Green Hydrogen Production and Technology - Batch 2

Comparative Analysis of Pore Network Modelling (PNM) and Computational Fluid Dynamics (CFD) for Transport Modeling in Alkaline Water Electrolyser Porous Electrode

2026-02-12T12:08:28Z

Comparative Analysis of Pore Network Modelling (PNM) and Computational Fluid Dynamics (CFD) for Transport Modeling in Alkaline Water Electrolyser Porous Electrode Traore, Mariam Green hydrogen production via alkaline water electrolysis (A-WE) is a crucial technology for sustainable energy transition. The efficiency and durability of electrolyzers strongly depend on the transport properties within porous electrodes. This thesis presents a comparative analysis of two numerical modelling approaches, Pore Network Modeling (PNM) and Computational Fluid Dynamics (CFD), to predict transport phenomena in realistic 3D microstructures of sintered nickel electrodes obtained from X-ray microtomography (μCT). Microtomography μCT image was processed and SNOW2 algorithm was used to extract detailed pore networks. The porosity and interfacial area per volume were computed. These geometric properties were validated against image analysis data with agreement, confirming the accuracy of the reconstruction method. Subsequently, single-phase flow simulations were conducted using the pore network (PN) (OpenPNM) with various geometric models and CFD (OpenFOAM) directly on meshed μCT data to evaluate absolute permeability and tortuosity. Results demonstrated a strong correlation between PNM and CFD for tortuosity prediction, with 1.4% relative error, highlighting PNM’s ability to reliably represent the complexity of diffusion pathways. Permeability predictions showed larger variations depending on pore and throat geometry, with relative errors ranging from 17% (cones and cylinders) to 260% (cubes and cuboids). PNM simulations was performed in 15 minutes while CFD simulation took around 7 hours. These results show PNM computational efficiency and its flexibility to simulate multiple geometric configurations rapidly, enabling comprehensive parametric studies and optimization of porous media microstructures. This capability supports accelerated design of porous layers with enhanced transport properties, potentially improving electrolyzer performance and lifespan while reducing experimental costs. So, validated by CFD or experimental data, PNM proves to be an effective tool for predicting transport phenomena in porous electrodes. Its ability to efficiently explore diverse pore geometries makes it invaluable for guiding rational design and innovation in alkaline water electrolysis technology and other electrochemical applications. A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use, the Université Felix Houphouët-Boigny, Cote d’Ivoire, and the Jülich Forschungszentrum in partial fulfillment of the requirements for the International Master Program in Renewable Energy and Green Hydrogen (Green Hydrogen Production and Technology)

Synthesis and Characterization of Amine-Modified Carbon Nanofibers for Direct Air Capture of CO2

2026-02-12T12:00:23Z

Synthesis and Characterization of Amine-Modified Carbon Nanofibers for Direct Air Capture of CO2 Seyni Harouna, Saadatou This work investigates the development and evaluation of aminosilane-functionalized carbon nanofibers as adsorbents for Direct Air Capture. The study focused on the impact of surface modification and textural tailoring on CO2 adsorption performance under ultradilute conditions (~400 ppm), ambient temperature, and in the presence of atmospheric humidity. A series of modifications was applied to electrospun PAN fibers, such as stabilization, carbonization, oxidation with H₂SO₄/KMnO₄, KOH activation, and silanization with (3-aminopropyl)trimethoxysilane (APTMS). Energy-Dispersive X-ray Spectroscopy (EDX), BET surface area measurements, pore size distribution, Thermogravimetric Analysis (TGA), and Scanning Electron Microscopy (SEM) were used to analyze the structural, morphological, and surface chemical properties of the fibers. H2O and CO2 adsorption isotherms, were performed to evaluate performance under conditions that are similar to direct air capture. The unmodified and oxidized carbon nanofibers showed limited microporosity and low BET surface areas of 7.8 and 77.6 m2 g-1, respectively, resulting in negligible CO2 uptake (< 0.1 mmol g-1 at 400 ppm CO2). The introduction of oxygen-containing groups during oxidation was verified by TGA, which resulted in an increase in the surface functionality. KOH activation expanded microporosity, raising the BET surface area to 436.9 m2 g-1 and micropore volume to 0.239 cm3 g-1. This resulted in a physisorptive CO2 capacity of approximately 0.45 mmol g-1 at 400 ppm. The greatest enhancement was achieved by APTMS silanization, which grafted primary amines onto carbon nanofiber surfaces, yielding a surface area of 58.9 m2 g-1 and CO2 uptake exceeding 0.7 mmol g-1 under DAC-relevant conditions. Overall, this work shows that the combination of KOH activation and APTMS functionalization creates CNFs with complementary improvements in porosity and surface chemistry, enabling enhanced CO2 capture performance under DAC scenarios. The results show that optimizing functionalization protocols such as coating time, reagent quantities, and grafting conditions, is essential to enhance adsorbents performance. A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use, the Université Felix Houphouët-Boigny, Cote d’Ivoire, and the Jülich Forschungszentrum in partial fulfillment of the requirements for the International Master Program in Renewable Energy and Green Hydrogen (Green Hydrogen Production and Technology)

