Effect of Simultaneous Modification with Metal Loading and Mesoporous Layer on H₂ Sensing Properties of SnO₂ Thick Film Sensors

Abstract

Effect of metal loading on the H₂ sensing properties of semiconductor gas sensors prepared by the SnO₂ powders modified with a mesoporous SnO₂ layer has been investigated. Metal loading on the SnO₂ powder prior to the modification with the mesoporous SnO₂ layer resulted in larger H₂ response than the sensor prepared by loading after the modification. This phenomenon was highlighted in the case of Ru loading, in comparison with Pd, probably due to its moderate catalytic activity. The markedly improved H₂ response was considered to arise from a synergistic effect of the diffusion control by the mesoporous SnO₂ layer and the chemical sensitization by the Ru loaded on the SnO₂ powder surface. The smaller response induced by the Ru loading after the modification with the mesoporous SnO₂ layer was attributed to consumption of H₂ at the surface of the mesoporous SnO₂ layer.