Bahareh Feizi Mohazzab

Zusammenfassung: Die elektrochemische Reduktion von Stickstoffverbindungen bietet einen nachhaltigen Ansatz zur Minderung der Stickstoffbelastung der Umwelt und ermöglicht gleichzeitig die Herstellung wertvoller Chemikalien wie Ammoniak, Hydroxylamin und C–N‐gekoppelter organischer Stickstoffverbindungen. Die praktische Umsetzung herkömmlicher potentiostatischer Verfahren wird jedoch durch eine geringe Produktselektivität und die konkurrierende Wasserstoffentwicklung behindert. Die gepulste Elektrolyse hat sich als transformative Strategie erwiesen, um diese Herausforderungen zu bewältigen, indem sie die Dynamik der Katalysatoroberfläche mit lokalen mikroumweltbedingten Veränderungen und der Reaktionskinetik synchronisiert. Diese Mini‐Übersicht beleuchtet die jüngsten Fortschritte in der gepulsten Elektrolyse zur Reduktion von Stickstoffverbindungen, mit besonderem Fokus darauf, wie dynamische Potenziale das Verhalten von Elektrokatalysatoren und die Reaktionsumgebung beeinflussen. Wichtige mechanistische Erkenntnisse und innovative Forschungsergebnisse werden diskutiert, gefolgt von einem Ausblick auf etablierte Systeme und zukünftige Entwicklungen hin zu einer skalierbaren und energieeffizienten Stickstoffaktivierung.

The electrochemical reduction of nitrogen species offers a sustainable route to mitigate environmental nitrogen pollution while enabling the production of value‐added chemicals such as ammonia, hydroxylamine, and C─N coupled organonitrogen compounds. However, the practical implementation of conventional potentiostatic methods is hindered by poor product selectivity and competing hydrogen evolution. Pulsed electrolysis has emerged as a transformative strategy to address these challenges by synchronizing catalyst surface dynamics with local microenvironmental changes and reaction kinetics. This mini‐review highlights recent advances in pulsed electrolysis for nitrogen species reduction, with a particular focus on how dynamic potentials influence electrocatalyst behavior and the surrounding reaction environment. Key mechanistic insights and cutting‐edge research findings are discussed, followed by an outlook on established systems and future directions toward scalable and energy‐efficient nitrogen activation.

The electrochemical reduction of nitrogen species offers a sustainable route to mitigate environmental nitrogen pollution while enabling the production of value-added chemicals such as ammonia, hydroxylamine, and C–N coupled organonitrogen compounds. However, the practical implementation of conventional potentio-static methods is limited by poor product selectivity and competing hydrogen evolution. Pulsed electrolysis has emerged as a transformative strategy to address these challenges by synchronizing catalyst surface dynamics with reaction kinetics and microenvironmental changes. This mini-review highlights recent advances in pulsed electrolysis for nitrogen species reduction, with a particular emphasis on how dynamic potentials influence electrocatalyst modulation and the reaction microenvironment. Key mechanistic insights and cutting-edge research findings are discussed, followed by an outlook on current challenges and future directions toward scalable, energy-efficient nitrogen activation.

Electrochemical nitrate reduction represents a promising pathway for sustainable ammonia production, yet its practical deployment is constrained by the limited efficiency of current electrocatalysts and underdeveloped system architectures. Here, we report the rational design of a self-assembled copper–nickel–tungsten tri-component electrocatalyst synthesized via a sequential microwave–hydrothermal route. Under pulsed electrolysis conditions, the catalyst achieves a remarkable Faradaic efficiency of 97.1% and a high ammonia yield rate of 43.87 mg h-1 cm-2. Online differential electrochemical mass spectrometry (DEMS) reveals key reaction intermediates, while density functional theory (DFT) calculations uncover a synergistic interplay among the metal components: Cu facilitates nitrate adsorption and deoxygenation, Ni promotes water dissociation for *H generation, and W serves as a dynamic *H reservoir. This cooperative mechanism suppresses the hydrogen evolution reaction and enhances ammonia selectivity. Furthermore, coupling with glucose oxidation as the anodic reaction demonstrates the potential for energy-efficient ammonia electrosynthesis. This work offers mechanistic insights and design strategies for next-generation multi-component electrocatalysts aimed at scalable and sustainable nitrogen-based chemical production.

