Pulse electrodeposition of Ag, Cu nanoparticles on TiO2 nanoring/nanotube arrays for enhanced photoelectrochemical water splitting

In this paper, plasmonic Ag and Cu nanoparticles were co-deposited on TiO2 nanoring/nanotube arrays (TiO2 R/T) by using two-step pulse electrodeposition method for investigating the optical and photoelectrochemical properties, in comparison to monometallic Ag, Cu decoration. By optimizing the electrodeposition cycle times and electrolyte concentration, bimetallic Ag–Cu/TiO2 R/T-0.5 with moderate densities and sizes of Ag and Cu nanoparticles was fabricated and shows great photocatalytic potential, in which, Ag mainly facilitates the generation of hot electrons by absorbing visible light and Cu plays an important role in accelerating the separation and transportation of hot electrons. The hydrogen production rate was tested as 425 μL h−1 cm−2, which is about 1.34-fold enhanced H2 production over TiO2 R/T. Furthermore, molecular dynamics simulations were made for analyzing the interface electrostatic properties between plasmonic nanoparticles of Ag or Cu and the semiconductor TiO2. It is calculated that bimetallic Ag–Cu/TiO2/H2O system has larger interfacial Helmholtz potential than monometallic Ag/TiO2/H2O, Cu/TiO2/H2O and pure TiO2/H2O systems, accelerating the four-electron reaction occurring at the semiconductor/electrolyte interface. This research put forward a feasible and simple pulse electrodeposition method to fabricate bimetallic photoanodes for enhanced hydrogen evolution and an important analysis method of semiconductor/ metal/electrolyte interface characteristics.