Multifunctional Ti3C2Tx-alginate foams for energy harvesting and fire warning

Abstract

Foams that combine seemingly opposite properties, such as high thermal insulation and electrical conductivity, are highly sought after for modern-day advanced applications. However, achieving a balance of these properties necessitates careful tuning of material compositions. Here, we prepared ice-templated Ti₃C₂T_x-alginate composite foams and investigated the role of Ti₃C₂T_x MXene in triboelectric energy production, thermal insulation, and flame retardancy. Our results show that adding 5 wt% Ti₃C₂T_x enhances the triboelectric output of 6 mm thick foams (380 V, 7.7 μA, 43 mW m⁻²) by 110%. Despite incorporating electrically conducting Ti₃C₂T_x, these macroporous composite foams have a thermal conductivity of only 62 mW m⁻¹ K⁻¹, while they also show flame-retardant properties, exhibiting self-extinguishing behavior. Finally, we demonstrate these composite foams for constructing smart fire alarm systems as they respond to small changes in electrical resistance induced by fire. Our findings prove that Ti₃C₂T_x is a versatile filler for biopolymer foams, introducing complementary functionalities that can be exploited in energy and safety applications.