Archive for category: Publications

New paper published in Desalination on the ion selectivity of carbon nanopores. It is well known that electrolyte confinement inside carbon nanopores strongly affects ion electrosorption in capacitive deionization. A thorough understanding of the intricate pore size influence enables enhanced charge storage performance and desalination in addition to ion separation. In subnanometer pores, where the pore size is smaller than hydrated ion size, a dehydration energy barrier must be overcome before the ions can be electrosorbed into the pores. Ion sieving is observed when the dehydration energy is larger than the applied energy. However, when a high electrochemical potential is used, the ions can desolvate and enter the pores. Capitalizing on the difference in size and dehydration energy barriers, this work applies the subnanometer porous carbon material, and a high electrochemical ion selectivity for Cs⁺ and K⁺ over Na⁺, Li⁺, Mg²⁺, and Ca²⁺ is observed. This establishes a viable way for selective heavy metal removal by varying pore and solvated ion sizes. Our work also shows the transition from double-layer capacitance to diffusion-limited electrochemical features in narrow ultramicropores.

New paper entitled “Spray-dried pneumococcal membrane vesicles are promising candidates for pulmonary immunization” published in the International Journal of Pharmaceutics. This collaborative work spearheaded by experts from the Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) and Saarland University explores optimized vaccine microparticles with a mean particle size of 1–2 µm, corrugated surface, and nanocrystalline nature.

New paper published in the Journal of Materials Chemistry A. Our work entitled “Design of high-performance antimony/MXene hybrid electrodes for sodium-ion batteries” explores the synergy of the 2D nanomaterial MXene (conductive, nanotextured) and antimony (large sodium-ion storage capacity via alloying). This work is the latest outcome of our collaboration with the group and team of Riccardo Ruffo (Università degli Studi di Milano-Bicocca) and Stefano Marchionna (Ricerca sul Sistema Energetico). Special thanks to visiting Ph.D. student Antonio Gentile from Riccardo’s team!

New paper published in Chemical Engineering Journal. The work with the title “Electro-assisted removal of polar and ionic organic compounds from water using activated carbon felt” was done in collaboration with the Department of Environmental Engineering at the UFZ site in Leipzig.

New paper published in Advanced Energy Materials. Our work used densely carboxylated but conducting
graphene derivative (graphene acid) to enable effective operation without compromising the mechanical or chemical stability of the electrode. In our studies, we found a maximum performance of 800 mAh/g at a rate of 0.05 A/g and 174 mAh/g at 2.0 A/g. This Czech-German work was done in strong collaboration especially with the team of Aristides Bakandritsos from the Technical University of Ostrava.

New paper published in Cell Press Physical Science on the use of sub-nanometer pores for capacitive deionization to enable membrane-free seawater desalination. Big pores are mighty powerful when it comes to capacitive deionization (CDI). CDI is highly appreciated as a potentially energy-efficient desalination technology, rendering saline water into desalinated (potable/processable) water. However, once we move from saline media with low salt concentrations (like in brackish water regimes) towards higher salt concentrations (as you find in ordinary seawater), CDI become less attractive: the desalination capacity and charge efficiency (think of it as salt removal per invested charge) drop drastically. This issue is linked to the limited permselectivity of carbon pores commonly found in CDI electrodes. Put simply: the invested charge is not only used for adding “extra “ions into the pore (thereby: lowering the feedwater ion concentration) but also to eject ions that are already inside the pore (which basically increases the ion concentration in the effluent stream). We can address this issue by implementing an ion exchange membrane (adding costs and a more complex design) or using charge-transfer materials (giving rise to desalination batteries). But is there a way to keep low-cost, nanoporous carbon and still enable direct, membrane-free seawater desalination? The answer is a resounding YES. In our 2020 paper in Sustainable Energy & Fuels, we showed already the proof of concept of using quasi-ionophobic, and thereby permselective, carbon pores. Now, our work extends the scope and demonstrates this effect’s intricate pore size dependency. The key is a subtle play of pore size and hydrated ion diameter, which allows the pore to only uptake (extra) ions once an electric potential is applied. This work was a great collaboration with the team of Guang Feng at HUST, China, and Christian Prehal at ETH Zürich that puts together simulation and experimental work.

New paper published in ACS Applied Materials & Interfaces. This work in collaboration with the teams of Markus Gallei and Guido Kickelbick (both at Saarland University) explores shear-induced co-assembly as a step towards creating unique (ordered) materials. The latter can be conveniently converted to metal oxide / carbon hybrids via thermal annealing. For example, titanium niobium oxide / carbon obtained this way profided 335 mAh/g at 10 mA/g and a capacity retention of 84% after 1000 cycles at 250 mA/g.

New paper published in the AAAS journal Research on the use of hollow / nanosheet / needle-like cobalt hydroxide for the use for high performance electrochemical desalination. This material architecture allows for rapid ion removal and high stability in absence of strain-build-up. This work was done in collaboration with the team of Jie Ma at Tongji University.

New paper published in ACS Applied Polymer Materials on the use of redox-responsive 2-aminoanthraquinone core-shell particles for structural colors and carbon capture. This work was done in collaboration with the group of Markus Gallei (Saarland University), Karin Jacobs (Saarland University), and T. Alan Hatton (MIT).

New paper published in Sustainable Energy & Fuels on the degradation processes of lithium iron phosphate during electrochemical lithium recovery. Removal of dissolved oxygen suppresses the degradation but also coating of LFP with a thin layer of carbon. This work was done in collaboration with the group of Guido Kickelbick at Saarland University.