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Three dimensional simulations of FRC beams and panels with explicit definition of fibres-concrete interaction
- Ireneusz Marzec
- Jan Suchorzewski
- Jerzy Bobiński
High performance concrete (HPC) is a quite novel material which has been rapidly developed in the last few decades. It exhibits superior mechanical properties and durability comparing to normal concrete. HPC can achieve also superior tensile performance if strong fibres (steel or carbon) are implemented in the matrix. Thus, there exist the unabated interest in studying how the addition of different types of fibres modifies the behaviour of HPC. Nowadays, a standard numerical approaches to model the behaviour of fibre reinforced concrete (FRC) are carried out by means of the smeared or discrete crack modelling of homogenous media with appropriately changed stress-strain relationships. The objective of this paper is to develop a new and efficient mesoscale modelling approach for steel fibre reinforced high-performance concrete. The main idea of presented approach is to assume the fully 3D modelling with taking into account explicitly the distribution and orientation of the steel fibres. As a benchmark, results obtained from experimental campaign on beams and panels made from high-performance concrete with steel fibres of different sizes and dosages were taken. Results of numerical simulations were directly compared with experimental outcomes in order to validate and calibrate FE-model and to introduce the efficient numerical modelling tool.
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Three modes of electrochemical impedance spectroscopy measurements performed on vanadium redox flow battery
- Joanna Krakowiak
- Wojciech Bącalski
- Grzegorz Lentka
- Pekka Peljo
- Paweł Ślepski
This article presents an innovative approach to monitor working redox flow batteries using dynamic electrochemical impedance spectroscopy, diverging from the commonly sequential impedance methods carried out under potentiostatic or galvanostatic conditions close to the open circle voltage. The authors introduce a fresh variation of dynamic impedance measurement that leverages an amplitude-modulated multi-frequency alternating current perturbation signal. This technique leads to a reduction in measurement time, making it possible to monitor impedance in real-time under typical operational conditions. Consequently, it effectively addresses the limitations stemming from the absence of stationary conditions during impedance measurements. There is no doubt that measurement techniques enabling the study of processes during the operational life of a battery provide the most valuable insights into the properties of these systems. The potential of this proposed approach is exemplified through the examination of a full vanadium redox flow battery as a case study. Classical impedance measurements were also conducted under potentiostatic and galvanostatic conditions with sequential frequency signal change, which requires stopping the battery operation, resulting in electrode potential changes of over 200 mV compared to the working system. Spectra for all modes of measurements were compared. In the case of dynamic measurements, such significant differences in spectra during charging and discharging are not observed, which is characteristic of classical measurements. The authors deliberately and consciously refrain from analyzing the results by fitting equivalent circuits.
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Three-component NiO/Fe3O4/rGO nanostructure as an electrode material towards supercapacitor and alcohol electrooxidation
- Mohammad Bagher Askari
- Mohammad Taghi Tourchi Moghadam
- Parisa Salarizadeh
A nanocomposite made of nickel oxide and iron oxide (NiO/Fe3O4) and its hybrid with reduced graphene oxide (rGO) as a conductive substrate with a highly functional surface (NiO/Fe3O4/rGO) was synthesized using a simple hydrothermal approach. This study addresses the challenge of developing efficient materials for energy storage and alcohol fuel cells. After confirming the synthesis through structural analysis, the potential of these nanocomposites as supercapacitor electrodes and catalysts for methanol and ethanol oxidation in alcohol fuel cells were evaluated. The synergy of combining the two metal oxides and adding rGO to the composite structure led to excellent electrocatalytic activity in alcohol oxidation. For the modified NiO/Fe3O4/rGO electrode in the methanol oxidation reaction (MOR), a current density of 450 mA/cm2 at 0.67 V and excellent catalyst stability of 98.7 % over 20 h in chronoamperometric analysis were observed. In the ethanol oxidation reaction (EOR), an oxidative current of 235 mA/cm2 at a peak potential of 0.76 V was seen, with catalyst stability of 96.4 % after 20 h. As a supercapacitor electrode, the NiO/Fe3O4 composite demonstrated a specific capacitance of 946 F/g, while NiO/Fe3O4/rGO showed 1155 F/g. The stability of these electrodes after 10000 GCD cycles was 83.6 % and 90.6 %, respectively. These findings suggest that the proposed structures are cost-effective and reliable alternatives for energy storage and production, suitable for alcohol fuel cells and supercapacitors.
