Preparation of a Water‐Soluble ZnXCd1‐XS Quantum Dot Photocatalyst at Room Temperature Assisted by 3‐Mercaptopropionic Acid

An effective path to synthesize ZnxCd1‐xS quantum dots (ZCS QDs) in aqueous phase at room temperature has remained relatively unexplored. Here, we developed a room‐temperature, aqueous‐phase approach to ZCS QDs, using 3‐mercaptopropionic acid (MPA) to adjust the pH of the reaction precursor solution to regulate the competition between sulfur source and hydroxyl group, and realize the large‐scale preparation of water‐soluble ZCS QDs photocatalyst at room temperature. Without recombination with other materials, and only by regulating the ratio of pH, excess sulfur sources and Zn/Cd, the photocatalytic degradation of rhodamine B (RhB) can reach 98% within 1 min, showing high photocatalytic activity. ZCS QDs show high stability and recoverability, and are expected to be able to deal with organic pollutants on a large scale. This study provides a new idea for the preparation of other QDs at room temperature. MPA is used to regulate the pH value and consume hydroxyl groups, making the sulfur source bond with cations in water in the form of covalent bonds and nucleation growth. Subsequently, the water‐soluble ZCS QDs photocatalyst is successfully prepared at room temperature. ZCS QDs show high photocatalytic activity, stability and recovery.