Self-powered zinc-air battery-driven NO2 gas sensor enabled by multiple grain boundary-engineered CeO2

Real-time, room-temperature nitrogen dioxide (NO 2 ) monitoring is crucial for protecting human health and the environment, yet conventional sensors face limitations on high-temperature operation and external power dependence. Here, we report a self-powered zinc-air battery-driven NO 2 gas sensor based on a multiple grain boundary-engineered CeO 2 (MGB-CeO 2 ) air cathode. Abundant grain boundaries in MGB-CeO 2 promote oxygen vacancy formation, providing more active sites that facilitate NO 2 adsorption and charge transfer. Compared to nanorod CeO 2 (NR-CeO 2 ) sensor, the MGB-CeO 2 sensor achieves a 3.5-fold higher response of 21.2 % to 10 ppm NO 2 , along with shorter response and recovery times. Density functional theory (DFT) calculations confirm significantly higher NO 2 adsorption energy for MGB-CeO 2 than that for NR-CeO 2 , which can be attributed to its defect-rich structure. The MGB-CeO 2 sensor presents outstanding selectivity, low practical limit of detection, and excellent long-term stability. This work provides a novel strategy for the development of self-powered gas sensors, offering valuable insights into electrochemical sensing for practical implications.