Spatially confined Pt nanoparticles in conductive metal-organic frameworks for highly sensitive room-temperature ammonia sensing.

Ammonia (NH3) leakage poses significant risks to industrial safety, environmental quality, and human health, highlighting the development of highly sensitive sensors operating at room temperature. Herein, ultrasmall platinum nanoparticles (Pt NPs, ∼2 nm) were confined within the ordered channels of conductive Cu3(HHTP)2 metal-organic framework (MOF) via an in-situ reduction strategy to construct Pt@Cu3(HHTP)2 nanocomposites. Benefiting from the spatial confinement effect, the Pt NPs were uniformly dispersed without disrupting the crystallinity of Cu3(HHTP)2, with Pt predominantly existing in metallic state (Pt0). The resulting Pt@Cu3(HHTP)2 sensor exhibited a high response of 142% toward 4 ppm NH3 at room temperature, along with fast response and recovery times (124/68 s), and a low detection limit of 157 ppb. In addition, the sensor demonstrated excellent repeatability, long-term stability, and high selectivity against multiple interfering gases. The introduction of Pt NPs promotes oxygen adsorption and dissociation through synergistic chemical and electronic sensitization effects, thereby facilitating interfacial electron transfer and improving sensing performance. This work provides a rational strategy for engineering conductive MOF-noble metal composites and highlights their potential for reliable room-temperature NH3 monitoring.