Gas sensor properties of nanopore-bearing Co₃O₄ particles containing Pt or Pd particles

Nanopores were successfully formed in cobalt oxide particles by carrying out sintering to remove the shell of core-shell type cobalt oxide particles comprised of a cobalt oxide core and a polyvinylpyrrolidone (PVP) shell. During synthesis of the cobalt oxide partices, PVP-covered Pt or Pd particles were added to achieve metal loading on the nanopores and surfaces of the cobalt oxide particles. The crystallite size of the cobalt oxide particles was 15 nm, the particle diameter was 50 nm, and the nanopores measured 2-6 nm in diameter. The positions of the Pt or Pd particles in the cobalt oxide particles were verified by stereo-transmission electron microscopy observations. In terms of the particle gas sensor properties, the loading of Pt or Pd particles into the cobalt oxide particle nanopores increased the responsiveness to acetone gas, and as a result, the acetone gas selectivity was improved over hydrogen gas. Upon comparison between cobalt oxide particles bearing Pt or Pd particles only on the surface and those containing Pt or Pd particles within the pores, the later was found to exhibit an approximately 4-fold acetone/hydrogen gas selectivity.