First-Principles Study on CO Removing Mechanism on Pt-Decorated Oxygen-Rich Anode Surfaces (Pt₂/o-MO₂(110), M = Ru and Ir) in DMFC

Abstract

Direct methanol fuel cell (DMFC) is an efficient power source. However, the DMFC anodes are easily toxified by CO or other hydrocarbons, which terminates the methanol oxidation reaction (MOR). The most commonly used high performance catalyst on DMFC anodes is Pt or bimetallic PtRu. In this work, we apply density functional theory (DFT) to investigate the adsorption of CO and H2O on pristine Pt2/MO2(110) and the oxygen-rich Pt2/o-MO2(110) surfaces (M = Ru and Ir). We find that the application of the oxygen-rich surfaces significantly reduces the adsorption energies of CO and H2O molecules as well as the major reaction barrier (CO + OH → CO2) in the water–gas–shift-like (WGS-like) reactions forming CO2. Our detailed analyses on the electronic interaction between the catalysts and adsorbates indicate that Pt2/o-MO2(110) may be a promising DMFC anode material, which reduces the poison problem, and that it may be the actual experimental system that is responsible for the observed efficient CO removal.

Termination Effects of Pt/v-Tin+1CnT2 MXene Surfaces for Oxygen Reduction Reaction Catalysis

“…The active center is constructed by a single Pt atom adsorption for the ORR intermediates to adsorb and to react. Single-atom catalysis has been reported to provide a superior catalytic performance in many systems. − From the computational point of view, the single-atom catalyst represents a simplified, primary model that provides fundamental insights and explanation to the material properties, as is frequently constructed in many theoretical studies, − for example, single Pt atom catalysis for ORR on doped graphene. , Our detailed density of states (DOS) and Bader charge population analyses indicate a weaker bonding between the surfaces with the F terminators than those with O, and we observe a linear variation between the overall ORR performance and the O/F ratio. The free-energy diagrams as well as the volcano plots for the ORR intermediates are also computed.…”

“…We therefore consider the adsorption of Pt on the vacancy site of the v-Ti n +1 C n T 2 surfaces, with one O or F terminator removed from the surfaces (Figure S2a,e). The adsorbed Pt takes a rare trigonal coordination with respect to the more commonly observed bridge site adsorption. ,, In general, the adsorption energies, Δ E ads , are much more negative when Pt is adsorbed at the vacancy site of v-Ti n +1 C n T 2 (Δ E ads ≈ −4.2 eV) than on the pristine Ti n +1 C n O 2 (Δ E ads ≈ −2.0 eV), as shown in Table . Figure S2 reveals the Bader charge populations of the Pt/v-Ti n +1 C n T 2 surfaces.…”

“…The adsorbed Pt takes a rare trigonal coordination with respect to the more commonly observed bridge site adsorption. 51,68,69 In general, the adsorption energies, ΔE ads , are much more negative when Pt is adsorbed at the vacancy site of v-Ti n+1 C n T 2 (ΔE ads ≈ −4.2 eV) than on the pristine Ti n+1 C n O 2 (ΔE ads ≈ −2.0 eV), as shown in Table 1. Figure S2 ) by the trigonal coordination between Pt and the three "active" Ti atoms (labeled as Act.…”

DFT Study on the Mechanism of the Water Gas Shift Reaction Over NixPyCatalysts: The Role of P

“…Transition state (TS) searches are performed at the same theoretical level with the CI-NEB method, , and all activation barriers are given with zero-point energy (ZPE) and entropy effect correction (for details of the energy values, see Table S5, Supporting Information). The Bader charge − and electron density difference are calculated to show the electron transfer between Ni and P elements on clean surfaces and electronic interactions between the Ni x P y catalysts and adsorbates (CO and H 2 O).…”

Water-Gas-Shift Reaction on Au/TiO2–x Catalysts with Various TiO2 Crystalline Phases: A Theoretical and Experimental Study

“…Transition state (TS) searches are performed at the same theoretical level with the CI-NEB method. , All the models are the most stable structures obtained through optimization and screening. The Bader charge analysis and electron density differences are calculated in order to display the electron transfer among Au, O, and Ti elements on surfaces and electronic interaction between the catalysts and adsorbates (CO and H 2 O).…”