Fabrication, characterization, and photovoltaic performance of titanium dioxide/metal-organic framework composite
Phuti S. Ramaripa, Kwena D. Modibane, Katlego Makgopa, Ostar A. Seerane, Manoko S. Maubane‐Nkadimeng, Edwin Makhado, Mpitloane J. Hato, Morongwa E. Ramoroka, Kerileng M. Molapo, Deepanraj Balakrishnan, Emmanuel I. Iwuoha
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 m2 g−1 as compared to the surface area values of 262.90 and 464.76 m2 g−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.