Comparative NH3-sensing in palladium, nickle and cobalt tetra-(tert-butyl)-5,10,15,20-tetraazaporphyrin spin-coating films

Spin-coating films of palladium, nickle, and cobalt tetra-(tert-butyl)-5,10,15,20-tetraazaporphyrin complex (Pd, Ni, and CoTAP(t-Bu)4) were obtained and characterized by absorption spectra and atomic force microscopy. The gas sensing behaviors of the films were investigated with respect to NH3 at room temperature. In addition, the effects of film morphology and center metal on gas sensing properties were also discussed. It was found that the MTAP(t-Bu)4 complexes exhibited good response, reversibility, stability and ultrafast response and recovery characteristic to NH3. The responses were in the following order: PdTAP(t-Bu)4, NiTAP(t-Bu)4 and CoTAP(t-Bu)4. The response and recovery times of Pd, Ni, and CoTAP(t-Bu)4) films were <20 s, 70 s and 50 s, respectively.