Interrupted growth and photoelectrochemistry of Cu2O and Cu particles on TiO2

The enhancement of photo-current conversion and/or photocatalytic efficiency in the heterostructure of TiO2 combined with Cu2O particles has been obtained by many groups, whereas studies about the controllable growth of the Cu2O particles are missing. In this study, Cu2O is fabricated on TiO2 flat surface using a special interrupted pulse-electrodeposition and the microstructural and morphological evolution of the Cu2O particles during the interrupted growth has been investigated. The rational control of the particle size and density is achieved by varying the deposition parameters and especially the interruption times during the Cu2O growth. The photoelectrochemical performance of the Cu2O/TiO2 heterostructure is therefore modified significantly. The photocurrent of the Cu2O/TiO2 heterostructure under zero bias obviously decreases during the photoelectrochemical measurement, and the transformation of Cu2O to Cu is observed, along with the stabilized photocurrent. Compared with the pure TiO2 layer on Ti substrate, large enhancement of the photoelectrochemical activity is obtained when Cu2O or Cu particles are covered on TiO2 surface, and different mechanisms behind the enhancement are suggested. The electrodeposition method proposed in this study achieves the optimal photoelectrochemical activity by opening a new way to grow Cu2O or Cu particles on TiO2 with tunable grain size and density. (C) 2012 Elsevier Ltd. All rights reserved.