advanced energy technologies converting renewable electrical energy into chemical energy becomes particularly crucial. Supercapacitor is a novel type of electrochemical energy storage device that enables the rapid cycle of discharge and charge. Its greater power density, rapid charge-discharge capabilities, wider operating temperature range and safety allow widespread applications in industrial backup power supplies, electric vehicles, the military sector, and other fields. Therefore, in the current doctoral thesis, metal oxides and metal phosphide materials have been employed as supercapacitor electrodes for the study of energy storage mechanisms and explore the potential for practical applications. On the other hand, converting sustainable electrical energy into chemical energy for storage and utilization is also an effective way, in which electrical energy is employed to drive non-spontaneous chemical reactions. The current doctoral thesis developed a metal phosphide catalyst using a green and pollution-free synthesis method and applied it to electrocatalytic water-splitting reactions. Experimental results show that the material can operate stably for a long time at high current density. Furthermore, electrocatalytic conversion of nitrate to ammonia is considered an efficient route for nitrate wastewater treatment and production of hydrogen-rich ammonia fuel. We successfully prepared a bimetallic carbide catalyst using a sonochemical method, which exhibits excellent low overpotential nitrate reduction and high-efficiency ammonia yield properties. / Hu, J. (2024). Metal Oxides, Carbides and Phosphides for Supercapacitor and Electrocatalysis [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/207537 / Compendio