Tetradecylamine/MXene/porous sorghum straw biochar composite with high latent heat for thermal energy storage and efficient photo-electro-thermal conversion

Despite the promise of biomass-derived porous carbon for phase change energy storage, the simultaneously achieving high energy storage density, enhanced thermal conductivity, and efficient multi-modal energy conversion remains a challenge. To address this, we developed a composite of MXene and sorghum straw-derived biochar (MXene/SSBC) was synthesised, and tetradecylamine (TDA) was subsequently incorporated via vacuum impregnation to fabricate tetradecylamine/MXene/sorghum straw-derived biochar composite phase change materials (TDA/MXene/SSBC CPCMs). This work highlights the synergistic effect between the three components, enabled by the MXene/SSBC three-dimensional network effectively hosts TDA via capillary forces. The findings demonstrated that the specific surface area of the MXene/SSBC aerogel reached 247.3 m 2 /g. The latent heat of the TDA/MXene/SSBC CPCMs attained 220.2 J/g, a competitive value among reported biochar-based PCMs. After 50 thermal cycles, the composite retained 85.7% of its latent heat (188.7 J/g), demonstrating good cycling stability. Moreover, the thermal conductivity of TDA/MXene/SSBC CPCM-3 was measured at 0.408 W/(m·K), representing a 1.49-fold enhancement compared with pure TDA. The TDA/MXene/SSBC CPCMs displayed outstanding photothermal and electrothermal conversion efficiencies, reaching up to 95.6% and 87%, respectively.