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- Benzimidazole Schiff base copper(II) complexes as catalysts for environmental and energy applications: VOC oxidation, oxygen reduction and water splitting reactionsPublication . Paul, Anup; Silva, Tiago A. R.; Soliman, Mohamed M. A.; Karacic, Jozo; Sljukic, Biljana; Alegria, Elisabete; Khan, Rais Ahmad; Guedes Da Silva, M. Fátima C.; Pombeiro, ArmandoThe new copper(II) complexes [Cu(mu-1 kappa O:2 kappa ONN'-HL1)(mu-1 kappa O:2 kappa O'-NO3)](2)center dot[Cu(mu-1 kappa O:2 kappa ONN'-HL1)(CH3OH)](2)(NO3)(2) (1) and [Cu(kappa ONN'-HL2)(mu-1 kappa OO':2 kappa O'-NO3)](n) (2), derived from the new pro-ligands H(2)L1 = 2-(5,6-dihydroindolo[1,2-c]quinazolin-6-yl)-5-methylphenol and H(2)L2 = 2-(5,6-dihydroindolo[1,2-c]quinazolin-6-yl)-4-nitrophenol, were synthesized and characterized by elemental analysis, FT-IR, ESI-MS, and their structural features were unveiled by single-crystal X-ray diffraction analysis. This discloses a dimeric structure for 1 and a polymeric infinite 1D metal-organic chain for 2. The complexes were evaluated as catalysts for the oxidation of toluene, a volatile organic compound (VOC), and for oxygen reduction and water splitting reactions. 1 exhibits a higher activity for the peroxidative conversion of toluene to oxygenated products (total yields up to 38%), whereas 2 demonstrates a superior performance for electrochemical energy conversion applications, i.e., for oxygen reduction (ORR), oxygen evolution (OER) and hydrogen evolution (HER) reactions in an alkaline medium in terms of higher ORR current densities, lower Tafel slope (73 mV dec(-1)) and higher number of electrons exchanged (3.9), comparable to that of commercial Pt/C. Complex 2 also shows a better performance with lower onset potential and higher current densities for both OER and HER when studied as electrocatalyst for water splitting.
- Carbon aerogels and xerogels: next-generation materials for sustainable energy and environmental solutionsPublication . Tomić, David; Radinović, Kristina; Mladenović, Dušan; Milikić, Jadranka; Santos, Diogo; Pombeiro, Armando; Paul, Anup; Sljukic Paunkovic, BiljanaAbstract Carbon aerogels and xerogels, with their 3D porous architectures, ultralow density, high surface area, and excellent conductivity, have emerged as multifunctional materials for energy and environmental applications. This review highlights recent advances in the synthesis of these materials via polymerisation, drying, and carbonisation, as well as the role of novel precursors such as graphene, carbon nanotubes, and biomass. Emphasis is also placed on doped and metal-decorated carbon gels as efficient electrocatalysts for oxygen reduction reactions, enabling four- and two-electron pathways for energy conversion and the production of green H2O2, respectively. Aerogels’ high specific capacitance and stability also position them as promising materials for supercapacitors. The versatility of carbon aerogels and xerogels offers exciting prospects for future innovations in catalysis, energy storage, and sustainable technologies.
- Low-cost transition metals (Fe, Ni, Co) on carbon aerogel for water electrolysis and supercapacitor applicationsPublication . Mladenović, Dušan; Martins, Marta; Samanci, Meryem; Charneca, Miguel; Paul, Anup; Santos, Diogo; Bayrakçeken, Ayşe; Sljukic Paunkovic, BiljanaAbstract Cost-effective transition metals (TM = Fe, Ni, Co) were immobilized on carbon aerogel (CA) using microwave irradiation, followed by nitrogen doping into one catalyst series through heat treatment. The physical characterization of the synthesized catalysts included N2 sorption, inductively coupled plasma-mass spectrometry, X-ray diffraction analysis, transmission electron microscopy, Raman spectroscopy, FTIR spectroscopy, and X-ray photoelectron spectroscopy. Co/CA displayed the best performance for oxygen evolution reaction (OER) electrocatalysis in alkaline water electrolysis, followed by Ni/CA. Co/CA exhibited a small Tafel slope of 110 mV dec−1 and required an overpotential of just 276 mV to reach 10 mA cm−2, lower than that of the commercial IrO2 electrocatalyst. Additionally, Co/CA and Ni/CA demonstrated excellent long-term stability during OER, with activity increasing over time. Capacitance measurements also showed the potential of TM/CA materials as supercapacitor electrodes. Fe/CA achieved the highest performance, with a specific capacitance of 322 F g-1 at a moderate current of 1 A g-1. It retained up to 96 % of its capacitance over 1000 cycles, indicating excellent stability.