Elucidating the role of CZTS QDs and CNTs for boosting the photoelectrochemical response of TiO2

This work highlights the potential of carbon nanotubes (CNTs) and Cu2ZnSnS4 quantum dots (CZTS QDs) for enhancing the photoelectrochemical properties of TiO2 thin film. A combination of eco-friendly materials with a simple approach to synthesis makes the system effective. The photoelectrodes have been prepared by depositing CZTS QDs over both TiO2 as well as TiO2-CNT composite. An enhanced photocurrent density of 1.5 mA cm(-2) at 1.23 V/RHE has been observed for CZTS QDs modified TiO2-CNT composite which is 15-fold increased in contrast to pristine TiO2. Here, CZTS QDs, as well as CNTs both, provide a widening of the light absorption characteristics of TiO2 from UV to the visible region. Further, the p-n junction created between CZTS QDs and TiO2-CNT plays a crucial role in charge separation process through electric field generated at the junction. Various characterization techniques have been used for structural, morphological and optical properties analysis. The increased photoelectrochemical (PEC) performance of photoelectrode has been justified with the help of UV-Vis spectra, Mott-Schottky, Nyquist and transient open circuit potential plots.