The use of nanometer-sized hydrographene species for support material for fuel cell electrode catalysts: a theoretical proposal

Abstract

Density functional theory (DFT) calculations propose that nanometer-sized hydrographene species, graphene-based clusters terminated by H atoms are a promising candidate for a support material for Pt catalysts in fuel cell. The proposal is based on the following three criteria: a small HOMO-LUMO gap of a nanometer-sized hydrographene species with and without a Pt cluster being comparable to zero-gap in infinite-size graphene, strengthening interactions of a Pt cluster with hydrographene species by utilizing its edge, and spontaneous H(2) activation by a Pt cluster on a carbon surface.

Graphene-based electrochemical energy conversion and storage: fuel cells, supercapacitors and lithium ion batteries

“…The small HOMO-LUMO gap is still retained after a Pt cluster binds to an edge of a sp 2 C surface to form two Pt-C bonds. 85 This theoretical calculation demonstrates that Pt clusters bond more strongly to the surface of the hydrogen terminated graphene than to infinite-size graphene and that Pt clusters prefer the edge over the surface in the hydrogen terminated graphene. In addition, oxygen containing functional groups will not only function as anchoring sites for Pt precursors but also influence the position of Pt cluster on the graphene sheets and the bonding energy with the sp 2 carbon in the graphene.…”

“…As calculated by DFT, H terminated graphene has the advantage of enhancing the interactions between a Pt 6 cluster and an sp 2 carbon surface. 85 As noted previously, nitrogen and boron can also be used to modify the electronic structure of the carbon support materials, thus improving the electrocatalytic activity and catalyst durability. The binding energy between a single platinum atom and several nitrogen-doped carbon graphene structures was evaluated using DFT.…”

Practical Challenges Associated with Catalyst Development for the Commercialization of Li-air Batteries

“…the particular type of catalyst; 114,[119][120][121][122][123] e.g., Pt particles were found to show maximal mass catalyst activity 124) when their size is ranging from 2 to 4 nm. Note that in the case of the Au catalyst, the particle size for maximum activity is smaller than that of Pt catalyst.…”

“…Thus, approaches for catalyst R&D should be multidisciplinary. 19,120,123,172) Regarding hybrid Li-air cells, there are also various parameters associated with cell performance, such as cathodic potential, oxygen purity, mass flow rate, cathode surface area, pH, and temperature. 159) However, this is a wholly different kind of challenge compared to that of non-aqueous Li-air cells as pointed out in the discussion section: No suitable electrolyte for nonaqueous Li-air cells has yet been discovered, and it is still a matter of controversy concerning the effects of catalysts due to undetermined ORR and OER mechanisms.…”

Computational chemistry for graphene-based energy applications: progress and challenges

“…One focus of such studies has been the sintering mechanism of the graphene-adsorbed Pt nanoparticles (PtNPs), which could conceivably take place either via coalescence or Ostwald ripening 161 . Yumura et al 159 considered finite-sized hydrogen-terminated graphene flakes and used both real-space DFT calculations with traditional functionals (the hybrid B3LYP 162 and LDA 163,164 ) and modestsized basis sets, and fully-periodic plane-wave DFT (PW-DFT) calculations (with the PW91 functional 165 ), to calculate the structure and energetics of surface binding of Pt, Pt 5 and Pt 6 on graphene (see Fig 7). Unlike many other studies of PtNP adsorption, these authors considered a range of possible PtNP configurations.…”