Mid Sweden University

The rising demand for wireless electronics and sustainable energy solutions drives the search for alternatives to conventional batteries. Triboelectric nanogenerators (TENGs) offer a promising route by converting mechanical energy into electricity via frictional events between two different material surfaces. Here, a simple and scalable surface modification method using conventional laser printing was applied to investigate the effect on triboelectric performance of cellulose-based materials against polytetrafluoroethylene (PTFE). Regenerated cellulose (RC) and cellulose acetate (CA) films were print patterned with black toner in a conventional laser printer at different surface coverages from 0% to 100%. The measured power output for RC films against PTFE showed minimal response from the patterning over the whole range and could be considered as constant with an average of 52 ± 2 W m−2. On the other hand, the CA sample films showed a significant and gradual increase in power output from 45 to 65 W m−2 as the toner print coverage increased from 0% to 100%. These results demonstrate that synergistic interactions between the printed toner and the substrate can strongly influence TENG performance and are highly dependent on the physical and chemical properties of the underlying material. In CA, toner–substrate intermixing enabled by laser printing temperatures exceeding the glass transition temperature provides a proof-of-concept for enhancing triboelectric performance through controlled surface–bulk interactions. 

Cellulose has emerged as a promising sustainable material for advanced applications, including energy harvesting and sensing via triboelectric nanogenerators (TENGs). Despite significant progress in cellulosic TENGs, the role of carbonaceous nanomaterials with different morphologies and surface chemistries remains insufficiently understood. In this study, regenerated cellulose was used as a matrix to incorporate different carbon allotropes, including nanodiamonds, multi-walled carbon nanotubes (MWCNTs), and graphene nanoplatelets, to systematically evaluate their effect on triboelectric performance. Cellulose was dissolved in cold alkaline solution, and composites containing 2.5, 5, 7.5, 10, and 20 wt% of nanoparticles were prepared and tested as tribolayers against PTFE in a TENG configuration. The results showed that graphene-, MWCNT-, and nanodiamond-based composites improved power output by up to 76%, 51%, and 40%, respectively, compared to pure cellulose (34.3 W m−2). Physical and structural analyses, including dielectric spectroscopy, electrical conductivity measurements, scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), FTIR, and Raman spectroscopy, were employed to investigate the structure-property relationships of regenerated cellulose‑carbon allotrope composites. The findings provide insight into the role of carbon nanomaterials in tuning the triboelectric behavior of regenerated cellulose and offer guidance for the design of high-performance, sustainable functional composites. 

Regenerated cellulose is a promising tribopositive material for sustainable triboelectric nanogenerators (TENGs), although its electrical output remains sensitive to surface and interfacial properties. In this study, regenerated cellulose was modified using atomic layer deposition (ALD) of Al2O3, TiO2, and ZnO to investigate how nanoscale oxide coatings influence triboelectric performance against a tribonegative PTFE counter layer. Two deposition regimes were examined: 7 ALD cycles, representing the early stage of ALD growth, and 200 cycles, representing a more developed coating regime. Triboelectric measurements, dielectric spectroscopy, structural characterization and contact angle analysis, were used to evaluate how ALD modification influences the electrical response of regenerated cellulose. All ALD-modified samples exhibited increased surface charge density and power output compared to unmodified cellulose, while also showing improved retention of triboelectric performance at elevated relative humidity. The 7-cycle samples consistently outperformed the corresponding 200-cycle coatings under low-humidity conditions, whereas the 200-cycle ZnO sample exhibited the highest humidity stability. No direct correlation between wettability and triboelectric output was observed. The results suggest that relatively small interfacial modifications introduced by ALD are sufficient to influence both the triboelectric response and humidity-dependent charge dissipation behavior of regenerated cellulose.