Synthesis of Co3O4/Ag/TiO2 nanotubes arrays via photo-deposition of Ag and modification of Co3O4 (311) for enhancement of visible-light photoelectrochemical performance

A composite Co3O4/Ag/TiO2 nanotubes (NTs) electrode, that subsequently photo-reduction of Ag and thermal decomposition of Co3O4 nanoparticles onto electrochemical anodized TiO2-NTs, was synthesized for enhancement of visible light photoelectrochemical (PEC) performance. The visible light response of Co3O4/Ag/TiO2-NTs with highest photocurrent of 0.54 mA/cm2 was obtained under calcination temperature of 400 °C for Co3O4 (311) crystal formation. The Co3O4/Ag/TiO2-NTs electrode provided a remarkable photoconversion efficiency of 0.18% at an on-set potential of 0.44 V which was twice than that of Co3O4/TiO2-NTs electrode (0.06%). The synergetic effect for degradation of nitrobenzene (NB) and reduction of Cr(VI) was studied to analyze the possible mechanism of Co3O4/Ag/TiO2-NTs. It was proposed that Ag nanoparticle acted as bridge transferred the photo-induced electrons from Co3O4 to TiO2-NTs and then largely facilitated the electron-holes separation to enhance the PEC activity.