Photoelectrochemical performance of a nanostructured BiVO4/NiOOH/FeOOH–Cu2O/CuO/TiO2 tandem cell for unassisted solar water splitting

Abstract

An unassisted solar water splitting tandem cell is fabricated using FeOOH/NiOOH-coated BiVO₄ nanostructures as a photoanode and a TiO₂-protected heterojunction Cu₂O/CuO thin film as a photocathode. The individual photoelectrochemical (PEC) performance of the nanostructured BiVO₄/NiOOH/FeOOH photoanode produces a photocurrent of 2.05 mA cm⁻² at 1.23 V vs. RHE, while the Cu₂O/CuO/TiO₂ photocathode delivers −1.61 mA cm⁻² at 0 V vs. RHE under an AM 1.5 filtered illumination of 100 mW cm⁻². The operating point of tandem cell photocurrent is found to be 0.273 mA cm⁻² at 0.56 V vs. RHE. From two-electrode linear sweep voltammetry, the tandem cell (BiVO₄/NiOOH/FeOOH–Cu₂O/CuO/TiO₂) delivers an unassisted current density of 0.201 mA cm⁻² at 0 V. The chronoamperometry test further demonstrates the stable nature of the tandem cell, which retains a current density of 0.187 mA cm⁻² during a testing duration of 3000 seconds. The proposed tandem cell provides optimized solutions to designing a cost-effective and stable solar water splitting system for the fulfillment of the future energy needs.