Photo-assisted synthesis of protonated oxides for fuel cells

The absence of intrinsic protons in proton-conducting oxides (PCO) is a significant challenge that limits the proton conductivity of proton-conducting perovskites, such as Y-doped BaMO₃ (M = Zr, Ce), in proton ceramic fuel cells exhibit low conductivity (10^-3 to 10^-2 S cm^-1 at 600 °C). Herein, we introduce a photo-assisted synthesis method for incorporating protons into Al-doped ceria (Al_xCe_1-xO_2-δ, x = 0.2; M-ACO), leveraging the open cubic fluorite structure and photo-activated radical reactions. Specifically, photon-generated hydroxyl reactive $\left({\mathrm{OH}}^{\bullet }\right)$ and superoxide ( $O_2^{\bullet -}$ ) Radicals are generated and interact with the ACO crystal lattice, facilitating proton incorporation and resulting in the synthesis of native-proton-type PCO. This process results in a protonated (H-ACO) with a high proton conductivity of 0.14 S cm^-1 and exceptional power density of 922 mW cm^-2 at 500 °C. This versatile synthesis methodology offers broader development of advanced PCO for energy-related applications.