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Three-dimensional characterization of porosity in iron ore pellets: A comprehensive study
- Pasquale Cavaliere
- Behzad Sadeghi
- Leandro Dijon
- Aleksandra Laska
- Damian Koszelow
This paper presents a comprehensive study on the production and reduction of high-quality iron ore pellets characterized by a basicity index nearing 0.5 and diameters ranging from 1 to 2 cm. The reduction process was carried out in a hydrogen atmosphere at temperatures spanning 800–1000 ◦ C and a pressure of 8 bar. Initial f indings revealed substantial variations in pellet density and compressive strength, attributed to their mean dimensions. To delve into the microstructural transformations occurring during reduction, meticulous microtomographic analyses were conducted on each pellet before and after the reduction process. The research assessed reducibility factors such as porosity, pore size, and tortuosity adjustments across diverse reduction conditions. The study highlights the intimate connection between the reduction process rate, processing parameters, and pellet microstructure. Furthermore, the metallization tendencies were explored through extensive reduction experiments involving multiple pellets. These findings offer crucial insights into optimizing iron ore pellet performance during production and reduction processes, contributing to advancements in industrial applications.
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Timed rolling and rising tests in Duchenne muscular dystrophy ambulant boys: a feasibility study
- Agnieszka Sobierajska-Rek
- Joanna Jabłońska-Brudło
- Aneta Dąbrowska
- Wiktoria Wojnicz
- Jarosław Meyer-Szary
- Jolanta Wierzba
BACKGROUND: Functional activities are extensively used in motor assessments of patients with Duchenne muscular dystrophy. The role of timed items has been reported as an early prognostic factor for disease progression. However, there are two functional activities that are not widely assessed in clinical practice among Duchenne muscular dystrophy patients: rolling and bed rising. This study aimed to investigate whether the 360-degree roll (roll) and supine to sit-to-edge (bed rise) measurements are feasible tools reflecting the functional status of ambulatory DMD children by establishing possible correlations between validated measures: the Vignos Scale (VS), timed rise from floor and the 6-Minute Walk Test (6MWT). METHODS: A total of 32 ambulant boys with DMD were assessed using timed items, the 6MWT and VS. RESULTS: The roll and bed rise are correlated with each other. The 6MWT, the floor rise and VS are correlated with the roll and with the bed rise. CONCLUSIONS: Findings offer preliminary empirical evidence addressing feasibility and safety of roll and bed rise measurements. There is a potential clinical utility of these tests in assessing functional status of DMD ambulant patients.
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TiO2 and Reducing Gas: Intricate Relationships to Direct Reduction of Iron Oxide Pellets
- Pasquale Cavaliere
- Behzad Sadeghi
- Aleksandra Laska
- Damian Koszelow
In response to the imperative for sustainable iron production with reduced CO2 emissions, this study delves into the intricate role of TiO2 in the direct reduction of iron oxide pellets. The TiO2-dependent reducibility of iron oxide pellets utilizing H2 and CO gas across varied temperatures and gas compositions is thoroughly investigated. Our findings unveil the nuanced nature of the TiO2 effect, underscored by its concentration-dependent behavior, revealing an optimal range between 1 and 1.5 pct TiO2, where a neutral or positive impact on reduction kinetics and diffusion coefficient is observed. Notably, the synergistic interplay of CO and H2 at 1000 C emerges as particularly efficacious, suggesting complementary effects on the reduction process. The introduction of H2 into the reducing atmosphere regulated by CO not only extends the transition range but also markedly expedites the rate of reduction. Furthermore, our study highlights the temperature sensitivity of the TiO2 effect, with higher TiO2 content correlating with prolonged reduction time in a 100 pct H2 atmosphere at 900 C. In a 100 pct H2 atmosphere, the non-contributory role of TiO2 stems from the water-gas shift reaction. Conversely, introducing H2 into a CO-controlled reducing atmosphere with TiO2 enhances the transition range and expedites the reduction rate. Additionally, our findings underscore the role of total iron content, revealing a direct correlation with the reduction process.
