Preparation of carbon quantum dots/Bi12O17Cl2 semiconductor composite and its enhanced photocatalytic oxygen evolution performance

A novel carbon quantum dots (CQDs)/Bi12O17Cl2 semiconductor composite was synthesized by a simple room-temperature precipitation method, in which the strong interaction between CQDs and Bi12O17Cl2 formed, and it was characterized by XRD, Raman spectroscopy, TEM, XPS, UV-vis DRS, N2 adsorption/desorption and electrochemical measurements. The performance of the CQDs/Bi12O17Cl2 composite for photocatalytic oxygen evolution from water splitting was studied under visible light irradiation at room temperature. The results indicated that the rate of oxygen evolution increased firstly and then decreased with the increase of CQDs content. A maximum oxygen evolution rate of 677 & mu;mol h-1 g-1 was achieved for the CQDs/Bi12O17Cl2 composite in which 5 mL CQDs solution was dispersed. Compared with the single Bi12O17Cl2, the CQDs/Bi12O17Cl2 composites with a relatively high specific surface area and large pore volume displayed much higher charge separation efficiency under visible light. The excellent photocatalytic oxygen evolution performance of the CQDs/Bi12O17Cl2 semiconductor composites is attributed to its strong visible-light absorption capability, high charge separation efficiency, and the more positive valence band position.