Institute of Fundamental Technological Research

Abstract:
The urea oxidation reaction (UOR) is characterized by a lower overpotential compared to the oxygen evolution reaction (OER) during electrolysis, which facilitates the hydrogen evolution reaction (HER) at the cathode. Charge
distribution, which can be modulated by the introduction of a heterostructure, plays a key role in enhancing the adsorption and cleavage of chemical groups within urea molecules. Herein, a facile all-room temperature synthesis of functional heterojunction NiCo2 S4 /CoMo 2 S4 grown on carbon cloth (CC) is presented, and the as-prepared electrode served as a catalyst for simultaneous hydrogen evolution and urea oxidation reaction. The Density
Functional Theory (DFT) study reveals spontaneous transfer of charge at the heterointerface of NiCo 2 S4 /CoMo 2 S4 , which triggers the formation of localized electrophilic/nucleophilic regions and facilitates the adsorption of electron donating/electron withdrawing group in urea molecules during the UOR. The NiCo2 S4 /CoMo 2 S4 // NiCo 2 S4 /CoMo 2 S4 electrode pair required only a cell voltage of 1.17 and 1.18 V to deliver a current density of 10 and 100 mA cm−2 respectively in urea electrolysis cell and display very good stability. Tests performed in real urine samples show similar catalytic performance to urea electrolytes, making the work one of the best transition
metal-based catalysts for UOR applications, promising both efficient hydrogen production and urea decomposition.

Abstract:
The key to tactile sensors' sliding perception is the stick-slip modulation of the soft material through surface design. Herein, in-situ sliding tests were conducted on polydimethylsiloxane (PDMS) film/substrate bilayer structures (PF/SBS) with three surface adhesion characteristics tailored by crosslinking degrees of PDMS film. Microscopic damage mechanisms during Schallamach wave propagation were analyzed using mixed-mode cohesive contact models. Intermolecular interaction mechanisms at microscopic crack tips were also explored using PDMS-Silica (SiO2) molecular models with varying PDMS crosslinking degrees. The Schallamach waves and tangential force strongly depended on the crosslinking degree of PDMS film. The varying effects of crosslinking degree on normal and tangential separation mechanisms lead to a transition in Schallamach wave damage from mixed mode to Mode II during propagation.

Keywords:
Stick-slip,Film/substrate bilayer structures,Cohesive contact model,Intermolecular interaction

Abstract:
Silicon carbide and an aluminum alloy (SiC/AlSi12) composite are obtained during the pressurized casting process of the aluminum alloy into the SiC foam. The foam acts as a high-stiffness skeleton that strengthens the aluminum alloy matrix. The goal of the paper is to describe the behavior of the material, considering its internal structure. The composite’s structure is obtained by using X-ray computing tomography. The thorough computer tomography analysis allows for the high-precision identification of the shape and distribution of the pores in the matrix. The computational model prepared in the framework of the peridynamics method takes into account the pores and their shape. The pores in the structure appeared in the fabrication process. The impact of a steel ball is studied employing the peridynamics method. The sample without any porosity and a porous one were considered during the analyses. It has been found that the porosity of the matrix influences the plastic strain development, but the damage parameter in the skeleton is not affected significantly. The damage advancement in the skeleton during the process is practically identical in both cases. The equivalent plastic strain field is much smoother in a non-porous matrix than in a porous one. The porous matrix has high equivalent
plastic strain concentrations, much higher than the non-porous matrix. The shape of the sample is affected by the porosity of the matrix. The sample with a porous matrix tends to fragment, and it shows a tendency towards spallation when in close contact to the surface with the base.

Keywords:
interpenetrated composite, impact, damage, perydynamics

Abstract:
The suitability of a range of interatomic potentials for elemental tin was evaluated in order to identify an appropriate potential for modeling the stanene (2D tin) allotropes. Structural and mechanical features of the flat (F), low-buckled (LB), high-buckled (HB), full dumbbell (FD), trigonal dumbbell (TD), honeycomb dumbbell (HD), and large honeycomb dumbbell (LHD) monolayer tin (stanene) phases, were gained by means of the density functional theory (DFT) and molecular statics (MS) calculations with ten different Tersoff, modified embedded atom method (MEAM), and machine-learning-based (ML-IAP) interatomic potentials. A systematic quantitative comparison and discussion of the results is reported.

