Preparation of Al3+-doped ZnO micro–nanospheres for highly sensitive CO gas sensors

Al3+-doped ZnO micro–nanospheres (AZO MNSs) were obtained in the method of collochemistry at a low cost, and the effects of the concentration of Al3+ on morphology, structural and gas-sensitive properties of the AZO MNSs were investigated. It was found that Al3+ doping reduced the particle size distribution of the MNSs and, in addition, also significantly enhanced the gas sensitivity of sensors which are based on ZnO MNSs. Sensor based on A1ZO MNSs showed the best response property for detection of carbon monoxide. Meanwhile, the response/recovery property of A1ZO MNSs and A1ZO nanoparticles (NPs) sensors was also compared and discussed. The sensor based on A1ZO MNSs exhibited a rapider response than A1ZO NPs ones did due to its less grain boundaries.