Cubic silicon carbide/zinc oxide heterostructure fuel cells

Multifunctional semiconductor cubic silicon carbide (3C-SiC) is employed for fuel cell electrolyte, which has never been used before. n-type 3C-SiC can be individually employed as the electrolyte in fuel cells, but delivers insufficient open circuit voltage and minuscule current density due to its electronic dominant property. By introducing n-type ZnO to form an n–n 3C-SiC/ZnO heterostructure, significant enhancements in the ionic conductivity of 0.12 S/cm and fuel cell performance of 270 mW cm−2 are achieved at 550 °C. It is found that the energy band bending and build-in electric field of the heterostructure play the pivotal role in the ionic transport and suppressing the electronic conduction of 3C-SiC, leading to a markable material ionic property and fuel cell performance. These findings suggest that 3C-SiC can be tuned to ionic conducting electrolyte for fuel cell applications through the heterostructure approach and energy band alignment methodology.