Sodium Lignosulfonate-Induced Defective ZIF-67 for Ultrasensitive Gas Sensing in Meat Freshness Monitoring

The design of efficient adsorption sites within triboelectric materials is crucial for improving the atmospheric response sensitivity and operational performance of triboelectric nanogenerators (TENGs). In this work, zeolitic imidazolate framework-67 (ZIF-67) was synthesized using sodium lignosulfonate (SLS) as a polymeric soft template (ZIF-67@SLS) and subsequently incorporated as a nanofiller with abundant adsorption sites into sodium carboxymethyl cellulose (CMC) and poly(vinyl alcohol) (PVA) matrices. The resulting flexible TENG exhibits a rapid and sensitive response to ammonia. The ZIF-67@SLS features a high specific surface area and dense active sites, which enhance ammonia molecule adsorption. The lone-pair electrons of ammonia neutralize surface charges on the TENG, altering the surface electron density and leading to a reduced output voltage. A clear concentration-dependent voltage drop is observed as the ammonia levels increase. Due to the high specific surface area and high triboelectric output performance, we used CMC/PVA/ZIF-67@0.1SLS (CPZS0.1) composite film for ammonia sensing performance evaluation. Compared to pristine ZIF-67, the CPZS0.1-based TENG shows a 41.67% reduction in response time (42 s vs 72 s) and a 58.81% increase in sensitivity (0.539 V/ppm vs 0.222 V/ppm) within the 0–180 ppm range. The optimized system enables accurate ammonia detection and effective monitoring of meat freshness in packaging applications. This study offers a promising strategy for constructing cellulose-based triboelectric composites with tailored gas-responsive behavior, advancing the development of smart sensing materials for environmental and food safety monitoring.