Stable Pt/PtO2-enhanced 3D inverse opal SnO2 gas sensor for high sensitivity and fast H2 sensing at low temperatures

H-2 sensors with high sensitivity and fast response rate are essential for the safety of hydrogen energy applications. However, metal oxide semiconductor based H-2 sensors generally need to operate at high temperatures (>200 degrees C), and the development of sensors with excellent H-2 sensing performance at low temperatures (<100 degrees C) remains a challenge. Herein, Pt/PtO2-loaded inverse opal (IO) SnO2 H-2 sensors with three-dimensionally (3D) ordered macropores are fabricated by a sacrificial template method and subsequent partial reduction to significantly reduce the operating temperature. Based on the strong interaction between the PtO2 layer and the metal Pt, stable Pt clusters spread on the SnO2 surface are innovatively obtained by partial reduction of PtO2 with insufficient amount of H-2. The experimental results show that the optimal operating temperature of the 3DIO Pt/PtO2/SnO2 H-2 sensor is reduced from 223 to 79 degrees C compared to SnO2 nanoparticles (NPs). The response to 1000 ppm H-2 at 79 degrees C is 197, which is 7.6 times higher than that of SnO2 NPs, with a response/recovery time of < 1/20 s. In addition, the 3DIO Pt/PtO2/SnO2 sensor also maintains excellent selectivity, outstanding repeatability and long-term stability. The excellent sensing performance is mainly attributed to the electronic and chemical sensitization of the Pt clusters, and the high specific surface area of the 3D ordered macropores. The high response, fast response/recovery and good selectivity at low temperatures suggests that 3DIO Pt/PtO2/SnO2 could be a promising candidate for low-energy consumption H-2 sensors.