Platinum-free counter electrode based on ZnCo₂O₄@NiO core-shell nanostructures in dye-sensitized solar cells

A nanocomposite material, core-shell ZnCo₂O₄@NiO, with a porous coating structure of transition metal oxide, was successfully fabricated using a straightforward hydrothermal process. This material serves as a Pt-free alternative for counter electrodes in dye-sensitized solar cells (DSSCs). The BET test results indicate a substantial specific surface area, offering numerous active sites for the redox reaction of electrolytes. This enhances electron transfer properties by DSSCs, and the nanocomposite exhibits outstanding electrocatalytic performance, particularly in the reduction of iodine electrolytes, leading to improved photoelectric conversion efficiency (PCE) in DSSCs. As a result, DSSCs incorporating ZnCo₂O₄@NiO CEs achieve a PCE of 8.43% (with J_SC of 17.95 mA cm², V_OC of 0.712 V, and FF of 0.66). This performance surpasses that of Pt CEs (7.75%) under identical lighting conditions. The superiority is attributed to the outstanding electrocatalytic capability and favourable electrical conductivity of the core-shell nanocomposite material.