Co-sensitization of TiO2 electrode with Eosin Y dye and carbon dots for photoelectrochemical water splitting: The enhanced dye adsorption and the charge transfer route

According to a stepwise adsorption approach, TiO2 NT photoanode was co-sensitized with Eosin Y and carbon dots for photoelectrochemical water splitting. The adsorption amount of Eosin Y in co-sensitized samples increases due to the presence of carbon dots regardless of co-sensitization sequence. The absorbance of Eosin Y/carbon dots/TiO2 NT in visible light region is stronger than that of carbon dots/Eosin Y/TiO2 NT, while carbon dots/Eosin Y/TiO2 NT exhibits higher photocurrent density and hydrogen production rate. Based on the shortest electron transport time, the electron diffusion coefficient in carbon dots/Eosin Y/TiO2 NT electrode is up to 14.94 × 10−19cm2s−1. A favorable energy levels alignment dominates in carbon dots/Eosin Y/TiO2 NT, which can further account for enhancement in charge transfer.