Synthesis, Structural and Optical Properties of ZrBi 2 Se 6 Nanoflowers: A Next-Generation Semiconductor Alloy Material for Optoelectronic Applications.

ZrBi 2 Se 6 nanoflower-like morphology was successfully prepared using a solvothermal method, followed by a quenching process for photoelectrochemical water splitting applications. The formation of ZrBi 2 Se 6 was confirmed by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The estimated value of work function and band gap were found to be 5.5 and 2.26 eV measured using diffuse reflection spectroscopy and ultraviolet photoelectron spectroscopy, suggesting the potential candidate for water splitting. The highest current density of 9.7 μA/cm 2 has been observed for the ZrBi 2 Se 6 photoanode for the applied potential of 0.5 V vs SCE. The flat-band potential value was -0.46 V, and the 1.85 nm width of the depletion region is estimated from the Mott-Schottky (MS) analysis. It also reveals that the charge carrier density for the ZrBi 2 Se 6 nanoflowers is 4.8 × 10 15 cm -3 . The negative slope of the MS plot indicates that ZrBi 2 Se 6 is a p-type semiconductor. It was observed that ZrBi 2 Se 6 nanoflowers had a high charge transfer resistance of ∼730 kΩ and equivalent capacitance of ∼40 nF calculated using electrochemical impedance spectroscopy (EIS) measurements. Using chronoamperometry, the estimated rise time and decay time were 50 ms and 0.25 s, respectively, which reveals the fast photocurrent response and excellent PEC performance of the ZrBi 2 Se 6 photoanode. Furthermore, an attempt has been made to explain the PEC activity of ZrBi 2 Se 6 nanoflowers using an energy band diagram. Thus, the initial results on ZrBi 2 Se 6 nanoflowers appear promising for the PEC activity toward water splitting.