Keywords:
2D materials, DFT, interatomic potentials

Abstract:
This study focuses on the development and characterization of a bulk Ti-Al-N
multiphase composite enriched with BN addition and sintered through hot pressing. The
research aimed to create a material with optimized mechanical and corrosion-resistant
properties suitable for demanding industrial applications. The composite was synthesized using a powder metallurgy approach with a mixture of AlN, TiN, and BN powders, processed under a high temperature and pressure. Comprehensive analyses, including microstructural evaluation, hardness testing, X-ray tomography, and electrochemical corrosion assessments, were conducted. The results confirmed the formation of a multiphase microstructure consisting of TiN, Ti₂AlN and Ti₃AlN phases. The microstructure was uniform with minimal porosity, achieving a hardness within the range of 500–540 HV2. Electrochemical tests revealed the formation of a passive oxide layer that provided moderate corrosion resistance in chloride-rich environment. However, localized pitting corrosion was observed under extreme conditions. The study highlights the potential of a BN admixture to enhance mechanical and corrosion-resistant properties and suggests directions for further optimization in sintering processes and material formulations.

Keywords:
AlN-TiN(BN) composite,hot-pressing,μCT,corrosion resistance

Abstract:
The paper examines the potential use of low-cost LiDAR for cave surveying. Mobile mapping using LiDAR complements traditional speleological surveying using a polygonal traverse. These methods assist each other, with one serving as an independent control measurement for the other, ultimately resulting in a more accurate 3D model. The testing results show that achieving high accuracy and detailed cave representation is possible using open hardware and open-source software. Both spacious and well-indented cave sections and narrow passages barely passable by humans were successfully mapped. The surveying process is significantly faster than traditional cave mapping, as drawing cave sketches by hand is unnecessary, being the most time-consuming task on site. This paper also presents a procedure for automated ground plan generation and profile generation from 3D point clouds, further expediting and simplifying the work for speleologists using scanning systems. Also, it is confirmed that the results are reproducible and do not depend on the subjective interpretation of the cartographer, as is the case with traditional speleological drawings.

Keywords:
cave mapping, mobile laser scanning, open hardware, open-source software, cave profiles

Abstract:
This study investigates the development and performance analysis of a supercapacitor using activated carbon synthesized from polyethylene oxide (PEO) as the electrode material, and a poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP)-based polymer electrolyte, prepared using a solution-cast technique for dye-sensitized solar cell (DSSC) application. This paper deals with polyether-based electrochemical devices, where electrode material is developed by polyethylene oxide (PEO), while an electrolyte is prepared using PVdF-HFP. Detailed electrical and photoelectrochemical studies were carried out using various characterization tools, and the results are discussed in detail. Sandwich structure supercapacitors and DSSCs are developed using maximum conducting polymer electrolyte that has an ionic conductivity of (8.3 × 10−5) Scm−1, exhibiting a high specific capacitance of 395 Fg−1 and DSSC efficiency ranging from 1.6 to 3.5% under 1 sun condition. The findings underscore the capability of PEO-derived carbon and polymer electrolytes in improving the efficiency of energy storage and conversion systems.

Keywords:
Polyether, Activated carbon, Supercapacitor, Dye-sensitized solar cell

Abstract:
Tomonaga–Luttinger liquid (TLL) theory is a canonical formalism used to describe 1D metals, where the low-energy physics is determined by collective Bosonic excitations. Herein, a theoretical model to compute the parameters of Tomonaga–Luttinger liquid (TLL) in multiwalled nanotubes (MWNTs) is presented. MWNTs introduce additional complexity to the usual Fermionic chains due to interactions and hybridization between their multiple coaxial shells. A model in which conducting paths along the length of the MWNTs are randomly distributed among the shells is considered. Since the valley degree of freedom remains a good quantum number, the TLL description in addition to spin and charge contains also valley degree of freedom and hence four-mode description applies. The values of all four TLL parameters are obtained for this model. A surprising outcome is that the compressibility of the holon mode becomes a universal quantity, while the parameters of neutral modes will depend on the details of intershell coupling. Finally, experiments where predictions can be tested are proposed.

Abstract:
Arm-Z is a concept of a hyper-redundant manipulator based on linearly joined sequence of congruent units. Each unit has only one degree of freedom (1-DOF) - the twist relative to the previous unit.
This paper presents the approach to design of modular robotic manipulator based on computer simulations. The approach is rather standard nowadays, however, it is applied to rather unique robotic system. The
CAD model of the module structure for a manipulator with 6 degrees of freedom and respective Denavit-Hartenberg notation are presented. Simulink - a MATLAB-based graphical programming environment was
used to determine the torques of individual modules. The results of three simulations are presented and discussed. Finally, based on critical observations, the drive and gear for the module of Arm-Z system were selected.

Keywords:
Simulation,Robotic arm,Manipulator,Arm-Z,MATLAB Simulink