Electron Transfer in Nanoelectrochemical Systems

GERMAN SOLDANO; WOLFGANG SCHMICKLER; FERNANDA JUAREZ; PAOLA QUAINO; ELIZABETH SANTOS

Nanoelectrochemistry

CRC Press Taylor and Francis Group

Lugar: London; Año: 2015; p. 3 - 28

Ever since the invention of the fuel cell by Grove, electrochemists have looked for better and cheaper catalysts. There have been significant improvements, but mainly in the reduction of the load of precious metals, not in finding a material significantly more active than platinum. All plausible pure metals, many binary, ternary, even quaternary alloys have been tried, but without much success. One gets the impression that progress has been slow and incremental,and that with bulk materials we are meeting the law of diminishing returns.But the development of nanotechnology has given us new hope. Nanostructures have dimensions that lie between those of individual molecules and bulk compounds; they often exhibit special geometries, like nanotubes or -wires, have different bonding patterns, exhibit quantum effects. A new world of materials has been discovered, and is being intensively investigated. So far, the most fascinating nanostructures that have been discovered are new modifications of carbon, and some of them are finding their way into electrochemicalapplications. But there are other structures, like core-shell metal particles, metal overlayers or island on foreign metals, various types of nanotubes or -pores, which promise to be good electrocatalysts. So there is reason for optimism.This is the context, in which our own theoretical work on electron transfer in nanoelectrochemical systems has to be seen. In contrast to most groups who work in this area, we do not rely on quantum chemical methods like DFT (density functional theory) alone, but have developed out own theory for electrocatalytic reactions. So we shall start this review by giving a brief overview over our method, and then give a systematic exposition of some of the nanostructures that we have investigated, focusing on their electronic properties, their stability, and, of course, on their catalytic properties, using hydrogen evolution as a test reaction.