Preparation of carbon dots/TiO2 electrodes and their photoelectrochemical activities for water splitting

Carbon dots with various functional groups can be employed as the potential sensitizer. In this study, carbon dots are obtained by electrochemical ablation of graphite rods in alkaline electrolyte. The better preparation condition is the applied potential of 40 V and the ablation time of 5 h. TiO2 nanotube arrays and TiO2 nanoparticles photoelectrodes are sensitized by the as-prepared carbon dots through using impregnation method. Carbon dots/TiO2 nanotube arrays electrodes exhibit greater photoelectrochemical hydrogen production activities than carbon dots/TiO2 nanoparticles electrodes. It is because more carbon dots can be well combined with TiO2 nanotube arrays. Based on the IPCE values in visible light region, the role of carbon dots on TiO2 nanotube arrays electrode depends on the up-converted PL behaviors from their surface states and the alkaline electrolyte. The results provide insight into carbon dots that serve as sensitizer of TiO2 photoelectrode in water splitting system of alkaline solution.