The generation of porous silica with hierarchically organized bimodal mesoporosity of adjustable size and well-defined shape was investigated by using surfactant mixtures and the nanocasting procedure (liquid crystalline templating). A systematic study of combinations of various block copolymers (Pluronics F127, KLE (poly(omega-hydroxypoly(ethylene-co-butylene)-co-poly(ethylene oxide))) and SE (PS-co-PEO)) with smaller surfactants (Pluronics P123, C16mimCl, and CTAB) revealed that hierarchical bimodal mesopore architectures could only be obtained by the usage of block copolymers with a strong hydrophilic-hydrophobic contrast, such as KLE and SE, giving rise to pores between 6 and 22 nm. Furthermore, the ionic liquid (IL) C16mimCl appeared to have advantageous templating properties, resulting in 2-3-nm pores being located between the block copolymer mesopores, whereas phase separation was observed for Pluronics and CTAB as small templates. Thereby, the study provided also general insights into the mixing and co-self-assembly behavior of block copolymers and ionic surfactants in water and confirmed the special templating properties of ILs, as recently proposed. In addition to the bimodal mesoporosity, additional tunable macroporosity was created by the presence of poly(styrene) or poly(methyl methacrylate) spheres, leading to well-defined trimodal hierarchical pore architectures with the small pores being located in the walls of the respective larger pores. As a major improvement, due to the pore hierarchy, these large-pore materials showed relatively large surface areas and pore volumes, and the size of densely packed macropores could even be decreased down to 90 nm. The materials were characterized by electron microscopy, small-angle X-ray scattering, and nitrogen sorption using a proper NLDFT (nonlocal density functional theory) approach for calculations of the pore size distribution in the entire range of micro- and mesopores.

metric and dynamic deconvolution of global EQCM response of carbon nanotube based electrodes by Ac-electrogravimetry. Electrochemistry Communications, Elsevier, 2016, 70, pp.73 -77

Fast ionic transfer and transport properties continue to be one of the main pressing research concerns regarding energy storage materials (batteries, supercapacitors). Accompanying this search for optimal materials, appropriate characterization tools to assess key parameters of newly developed materials are required. In spite of its great relevance, fast electrogravimetric methods, i.e., coupling fast quartz crystal microbalance (QCM) and electrochemical impedance spectroscopy (EIS) (ac-electrogravimetry), have not yet been used for studying transfer and transport phenomena in materials for charge storage (except for the use of QCM along with cyclic voltammetry experiments (EQCM)). This coupled method, socalled ac-electrogravimetry, differs from classical EQCM and measures the usual electrochemical impedance, ΔE/ΔI (ω), and the mass variations of the film under a sinusoidal potential perturbation, Δm/ΔE (ω), simultaneously. This coupling has the ability to detect the contribution of the charged or uncharged species and to separate the anionic, cationic, and free solvent contributions during the various (pseudo)capacitive processes. The Li-birnessite type MnO 2 thin films were studied in two different media, LiClO 4 and NaClO 4 , by ac-electrogravimetry. The Li + ions, Na + ions, and their respective hydrated ionic species are detected to be involved in the pseudocapacitive charge storage of Li-birnessite type MnO 2 thin films. The kinetics (fc i ) and resistance (Rt i ) of charged and noncharged species transferred at the electrode/electrolyte interfaces and the number of water molecules in the hydration shell of the ions are estimated considering integer values. The opposite flux direction of free water molecules was also detected by ac-electrogravimetry. This indicates that there is a population of hydrated Li + or hydrated Na + ions losing their hydration shell before being transferred at the electrode/electrolyte interfaces. Therefore, the effect of desolvation is clearly and experimentally demonstrated. The ac-electrogravimetry responses of the electrodeposited Li-birnessite type MnO 2 thin films can serve as a gravimetric probe for studying the charge-storage mechanisms and extracting subtleties unreachable with classical tools.