Kinetics‐Driven Dual Hydrogen Spillover Effects for Ultrasensitive Hydrogen Sensing
Haijie Cai, Na Luo, Xiaowu Wang, Mengmeng Guo, Xiaojie Li, Bo Lü, Zhenggang Xue, Jiaqiang Xu
Abstract
Abstract Palladium (Pd)‐modified metal oxide semiconductors (MOSs) gas sensors often exhibit unexpected hydrogen (H 2 ) sensing activity through a spillover effect. However, sluggish kinetics over a limited Pd‐MOS surface seriously restrict the sensing process. Here, a hollow Pd‐NiO/SnO 2 buffered nanocavity is engineered to kinetically drive the H 2 spillover over dual yolk‐shell surface for the ultrasensitive H 2 sensing. This unique nanocavity is found and can induce more H 2 absorption and markedly improve kinetical H 2 ab/desorption rates. Meanwhile, the limited buffer‐room allows the H 2 molecules to adequately spillover in the inside‐layer surface and thus realize dual H 2 spillover effect. Ex situ XPS, in situ Raman, and density functional theory (DFT) analysis further confirm that the Pd species can effectively combine H 2 to form Pd‐H bonds and then dissociate the hydrogen species to NiO/SnO 2 surface. The final Pd‐NiO/SnO 2 sensors exhibit an ultrasensitive response (0.1–1000 ppm H 2 ) and low actual detection limit (100 ppb) at the operating temperature of 230 °C, which surpass that of most reported H 2 sensors.