Lotus pollen derived 3-dimensional hierarchically porous NiO microspheres for NO2 gas sensing

Hierarchically porous NiO microspheres with interconnected nano-pores were prepared with chemical bath deposition by using lotus pollens as bio-templates. The NiO microspheres thus derived have a specific surface area of 95.58 m(2)/g and the average pore size is 20.98 nm, such a nanostructure is ideal for gas sensing. To enhance the performances, the NiO microspheres were further decorated with Pd/PdO, and the sensor based on the Pd-decorated NiO microspheres demonstrated a high sensitivity (S=203), fast response/recovery (73 s/169 s) and excellent selectivity to 1.8 ppm NO2 gas at 250 degrees C. Compared with the other NO2 gas sensors based on NiO reported in previous works, the sensitivity of the NO2 sensor of this work is the highest and the response/recovery is among the fastest. (C) 2015 Elsevier B.V. All rights reserved.