Ammonium nitrate (NH4NO3) is one of the most widely produced bulk chemicals globally with a production of approximately 50 Mt per year. NH4NO3 is produced by the Haber-Bosch process (which converts elemental nitrogen to ammonia), followed by the Ostwald process (which converts ammonia to nitric acid). These thermal catalytic processes are estimated to contribute approximately 2 % of the global annual energy demand. In contrast, photocatalysis is a promising alternative for the direct conversion of nitrogen into nitrogen-containing compounds under mild reaction conditions. However, using photocatalysis for the simultaneous production of ammonium and nitrate in one reactor ( so-called overall nitrogen fixation) is still challenging. Herein, we report a proof-of-principle study that demonstrates the direct gas-phase photocatalytic conversion of elemental nitrogen into ammonium nitrate. As a heterogeneous photocatalyst, we used cobalt-containing polyoxometalate Na10[Co4(H2O)2(PW9O34)2] deposited on commercial TiO2 nanoparticles (P25). UV-light irradiation of a gaseous mixture of nitrogen (N-source), water (proton source), and oxygen (oxidant) at 150 °C resulted in the simultaneous production of ammonium and nitrate, as well as a minor amount of nitrite. Mechanistic studies provide initial insights into the performance and stability of heterogeneous catalysts. This study opens a new paradigm for photochemical production of ammonium nitrate from nitrogen, oxygen, and water.

A comprehensive review of advanced design strategies of nanostructured 2D electrodes for sustainable biomass valorization coupled with the HER.

Electrocatalytic water splitting driven by renewable energy is a promising strategy for sustainable hydrogen production. However, the slow oxygen evolution reaction (OER) kinetics severely limit the rate of the hydrogen evolution reaction (HER) and the overall energy conversion efficiency of the water electrolyzer. To overcome this challenge, hybrid water electrolysis systems have been developed which replace the sluggish OER with thermodynamically and kinetically favorable biomass (photo-)electro-oxidation. In addition, these system allow for the simultaneous production of value-added chemical products. This review highlights the design strategies related to the host structure remodeling and structure assembly design of two-dimensional (2D) nanomaterial-based (photo)electrocatalysts, as well as their wide application in hybrid water electrolysis. Moreover, the current challenges and emerging strategies for the development of advanced (photo-)electrocatalysts and industrial-scale systems are emphasized.

Radio frequency plasma is one of the means to modify the polymer surface namely in the activation of polypropylene membranes (PPM) with O₂ plasma. Activated membranes were deposited with TiO₂ nanoparticles by the dip coating method and the bare sample and modified sample (PPM5-TiO₂) were irradiated by UV lamps for 20–120 min. Characterization techniques such as X-ray diffraction (XRD), Attenuated total reflection technique- Fourier transform infrared spectroscopy (ATR-FTIR), Thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), Scanning electron microscope (SEM) and water contact angle (WCA) measurements were applied to study the alteration of ensuing membrane surface properties which shows the nanoparticles on the sample surface including the presence of Ti on PPM. The WCA decreased from 135° (PPM) to 90° (PPM5-TiO₂) and after UV irradiation, the WCA of PPM5-TiO₂ diminished from 90° to 40°.

The immobilization of palladium nanoparticles (Pd NPs) on stainless-steel mesh is described in two short steps via deposition of graphene oxide (GO) on the stainless-steel mesh (mesh-GO) by electrophoretic deposition (EPD), preparation of Pd NPs using laser ablation in liquids (LAL) and finally the immobilization of Pd NPs on the mesh-GO by immersion in a Pd NP colloidal solution. The novel, efficient and reusable mesh-GO/Pd catalyst was characterized by various techniques such as SEM, EDS, UV-Vis and FT-IR spectroscopy and its catalytic activity was investigated for the Suzuki–Miyaura and Stille coupling reactions in ethanolic water.