A kinetic study of CdS photocorrosion by intensity modulated photocurrent and photoelectrochemical impedance spectroscopy

The steady state and dynamic photoelectrochemical behaviour of single cryst al cadmium sulfide in non-stabilising electrolytes has been compared with t he response of the same electrode in the hole scavenging electrolyte Na,SO, . The kinetics of the elementary steps involved in photo-dissolution have b een investigated by intensity modulated photocurrent spectroscopy (IMPS) an d photoelectrochemical impedance spectroscopy (PEIS). The theoretical PEIS responses for a two hole transfer process have been derived and related to the corresponding theoretical IMPS responses. PEIS and IMPS data as well as the steady state photocurrent characteristics have been analysed within th e framework of a model involving hole capture to form a surface bound inter mediate species. The effects of the accumulation of this species on the ste ady state and dynamic response of the electrode are discussed. (C) 1999 Els evier Science S.A. All rights reserved.