Electroswitchable photoelectrochemistry by Cu²⁺-polyacrylic acid/CdS-nanoparticle assemblies

CdS nanoparticles are incorporated into a poly(acrylic acid) (PAA) film associated with an Au electrode, and the nanoparticles are covalently linked to the matrix. Cu²⁺ ions are incorporated into the CdS-nanoparticle-PAA film, and the electroswitchable photocurrent generation by the system, in the presence of triethanolamine as sacrificial electron donor, is demonstrated. The electrochemical reduction of the CdS-Cu²⁺-PAA state to the CdS-Cu⁰-PAA state (-0.55 V vs SCE) leads to the formation of conductive metal nanoclusters that facilitate electron transfer of the CdS-conduction-band electrons to the electrode, and the generation of the photocurrent. The oxidation of the Cu⁰ clusters to Cu²⁺ ions linked to the carboxylate units of PAA (applied potential +0.55 V vs SCE) switches off the photocurrent. The system not only is active for the reversible electroswitchable photocurrent generation but also acts as a photoelectrochemical detector of Cu²⁺ ions.