Recyclable gelatin/graphene oxide-based direct-current tribovoltaic nanogenerators for wearable energy harvesting

Sustainable direct-current tribovoltaic nanogenerators (DC-TENGs) have attracted increasing interest for self-powered wearable electronics; however, many existing systems still rely on petroleum-based materials and non-recyclable device structures. Herein, a biodegradable gelatin/graphene oxide (GO)-based composite film capable of intrinsic direct-current output is developed through a fully water-based fabrication process. The incorporation of defect-rich GO nanosheets enhances interfacial coupling, asymmetric charge transport, charge trapping, and structural stability. As a result, the device achieves an open-circuit voltage of ~0.8 V, a short-circuit current of ~53 μA, and a peak power density of ~1.2 μW cm^-2. The device also exhibits distinguishable electrical responses under various biomechanical motions, demonstrating its potential for self-powered sensing applications. In addition, the composite films can be recycled through a simple dissolution-recasting process, with regenerated devices retaining over 70% of voltage output and 80% of current performance. Structural analyses reveal partial GO rearrangement after recycling, while Kelvin probe force microscopy confirms relatively stable interfacial electronic characteristics. By correlating material evolution, interfacial behavior, and electrical performance, this work provides insight into recyclable DC-TENG systems and presents a sustainable strategy for biodegradable, recyclable, and reusable self-powered electronic platforms.