Atomically dispersed Pt on 3DOM WO3 promoted with cobalt and nickel oxides for highly selective and highly sensitive detection of xylene

Xylene is widely used in different fields but harmful to the environment. Development of an efficient detection method becomes urgent. Metal oxide semiconductor gas sensors are regarded as one of the promising tools due to their rapid response and low power. However, low sensitivity and poor selectivity obstruct their broad applications. In this paper, Pt loaded three-dimensionally ordered macroporous (3DOM) WO3 sensing materials promoted with transition metal oxides of cobalt and nickel were synthesized. 3DOM PtCo-WO3 and PtNi-WO3 exhibited high selectivity and high sensitivity for xylene detection due to the synergistic effect of Pt and transition metal oxides. 3DOM PtCo-WO3 with atomically dispersed Pt exhibited the highest sensitivity (3.91 ppm(-1)) and the lowest detection limit (1.08 ppb) with rapid response speed and long-term stability. The addition of cobalt and nickel led the formation of oxygen vacancy, which helped to anchor the single atomic Pt sites. Atomically dispersed Pt increased the number of active sites and the content of adsorbed oxygen. Besides, the oxygen vacancy decreased the band gap and increased the electron mobility of the synthesized sensing materials. These reasons resulted in a significant resistance change of the sensors and high sensitivity for xylene detection. The selective adsorption of xylene from other volatile organic compounds on the uniform single atom Pt sites established high selectivity displayed by the PtCo-WO3 and PtNi-WO3 sensors.