WO3/α-Fe2O3/Bi2S3 ternary photoanode for improved the oxygen evolution reaction in photoelectrochemical water splitting

This study presents a ternary WO3/α-Fe2O3/Bi2S3 photoanode system suitable for photoelectrochemical water-splitting applications. WO3/α-Fe2O3 heterojunction is obtained using a hydrothermal approach, while Bi2S3 is deposited onto WO3/α-Fe2O3 via the successive ionic layer adsorption and reaction (SILAR) method. The cycle count is adjusted to determine the optimal photocatalytic photoanode. X-ray diffraction analysis confirms different morphologies and phases for the photoelectrodes: WO3 is deposited as plates with monoclinic phases, α-Fe2O3 as nanorods with hexagonal phases, and Bi2S3 in the form of nanoparticles (NPs) with orthorhombic phases. Solar light absorption spectra indicate that ternary WO3/α-Fe2O3/Bi2S3 photoanodes absorb a larger portion of the solar spectrum and display a large red shift in wavelength compared to binary WO3/α-Fe2O3 photoanodes. Chronoamperometric and electrochemical impedance spectroscopy measurements indicate that the as-prepared WO3/α-Fe2O3/Bi2S3 photoanode exhibits notable stability and low charge transfer resistance (Rct) compared to binary electrodes and pristine WO3 plates in faradaic photoelectrochemical conversion for the oxygen evolution reaction and S-2/S2 processes. Linear sweep voltammetry studies show that the WO3/α-Fe2O3/Bi2S3 photoanode, sensitized with 8 SILAR cycles, achieves the maximum photocurrent density of 5.777 mA.cm-2 at 1.0 V vs. RHE under 100 mW cm-2 simulated solar irradiation.