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Torsional earthquake-induced pounding between adjacent buildings founded on different soil types
- Mahmoud Miari
- Robert Jankowski
This paper investigates the effect of the soil type on the torsional response of build- ings experiencing torsional pounding due to earthquake excitations. Six buildings (one 4-storey building and five 6-storey buildings) with different configurations have been considered. First, pounding between different structures has been analysed for a specified soil type and the effect of the torsional pounding and the contact asymmetry on the torsional response of colliding buildings has been investigated. Then, these pounding cases have been considered for different soil types to study the effect of the soil type on the torsional response of buildings experiencing torsional pounding. Five soil types have been considered, i.e. hard rock, rock, very dense soil and soft rock, stiff soil and soft clay soil. The results of the study indicate that the earthquake-induced torsional pounding causes an increase in the peak storey rotation of the colliding buildings as compared to the symmetric pounding in all cases. Higher peak storey rotations have been experienced for colliding buildings founded on the soft clay soil, then for buildings founded on the stiff soil, then for buildings founded on very dense soil and soft rock, and finally for buildings founded on the rock and hard rock.
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Toward an understanding of occupational burnout among employees with autism – the Job Demands‑Resources theory perspective
- Michał Tomczak
- Konrad Kulikowski
This article aims to gain insight into the phenomenon of occupational burnout among employees with autism based on the theoretical framework of the Job Demands-Resources theory and the literature on employees with autism in the workplace. Firstly, we argue that although the resources and demands of the neurotypical and neurodivergent employees might be different, the theoretical mechanism of occupational burnout formation remains similar among the neurotypical and neurodivergent employees, leading to the similar burnout experience. Next, we distinguish key demands that might drain neurodiverse employees’ energy, and spark burnout, and propose a set of resources that might foster their achievement of work goals and mitigate demanding working conditions. We emphasise that the nature of job demands/resources that may cause burnout is not universal but might depend on how employees evaluate them, thus neurotypical and neurodiverse workers who evaluate the same work characteristics differently might complement each other, increasing organisational diversity without losing productivity. Our conceptual elaboration contributes to the theory and practice of healthier workplaces by providing tools and inspiration to managers, policymakers, and all stakeholders interested in creating a diverse and productive workplace. Moreover, our work might spark a much needed debate on occupational burnout among employees with autism and encourage conducting further empirical studies.
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Toward Human Chromosome Knowledge Engine
- Maiqi Wang
- Yi Lai
- Minghui Li
- Haoxi Zhang
- Edward Szczerbicki
Human chromosomes carry genetic information about our life. Chromosome classification is crucial for karyotype analysis. Existing chromosome classification methods do not take into account reasoning, such as: analyzing the relationship between variables, modeling uncertainty, and performing causal reasoning. In this paper, we introduce a knowledge engine for reasoning-based human chromosome classification that stores knowledge of chromosomes via a novel representation structure, the Chromosome Part Description (CPD), and reasons over CPDs by utilizing the probability tree model (PTM) for classification. Each CPD keeps information on a particular feature of chromosomes, while the PTM provides causal reasoning capability taking CPDs as nodes and dependencies between CPDs and types as edges. Experimental results show that the proposed knowledge engine’s performance increases when providing more CPDs and achieves 100% classification accuracy with more than three CPDs.
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Toward Sustainable Development: Exploring the Value and Benefits of Digital Twins
- Paweł Weichbroth
- Krystian Jandy
- Józef Żurada
The complexity and number of data streams generated by internal processes exceed the capabilities of most current simulation environments. Consequently, there is a need for the development of more advanced solutions that can handle any number of simultaneous simulations. One of the most promising ideas to address these and other challenges is the concept of a Digital Twin (DT), which refers to a digital representation or a virtual model designed to accurately reflect an intended or actual physical product, system, or process (i.e., a physical twin). As a Digital Twin spans the life-cycle of its physical twin, its development and application can bring considerable benefits to organizations seeking to improve existing processes as well as implement new ones. However, few studies have comprehensively examined the value and benefits of Digital Twins. To fill this gap, this study aims to provide a better understanding of this technology by reviewing the contemporary literature, with a particular focus on the documented case studies, as well as reported business and industrial deployments. The results obtained show that Digital Twins have proven beneficial for maintenance, cost reduction, optimization, simulation performance, monitoring, product life-cycle understanding, assessment validation, performance evaluation, product design, and safety and risk mitigation. In addition, when considering the human factor, DTs can facilitate education and training, team collaboration, and decision making. Undeniably, Digital Twins are a game changer for safer, faster, and more sustainable development.
