Energy Harvesting Using High-Strength and Flexible 3D-Printed Cellulose/Hexagonal Boron Nitride Nanosheet Composites

As a natural polymer, cellulose is abundant, low-cost,robust,and biodegradable and can be chemically modified. This work exploresthe enhancement of mechanical, thermal, and flexoelectric propertiesof three-dimensional (3D)-printed carboxymethyl cellulose (CMC) dueto the addition of mechanically exfoliated hexagonal boron nitride(hBN). hBN was observed to act as a rheology modifier, and CMC reinforcedwith 2% hBN exhibited the maximum apparent viscosity of 12.24 Pa & BULL;sat a shear rate of 100 s(-1). The 0.5% hBN/CMC filmexhibited the highest mechanical and thermal stability. A flexoelectricenergy harvester was fabricated out of 3D-printed hBN/CMC compositesto test the effectiveness of strain-induced charge production. Byvarying the load resistance and applied pressure, we were able tomeasure the voltage and current flowing through the device. We foundthat a load resistance of 180 k & omega; connected across a 2% hBN/CMCdevice resulted in the highest power delivery of 5.5 nW. When mechanicalstrain is applied, a charge state fluctuation and spontaneous polarizationin the hBN/CMC matrix are seen. This phenomenon can be explained basedon the flexoelectric energy-harvesting mechanism, supported by densityfunctional theory (DFT) calculations.