Investigation of glucose electrooxidation mechanism over N-modified metal-doped graphene electrode by density functional theory approach.

In this work, various precious and non-precious metals reported in the literature as the most effective catalysts for glucose electrooxidation reaction were investigated by the density functional theory (DFT) approach in order to reveal the mechanisms taking place over the catalysts in the fuel cell. The use of a single-atom catalyst model was adopted by insertion of one Au, Cu, Ni, Pd, Pt, and Zn metal atom on the pyridinic N atoms doped graphene surface (NG). ß form of d-glucose in alkaline solution was used to determine the reaction mechanism and intermediates that formed during the reaction. DFT results showed that the desired glucono-lactone was formed on the Cu-3NG electrode in a single-step reaction pathway whereas it was produced via different two-step pathways on the Au and Pt-3NG electrodes. Although the interaction of glucose with Ni, Pd, and Zn-doped surfaces resulted in the deprotonation of the molecule, lactone product formation did not occur on these electrode surfaces. When the calculation results are evaluated in terms of energy content and product formation, it can be concluded that Cu, Pt, and especially Au doped graphene catalysts are effective for direct glucose oxidation in fuel cells reactor.

A DFT study on the [VO]1+-ZSM-5 cluster: direct methanol oxidation to formaldehyde by N2O.

The mechanism of direct oxidation of methanol to formaldehyde by N2O has been theoretically investigated by means of density functional theory over an extra framework species in ZSM-5 zeolite represented by a [(SiH3)4AlO4](1-)[V-O](1+) cluster model. The catalytic reactivity of these species is compared with that of mononuclear (Fe-O)(1+) sites in ZSM-5 investigated in our earlier work at the same level of theory (J. Catal. 2011, 282, 191). The [V-O](1+) site in ZSM-5 zeolite shows an enhanced catalytic activity for the reaction. The calculated vibrational frequencies for grafted species on vanadium sites on the surface are in good agreement with the experimental values. According to the theoretical results obtained in this study the [V-O](1+) site in the ZSM-5 catalyst has an important role in the direct catalytic oxidation of methanol to formaldehyde by N2O.

High-throughput synthesis and screening of new catalytic materials for the direct epoxidation of propylene.

Nanoparticles of 35 individual metals as well as their binary combinations were synthesized using High Throughput pulsed laser ablation (PLA), and collected on Al(2)O(3), CeO(2), SiO(2), TiO(2), and ZrO(2) pellets. These materials were then screened for their catalytic activities and selectivities for the partial oxidation of propylene, in particular for propylene oxide (PO), using array channel microreactors. Reaction conditions were the following: 1 atm pressure, gas hourly space velocity (GHSV) of 20,000 h-1, temperature 300 degrees C, 333 degrees C, and 367 degrees C, and feed gas composition 20 vol% O(2), 20 vol% C(3)H(6) and balance He. Initial screening experiments resulted in the discovery of SiO(2) supported Cr, Mn, Cu, Ru, Pd, Ag, Sn, and Ir as the most promising leads for PO synthesis. Subsequent experiments pointed to bimetallic Cu-on-Mn/SiO(2), for which the PO yields increased several fold over single metal catalysts. For multimetallic materials, the sequence of deposition of the active metals was shown to have a significant effect on the resulting catalytic activity and selectivity.