A green and facile self-assembly preparation of gold nanoparticles/ZnO nanocomposite for photocatalytic and photoelectrochemical applications

Gold nanoparticles (GNP) passivated by dithiolated diethylenetriaminepentaacetic (DTDTPA) linkers, GNP@DTDTPA, have been synthesized. The well-defined ZnO nanocomposite (GNP@DTDTPA/ZnO) functionalized by GNP@DTDTPA was prepared via a facile and green self-assembly approach. The specific interaction mechanism responsible for the self-assembly motif was elucidated by XPS, zeta potential and FTIR analysis. The self-assembly process was established primarily by a large amount of polar functional groups such as carboxyl (COOH), carbonyl (CO), and amide (NH–CO) groups in the DTDTPA profile, which impels GNP@DTDTPA to bind intrinsically with hydroxyl groups on the ZnO surface through hydrogen bonding interactions. On the other hand, the attractive electrostatic force between the negatively charged GNP@DTDTPA and the positively charged ZnO surface also contributes to the monodispersivity of GNP@DTDTPA on the ZnO support. The GNP/ZnO obtained after calcination of GNP@DTDTPA/ZnO retains the mono-distribution of GNP and exhibits more enhanced photocatalytic and photoelectrochemical performances compared to pure ZnO. We propose a possible mechanism that the well-distributed GNP could serve as an “electron reservoir” and improve the separation efficiency of photogenerated electron–hole pairs. This method could provide a simple and straightforward approach for achieving a uniform distribution of noble-metal nanoparticles on the surface of semiconductors for versatile photocatalytic and photoelectrochemical applications.