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Towards a reliable method for extrapolation of propulsion performance for vessels with twin-crp-pod system
- Hanna Pruszko
- Maciej Reichel
- Marek Necel
- Sören Brüns
The study presents power performance prediction of an Ultra Large Container Ship (ULCS) with hybrid twin-crp-pod propulsion system. Twin crp-pod propulsion system is a combination of three concepts: twin screw, contra-rotating propellers (crp) and conventional shaft propellers with pod propulsors behind. The presented study shows the current extrapolation method for crp propulsion systems and tries to point out its weaknesses. As a case study, a 400 m ULCS has been investigated in full-scale and in model scales of 24 and 37.416. The analyses were carried out for all scales with use of CFD numerical methods and for the scale of 37.416 based on towing tank tests. All the results have been extrapolated with the same method and results have been compared. The investigations clearly show differences in delivered power prediction extrapolated from towing tank results giving the maximum value and from CFD made to scale of 24 the minimum value. Finally, conclusions on possible sources of differences, including the numerical and analytical methods are presented.
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Towards an analysis framework for operational risk coupling mode: A case from MASS navigating in restricted waters
- Cunlong Fan
- Jakub Montewka
- Victor Bolbot
- Yang Zhang
- Yuhui Qiu
- Shenping Hu
Maritime Autonomous Surface Ships (MASSs) constitute highly interconnected and tightly coupled multistate systems. Incorporating the coupling effects of both interactions and dependencies is centrally important to ensure navigation safety of MASSs. This paper proposes a framework for examining the coupling effects in the operational modes (OM) of MASSs. Failure Modes (FMs) of MASSs related to interactions with the environment and subsystems are identified using 24Model developed based on conventional ship accidents involving grounding in the west of Shenzhen port, China. FMs related to grounding are classified into the five risk types of human, organization, ship, environment, and technology, considering three OMs (states), i.e., manual control, remote control, and autonomous control. Based on this classification, the N-K model is applied to calculate the risk coupling values of scenarios involving multiple risk types. These scenarios are then ranked by the risk coupling values of the three OMs, and values are compared among different OMs. The results indicate that for grounding in the west of Shenzhen port most risk coupling values increase with increasing risk type diversity. Furthermore, the risk coupling mechanism in remote control differs significantly from that in manual control and autonomous control, thus risk management of MASS OMs should vary.
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Towards ecological transformation: developing architectural education and research through L’Art Urbain initiatives
- Izabela Burda
- Katarzyna Zielonko-Jung
- Louis Moutard
- Aude Vapard
- Anne Durand
The aim of this study was to examine the collaboration between the Faculty of Architecture at Gdańsk University of Technology (Gdańsk Tech), Poland and L’Art Urbain dans les Territoires, Paris, France, recognised for its involvement in transforming urban development over four decades. The focus is placed on the evolution of the association’s annual competition, highlighting the growing emphasis on sustainability. Special attention is dedicated to the integration of themes relating to environmental and social sustainability into the curriculum of Master’s level design courses. This study highlights the role of the competition in enhancing education in architecture and urban planning, as well as in developing research at Gdańsk Tech, especially in fields related to the social and environmental aspects of urban regeneration. Moreover, the research also considers the wider implications of this collaboration, in particular its effectiveness in linking theoretical education to real-world challenges and in equipping architects to deal with the complexities of sustainable urban development.
