TY - JOUR A1 - Kazamer, Norbert A1 - Tack, Meike A1 - Spree, Mathias A1 - Underberg, Martin A1 - Rost, Ulrich A1 - Reichenberger, Sven A1 - Cieluch, Maximilian A1 - Salih, Haujin A1 - Wirkert, Florian Josef A1 - Böhm, Leonard A1 - Roth, Jeffrey A1 - Nallathambi, Varatharaja A1 - Gault, Baptiste A1 - Baer, Christoph A1 - Orend, Kerstin A1 - Barcikowski, Stephan A1 - Hülser, Tim A1 - Brodmann, Michael T1 - Ultrasonically Deposited Boron-Doped Silicon Decorated with Laser-Generated Iridium Nanoparticles as Manufacturing Approach for OER Electrodes in PEM Water Electrolysis JF - Advanced Materials Interfaces N2 - The study introduces flexible and scalable manufacturing approach for electrodes utilizing boron-doped silicon as conductive support for iridium nanoparticles, addressing the challenges of cost and scarcity associated with noble catalysts for oxygen evolution reaction (OER). Colloidal Ir nanoparticles are synthesized via pulsed-laser ablation (≈4–7 nm) and decorated on B-doped Si (≈100 nm) through electrostatic adsorption. Titanium substrates are ultrasonically sprayed with Si:B – Ir and Ir nanoparticles with very low iridium loading of 12 wt.%. Crystalline Ir phases (Ir(111), Ir(200)) are observed and known to enhance the OER mechanism. Additionally, atom probe tomography confirms that the Si support particles contained 0.03-0.5 at.% of boron throughout the entire particle, while electrical permittivity and through-plane measurements reveal a positive impact of B-doped Si on the electrical conductivity of the nanocatalysts and of the ultralow-loaded catalyst coated Ti substrates (0.12 mgIr cm−2), respectively. Rotating disk electrode results show pronounced oxidation peaks for decorated Ir nanoparticles. The Si:B-Ir 4 nm catalyst exhibits the highest turnover frequency (2.62 s−1) and a competitive electrochemical surface area (25 m2 gIr−1) compared to Si:B-Ir 7 nm (0.96 s−1; 37.5 m2 gIr−1) and Ir black (0.24 s−1; 5 m2 gIr−1). The overall analysis of the parameters highlights a performant catalytic efficiency, through balancing activity and reaction kinetics effectively. KW - PEM Water Electrolysis KW - OER Electrodes Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:1010-opus4-46883 VL - 2025 IS - Volume 12, Issue 8 PB - Wiley ER - TY - JOUR A1 - Böhm, Leonard A1 - Cieluch, Maximilian A1 - Kazamer, Norbert A1 - Wirkert, Florian Josef A1 - Marginean, Gabriela A1 - Apfel, Ulf-Peter A1 - Brodmann, Michael T1 - Electrodeposition of Mo-Rich NiMo Catalysts: Effect of Deposition Parameters and Oxygen Content on the Alkaline Hydrogen Evolution Reaction Activity JF - ChemElectroChem N2 - Electrodeposited Mo-rich NiMo catalysts offer enhanced catalytic activity for the alkaline hydrogen evolution reaction (HER) and provide an electrically conductive, binder-free substrate connection, making them promising catalysts for green hydrogen production. However, creating Mo-rich deposits is challenging, as the codeposition process typically favors Ni. Optimal deposition conditions for Mo-rich NiMo catalysts remain insufficiently explored. This article investigates Mo-rich NiMo electrodeposition from an ammonia-free citrate bath using NaSO4 as a chlorine-free support electrolyte. The effects of the deposition parameters, 1) sodium molybdate concentration in the electrolyte, 2) deposition current density, and 3) enhanced mass transport via working electrode rotation on the alkaline HER activity, were studied. The electrodeposits, containing 44–66 wt% Mo, exhibited increased surface area due to a rough, cracked morphology and variable oxygen content of the catalyst. The oxygen content was linked to HER activity, revealing an inhibiting effect. The lowest overpotential of 118 mV at −10  mA cm−2 for the alkaline HER was achieved using an electrolyte with 0.02 mol L−1 sodium molybdate, a deposition current density of 600 mA cm−2, without electrode rotation. Respective samples combined a favorable Ni:Mo ratio comprising 56 wt% Mo content with increased surface area and low oxygen content. Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:1010-opus4-48327 VL - 2025 PB - Wiley-VCH ER -