CO2-Assisted Steam Electrolysis Enhancement in Protonic Ceramic Electrolysis Cells through Dendritic Architecture and Catalytic Integration

Abstract Protonic ceramic electrolysis cells (PCECs), as an emerging high-temperature electrolysis technology, demonstrate substantial potential in renewable energy conversion and carbon resource recycling. In this study, the reaction mechanism of CO2-assisted steam electrolysis in PCECs was systematically investigated, and an efficient electrode design strategy employing a dendritic porous structure was proposed. Electrochemical tests and product analysis clarified the CO2 reduction mechanism at the fuel electrode. The results confirmed that CO2-assisted electrolysis significantly reduces both operating voltage and polarization resistance compared to steam electrolysis. To enhance electrochemical performance, a NiO-BZCYYb fuel electrode support featuring interconnected dendritic pores was fabricated using phase inversion, followed by vacuum-assisted impregnation of a 6 wt % Pt–GDC nanofiber catalyst into the porous channels, effectively coupling structural design with functional enhancement. Experimental results indicated that under CO2-assisted electrolysis at 650 °C, the operating voltage decreased by 17.75%, and polarization resistance was significantly reduced compared with steam electrolysis. Catalyst loading further improved performance, raising CO2 conversion from 36.13% to 50.63%, additionally reducing the operating voltage by 11.51%, and enabling effective control of syngas composition. Long-term stability testing demonstrated that catalyst modification extended the stable operating duration of the electrode from 118 to 184 h. Comprehensive characterizations confirmed the effectiveness of the catalyst in suppressing carbon deposition. This study provides critical mechanistic insights and a viable technical approach for developing CO2-assisted high-temperature electrolysis technologies, showing broad application prospects in renewable energy storage and carbon-neutral technologies.