Photo-radical induced protonation of superionic conducting oxide for high-performance protonic ceramic fuel cells

Proton-conducting ceramic fuel cells (PCFCs) offer a promising sustainable energy technology due to their high efficiency and environmentally friendly operation. However, a significant challenge remains in achieving the desired proton conductivity for the high-performance targets, as many conventional oxide electrolytes, lacking of intrinsic protons, do not support efficient proton transport, resulting in low conductivity (10⁻³-10⁻² S cm⁻¹ at 600 °C). We introduce a novel photo-activated radical process to protonate Ce-doped alumina oxide (Ce_xAl_1-xO_2-δ, x = 0.2, CAO). The resultant material, protonated CAO (H-CAO), creates a distinct and efficient pathway for proton incorporation, leading to intrinsic proton enrichment. H-CAO has reached a high proton conductivity of up to 0.14 S cm⁻¹ and, as the electrolyte for PCFCs, has succeeded in achieving peak power density of 1029 mW cm⁻² at 500 °C. This research advances proton-conducting materials through a sustainable photo-activation process, representing an effective approach to enhance proton transport and optimize PCFC performance.