Highly sensitive detection of H₂S gas at low temperature based on ZnCo₂O₄ microtube sensors

It is extremely necessary to detect Hydrogen sulfide (H₂S) due to the hazardous nature. Thus, it is required to design a material which can detect H₂S gas at low temperature. In this work, ZnCo₂O₄ microtubes are prepared by using absorbent cotton as template, combining immersion method in metal salt solution (Zn:Co=1:2) with calcination treatment in air. The influence of calcination temperature on the particle size and sensing property was also discussed. The diameter of particles on the ZnCo₂O₄ microtubes increases with increasing calcination temperature. The hollow microtubes of ZnCo₂O₄ materials calcined at 600 °C (ZCO-600) exhibit superb sensing performance to H₂S at 90 °C with the lowest detection limit of 50 ppb. The optimum operating temperature (90 °C) was lower than the other reported ZnCo₂O₄ sensors. ZCO-600 sensor also shows excellent selectivity, repeatability, stability, humidity resistance and the good linear relationship in ppb and ppm level H₂S. In addition, the feasible sensing mechanism of ZCO-600 to H₂S is explored on the basis of XPS analysis. Thus, ZnCo₂O₄ as a sensing material possesses widespread application prospects for the detection of trace H₂S gas.