Core-Shell Branched Bi2S3@Cr-doped ZnO Nanorods as Photo-anode for Enhanced Interface Stability and Photoelectrochemical Activity

Abstract

A novel, interface stable and visible light active branched core-shell Bi2S3/Cr-doped ZnO NRs photo-anode was synthesized using Hydrothermal and SILAR method successively. The purity, structure of crystals and elemental constitution was investigated using X-ray diffraction and energy-dispersive X-ray spectroscopy (EDS) techniques respectively. SEM (Scanning electron microscopy) results illustrates the branched and core-shell nanorods morphology of all the samples, whether doped or undoped. The study of optical characteristics of all the photo-anodes was conducted with the aid of UV/vis DRS (UV/visible diffuse reflectance spectroscopy), Raman spectroscopy and FL (Fluorescence spectroscopy). The results from FL and UV-vis DRS exhibit the efficient charge separation and enhanced visible light utilization, respectively. The electrical properties of the photoanodes were studied using Linear sweep voltammetry (LSV), Chronoamperometry (CA), Mott-Schottky and Electrochemical impedance spectroscopy (EIS). The optimized sample 10-Bi2S3/6% Cr-doped ZnO NRs shows the highest photo-current density of 2.360 mA cm- 2 at 1.23 V vs RHE and photo-conversion efficiency (%PCE) of 0.565% at 0.39 V vs RHE. This enhanced photo-electrochemical performance is linked to increased absorption of visible light by Bi2S3, efficient transfer of electron via the Schottky barrier due to the suitable band alignment and enhanced interface stability due to Chromium doping.