Noble metal

About: Noble metal is a research topic. Over the lifetime, 15113 publications have been published within this topic receiving 337947 citations.

The stability number as a metric for electrocatalyst stability benchmarking

Abstract: Reducing the noble metal loading and increasing the specific activity of the oxygen evolution catalysts are omnipresent challenges in proton-exchange-membrane water electrolysis, which have recently been tackled by utilizing mixed oxides of noble and non-noble elements. However, proper verification of the stability of these materials is still pending. Here we introduce a metric to explore the dissolution processes of various iridium-based oxides, defined as the ratio between the amounts of evolved oxygen and dissolved iridium. The so-called stability number is independent of loading, surface area or involved active sites and provides a reasonable comparison of diverse materials with respect to stability. The case study on iridium-based perovskites shows that leaching of the non-noble elements in mixed oxides leads to the formation of highly active amorphous iridium oxide, the instability of which is explained by the generation of short-lived vacancies that favour dissolution. These insights are meant to guide further research, which should be devoted to increasing the utilization of highly durable pure crystalline iridium oxide and finding solutions to stabilize amorphous iridium oxides.

Electrodeposition of Noble Metal Nanoparticles on Carbon Nanotubes

Abstract: Noble metal nanoparticles can be electrodeposited on carbon nanotubes under potential control. The nanotube sidewalls serve both as the electrodeposition template and as the wire electrically connecting the deposited nanoparticles.

CO adsorption on close-packed transition and noble metal surfaces: trends from ab initio calculations

Abstract: We have studied the trends in CO adsorption on close-packed metal surfaces: Co, Ni, Cu from the 3d row, Ru, Rh, Pd, Ag from the 4d row and Ir, Pt, Au from the 5d row using density functional theory. In particular, we were concerned with the trends in adsorption energy, geometry, vibrational properties and other parameters derived from the electronic structure of the substrate. The influence of specific changes in our set-up, such as choice of the exchange correlation functional, the choice of pseudopotential, size of the basis set and substrate relaxation, has been carefully evaluated. We found that, while the geometrical and vibrational properties of the adsorbate–substrate complex are calculated with high accuracy, the adsorption energies calculated with the gradient-corrected Perdew–Wang exchange–correlation energies are overestimated. In addition, the calculations tend to favour adsorption sites with higher coordination, resulting in the prediction of the wrong adsorption sites for the Rh, Pt and Cu surfaces (hollow instead of top). The revised Perdew–Burke–Erzernhof functional (RPBE) leads to lower (i.e. more realistic) adsorption energies for transition metals, but to the wrong results for noble metals—for Ag and Au, endothermic adsorption is predicted. The site preference remains the same. We discuss trends in relation to the electronic structure of the substrate across the periodic table, summarizing the state-of-the-art of CO adsorption on close-packed metal surfaces.