One-pot hydrothermal synthesis of CuO–ZnO composite hollow spheres for selective H2S detection

Pure ZnO and CuO–ZnO composite hollow spheres were prepared by one-pot, glucose-mediated hydrothermal reaction with subsequent heat treatment. The pure ZnO hollow spheres could selectively detect C2H5OH at 475°C. The CuO–ZnO hollow spheres prepared from the solutions with the compositions of [Cu2+]/([Cu2+]+[Zn2+])=0.02 and 0.04 showed high responses to 5ppm H2S (Ra/Rg=13.3 and 32.4, Ra: resistance in air, Rg: resistance in gas) with negligible cross responses to 100ppm C2H5OH, C3H8, CO and H2 (Ra/Rg=1.4–1.8) at 336°C. They also showed selective C2H5OH detection at 475°C. The dual selective detection of H2S and C2H5OH by the composite particles was due to electrochemical interactions with H2S of nano-scale p(CuO)–n(ZnO) junctions within the hollow spheres.