Influence of defective sites in Pt/C catalysts on the anode of direct methanol fuel cell and their role in CO poisoning: a first-principles study

Abstract

Carbon-supported Pt catalyst systems containing defect adsorption sites on the anode of direct methanol fuel cells were investigated, to elucidate the mechanisms of H 2 dissociation and carbon monoxide (CO) poisoning. Density functional theory calculations were carried out to determine the effect of defect sites located neighboring to or distant from the Pt catalyst on H 2 and CO adsorption properties, based on electronic properties such as adsorption energy and electronic band gap. Interestingly, the presence of neighboring defect sites led to a reduction of H 2 dissociation and CO poisoning due to atomic Pt filling the defect sites. At distant sites, H 2 dissociation was active on Pt, but CO filled the defect sites to form carbon π-π bonds, thus enhancing the oxidation of the carbon surface. It should be noted that defect sites can cause CO poisoning, thereby deactivating the anode gradually.

Density functional theory study of CH4and CO2adsorption by fluorinated graphene

“…The results of this investigation also shed light on further possibilities for computational research on fluorinated carbon-based materials.The DFT calculations were conducted using the Biovia DFT package DMol3 [11], considering the generalized-gradient-approximation (GGA) as well as the Perdew-Burke-Ernzerhof (PBE) exchange and correlation functionals with the double numerical polarized basis set. The GGA-PBE functional has been successfully used to describe the interaction between organic molecules and a carbon-based substrate [12][13][14][15][16][17][18] or an inorganic substrate [19][20][21][22][23]. We used a 5 × 5 × 1 Monkhorst-Pack k-point mesh [24] with a 12.30 Å × 12.30 Å × 15.00 Å periodic boundary condition for the graphene substrate.The adsorption energy (E ads ) was defined aswhere E substrate+gas represents the energy of the entire system, E substrate is the energy of the substrate system alone, and E gas is the energy of the isolated gas molecule.…”

Replacement effect of fresh electrolyte on the accelerated deactivation test and recovery process of Pt/C catalysts in a half-cell system

“…There are four main degradation factors known to date: agglomeration of Pt nanoparticles, Pt dissolution/re-deposition, CO poisoning, and corrosion of the carbon support [2][3][4][5][6][7]. These phenomena generally occur under abnormal operating conditions, such as start-up and shut-down, rather than under normal conditions, and decrease the cell performance [8].…”

Substrate Effect of Platinum-Decorated Carbon on Enhanced Hydrogen Oxidation in PEMFC

“… 1 , 2 Fuel cells hold great potential as a viable nonpolluting power generation option, owing to their high energy densities and a wide range of operating temperatures. 3 , 4 Eco-friendly and highly efficient fuel cell systems, such as proton-exchange membrane fuel cells (PEMFCs), operating at low temperatures (<150 °C) are a promising electrochemical energy device for directly converting hydrogen into power. 5 − 7 In addition, PEMFC is a commercially available candidate for replacing conventional power sources in the field of automotive, marine, and portable applications as they generally operate below 120 °C and have an easy start-up and high energy efficiency.…”

“…Efficient and economical future energy systems have been extensively studied to replace the existing hydrocarbon-based power generation because global climate change is partly attributed to conventional energy systems. , Fuel cells hold great potential as a viable nonpolluting power generation option, owing to their high energy densities and a wide range of operating temperatures. , Eco-friendly and highly efficient fuel cell systems, such as proton-exchange membrane fuel cells (PEMFCs), operating at low temperatures (<150 °C) are a promising electrochemical energy device for directly converting hydrogen into power. − In addition, PEMFC is a commercially available candidate for replacing conventional power sources in the field of automotive, marine, and portable applications as they generally operate below 120 °C and have an easy start-up and high energy efficiency . However, several aspects of fuel cells could be improved, such as their efficiency, moisture control, and resistance to pollutants.…”