The preparation of porous gas diffusive electrodes is the key to an excellent electrochemical sensor for determination of formaldehyde, in which the microstructure of catalyst direct affects the response capability. The catalysts of gold nanoparticles/activated carbon and gold nanoparticles/carbon nanotubes were prepared by sodium citrate reduction method. The gas diffusion porous electrodes have been obtained and characterized by SEM (scanning electron microscopy). The formaldehyde gas sensor C had the best response when formaldehyde concentration was 0.24 and 0.63 mg/m³. The linear regress equation was y＝10.515x＋4.4049 (R²＝0.9917) when concentration of formaldehyde ranged from 0.1 to 0.84 mg/m³, and the response time was about 80 s. The relationship between microstructure of the gas diffusion electrode and response characteristic of formaldehyde was studied.

Key words: gold nanoparticle, activated carbon, carbon nanotube, formaldehyde, porous gas diffusion electrode, electrochemical sensor