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

Real-time, room-temperature nitrogen dioxide (NO₂) 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 NO₂ gas sensor based on a multiple grain boundary-engineered CeO₂ (MGB-CeO₂) air cathode. Abundant grain boundaries in MGB-CeO₂ promote oxygen vacancy formation, providing more active sites that facilitate NO₂ adsorption and charge transfer. Compared to nanorod CeO₂ (NR-CeO₂) sensor, the MGB-CeO₂ sensor achieves a 3.5-fold higher response of 21.2 % to 10 ppm NO₂, along with shorter response and recovery times. Density functional theory (DFT) calculations confirm significantly higher NO₂ adsorption energy for MGB-CeO₂ than that for NR-CeO₂, which can be attributed to its defect-rich structure. The MGB-CeO₂ 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.