Electrochemical Processes and Technology

Abstract

Electrode processes that involve the transfer of several electrons, usually accompanied by the breaking and creation of bonds, commonly proceed slowly or not at all in the absence of electrocatalysts, in contrast to most simple electrode processes that involve the transfer of a single electron without associated ion/atom transfer. Such complex electrode processes, an example of which is the reduction of molecular oxygen by a four-electron process to water or by a two-electron process to hydrogen peroxide (Chap. 2), often involve high-energy intermediates that must be stabilized by interactions with suitable molecules or complexes if the electrode reactions are to proceed at reasonable rates. These intermediate-stabilizing species are the electrocatalysts [1, 2]. In electrocatalysis, multifunctionality is obligatory: for obtaining high performance, some combination of surface reactivity, electronic and ionic conductivity, separation of electron–hole pairs, or facile mass transport of molecules must be provided to enhance the molecular conversion.