Developing cuprospinel CuFe2O4–ZnO semiconductor heterostructure as a proton conducting electrolyte for advanced fuel cells.

The interfacial properties of electrolyte materials have a crucial impact on the ionic conductivity of solid batteries and solid oxide fuel cells. Here we construct cuprospinel CuFe 2 O 4 (CFO)–ZnO composite as a functional electrolyte for fuel cell device. In an optimal composition of 0.3CFO-0.7ZnO electrolyte fuel cell, the maximum power output of 675 mW cm−2 is obtained at 550 °C. The electrical properties and electrochemical performance are strongly dependent on the ratios between CFO and ZnO in CFO-ZnO composite. Notably, surprising fuel cell performance with high ionic conductivity is attained by constructing this p-type CFO composited with n-type ZnO. Proton conduction was further verified experimentally. The interfacial ionic conduction pathway between the two constituent phases plays a vital role to enhance the proton conductivity, and the bulk p-n heterojunction can block internal electronic pass. An excellent current and power densities of CFO-ZnO composite are observed along with a high conductivity of 0.35 S·cm-1 at 550 °C. This work opens a new perspective for the semiconductor materials that can widely be developed for electrolytes, based on their tunable band structure. • CFO–ZnO heterostructure composite was developed as the functional electrolyte. • 0.3CFO-0.7ZnO achieved super proton conductivity of 0.35 S·cm-1 at 550 °C. • Fuel cell-based on 0.3CFO-0.7ZnO demonstrated high performance. • Bulk p-n heterostructure effect of CFO-ZnO resulted in high fuel cell performance. [ABSTRACT FROM AUTHOR]