Dye-sensitized solar cells (DSSCs) are promising low-cost photovoltaics, but their dependence on expensive platinum counter electrodes limits practical application. In this regard, we fabricated the CeO2/Co3O4@BC composite counter electrode via a straightforward hydrothermal technique, incorporating CeO2 and Co3O4 nanoparticles onto a biocarbon. The physicochemical characteristics of the prepared samples were systematically examined using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The results demonstrated the coexistence of cubic CeO2 and spinel Co3O4 phases uniformly anchored on the porous BC surface without structural distortion. XPS analysis confirmed the existence of mixed oxidation states of Ce3⁺/Ce4⁺ and Co2⁺/Co3⁺, facilitating rapid redox conversion at the electrode–electrolyte interface. The CeO2/Co3O4@BC composite demonstrated a substantial surface area with pronounced mesoporosity, promoting improved electrolyte infiltration and ion transport. The pristine biocarbon electrode demonstrated moderate electrocatalytic activity attributed to its conductive and porous characteristics, however the CeO2/Co3O4@BC composite exhibited markedly improved performance due to synergistic interactions between the metal oxides and the carbon matrix. Electrochemical characterization by cyclic voltammetry (CV), Tafel polarization, and electrochemical impedance spectroscopy (EIS) demonstrated superior catalytic activity and reduced charge-transfer resistance (Rct ≈ 7.5 Ω cm2) toward the I₃⁻/I⁻ redox couple. The fabricated DSSC incorporating CeO2/Co3O4@BC as a counter electrode achieved a promising power conversion efficiency (PCE) of 7.5%, comparable to that of the Pt-based device (8.2%). Additionally, the device retained about 97 to 99% of its initial efficiency after 30 days of continuous operation, indicating good stability under tested conditions. These findings suggest that the synergistic coupling between CeO2, Co3O4, and bio-carbon significantly enhances electrocatalytic activity, establishing CeO2/Co3O4@BC as a competitive Pt-free counter electrode for advanced DSSC applications.

Biocarbon wrapped CeO₂/Co₃O₄ heterostructure as a high-performance counter electrode for efficient Pt-free dye-sensitized solar cells

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发表日期：

2026年5月2日

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D. Sengeni,
J. Joy Priscilla,
V. Samuthira Pandi,
K. R. Pasupathy,
S. Sevvanthi

摘要

Dye-sensitized solar cells (DSSCs) are promising low-cost photovoltaics, but their dependence on expensive platinum counter electrodes limits practical application. In this regard, we fabricated the CeO₂/Co₃O₄@BC composite counter electrode via a straightforward hydrothermal technique, incorporating CeO₂ and Co₃O₄ nanoparticles onto a biocarbon. The physicochemical characteristics of the prepared samples were systematically examined using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The results demonstrated the coexistence of cubic CeO₂ and spinel Co₃O₄ phases uniformly anchored on the porous BC surface without structural distortion. XPS analysis confirmed the existence of mixed oxidation states of Ce³⁺/Ce⁴⁺ and Co²⁺/Co³⁺, facilitating rapid redox conversion at the electrode–electrolyte interface. The CeO₂/Co₃O₄@BC composite demonstrated a substantial surface area with pronounced mesoporosity, promoting improved electrolyte infiltration and ion transport. The pristine biocarbon electrode demonstrated moderate electrocatalytic activity attributed to its conductive and porous characteristics, however the CeO₂/Co₃O₄@BC composite exhibited markedly improved performance due to synergistic interactions between the metal oxides and the carbon matrix. Electrochemical characterization by cyclic voltammetry (CV), Tafel polarization, and electrochemical impedance spectroscopy (EIS) demonstrated superior catalytic activity and reduced charge-transfer resistance (R_ct ≈ 7.5 Ω cm²) toward the I₃⁻/I⁻ redox couple. The fabricated DSSC incorporating CeO₂/Co₃O₄@BC as a counter electrode achieved a promising power conversion efficiency (PCE) of 7.5%, comparable to that of the Pt-based device (8.2%). Additionally, the device retained about 97 to 99% of its initial efficiency after 30 days of continuous operation, indicating good stability under tested conditions. These findings suggest that the synergistic coupling between CeO₂, Co₃O₄, and bio-carbon significantly enhances electrocatalytic activity, establishing CeO₂/Co₃O₄@BC as a competitive Pt-free counter electrode for advanced DSSC applications.

Biocarbon wrapped CeO2/Co3O4 heterostructure as a high-performance counter electrode for efficient Pt-free dye-sensitized solar cells

摘要

Biocarbon wrapped CeO₂/Co₃O₄ heterostructure as a high-performance counter electrode for efficient Pt-free dye-sensitized solar cells