Photoelectrochemical performance of a nanostructured BiVO/NiOOH/FeOOH-CuO/CuO/TiO tandem cell for unassisted solar water splitting.

An unassisted solar water splitting tandem cell is fabricated using FeOOH/NiOOH-coated BiVO nanostructures as a photoanode and a TiO-protected heterojunction CuO/CuO thin film as a photocathode. The individual photoelectrochemical (PEC) performance of the nanostructured BiVO/NiOOH/FeOOH photoanode produces a photocurrent of 2.05 mA cm at 1.23 V RHE, while the CuO/CuO/TiO photocathode delivers -1.61 mA cm at 0 V RHE under an AM 1.5 filtered illumination of 100 mW cm. The operating point of tandem cell photocurrent is found to be 0.273 mA cm at 0.56 V RHE. From two-electrode linear sweep voltammetry, the tandem cell (BiVO/NiOOH/FeOOH-CuO/CuO/TiO) delivers an unassisted current density of 0.201 mA cm 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 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.