Dual Heterojunction Strategy on ZIF‐8 for High‐Performance Ammonia Sensor

ABSTRACT The reliable detection of trace ammonia (NH 3 ) under high‐humidity conditions, primarily in exhaled breath and environmental settings, remains a challenge due to issues of long‐term stability, selectivity, and interference from other gases. Heterostructure engineering has recently emerged as a promising pathway to overcome these limitations. Here, we present a dual heterojunction sensor based on zeolitic imidazolate framework‐8 (ZIF‐8) functionalized with a conformal copper oxide (CuO) nanolayer and an electrically conductive poly(3,4‐ethylenedioxythiophene)‐poly(styrene sulfonate) (PEDOT: PSS) film via a kinetically controlled solvothermal process followed by dip coating. The dual heterojunction within ZIF‐8@CuO@PEDOT: PSS nanostructure resulted in enhanced NH 3 absorption, rapid charge transfer, and efficient gas diffusion. The sensor exhibited a fast response magnitude of 9954 toward 50 ppm NH 3 , a rapid response/recovery of 8/2 s, excellent long‐term stability, and high selectivity against common interfering gases at ambient conditions. The superior sensing performance is attributed to the synergistic interactions among the porous ZIF‐8 scaffold, CuO catalytic sites, and the π‐conjugated PEDOT: PSS network, which collectively enable efficient signal transduction and robust functionality under different environments. This work introduces a new paradigm in dual heterojunction ZIF‐8‐based nanostructured sensor, demonstrating strong potential for environmental monitoring and non‐invasive clinical diagnostics for kidney dysfunction.