Extended visible photosensitivity of carboxyethyltin functionalized polyoxometalates with common organic dyes enabling enhanced photoelectric performance

Abstract

A kind of broad spectral responsive photoelectrode has been assembled from open-chain carboxyethyltin functionalized Dawson sandwich-type polyoxometalates (POMs) [{Sn(CH2)2COO}2M2(P2W15O56)2]16− (SnR-M-P2W15, M = Mn, Co, Cu and Zn) and organic dyes such as rhodamine B (RhB) and methylene blue (MB) through the layer-by-layer (LBL) self-assembly method. SnR-M-P2W15 shows strong adsorption towards RhB and MB. The adsorption capacity of SnR-Co-P2W15 towards RhB and MB reached 217.36 and 288.76 mg g−1 in 10 min, respectively. Compared to Keggin sandwich-type open-chain carboxyethyltin-POM and closed-ring carboxyethyltin-POM derivatives such as [Zn2{Sn(CH2)2COO}2[(PW9O34)2]10− (SnR-Zn-PW9) and [K3{Sn(CH2)2COO}2(PW9O34)2]11− (SnR-PW9), and the parent POMs [M4(H2O)2(P2W15O56)2]16− (M-P2W15, M = Mn, Co, Cu and Zn), SnR-M-P2W15-based photoelectrodes showed significantly enhanced photocurrent owing to their greater visible light harvesting. Also, the photoelectric performances of LBL multilayer films can be adjusted by controlling the number of deposited layers, adsorbed dye types and incorporated transition metal ions in the POMs.