Band edge engineering of TiO2@DNA nanohybrids and implications for capacitive energy storage devices

DNA: Novel Crystallization Regulator for Solid Polymer Electrolytes in High-Performance Lithium-Ion Batteries

In this work, we designed a novel polyvinylidene fluoride (PVDF)@DNA solid polymer electrolyte, wherein DNA, as a plasticizer-like additive, reduced the crystallinity of the solid polymer electrolyte and improved its ionic conductivity. At the same time, due to its Lewis acid effect, DNA promotes the dissociation of lithium salts when interacting with lithium salt anions and can also fix the anions, creating more free lithium ions in the electrolyte and thus improving its ionic conductivity. However, owing to hydrogen bonding between DNA and PVDF, excess DNA occupies the lone pairs of electrons of the fluorine atoms on the PVDF molecular chains, affecting the conduction of lithium ions and the conductivity of the solid electrolyte. Hence, in this study, we investigated the effects of adding different DNA amounts to solid polymer electrolytes. The results show that 1% DNA addition resulted in the best improvement in the electrochemical performance of the electrolyte, demonstrating a high ionic conductivity of 3.74 × 10-5 S/cm (25 °C). The initial capacity reached 120 mAh/g; moreover, after 500 cycles, the all-solid-state batteries exhibited a capacity retention of approximately 71%, showing an outstanding cycling performance.

Synergistic redox enhancement: silver phosphate augmentation for optimizing magnesium copper phosphate in efficient energy storage devices and oxygen evolution reaction

The implementation of battery-like electrode materials with complicated hollow structures, large surface areas, and excellent redox properties is an attractive strategy to improve the performance of hybrid supercapacitors. The efficiency of a supercapattery is determined by its energy density, rate capabilities, and electrode reliability. In this study, a magnesium copper phosphate nanocomposite (MgCuPO4) was synthesized using a hydrothermal technique, and silver phosphate (Ag3PO4) was decorated on its surface using a sonochemical technique. Morphological analyses demonstrated that Ag3PO4 was closely bound to the surface of amorphous MgCuPO4. The MgCuPO4 nanocomposite electrode showed a 1138 C g-1 capacity at 2 A g-1 with considerably improved capacity retention of 59% at 3.2 A g-1. The increased capacity retention was due to the fast movement of electrons and the presence of an excess of active sites for the diffusion of ions from the porous Ag3PO4 surface. The MgCuPO4-Ag3PO4//AC supercapattery showed 49.4 W h kg-1 energy density at 550 W kg-1 power density and outstanding capacity retention (92% after 5000 cycles). The experimental findings for the oxygen evolution reaction reveal that the initial increase in potential required for MgCuPO4-Ag3PO4 is 142 mV, indicating a clear Tafel slope of 49 mV dec-1.

Density Functional Tight Binding Theory Approach for the CO2 Reduction Reaction Paths on Anatase TiO2 Surfaces

Herein, we have investigated the CO₂ reduction paths on the (101) anatase TiO₂ surface using an approach based on the density functional tight binding (DFTB) theory. We analyzed the reaction paths for the conversion of carbon dioxide to methane by performing a large number of calculations with intermediates placed in various orientations and locations at the surface. Our results show that the least stable intermediate is CO₂H and therefore a key bottleneck is the reduction of CO₂ to formic acid. Hydrogen adsorption is also weak and would also be a limiting factor, unless very high pressures of hydrogen are used. The results from our DFTB approach are in good agreement with the hybrid functional based density functional theory calculations presented in the literature.

Electric Double Layer and Orientational Ordering of Water Dipoles in Narrow Channels within a Modified Langevin Poisson-Boltzmann Model

The electric double layer (EDL) is an important phenomenon that arises in systems where a charged surface comes into contact with an electrolyte solution. In this work we describe the generalization of classic Poisson-Boltzmann (PB) theory for point-like ions by taking into account orientational ordering of water molecules. The modified Langevin Poisson-Boltzmann (LPB) model of EDL is derived by minimizing the corresponding Helmholtz free energy functional, which includes also orientational entropy contribution of water dipoles. The formation of EDL is important in many artificial and biological systems bound by a cylindrical geometry. We therefore numerically solve the modified LPB equation in cylindrical coordinates, determining the spatial dependencies of electric potential, relative permittivity and average orientations of water dipoles within charged tubes of different radii. Results show that for tubes of a large radius, macroscopic (net) volume charge density of coions and counterions is zero at the geometrical axis. This is attributed to effective electrolyte charge screening in the vicinity of the inner charged surface of the tube. For tubes of small radii, the screening region extends into the whole inner space of the tube, leading to non-zero net volume charge density and non-zero orientational ordering of water dipoles near the axis.

