Gd3+ and Sm3+ doped CeO2 for IT-SOFC and room temperature formaldehyde gas sensing applications

An alternative solid electrolyte is imperative to replace YSZ for better IT-SOFC. Gd3+/Sm3+ doped ceria (Ce0.9Gd0.1O2-δ-GDC1, Ce0.8Gd0.2O2-δ-GDC2, Ce0.8Sm0.2O2-δ-SDC) were synthesized via sol–gel method. These compounds were investigated by using X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM), Energy dispersive X-ray (EDX) spectra, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), Raman and impedance spectroscopy. FESEM micrographs manifested that GDC1 has larger grain sizes than GDC2 and SDC. Interestingly, SDC exhibited more grain boundaries than GDC1 and GDC2. These high dense sol–gel derived compounds have exhibited better ionic conductivity than some of the previously reported Gd3+/Sm3+ doped ceria. Furthermore, the selectivity of calcinated GDC1, GDC2 and SDC sensors at room temperature (RT) for ammonia, methanol, ethanol and formaldehyde gases at 100 ppm was examined and found that GDC1 has displayed an applausive selectivity with superior response for formaldehyde gas sensing at RT as an operating temperature. The Raman analysis avowed the presence of oxygen vacancies which were identified as instrumental in both applications. The multiple gases detected by GDC1 at RT might provide various strategies to design novel gas sensors.