A promising new form-stable phase change material (PA/PB) was fabricated using pinecone biochar (PB) as the supporting material of palmitic acid (PA). The biochar of PB with large surface area was produced by forest residue of pinecone, and it was cheap, environment friendly and easy to prepare. The PB was firstly utilized as the supporter of PA and the characterizations of PA/PB were analyzed by the BET, SEM, XRD, DSC, TGA, FT-IR and thermal conductivity tester. The results demonstrated that the PA was physically absorbed by the PB and the crystal structure of the PA was not destroyed. The results of DSC showed that the fusing and crystallization points of the form-stable phase change material with the maximum content of PA (PA/PB-4) were 59.25 °C and 59.13 °C, and its fusing and freezing latent heat were 84.74 kJ/kg and 83.81 kJ/kg, respectively. The results of TGA suggested that the thermal stability of the PA/PB-4 composite was excellent, which could be used for the applications of thermal energy storage. Furthermore, the thermal conductivity of PA/PB-4 was 0.3926 W/(m∙K), which was increased by 43.76% compared with that of the pure PA. Thus, the study results indicated that the PA/PB-4 had great potential for thermal energy storage applications.

Freshwater pollution and shortage have become an imminent problem. Therefore, it is necessary to develop a multi-functional membrane for the production of fresh water. In this work, the regenerated lignocellulose modified cotton fabric was developed as a novel, multi-functional and degradable membrane (LCPT@CF) for efficient oil–water separation and solar steam generation for the first time. The fabrication method has the merits of simple, environmentally friendly and cost effective. The regenerated lignocellulose was adhered on the surface of cotton fabric by tannic acid and polyvinyl alcohol complexes tightly, and the multilayered structures of the LCPT@CF can be formed, which endowed the membranes with underwater superoleophobic property and durability. The underwater superoleophobic property enabled LCPT@CF to purify various kinds of oil-in-water emulsions with a separation efficiency of more than 99.90%. Moreover, benefiting from the excellent photothermal conversion capacity of regenerated lignocellulose, the LCPT@CF achieved high evaporation rate of 1.39 kg m⁻² h⁻¹ and favorable evaporation efficiency of 84% under 1 sun illumination, and the LCPT@CF also presented excellent salt-resistance for evaporating seawater for 20 cycles, without salt accumulation. More importantly, the LCPT@CF could be naturally degradable by microorganisms in the natural condition within 3 months, which had outstanding environmental friendliness. These above results demonstrated that the green and efficient LCPT@CF could play great potential in oil–water separation and sewage purification.

Copper microsphere hybrid mesoporous carbon (MPC-Cu) was synthesized by the pyrolysis of polydopamine microspheres doped with copper ions that were prepared using a novel, facile and simple one-step method of dopamine biomimetic polymerization and copper ion adsorption. The resulting MPC-Cu was then used as a supporter for polyethylene glycol (PEG) to synthesize shape-stabilized phase change materials (PEG/MPC-Cu) with enhanced thermal properties. PEG/MPC-Cu was studied by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, differential scanning calorimetry and thermal constant analysis. The results demonstrated that the thermal conductivity of PEG/MPC-Cu was 0.502 W/(m K), which increased by 100% compared to pure PEG [0.251 W/(m K)]. The melting enthalpy of PEG/MPC-Cu was 95.98 J/g, indicating that PEG/MPC-Cu is a promising candidate for future thermal energy storage applications. In addition, the characterization results suggested that PEG-MPC-Cu possessed high thermal stability. Therefore, the method developed in this paper for preparing shape-stabilized phase change materials with improved thermal properties has substantial engineering application prospects.

Mesoporous silica nanoscale microsphere (MSNM), with a special morphology, high porosity, large pore volume and specific surface area, was successfully prepared and used as the matrix material of lauric acid (LA) to prepare a favorable shape-stabilized phase change material (LA/MSNM). The porous network structure of MSNM is effective to prevent the leakage and enhance the thermal stability of LA/MSNM. For comparison, shape-stabilized phase change material of LA/AC, which contained commercially purchased active carbon (AC) and LA, was prepared by the same method. Characterizations of LA/MSNM and LA/AC, such as chemical properties, structure, thermal properties and crystallization properties were studied. The mechanisms of interaction between LA molecules and MSNM or AC were explicated. The results of TGA test showed that the LA/MSNM and LA/AC had superior thermal stability, and however, the melting and solidification enthalpies of LA/MSNM were much higher than that of LA/AC, which was attributed that the loading capacity of MSNM was better than that of LA/AC. All of the study results demonstrated that the mesoporous silica nanoscale microspheres of MSNM synthesized in this study possessed the potential for practical applications as a suitable supporter of organic phase change materials.