fig5
![A nanoscale perspective on solid oxide and semiconductor membrane fuel cells: materials and technology](https://image.oaes.cc/2e2694c7-3820-4a81-9a76-4657d9f32494/4288.fig.5.jpg)
Figure 5. TCO SLFC built on the nano-redox unit/reactor (as illustrated above) and charge separation mechanism (as illustrated below). Ec: Energy of conduction band; Ev: energy of valence band; Ef: energy of Femi level; IEF: internal electric field; TCO: triple-charge conducting oxide; SLFC: single-layer fuel cell; HOR: hydrogen oxidation reaction; ORR: oxygen reduction reaction; CB: conduction band; VB: valence band.