Seoul National University team creates five-metal oxide sensor for ethanol detection

New sensor beats conventional models

Professor Ho Won Jang led the group in creating an oxide combining indium, tin, iron, zinc and tungsten. When exposed to 50 ppm ethanol at 300°C, this material showed a response of 5,135 percent. That figure is 12.6 times higher than the low-entropy oxide used for comparison in the study. It additionally captured a reaction speed of 3 seconds along with a restoration period of 73 seconds once ethanol was eliminated.

High entropy design changes surface sites

Conventional sensors using single metal oxides have limited surface sites for gas reactions which hinders detection of small amounts. Researchers previously tried adding noble metals like gold or platinum but faced stability issues and high costs. The new approach mixes five metal elements in similar proportions within a single oxide structure to alter atomic environments. Such variety could alter the characteristics of surface locations where gas particles attach and respond to the substance.

Published findings in Advanced Science

The team synthesized nanostructures with uniformly distributed elements and compared them against low or medium entropy oxides under identical conditions. Results showed the high-entropy oxide was 7.9 times better than the medium-entropy version which recorded a response of 654 percent. The theoretical limit of detection calculated from these signals is 4.8 ppb based on measurement data. These values appear in the paper published in the journal Advanced Science by the research group.