Synthesis of Copper, Silver, and Copper–Silver Powders via Ultrasonic Spray Pyrolysis and Hydrogen Reduction

2026-02-12T11:53:21Z

Synthesis of Copper, Silver, and Copper–Silver Powders via Ultrasonic Spray Pyrolysis and Hydrogen Reduction Faye, Mame Haicha This thesis investigates the synthesis of copper (Cu), silver (Ag), and copper–silver (Cu-Ag) powders via ultrasonic spray pyrolysis (USP) and hydrogen reduction, focusing on how gas atmosphere, reduction temperature, and precursor ratio affect their morphology, particle size, purity, and stability. Understanding these parameters is important because they control how nanoparticles form, which affects their conductivity, catalytic activity, and resistance to oxidation. These properties are very important for many uses, such as making conductive inks and printed circuits for electronics, catalysts for chemical and energy processes, and protective coatings that stop corrosion or kill germs. In this work, four solutions were made using copper nitrate trihydrate and silver nitrate, then sprayed in a USP reactor and reduced under hydrogen and argon at temperatures between 500 °C and 700 °C. The powders made were studied with SEM and ImageJ to see their size and shape, and EDS to check their composition. The results show that the gas atmosphere had a strong effect on the particle size and shape. Hydrogen made particles more pure but also bigger and less uniform for silver, while argon gave more and smaller particles that looked more similar. For copper, using 600 °C and 650 °C made even smaller ones but with more clumping, which could help in catalytic use. For the Cu-Ag powders, the ratio of the two metals affected how stable the powders were: a 1:1 ratio gave small, uniform, core-shell particles without oxidation, while a 1:3 ratio caused clumping and surface oxidation. This work shows that gas type, temperature, and metal ratio are key to controlling the final powders with tunable surfaces and better stability. A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use, the Université Felix Houphouët-Boigny, Cote d’Ivoire, and the Jülich Forschungszentrum in partial fulfillment of the requirements for the International Master Program in Renewable Energy and Green Hydrogen (Green Hydrogen Production and Technology)

Investigation of Electronic and Ionic Structures of Selected High Entropy Chlorides for Application as an Electrode in Batteries

2026-02-12T10:59:36Z

Investigation of Electronic and Ionic Structures of Selected High Entropy Chlorides for Application as an Electrode in Batteries Jalloh, Mamaja The integration, growth, and penetration of renewable energy requires durable, cost-effective, and sophisticated materials for energy storage. Current Lithium-ion batteries (LIBs) are the major players due to their longer cycle life, high energy density, and other advantages; however, their performance is limited by the materials used for the cathodes, namely the common transition oxides. High-entropy materials (HEMs) and high-entropy chlorides (HECls) are promising alternatives due to their entropy stability and optimised transport properties. This work explores electronic and ionic structures of such systems as Li2[Me2+]Cl4 where Me is Zn, Mn, Co, Mg, and Fe to crown their potential as cathode materials. Density functional theory (DFT) calculations using the Quantum ESPRESSO package were done by including both constant and element-dependent Hubbard U corrections to consider the present correlation effects due to transition-metal d-orbitals suitably. From the analysis, the density of states (DOS), band structure, and the spin polarisation in single-component as well as multi-component chlorides were focused on. Binary chlorides such as, FeCl4, MnCl4, and CoCl4 exhibit an insulating nature through intense spin polarisation, while ZnCl4 and MgCl4 are wide-bandgap non-magnetic insulators. Multi-component high-entropy chlorides exhibit a broader electronic-state distribution across the Fermi surface, characterised by d-bands, resulting in a range of semiconductor or insulating properties. The results show that the entropy effect found in high-entropy chlorides results in substantial electronic changes, which can potentially enhance the conductivity and cycling stability of the single-component counterparts. The electronic density of states computed here will facilitate and help to explain the subsequent experimental results (XANES, EXAFS) from Forschungszentrum Jülich colleagues. This work maps out a pathway to developing high-entropy halide cathodes and suggests Li2[Me2+]Cl4 as potential materials for next-generation rechargeable batteries. A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use, the Université Felix Houphouët-Boigny, Cote d’Ivoire, and the Jülich Forschungszentrum in partial fulfillment of the requirements for the International Master Program in Renewable Energy and Green Hydrogen (Green Hydrogen Production and Technology)