Environmentally stable and adhesive hemicellulose eutectogel for n-type ionic thermoelectrics

Thermoelectric materials capable of harvesting low-grade heat energy for powering wearable electronics hold significant promise, but their widespread application remains limited by inadequate thermoelectric efficiency and environmental tolerance. Here, we propose an n-type ionic thermoelectric (i-TE) eutectogel through doping ZnCl 2 into a soft carboxymethyl hemicellulose (CMHC)/poly(acrylic acid) matrix, using deep eutectic solvent (DES) as the medium. CMHC simultaneously immobilizes Zn 2+ and reinforces the mechanical performance. The resulting eutectogel achieves an exceptional thermopower of −8.95 mV K −1 , and a remarkable stretchability of 841.8%. Besides, the adoption of DES endows the i-TE eutectogel with strong adhesion, excellent anti-freezing, and anti-drying properties. The integration of four-eutectogel units in series generates an open-circuit voltage of 141.7 mV under a temperature difference of 4 K, and successfully powers a temperature sensor. This work demonstrates the potential of hemicellulose eutectogel in the development of high performance i-TE materials and establishes a promising route toward sustainable and reliable power for next generation wearable devices.