We report a new energy conversion technology joining electrochemical and physical principles. This technology can realize the fuel cell function but built on a different scientific principle. The device consists of a single component which is a homogenous mixture of ceria composite with semiconducting materials, e.g. LiNiCuZn-based oxides. The test devices with hydrogen and air operation delivered a power density of 760 mW cm⁻² at 550 °C. The device has demonstrated a multi-fuel flexibility and direct alcohol and biogas operations have delivered 300–500 mW cm⁻² at the same temperature. Device physics reveal a key principle similar to solar cells realizing the function based on an effective separation of electronic and ionic conductions and phases within the single-component. The component material multi-functionalities: ion and semi-conductions and bi-catalysis to H₂ or alcohol (methanol and ethanol) and air (O₂) enable this device realized as a fuel cell.