P-CuPcTS/n-SnO2 organic-inorganic hybrid film for ppb-level NO2 gas sensing at low operating temperature

•Organic-inorganic hybrid composites for gas sensing is a promising strategy to combine the advantages of organic and inorganic materials.•CuPcTS/SnO2 organic-inorganic hybrid film was prepared through a simple soak-assembling process.•Due to the low adsorption energy of NO2 on CuPcTS, the CuPcTS/SnO2 hybrid film exhibits significantly improved sensing performance to ppb-level NO2.

Design and fabrication of organic-inorganic hybrid sensing materials is a promising strategy to combine the advantages of good stability of inorganic species and high sensitivity, selectivity and low operating temperature of organic ones. In this work, CuPcTS(Copper (II) Phthalocyanine Tetrasulfonic Acid Tetrasodium Salt)/SnO2 organic-inorganic hybrid film was prepared through a simple soak-assembling process. The p-type CuPcTS molecules were homogenously adsorbed on the surfaces of n-type SnO2 film to form p-n heterojunctions. Due to the low adsorption energy of NO2 on CuPcTS at low temperature, the CuPcTS/SnO2 hybrid film exhibits significantly improved sensing performance towards ppb-level NO2 with high sensitivity (Rg/Ra = 2400 up to 1 ppm NO2), ultra-low theoretical detection limit (∼40 ppb when signal-to-noise ratio is 3) and excellent selectivity. The ultrahigh sensitivity and selectivity upon ppb-level NO2 indicate the promising capability of CuPcTS/SnO2 hybrid film for environmental monitoring of NO2 concentrations.

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