A Novel Co ₃ O ₄ @Co ₃ (HITP) ₂ ‐Based Sensor for Low‐Temperatures H ₂ S Detection: Fabrication, Performance, and Preliminary Exploration in Monitoring Pork Spoilage

Conductive metal-organic frameworks (cMOFs) are promising for room-temperature gas sensing, yet their development for highly sensitive detection at refrigeration temperature remains a challenge. This work addresses this gap by developing a heterostructured Co₃O₄@Co₃(HITP)₂ chemiresistor for hydrogen sulfide (H₂S) sensing. The decoration of Co₃(HITP)₂ with Co₃O₄ nanoparticles facilitates carrier transfer and lowers the activation energy for H₂S reaction. The optimized sensor demonstrates notable sensitivity, with response values (R_g/R_a) of 3.0 and 1.4 toward 10 ppm H₂S at 25°C and 40°C, respectively. The excellent low-temperature performance is primarily attributed to the Co₃(HITP)₂. As a proof-of-concept, a portable device with a smartphone interface was employed to monitor H₂S released from pork spoilage at both temperatures. It is important to note that early spoilage involves complex volatile profiles, and sole reliance on H₂S detection may be limited due to potential temporal mismatches with other key spoilage markers. This study presents a functionalization strategy to extend cMOF-based sensing into lower temperature regimes, offering a material platform for chilled meat safety monitoring while acknowledging the constraints of single-analyte detection for early warning.