1. From waste to hydrogen: utilizing waste as feedstock or catalysts for hydrogen generationDavid Tian Hren, Andreja Nemet, Danijela Urbancl, 2025, review article Abstract: With the world facing the twin pressures of a warming climate and an ever-increasing amount of waste, it is becoming increasingly clear that we need to rethink the way we generate energy and use materials. Despite growing awareness, our energy systems are still largely dependent on fossil fuels and characterized by a linear ‘take-make-dispose’ model. This leaves us vulnerable to supply disruptions, rising greenhouse gas emissions, and the depletion of critical raw materials. Hydrogen is emerging as a potential carbon-free energy vector that can overcome both challenges if it is produced sustainably from renewable sources. This study reviews hydrogen production from a circular economy perspective, considering industrial, agricultural, and municipal solid waste as a resource rather than a burden. The focus is on the reuse of waste as a catalyst or catalyst support for hydrogen production. Firstly, the role of hydrogen as a new energy carrier is explored along with possible routes of waste valorization in the process of hydrogen production. This is followed by an analysis of where and how catalysts from waste can be utilized within various hydrogen production processes, namely those based on using fossil fuels as a source, biomass as a source, and electrocatalytic applications.
Keywords: hydrogen production, waste-derived catalysts, renewable energy, biomass conversion
Published in DKUM: 25.09.2025; Views: 0; Downloads: 7
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2. Deactivation of copper electrocatalysts during CO [sub] 2 reduction occurs via dissolution and selective redeposition mechanismBlaž Tomc, Marjan Bele, Mohammed Azeezulla Nazrulla, Primož Šket, Matjaž Finšgar, Angela Šurca Vuk, Ana Rebeka Kamšek, Martin Šala, Jan Šiler Hudoklin, Matej Huš, Blaž Likozar, Nejc Hodnik, 2025, original scientific article Abstract: As electrochemical CO2 reduction (ECR) nears industrialisation levels, addressing the uncontrolled stability, restructuring, and deactivation of copper (Cu) catalysts during operation becomes as crucial as achieving high activity and selectivity for a single product. This study used a high-surface area Cu catalyst that exhibited changes in ECR product selectivity over prolonged operation. The detection of dissolved Cu species during electrolysis confirmed an intermediates-mediated Cu dissolution mechanism at ECR potentials (−0.8 to −1.1 V vs. reversible hydrogen electrode). The findings suggest that the electrodeposition of dissolved Cu species is biased towards Cu catalyst sites with lower reaction intermediates coverage, e.g. adsorbed CO (*CO). A dynamic equilibrium between dissolution and subsequent selective redeposition gradually led to morphological restructuring, resulting in a shift in selectivity away from ECR and towards hydrogen production. With the obtained extensive experimental results, theoretical modelling, and literature data, four interconnected parameters governing restructuring and selectivity shifts were recognised: (i) size and (ii) crystallographic orientation of facets rsc.li/materials-a Introduction of the nanoparticles, (iii) *CO coverage and (iv) CObridge vs. COatop ratio.
Keywords: elektrokemija, katalizatorji, baker, proizvodnja vodika, electrochemistry, catalysts, copper, hydrogen production
Published in DKUM: 20.03.2025; Views: 0; Downloads: 4
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3. (Magnetic) cross-linked enzyme aggregates of cellulase from T. Reesei: a stable and efficient biocatalystDušica Ifko, Katja Vasić, Željko Knez, Maja Leitgeb, 2023, original scientific article Keywords: immobilized catalysts, biocatalysis, enzymes, cellulase activity, CLEAs, mCLEAs, optimization, characterization, parameters
Published in DKUM: 06.12.2023; Views: 501; Downloads: 172
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4. Preparation of WO[sub]3 aerogel catalysts using supercritical CO[sub]2Zoran Novak, Petra Kotnik, Željko Knez, 2004, original scientific article Abstract: Single tungsten oxide aerogels (WO3), binary oxide aerogels (WO3-Al2O3) and ternary oxide aerogels (WO3-SiO2-Al2O3) were prepared using standard sol-gel route. Tungsten oxide tetraethoxide (WO(OCH2CH3)4) was used as the sol-gel precursor. The excellent properties of the gels obtained by the sol-gel synthesis were preserved upon supercritical drying with CO2. After supercritical drying at 40 °C and 100 bar, all aerogels were calcined to 800 °C. The influence of the synthesis parameters on the catalytic activity of WO3as supported on silica andžor alumina aerogels was investigated through thetransformation of N-(phosphonomethyl)iminodiacetic acid to N-(phosphonomethyl)glycine. Despite including WO3 into single and mixed silicaand alumina aerogels, high specific surface areas (284-653 m2 g-1) were preserved. Higher conversion was obtained for catalysts with higher ratios of WO3 in the mixed silica-alumina aerogels that were calcined at 800 °C.
Keywords: chemical processing, aerogels, catalysts, tungsten oxides, preparation of aerogels, characterisation of aerogels, supercritical CO2, supercritical drying, high pressure technology
Published in DKUM: 01.06.2012; Views: 2113; Downloads: 53
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