Self‐Embedded Schottky Junctions in Liquid‐Metal‐Derived 2D Oxides for Fast and Selective Room‐Temperature H2 Sensing

Abstract Semiconductor‐based hydrogen sensors provide cost‐efficient solutions for safety and a circular hydrogen‐based economy. Liquid metal‐derived 2D metal oxides show promise as ultrathin sensing materials. However, conventional exfoliation inevitably introduces metallic resides, which are often removed post‐synthesis. Here the residual indium nano‐islands are strategically retained within annealed 2D ultrathin In 2 O 3 layers, creating self‐embedded Schottky junctions. This unique architecture enhances gas‐solid coupling at In/In 2 O 3 interfaces. Tuning the composition and spatial distribution of the indium nano‐islands amplifies the thermionic electron emission across the Schottky barriers. The resulting sensor achieves room‐temperature hydrogen detection with a rapid response time of 4.4 s, high sensor response of 3.4, and >2.5 selectivity against common interferents. Remarkably, it exhibits only a 6.7% performance deviation after 6 weeks and shows good humidity resistance. These merits underscore the potential of the material and method for addressing the formidable challenge in developing room‐temperature high‐performance hydrogen sensors.