Recycled carbon fibre/cement-based triboelectric nanogenerators toward energy-efficient and smart civil infrastructure

This study investigated the development of recycled carbon fibre (rCF)-reinforced cementitious composites for cement-based triboelectric nanogenerators (CBTENGs), marking a novel integration of rCF into cementitious systems for energy-harvesting in buildings and civil infrastructure. By incorporating rCF into cement matrices, the electrical conductivity and mechanical properties of the composites were significantly improved, addressing the limitations of traditional cementitious materials. A comprehensive series of tests evaluated the electrical, mechanical, and triboelectric performance of CBTENGs with rCF contents ranging from 0 to 5 % by weight of the binder. The results revealed that an optimal rCF content of 0.5 % yielded the highest triboelectric output, with a peak power density of 281 mW/m², a short-circuit current of 7 μA, and an open-circuit voltage of 250 V. However, higher rCF concentrations led to fibre agglomerations, reducing both mechanical strength and electrical performance. The results demonstrated practical applications, including a laboratory-scale simulation in which a CBTENG interacted with a polytetrafluoroethylene (PTFE)-covered wheel, generating measurable electrical outputs. In a field-scale simulation, the CBTENGs successfully charged a 10 μF capacitor to nearly 4.0 V over 1200 wheel passes, powering 26 LEDs. These findings highlight the potential of rCF-reinforced CBTENGs as sustainable, renewable and, cost-effective solutions for energy-harvesting in buildings and civil infrastructure, paving the way for smart and energy-efficient construction materials.