Volume-doped cobalt titanates for ethanol sensing: An impedance and X-ray absorption spectroscopy study

The dynamic C2H5OH sensitivity of ilmenite-type cobalt titanates volume-doped by 2 at% Li, Na, K, Sb, La, Sm, Gd, Ho and Pb was systematically studied with respect to exhaust monitoring. Therefore, the p-type semiconducting CoTiO3 materials were characterized as resistive gas sensors via high-throughput impedance spectroscopy toward 5-200 ppm C2H5OH at 300-500 °C. The best performing materials were tested further by time-resolved and long-term measurements whereby the CoTiO3 volume-doped with K exhibited an outstanding overall performance. X-ray absorption spectroscopy on this particular material gave evidence that the local structure around Co and Ti remains unaffected by the doping despite of a slight increase in static disorder. Hence, the effect of K doping does not originate from alteration in the metal-to-oxygen interaction as expected from previous findings.