Graphene Oxide Membrane Reactor for Electrochemical Deuteration Reactions.

The deuteration of organic molecules is considerably important in organic and medicinal chemistry. An electrochemical membrane reactor using proton-conducting graphene oxide (GO) nanosheets was developed to synthesize valuable deuterium-labeled products via an efficient hydrogen-to-deuterium (H/D) exchange under mild conditions at ambient temperature and atmospheric pressure. Deuterons (D+) formed by the anodic oxidation of heavy water (D2O) at the Pt/C anode permeate through the GO membrane to the Pt/C cathode, where organic molecules with functional groups (C≡C and C═O) are deuterated with adsorbed atomic D species. Deuteration occurs in outstanding yields with high levels of D incorporation. We also achieved the electrodeuteration of a drug molecule, ibuprofen, demonstrating the promising feasibility of the GO membrane reactor in the pharmaceutical industry.

Temperature-Induced Nanostructure Transition for Supramolecular Gelation in Water.

Thermogel is an injectable biomaterial that functions at body temperatures due to the ease of the sol-to-gel transition. However, most conventional physically cross-linked thermogels generally have relatively low stiffness, which limits various biomedical applications, particularly for stem-cell-based studies. While chemical cross-linking through double-network (DN) structures can increase the stiffness of the hydrogel, they generally lack injectable and thermoresponsive properties due to strong covalent bonds between molecules. To address this challenge, we have developed a temperature-induced nanostructure transition (TINT) system for preparing physical DN supramolecular hydrogels. These hydrogels possess injectable, thermoreversible characteristics and relatively high storage modulus (G'), which increases ∼14-fold from 20 to 37 °C (body temperature). Our bottom-up strategy is based on the co-assembly of aromatic peptide (Ben-FF) and poly(ethylene glycol) (PEG) to form a thermogel at 37 °C through a nanofiber dissociation pathway that differs from the well-known micelle aggregation or polymer shrinkage mechanisms. Peptide molecules form helical packing and weak, noncovalent interactions with PEG, resulting in co-assembled metastable nanofibers. Thermal perturbation initiates lateral dissociation of nanofibers into extensively cross-linked DN nanostructures and subsequent hydrogelation (ΔG = -13.32 kJ/mol). The TINT hydrogel is nontoxic to human mesenchymal stem cells and supports enhanced cell adhesion, suggesting the potential of this strategy in the applications of tissue engineering and regenerative medicine.

Physicochemical characteristics and photocatalytic performance of TiO2/SiO2 catalyst synthesized using biogenic silica from bamboo leaves.

In this work, TiO2/SiO2 composite photocatalysts were prepared using biogenic silica extracted from bamboo leaves and titanium tetraisopropoxide as a titania precursor via a sol-gel mechanism. A study of the physicochemical properties of materials as a function of their titanium dioxide content was conducted using Fourier transform infrared spectroscopy, a scanning electron microscope, a diffuse reflectance ultraviolet-visible (UV-vis) spectrophotometer, and a gas sorption analyzer. The relationship between physicochemical parameters and photocatalytic performance was evaluated using the methylene blue (MB) photocatalytic degradation process under UV irradiation with and without the addition of H2O2 as an oxidant. The results demonstrated that increasing the TiO2 helps enhance the parameters of specific surface area, the pore volume, and the particle size of titanium dioxide, while the band gap energy reaches a maximum of 3.21 eV for 40% and 60% Ti content. The composites exhibit photocatalytic activity with the MB degradation with increasing photocatalytic efficiency since the composites with 40 and 60% wt. of TiO2 demonstrated the higher degradation rate compared with TiO2 in the presence and absence of H2O2. This higher rate is correlated with the higher specific surface area and band gap energy compared with those of TiO2.

Boron Doped Graphene Quantum Structure and MoS2 Nanohybrid as Anode Materials for Highly Reversible Lithium Storage.

Herein, the boron-doped graphene quantum structure (BGQS), which contains both the advantages of 0-D graphene quantum dot and 2-D reduced graphene oxide, has been fabricated by top-down hydrothermal method and then mixed with molybdenum sulfide (MoS2) to serve as an active electrode material for the enhanced electrochemical performance of lithium ion battery. Results show that 30 wt% of BGQS/MoS2 nanohybrid delivers the superior electrochemical performance in comparison with other BGQS/MoS2 and bare components. A highly reversible capacity of 3,055 mAh g-1 at a current density of 50 mA g-1 is achieved for the initial discharge and a high reversible capacity of 1,041 mAh g-1 is obtained at 100 mA g-1 after 50 cycles. The improved electrochemical performance in BGQS/MoS2 nanohybrid is attributed to the well exfoliated MoS2 structures and the presence of BGQS, which can provide the vitally nano-dimensional contact for the enhanced electrochemical performance. Results obtained in this study clearly demonstrate that BGQS/MoS2 is a promising material for lithium ion battery and can open a pathway to fabricate novel 2-D nanosheeted nanocomposites for highly reversible Li storage application.