CeO ₂ Hollow Nanospheres Decorated with Pd and PdO Nanodots for Fast Methane Sensing

Abstract Reliable methane (CH 4 ) sensing is highly desired in the underground pipe networks, and even low‐concentration CH 4 leakage may cause disasters. However, it often suffers from instability and sluggish response caused by harsh working conditions (e.g., high humidity). Here, cerium oxide hollow nanospheres decorated with palladium and palladium oxide nanodots (Pd‐PdO NDs / CeO 2 HNSs) are reported for stable and fast CH 4 sensing, which have been prepared via combined bubble confinement and in situ photochemical deposition. As‐prepared Pd‐PdO NDs / CeO 2 HNSs are hollow nanospheres of ≈0.96 µm in diameter. Beneficially, the sensing materials exhibit 3 s fast response and 0.1 ppm limit of detection. Further, Pd‐PdO NDs / CeO 2 HNSs show excellent sensing stability of 510 days stability, 74% relative humidity tolerance, and 100 cycling stability. Theoretically, such outstanding CH 4 sensing performance is attributed to interface‐coupled modulation between Pd‐PdO NDs and CeO 2 HNSs, in which Pd‐PdO NDs serve as catalytic centers, while CeO 2 HNSs act as both oxygen vacancy modulator and structural optimizer. Compared with a commercial sensor, Pd‐PdO NDs / CeO 2 HNSs present superior response / recovery time, and a sensor prototype has been built to simulate the detection of CH 4 leakage with reliable responses.