Preparation and catalytic performance of high-entropy alloy-high-entropy oxide loaded nitrogen-doped carbon composites

Developing highly active, low-cost, and stable counter electrode catalysts is crucial for improving the photovoltaic performance of dye-sensitized solar cells. Currently, nitrogen-doped carbon (NC) materials exhibit certain catalytic potential in the triiodide reduction reaction (IRR), but the lack of active sites limits their practical application. Here, an FeCoNiMnCr high entropy alloy-high entropy oxide (HEA-HEO) heterostructure was constructed on NC support via a wet-impregnation method to obtain an HEA-HEO/NC composite catalyst. The electrochemical characteristics and photovoltaic performance of this composite material as a counter electrode in I₃⁻/I⁻ and Cu²⁺/Cu⁺ systems are systematically evaluated. Benefiting from the abundant active sites provided by the multi-metal composition and the synergistic effect of the porous conductive structure of the NC framework, HEA-HEO/NC exhibits excellent catalytic activity and electron transfer capability. In the I₃⁻/I⁻ system, the charge transfer resistance of the HEA-HEO/NC counter electrode is as low as 0.57 Ω·cm², and the power conversion efficiency (PCE) of the assembled device reaches 8.69%, higher than that of commercial Pt (7.51%) electrodes. In the Cu²⁺/Cu⁺ system, the PCE of the HEA-HEO/NC electrode assembly is 4.02%. Furthermore, 50 consecutive cyclic voltammetry tests demonstrate the excellent stability of the HEA-HEO/NC catalyst. This study provides a new approach for developing high-performance electrode materials.