Terminal group engineering of Ti₃C₂T_x MXene on thermal emitter performance

Ti₃C₂T_x MXene has emerged as a promising material for diverse nanophotonics applications. In this study, we investigate how Ti₃C₂T_x MXene terminal groups (-F, -O-, -OH) influence the performance of a planar thermal emitter with a VO₂/SiO₂/Ti₃C₂T_x MXene structure. By examining four variants of Ti₃C₂T_x MXene across the 2-20 µm spectral range, we demonstrate that the hysteresis loop threshold temperature remains constant for all MXene types due to the VO₂ phase change material. The average differential emissivity (Δε) between the semiconductor and metallic states of VO₂ varies significantly with terminal group composition. The VO₂/SiO₂/Ti₃C₂F₂ structure exhibits the highest differential emissivity of Δε = 0.42, while VO₂/SiO₂/Ti₃C₂(OH)₂ shows the lowest of Δε = 0.33. The remaining structures; VO₂/SiO₂/Ti₃C₂ and VO₂/SiO₂/Ti₃C₂O₂, demonstrate intermediate differential emissivity values of Δε = 0.41 and 0.38, respectively. These findings establish a foundation for controlling emissivity in applications such as energy harvesting, thermophotovoltaics, and radiative cooling systems. The ability to tailor thermal emission through MXene terminal group engineering presents opportunities for designing tunable photonic devices with precise thermal control capabilities for the next-generation of energy management systems.