Ultra-sensitive hydrogen sensing by Au1/In2O3 single-atom catalysts

Hydrogen energy is associated with notable safety concerns due to its inherent characteristics, such as flammability, low explosive limit, and high diffusivity. Reliable detection is therefore necessary throughout its production and use. Although metal oxide semiconductor (MOS) sensors, such as indium oxide (In 2 O 3 ), have the potential to sense hydrogen (H 2 ), they suffer from limitations in sensitivity, selectivity, and limit of detection. Noble metal nanoparticle modification improves MOS performance. However, high cost and low atom utilization hinder practical application. This work overcomes these limitations by synthesizing mesoporous, nanorod-like In 2 O 3 loaded with an ultra-low content (0.068 wt%) of single-atom gold (Au 1 /In 2 O 3 ) via co-precipitation. The Au 1 /In 2 O 3 sensor demonstrates advanced H 2 sensing performance at 200 °C, with a response value (Ra/Rg) of 31–10 ppm of H 2 . This represents a 7.2-fold improvement compared to pure In 2 O 3 . In addition, the Au 1 /In 2 O 3 sensor exhibits a reliable linear detection range, an ultra-low detection limit (0.025 ppm), favorable selectivity, repeatability, and long-term stability. These superior characteristics are attributed to the modification of single-atom Au, which leads to synergistic effects, including electronic sensitization, catalytic hydrogen activation, and increased oxygen vacancies. This provides a cost-effective, high-performance solution for detecting hydrogen at the critical demands of emerging hydrogen-based energy systems.