Insights into the room–temperature hydrogen sensing mechanism of metal/oxide Schottky diodes by regulating interfacial adsorbed oxygen/ hydroxyl

Implanting a high–dielectric insulating interlayer between the metals and semiconductors of hydrogen sensing diodes can improve the response, yet the underlying mechanism remains unclear. This study examines key factors for the improved hydrogen response by regulating interfacial adsorbed oxygen and hydroxyl (O_i–ads/OH_i–ads) through heat treatment. Heat treatment at 100 °C or 150 °C reduces the O_i–ads/OH_i–ads content of as–prepared Pt/TiO₂ diode, leading to an alleviated FLP effect and aggravated leakage current. The as–prepared Pt/TiO₂ and Pd nanoparticles (Pd NPs) decorated Pt/TiO₂ diodes show weak response (<25) to 1000 ppm H₂, while heat treatment at 100 °C for 1 h significantly enhances their responses, reaching 325 and 7 × 10³, respectively. Moreover, increased interfacial hydrogen by incomplete recovery in dry air subsequently results in higher response. Therefore, the alleviated FLP effect and the increased interfacial hydrogen are crucial factors for boosted hydrogen response.