Fabrication, characterization, and photovoltaic performance of titanium dioxide/metal-organic framework composite

Abstract

The titanium dioxide-metal-organic framework (TiO2−MOF) composite was prepared using the sol-gel method for photovoltaic applications. Raman analyses showed the presence of MOF clusters in the TiO2 sol-gel network. Using the Brunauer-Emmett-Teller method, the resultant composite material exhibited a surface area of 111.10 m2g−1 as compared to the surface area values of 262.90 and 464.76 m2g−1 for TiO2 and MOF, respectively. The small optical band gap values of 2.63 for direct electronic transition and 2.70 eV for indirect allowed electronic transition in TiO2/MOF composite were observed using ultraviolet-visible supported by cyclic voltammetry (CV). The chronoamperometry (CA) results showed the current drop of 0.21 mA observed at 0.025 s for TiO2 and the current drop of1.00 mA for MOF and 1.4 mA for TiO2−MOF composite at 0.3 s. The stability of the composite was achieved through the synergistic effect of MOF on TiO2 which resulted in a high current density. Electrochemical impedance spectroscopy showed a fast electron transfer as well as high ionic conductivity. The overall power conversion efficiency of 0.722% along with a photocurrent density of 0.46 mA cm−2 was achieved for the composite. The approach proposed in this work is facile and can be used for the large-scale fabrication of efficient and flexible photoanode electrodes for photovoltaic applications.