Bifunctional electrochromic-energy storage materials with enhanced performance obtained by hybridizing TiO2 nanowires with POMs

A bifunctional electrochromic-energy storage film with enhanced performance is designed and fabricated by hybridizing TiO₂ nanowires with POMs.

Layered Double Hydroxide-Based Functional Nanohybrids as Controlled Release Carriers of Pharmaceutically Active Ingredients

The chemical stability, degradation and penetration ability of pharmaceutically active ingredients in topical formulations are the greatest challenges because of problems with the protection of actives for long times and with delivery. Therefore, the development of unique and efficient substrate material is vital for their protection and controlled drug release. Layered double hydroxides (LDHs) known as hydrotalcite like compounds possess positive charges due to isomorphic substitutions, which are counterbalanced by hydrated exchangeable anions located in the interlayer region. Some of the active ingredient molecules can be intercalated into the inner region of the LDHs through ionic bonding, hydrogen bonding or van der Waals interaction to form nanohybrids, which are more potent for their protection and controlled-release. This account focuses on our recent research efforts and key scientific and technical challenges in the development of LDH based nanohybrids for commercial use in advanced controlled release carriers of active ingredients in topical formulations.

Multifunctional Gadolinium-Doped Mesoporous TiO2 Nanobeads: Photoluminescence, Enhanced Spin Relaxation, and Reactive Oxygen Species Photogeneration, Beneficial for Cancer Diagnosis and Treatment

Materials with controllable multifunctional abilities for optical imaging (OI) and magnetic resonant imaging (MRI) that also can be used in photodynamic therapy are very interesting for future applications. Mesoporous TiO₂ sub-micrometer particles are doped with gadolinium to improve photoluminescence functionality and spin relaxation for MRI, with the added benefit of enhanced generation of reactive oxygen species (ROS). The Gd-doped TiO₂ exhibits red emission at 637 nm that is beneficial for OI and significantly improves MRI relaxation times, with a beneficial decrease in spin-lattice and spin-spin relaxation times. Density functional theory calculations show that Gd³⁺ ions introduce impurity energy levels inside the bandgap of anatase TiO₂ , and also create dipoles that are beneficial for charge separation and decreased electron-hole recombination in the doped lattice. The Gd-doped TiO₂ nanobeads (NBs) show enhanced ability for ROS monitored via ^• OH radical photogeneration, in comparison with undoped TiO₂ nanobeads and TiO₂ P25, for Gd-doping up to 10%. Cellular internalization and biocompatibility of TiO₂ @xGd NBs are tested in vitro on MG-63 human osteosarcoma cells, showing full biocompatibility. After photoactivation of the particles, anticancer trace by means of ROS photogeneration is observed just after 3 min irradiation.

On/off-switchable anti-neoplastic nanoarchitecture

Throughout the world, there are increasing demands for alternate approaches to advanced cancer therapeutics. Numerous potentially chemotherapeutic compounds are developed every year for clinical trial and some of them are considered as potential drug candidates. Nanotechnology-based approaches have accelerated the discovery process, but the key challenge still remains to develop therapeutically viable and physiologically safe materials suitable for cancer therapy. Here, we report a high turnover, on/off-switchable functionally popping reactive oxygen species (ROS) generator using a smart mesoporous titanium dioxide popcorn (TiO₂ Pops) nanoarchitecture. The resulting TiO₂ Pops, unlike TiO₂ nanoparticles (TiO₂ NPs), are exceptionally biocompatible with normal cells. Under identical conditions, TiO₂ Pops show very high photocatalytic activity compared to TiO₂ NPs. Upon on/off-switchable photo activation, the TiO₂ Pops can trigger the generation of high-turnover flash ROS and can deliver their potential anticancer effect by enhancing the intracellular ROS level until it crosses the threshold to open the ‘death gate’, thus reducing the survival of cancer cells by at least six times in comparison with TiO₂ NPs without affecting the normal cells.