Photoinduced electron transfer between semiconducting nanosheets and acceptor molecules in the presence of colloidal clay particles

Abstract

Binary clay colloids prepared by mixing smectite and other particles can exhibit unusual properties based on physical and chemical interactions between the colloidal particles. We prepared a binary colloidal system of layered fluoroniobate (K2NbO3F) and synthetic hectorite (Laponite) particles and examined photoinduced electron transfer in the colloid to which electron accepting methylviologen (MV2+) was added. Exfoliation and nanosheet formation of the fluoroniobate were not evidenced, but it was transformed in water to 3D crystalline species that was easily settled down. Addition of a large amount of hectorite suppressed the settlement of the fluoroniobate particles to stabilize the colloid for a few days. When MV2+ ions were introduced to the binary colloid, the organic species was adsorbed on the hectorite particles and electron transfer occurred from the fluoroniobate particles to the MV2+ ions upon UV irradiation. Addition of propylammonium ions to the system enhanced the yield and stability of the photoproduct while an optimal amount was found. This was ascribed to the scarifying hole scavenging by the propylammonium species although the photoinduced electron transfer can occur in its absence.