High performance H2 sensor based on rGO-wrapped SnO2–Pd porous hollow spheres

Hydrogen (H 2 ) sensors based on metal oxide semiconductors (MOS) are promising for many applications such as a rocket propellant, industrial gas and the safety of storage. However, poor selectivity at low analyte concentrations, and independent response on high humidity limit the practical applications. Herein, we designed rGO-wrapped SnO 2 –Pd porous hollow spheres composite (SnO 2 –Pd@rGO) for high performance H 2 sensor. The porous hollow structure was from the carbon sphere template. The rGO wrapping was via self-assembly of GO on SnO 2 -based spheres with subsequent thermal reduction in H 2 ambient. This sensor exhibited excellently selective H 2 sensing performances at 390 °C, linear response over a broad concentration range (0.1–1000 ppm) with recovery time of only 3 s, a high response of ∼8 to 0.1 ppm H 2 in a minute, and acceptable stability under high humidity conditions (e. g. 80%). The calculated detection limit of 16.5 ppb opened up the possibility of trace H 2 monitoring. Furthermore, this sensor demonstrated certain response to H 2 at the minimum concentration of 50 ppm at 130 °C. These performances mainly benefited from the special hollow porous structure with abundant heterojunctions , the catalysis of the doped-PdO x , the relative hydrophobic surface from rGO, and the deoxygenation after H 2 reduction.