Tuning the Energy Band Structure at Interfaces of the SrFe0.75Ti0.25O3−δ−Sm0.25Ce0.75O2−δ Heterostructure for Fast Ionic Transport Naveed Mushtaq,† Chen Xia,†,§ Wenjing Dong,† Baoyuan Wang,† Rizwan Raza,*,‡ Amjad Ali,‡ Muhammad Afzal,§ and Bin Zhu