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Towards hand grip force assessment by using EMG estimators
- Robert Barański
- Wiktoria Wojnicz
- Bartłomiej Zagrodny
- Michał Ludwicki
- Agnieszka Sobierajska-Rek
The purpose of this study was to propose a method to assess individual regression (calibration) curves to establish a relationship between an isometric grip force and surface electromyography (EMG) estimator. In this study 18 healthy volunteers (12 male (23.0 ± 2.0 years) and 6 female (23.2 ± 0.7 years)) had been examined. Ten EMG estimators (mean absolute value, root mean square, entropy, energy, turns per second, mean of zero crossings, median power frequency, mean power frequency, and Hilbert transforms), two EMG locations (brachioradialis and flexor digitorum superficialis) and five types of regression curves (linear, exponential, power, logarithm, and quadratic polynomial) have been tested. Using a quadratic polynomial regression curve and energy EMG estimator of the flexor digitorum superficialis muscle, it was obtained the lowest dispersity of EMG estimator and the most accurate prediction of grip isometric force among all tested EMG estimators.
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Towards sustainable catalyst-free biomass-based polyurethane-wood composites (PU-WC): From valorization and liquefaction to future generation of biocomposites
- Adam Olszewski
- Paulina Kosmela
- Łukasz Piszczyk
A substantial aspect of materials engineering lies in the responsible process of designing polymer-based materials. Due to environmental pollution, excessive consumption of natural resources, and increasing environmental awareness of society, there is a massive need for polyurethane (PU) materials with reduced environmental impact. To date, research on catalyst-free polyurethane-wood composites (PU-WC) has demonstrated a huge potential for commercialization in industrial production and can be used as a replacement for commonly used wood-plastic composites and wood-based panels. Based on this research, the introduction of new greener alternatives for petrochemical polyols to develop PU-WCs with a high biomass share could be interesting. In this study, up to 80% of bio-based polyol (BP) synthesized via biomass liquefaction was introduced to the polymer matrix. The effect of petrochemical polyol substitution was examined by mechanical testing, scanning electron microscopy (SEM), water absorption tests, and thermal analysis. The conducted research revealed that the structure and properties of PU-WCs strongly depend on the share of BP. The most promising composites were manufactured with up to 40% BP. The flexural strength of the PU-WC decreases from 25 to 9 MPa, and the flexural modulus varies from 1780 to 800 MPa. This may be caused by deteriorated adhesion between composite phases and a reduction in the stiffness of the materials due to the decrease in crosslinking density, which was confirmed by the decrease in glass transition temperature from 96 to 26 °C. In summary, this work shows the next step towards cleaner production of PU-WCs by substituting petrochemical polyols for alternatives synthesized using renewable resources.
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Towards truly sustainable IoT systems: the SUPERIOT project
- Marcos Katz
- Tuomas Paso
- Konstantin Mikhaylov
- Luis Pessoa
- Helder Fontes
- Liisa Hakola
- Jaakko Leppäniemi
- Emanuel Carlos
- Guido Dolmans
- Julio Rufo
- Marcin Drzewiecki
- Hazem Sallouha
- Bruce Napier
- André Branquinho
- Kerstin Eder
This paper provides an overview of the SUPERIOT project, an EU SNS JU (Smart Networks and Services Joint Undertaking) initiative focused on developing truly sustainable IoT systems. The SUPERIOT concept is based on a unique holistic approach to sustainability, proactively developing sustainable solutions considering the design, implementation, usage and disposal/reuse stages. The concept exploits radio and optical technologies to provide dual-mode wireless connectivity and dual-mode energy harvesting as well as dual-mode IoT node positioning. The implementation of the IoT nodes or devices will maximize the use of sustainable printed electronics technologies, including printed components, conductive inks and substrates. The paper describes the SUPERIOT concept, covering the key technical approaches to be used, promising scenarios and applications, project goals and demonstrators which will be developed to the proof-of-concept stage. In addition, the paper briefly discusses some important visions on how this technology may be further developed in the future.
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Towards Universal Visualisation of Emotional States for Information Systems
- Michał Wróbel
- Agnieszka Landowska
- Karolina Makuch
The paper concerns affective information systems that represent and visualize human emotional states. The goal of the study was to find typical representations of discrete and dimensional emotion models in terms of color, size, speed, shape, and animation type. A total of 419 participants were asked about their preferences for emotion visualization. We found that color, speed, and size correlated with selected discrete emotion labels, while speed correlated with arousal in a dimensional model. This study is a first step towards defining a universal emotion representation for use in information systems.
