Direct correlation of oxygen adsorption on platinum-electrolyte interfaces with the activity in the oxygen reduction reaction

Abstract

The oxygen reduction reaction (ORR) on platinum catalysts is essential in fuel cells. Quantitative predictions of the relative ORR activity in experiments, in the range of 1 to 50 times, have remained challenging because of incomplete mechanistic understanding and lack of computational tools to account for the associated small differences in activation energies (<2.3 kilocalories per mole). Using highly accurate molecular dynamics (MD) simulation with the Interface force field (0.1 kilocalories per mole), we elucidated the mechanism of adsorption of molecular oxygen on regular and irregular platinum surfaces and nanostructures, followed by local density functional theory (DFT) calculations. The relative ORR activity is determined by oxygen access to platinum surfaces, which greatly depends on specific water adlayers, while electron transfer occurs at a similar slow rate. The MD methods facilitate quantitative predictions of relative ORR activities of any platinum nanostructures, are applicable to other catalysts, and enable effective MD/DFT approaches.

Single-site Pt-doped RuO 2 hollow nanospheres with interstitial C for high-performance acidic overall water splitting

“…The quantum mechanics calculations were carried out using the VASP software at the version of 5.4.4, with the Perdew, Burke, and Ernzerhof flavor of DFT (45). The projector augmented wave meth od was used to account for corevalence interactions (46)(47)(48). The kinetic energy cutoff for plane wave expansions was set to 400 eV, and reciprocal space was sampled by the gammacentered kmesh with a grid of 3 × 3 × 1.…”

Adsorption and Diffusion of Oxygen on Pure and Partially Oxidized Metal Surfaces in Ultrahigh Resolution

“…Interactions of gas molecules with metal surfaces and associated chemical reactions are critical in several subfields of chemistry. In heterogeneous catalysis, the knowledge of binding sites, binding strength, and surface mobility is helpful to understand reaction mechanisms and to make accurate predictions of reaction rates. − Likewise, in the corrosion of metals and alloys understanding oxygen interactions with metal surfaces is critical to predict mechanisms of oxidation, tailor corrosion-resistant materials, and mitigate annual damages of hundreds of billions of dollars. − Gas/metal interactions are also exploited in gas separations, such as pressure swing adsorption or temperature swing adsorption, , and in sensors with tailored surfaces and sorbents. Therefore, adsorption of gases has been studied extensively on many substrates, ,− including the structure and stability of adsorbed monolayers, multilayers, and coadsorption from gas mixtures. , Common measurements include changes in adsorbed mass, heat, spectroscopy and color, swelling, electrical properties, or chemical composition. − …”

“…As a result, the adsorption–desorption equilibria of O 2 on metals before OO bond dissociation and reactions, which span at least 10 6 cycles from nanoseconds to milliseconds, are largely unexplored to-date. ,,, We have no knowledge about the energy landscape of O 2 adsorption and dynamics on pure metals and on the partially oxidized surfaces that precede full oxidation. Neither experimental nor computational methods have so far been able to monitor these processes and quantitatively inform kinetic models of oxide growth.…”

“…In this Letter, we derive missing understanding in atomic detail. We analyzed the dynamics of O 2 molecules on 11 clean and partially oxidized Al and Ni (100), (110), and (111) surfaces using over 150 000 molecular mechanics (MM) and molecular dynamics (MD) simulations with the INTERFACE force field (IFF). ,− IFF matches lattice parameters of metals within 0.1%, includes recent order-of-magnitude improved parameters for gases, and reproduces surface energies of metals as well as gas-metal binding energies with only about 5% error relative to experiments. ,, Therefore, molecular simulations with IFF fill a gap in current methods by covering functionality unavailable in other force fields and by DFT methods, as well as high computational efficiency (see Section S1.1 in the Supporting Information for details).…”

Versatile nanoarchitectonics of Pt with morphology control of oxygen reduction reaction catalysts

“…Local hydrophobicity caused by a hierarchically rough surface can affect ORR activity, which may be one of the reasons [ 40 ]. This feature has also been invoked to explain disruption of coverage of the water layer at a rough Pt surface [ 41 ]. In this work, a hierarchical structure of nanosheets was observed for both Pt NFs and Pt NSs, while a curved nanotubes structure was observed for Pt NTs.…”