Characterizing the Blocking Electron Ability of the Schottky Junction in SnO₂–SDC Semiconductor–Ionic Membrane Fuel Cells

Abstract

Recent research has shown that fuel cells using semiconductor–ionic conductor material (SIM) as electrolytes can achieve good performance due to the enhancement of ionic conductivity, and the Schottky junction is expected to block the electron conduction to further address the shorting circuit issue, but efficient characterization of the blocking electron ability of the Schottky junction is absent. In this work, SnO2-Ce0.8Sm0.2O2−δ(SDC) SIM was applied as an electrolyte membrane to assemble the semiconductor–ionic membrane fuel cell (SIMFC). Although the SnO2-SDC SIM electrolyte possessed certain electron conduction, such a device can also deliver an open circuit voltage above 1 V, and the maximum output power reached 1059 W cm–2 at 550 °C without a shorting circuit problem. The rectifying curve was recorded under an inset gas atmosphere to evaluate the blocking electron ability of the Schottky junction. The UPS and UV–vis characterization revealed that the band energy alignment of the Schottky junction is the underlying reason for eliminating electron conduction in SIMFC, and the blocking electron capability is related to the barrier energy of the Schottky junction, which is determined by the difference between the work function of the metal and the Fermi level of the semiconductor. The characterization of band energy and rectifying curve provides a common methodology for SIMFC.

Electrochemical Properties of a Dual-Ion Semiconductor-Ionic Co0.2Zn0.8O-Sm0.20Ce0.80O2−δ Composite for a High-Performance Low-Temperature Solid Oxide Fuel Cell

“…However, an interesting argument is the formation of Schottky junction from the Ni metal produced from the surface of Ni-NCAL (H 2 -anode side) towards the Co 0.2 Zn 0.8 O-SDC semiconductor electrolyte, where it generated a built-in field and also supported the suppression of electronic conduction. Our results have met the requirements of the formation of a Schottky junction and are in line with the literature. ,,, Therefore, the built-in electric field (BIEF) in the direction of Ni metal to the Co 0.2 Zn 0.8 O-SDC electrolyte supports the fast transport of oxide ions and helps suppress the intrinsic and extrinsic electrons to flow through electrolyte toward the cathode. In addition, the interface formed between Co 0.2 Zn 0.8 O and SDC adds up in the fast transport of ionic conduction, as shown in the schematic presentation in Figure .…”

“…Our results have met the requirements of the formation of a Schottky junction and are in line with the literature. 24,40,69,70 Therefore, the built-in electric field (BIEF) in the direction of Ni metal to the Co 0.2 Zn 0.8 O-SDC electrolyte supports the fast transport of oxide ions and helps suppress the intrinsic and extrinsic electrons to flow through electrolyte toward the cathode. In addition, the interface formed between Co 0.2 Zn 0.8 O and SDC adds up in the fast transport of ionic conduction, as shown in the schematic presentation in Figure 10.…”

Advances in novel SDC@Al2O3 core−shell electrolyte for low‐temperature solid oxide fuel cell

“…Therefore, the Al 2 O 3 modification can extend the TPB region to further bring about the lower R p , it favors for the cell performance. In addition, the R p revolution with the Al 2 O 3 content has the same law with that of R 0 , it initially increases with Al 2 O 3 contents and then decreases as the Al 2 O 3 content further increases 38 …”

“…In addition, the R p revolution with the Al 2 O 3 content has the same law with that of R 0 , it initially increases with Al 2 O 3 contents and then decreases as the Al 2 O 3 content further increases. 38 The SDC@ Al 2 O 3 cell with 10% Al 2 O 3 content exhibited the minimal R p of 0.1431 Ω cm −2 at 550 • C. Figure 6B presents the EIS results of SDC@Al 2 O 3 (10%) cell at three different temperatures, and the corresponding impedance fit results at different temperatures are shown in Table 3. As shown in the figure and table, the ohmic resistance (R 0 ) and polarization resistance (R P ) increase as the temperature decreases, demonstrating the thermally activate process.…”

Standardized Procedures Important for Improving Low-Temperature Ceramic Fuel Cell Technology: From Transient to Steady State Assessment

“…To further illustrate the great influence of sweeping/scanning rate on the apparent power density of SJFC/SMFC, I – V – P curves were demonstrated. For example, the reported high oxide ion-conducting electrolytes, such as non-doped ceria (CeO 2 ) [ 19 , 20 ] and SDC-SnO 2 [ 21 ] heterostructure have fast ionic transportation as well as high power density at low operational temperature. In addition, the fabricated devices with schematic PEN structure, i.e., CeO 2 and SDC-SnO 2 electrolytes sandwiched with identical symmetrical NCAL electrode, are fabricated ( Figure S2 ).…”