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Trace metals in skeletal calcite of echinoderms from the Barents Sea
- Anna Iglikowska
- Anna Piwoni-Piórewicz
- Bartłomiej Cieślik
- Dominika Żyłan
- Patryk Waszczuk
- Piotr Kukliński
This study investigates the skeletal accumulation of selected elements (Al, Ag, As, Ca, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Pb, Sr, Zn) in echinoderms inhabiting Barents Sea, an area impacted by human activities from northern Norway and Kola Peninsula, known sources of metal pollution. The primary aim was to have insight whether metals incorporation in the skeleton of Arctic echinoderms is regulated physiologically by the organism or influenced by abiotic environmental conditions (expressed as distance from the source of metal pollution). Metal concentrations were analysed in 17 species from four echinoderm classes: Asteroidea, Ophiuroidea, Crinoidea and Echinoidea. The results revealed species-specific accumulation patterns for most metals, indicating a strong biological control over metal incorporation. In crinoid Heliometra glacialis, a negative correlation between body size and skeletal concentrations of Al, Fe, Mg and Mn was observed. This correlation was ascribed to age-related metabolic traits and a likely mechanism for removing foreign metals from the skeletal calcite. The relationships between environmental factors and metal accumulation patterns were less clear. However, higher concentrations of Al, Fe, Mg, Mn and Pb were found in suspension feeders collected near glaciers, which were potential sources of suspended material. Asteroids exhibited particularly high concentrations of Cu, Fe, Cr, Hg compared to species from the other regions, suggesting that their calcified skeletons may serve as storage mechanisms to prevent toxic effects in other body parts. These observations confirm that biologically-mediated processes predominantly govern metal bioaccumulation in Arctic echinoderms.
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Transforming urban design education through international competitions: a 20-year perspective
- Izabela Burda
Over the past two decades, international urban design competitions have transformed architectural education by fostering creativity and interdisciplinary learning. This article provides a 20-year perspective by focusing on five of the most prominent competitions: Europan, UIA Student Competitions, ULI Hines Student Competitions, Arturbain.fr and the Global Schindler Award. Through a comparative analysis of these competitions, the research examines their thematic focus, participation levels, educational engagement and impact on urban design education. The results show that these competitions emphasise sustainability, ecological change and shared learning among participants. An analysis of selected editions illustrates their evolution in addressing urban challenges, such as regional connectivity, public space accessibility and environmental resilience. This study highlights that participation in these competitions prepares future urban designers to address complex challenges by encouraging innovative and sustainable solutions. It also underscores the transformative role of competitions in shaping and advancing urban design education.
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Transparent TiO2 nanotubes supporting silver sulfide for photoelectrochemical water splitting
- Wiktoria Lipińska
- Stefania Wolff
- Katharina Dehm
- Simon Hager
- Justyna Gumieniak
- Agnieszka Kramek
- Ryan Crisp
- Emerson Coy
- Katarzyna Grochowska
- Katarzyna Siuzdak
Differences between photoelectrochemical and electrochemical activity were thoroughly investigated for the oxygen evolution reaction mediated by Ag2S deposited on two types of ordered titania substrates. Titanium dioxide nanotubes were fabricated by anodization of magnetron sputtered Ti films on ITO-coated glass substrates or directly from Ti foil. Further, Ag2S deposition on the nanotubes was carried out using successive ionic layer adsorption and reaction, known as SILAR, with 5, 25, and 45 cycles performed. Two types of nanotubes, one on transparent the other on non-transparent substrates were compared regarding their geometry, structure, optical, and electrochemical properties. It was demonstrated that the composite of Ag2S grown on transparent nanotubes exhibits higher catalytic activity compared to Ag2S grown on the nanotubes formed on Ti foil. The results showed that transparent nanotubes after modification with Ag2S by 25 SILAR cycles exhibit ca. 3 times higher photocurrent under visible light illumination than non-transparent ones treated with the same number of cycles. Furthermore, transparent nanotubes after 45 SILAR cycles of Ag2S exhibit enhanced activity towards oxygen evolution reaction with 9.3 mA cm−2 at 1.1 V vs. Ag/AgCl/0.1 M KCl which is six times higher than titania alone on Ti foil.