A PEDOT-coated quantum dot as efficient visible light harvester for photocatalytic hydrogen production

The photocatalytic electrode device comprised of Pt/TiO2/CdS/CdSe/PEDOT hybrid semiconductors exhibits stable and efficient hydrogen generation through photocatalytic water-splitting reactions. PEDOT polymer was electrochemically coated over a quantum dot-sensitized semiconductor and efficiently suppressed the back electron transfer from the semiconductor, thereby improving the photocurrent as compared to the uncoated control (13 vs 6 mA/cm(2), respectively). Impedance analysis revealed that the PEDOT-coated quantum dot electrode had reduced recombination resistance and increased electron lifetime values. Notably, the prepared electrode showed outstanding performance under visible-light irradiation in the absence of applied bias potential. Under this condition, the hybrid electrode structure generated hydrogen at a rate of 370 mu mol cm(-2) h(-1) with a sacrificial electrolyte. Furthermore, a quantum efficiency of 6.9% and turnover number of 2210 were achieved by the PEDOT-coated electrode. The photo-stability test revealed that the PEDOT polymer coated electrode showed longer stability compared to the uncoated electrode. The findings presented in this report highlight the advantages of designing and constructing the hybrid electrode structure and be applicable to other photocatalytic materials and photoelectrochemical reactions. (C) 2015 Elsevier B.V. All rights reserved.