Facile synthesis and ppb-level H2S sensing performance of hierarchical CuO microflowers assembled with nano-spindles

CuO microflowers were successfully synthesized via a hydrothermal route followed with a high-temperature treatment. The characterized results showed that CuO microflowers assembled with nano-spindles (length: 800 nm) were obtained and the diameter of microflowers were 2.0-2.5 mu m. The gas sensor based CuO microflowers showed a fine response to H2S at 25 degrees C and a fast recovery after a 10-s voltage pulse. The response (S = R-g/R-a) of CuO sensor was 9.92 to 1 ppm H2S at room temperature, and it even could detect 50 ppb H2S (S = 1.42). Furthermore, the gas sensor demonstrated excellent selectivity and repeatability. The sensing mechanism of CuO microspheres to H2S was also proposed and discussed. This work indicates that the prepared CuO microflowers have potential application in detecting extreme low-concentration H2S.