WO/α-FeO/BiS ternary photoanode for improved oxygen evolution reaction in photoelectrochemical water splitting.

This study presents a ternary WO/α-FeO/BiS photoanode system suitable for photoelectrochemical water-splitting applications. WO/α-FeO heterojunction is obtained using a hydrothermal approach, while BiS is deposited onto WO/α-FeO 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: WO is deposited as plates with monoclinic phases, α-FeO as nanorods with hexagonal phases, and BiS in the form of nanoparticles (NPs) with orthorhombic phases. Solar light absorption spectra indicate that ternary WO/α-FeO/BiS photoanodes absorb a larger portion of the solar spectrum and display a large red shift in wavelength compared to binary WO/α-FeO photoanodes. Chronoamperometric and electrochemical impedance spectroscopy measurements indicate that the as-prepared WO/α-FeO/BiS photoanode exhibits notable stability and low charge transfer resistance (R) compared to binary electrodes and pristine WO plates in faradaic photoelectrochemical conversion for the oxygen evolution reaction and S/S processes. Linear sweep voltammetry studies show that the WO/α-FeO/BiS photoanode, sensitized with 8 SILAR cycles, achieves the maximum photocurrent density of 5.777 mA.cm at 1.0 V vs. RHE under 100 mW cm simulated solar irradiation.