Cu₂FeSnS₄ decorated Ni-TiO₂ nanorods heterostructured photoanode for enhancing water splitting performance

Earth-abundant and visible light sensitive Cu₂FeSnS₄ layer is decorated on Ni-TiO₂ nanorods (CFTS/Ni-TiO₂ NRs) using wet chemical approach. First, Ni doping is performed on hydrothermally grown TiO₂ nanorods to achieve Ni on the surface of TiO₂. After surface doping of Ni, the bandgap of TiO₂ nanorod films changes from 3.0 eV to 2.79 eV. Once the layer of Cu₂FeSnS₄ is decorated on the Ni doped TiO₂ nanorods the absorption edge of the photoanode further shifted toward lower energy. Mott-Schottky analysis revealed more than 3-fold increase in photogenerated charge carrier density in CFTS/Ni-TiO₂ NRs. This heterostructured photoanodes demonstrated a significant increase in photocurrent from 0.730 mA/cm² to 2.09 mA/cm² (at 1.23 V vs RHE). The lifetime of photo-generated charge carriers also improves from 10.87 s to 15.36 s for CFTS/Ni-TiO₂ NRs as compared to TiO₂ NRs. The CFTS/Ni-TiO₂ NRs exhibit excellent photoelectrochemical properties with high stability, hence this heterostructure can be a potential candidate for solar energy device applications.