Tailoring triple charge conduction in BaCo_0.2Fe_0.1Ce_0.2Tm_0.1Zr_0.3Y_0.1O_3−δ semiconductor electrolyte for boosting solid oxide fuel cell performance

Introducing multiple-ionic transport through a semiconductor-electrolyte is a promising approach to realize the low-temperature operation of SOFCs. Herein, we designed and synthesized a single-phase Ce-doped BaCo_0.2Fe_0.3-xTm_0.1Zr_0.3Y_0.1O_3-δ semiconductor-electrolyte possessing triple-charge (H⁺/O²⁻/e⁻) conduction ability. Two different compositions are synthesized: BaCo_0.2Fe_0.3-xCe_xTm_0.1Zr_0.3Y_0.1O_3-δ [x = 0.1–0.2]. The 20% doped Ce composition exhibits an outstanding oxide-ion and protonic conductivity of 0.193 S cm⁻¹ and 0.09 S cm⁻¹ at 530 °C and the fuel cell utilizing BaCo_0.2Fe_0.2Ce_0.2Tm_0.1Zr_0.3Y_0.1O_3-δ as an electrolyte yields an excellent power density of 873 mW cm⁻² at 530 °C. Moreover, the fuel cell performed reasonably well (383 mW cm⁻²) even at a low temperature of 380 °C. Furthermore, the 10% Ce-doped utilized in fuel cell device illustrates lower performance (661 mW cm⁻² at 530 °C and 260 mW cm⁻² at 380 °C). Successful doping of Ce supports the formation of oxygen-vacancies at the B-site of perovskite and adjusting the ratio of Fe in the compositions. Moreover, the presence of Tm also assist in the creation of oxygen vacancies. Furthermore, the boosting of electrochemical performance and ionic conductivity of applied materials are enlightened by tuning the energy-band structure via employing the UPS and UV–Vis. The physical characterizations and verification of dual-ions (H⁺/O²⁻) in the semiconductor materials are performed via different electrochemical, spectroscopic, and microscopic techniques. A systematic study revealed triple charge conduction in this promising material, which helps in boosting the electrochemical performance of the LT-SOFC.