Pd-TiO 2 nanoparticles supported on reduced graphene oxide: Green synthesis and improved electrocatalytic performance for methanol oxidation

Application of chiral recyclable catalysts in asymmetric catalysis

Chiral drugs hold a significant position within the contemporary pharmaceutical market, and the chiral catalysts play a crucial role in their synthesis. However, current chiral catalysts encounter challenges pertaining to their separation from products and the recycling process. The utilization of chiral recyclable catalysts not only reduces production costs but also aligns with the growing emphasis on environmentally-friendly chiral synthetic chemistry. These recyclable catalysts exhibit diverse carriers and distinct characteristics. Chemists employ the distinctive attributes of individual carriers to render them recyclable, thereby yielding time and cost savings. This review examines the asymmetric recyclable catalytic reactions reported between January 2017 and October 2023, categorizing them based on carrier solubility, and elucidates the loading techniques, catalytic impacts, recovery approaches, and recycling processes associated with these carriers.

Preparation of Pt electrocatalyst supported by novel, Ti(1−x)MoxO2-C type of composites containing multi-layer graphene

Ball milling is a relative simple and promising technique for preparation of inorganic oxide–carbon type of composites. Novel TiO2-C and Ti0.8Mo2O2-C type of composites containing multi-layer graphene were prepared by ball milling of graphite in order to get electrocatalyst supports for polymer electrolyte membrane fuel cells. Starting rutile TiO2 was obtained from P25 by heat treatment. Carbon-free Ti0.8Mo2O2 mixed oxide, prepared using our previously developed multistep sol–gel method, does not meet the requirements for materials of electrocatalyst support, therefore parent composites with Ti0.8Mo2O2/C = 75/25, 90/10 and 95/5 mass ratio were prepared using Black Pearls 2000. XRD study of parent composites proved that the oxide part existed in rutile phase which is prerequisite of the incorporation of oxophilic metals providing CO tolerance for the electrocatalyst. Ball milling of TiO2 or parent composites with graphite resulted in catalyst supports with enhanced carbon content and with appropriate specific surface areas. XRD and Raman spectroscopic measurements indicated the changes of graphite during the ball milling procedure while the oxide part remained intact. TEM images proved that platinum existed in the form of highly dispersed nanoparticles on the surface of both the Mo-free and of Mo-containing electrocatalyst. Electrocatalytic performance of the catalysts loaded with 20 wt% Pt was studied by cyclic voltammetry, COads-stripping voltammetry done before and after the 500-cycle stability test, as well as by the long-term stability test involving 10,000 polarization cycles. Enhanced CO tolerance and slightly lower stability comparing to Pt/TiO2-C was demonstrated for Pt/Ti0.8Mo2O2-C catalysts.

A Review on Development of Ceramic-Graphene Based Nanohybrid Composite Systems in Biological Applications

Graphene-based nanocomposites constitute an interesting and promising material for various applications. Intensive progress in the development of this group of materials offers an opportunity to create new systems useful for drinking water decontamination or other biotechnological applications. Nanohybrid structures of graphene-ceramic systems can be obtained using covalent graphene surface modification with nanoparticles (NPs) of ceramic and/or co-deposition of metals with selected morphology and chemistry. The present paper systematizes the associated bio-related knowledge and inspires future development of graphene/NPs systems. Emerging knowledge and unique research techniques are reviewed within designing the required nanocomposite structure and chemical composition, development and optimization of new methods of covalent surface modification of graphene with NPs as well as analysis of mechanisms governing the formation of covalent bonding. Further, innovative research tools and methodologies are presented regarding the adjustment of functionalities of materials used for the application in drinking water decontamination or biocidal composites. This study provides a comprehensive base for rational development of more complex, hybrid graphene-based nanomaterials with various bio-functionalities that can be further applied in industrial practice.