Smart Flow Micro‐Reaction Device Integrated with Oxygen Reduction Catalysts for Gaseous Electrochemiluminescence Sensing

Abstract The sensitive detection of low‐concentration gases has significant implications for environmental monitoring, clinical diagnosis, and other fields of scientific inquiry. Electrochemiluminescence (ECL) is a widely accepted analytical technique known for its high sensitivity, precision, and minimal background interference. Nevertheless, it has rarely been documented in the context of gas‐oriented sensing. This study presents an innovative paradigm for gas sensing, which integrates oxygen reduction reactions (ORR) and a gas diffusion electrode (GDE) into a gas flow micro‐reaction device. The integration aims to optimize mass transfer, ensure adequate electrochemical contact, facilitate efficient electron transfer, and ultimately enhance ECL emission. The viability of this effective in situ gas sensing strategy under mild conditions without pre‐treatments is substantiated by experimental and model calculation evidence. This homemade micro‐reaction device enables the efficient quantification of formaldehyde with a limit of determination (LOD) as low as 12.7 ppb and paves the way for universal gaseous ECL sensing.