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 NH ₃ 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.