Pr/Mg Bimetallic Metal−Organic Framework-Embedded Reversible Ionic-Network Bio-Aerogel for Stable Triboelectric Energy Harvesting and Battery-Free Environmental Monitoring

Abstract

Aerogel-based triboelectric nanogenerators combine a 3D porous network with mechanical functionality, offering an appealing route toward sustainable energy harvesting. However, the irreversible structural degradation and limited reusability of the conventional porous triboelectric materials constrain their long-term operational stability. Herein, we report a reversible ionic-network-enabled bio-aerogel developed for stable triboelectric energy harvesting and environmental monitoring applications. The triboelectric device comprises a tribo-negative Ecoflex layer, a tribo-positive porous bio-aerogel with bimetallic MOF, and a Cu tape as the electrode layer. The porous bio-aerogel is synthesized through a Ca2+ mediated ionically cross-linked alginate-PVA network, following the egg-box model, thus enabling the reversible structural reconstruction through the water-mediated reprocessing. The Pr/Mg bimetallic MOF within the bio-aerogel acts as functional nanofillers that enhance microscale surface roughness, increasing the effective contact area during friction cycles and yielding an output voltage of 140.8 V and a power density of 0.14 W/m2 under periodic finger tapping. By illuminating LEDs and charging a capacitor, the device demonstrates excellent mechanical-to-electrical energy conversion. Furthermore, based on the device’s sensitivity (8.9 ± 0.9 V/kPa) and stability (over 3600 cycles), a battery-free environmental monitoring system is developed by integrating the triboelectric device with a Ni/NiO heterostructure-based chemiresistive gas sensor, which detects a broad concentration range (10 to 300 ppm) of xylene with excellent repeatability. In addition, the bio-aerogel exhibits regenerative characteristics through a water-mediated reprocessing strategy, enabling the regenerated triboelectric device to retain 96.2% of its initial output voltage, thereby paving the way for sustainable wearable electronics and battery-free environmental monitoring applications.