Composite phase change materials with carbon-mesh/CuS/ZnO interface biocarbon skeleton for solar energy storage, solar photocatalysis and electromagnetic shielding

The significant importance of developing phase change materials (PCMs) lies in their capability to meet diverse usage needs, particularly in the sphere of solar energy utilization. In this work, a thermal storage substrate was formed by adsorbing stearic acid in a biocarbon skeleton via vacuum impregnation. A composite PCM with multifunctional properties was subsequently synthesized by modifying the carbon mesh with copper sulfide (CuS) and zinc oxide (ZnO), compounding it onto the surface of the heat storage substrate. The biocarbon skeleton possesses a well-graded pore structure, which offers a significant number of channels for efficient heat transfer and effective electromagnetic shielding. The composite PCM retained a latent heat exceeding 155 J·g−1. The integration of the biocarbon skeleton and modified carbon mesh led to a remarkable 119.42 % enhancement in thermal conductivity within the composite system, as compared to pure stearic acid. Furthermore, granular ZnO and nanoflower-like CuS are effectively integrated on the surface of the carbon mesh, facilitating the formation of localized surface heterojunctions. The composite system exhibits excellent broad-spectrum light absorption capability, producing a significantly elevated photothermal conversion efficiency of 88.93 %. Moreover, the semiconductor effect contributes to a remarkable degradation efficiency of 99.33 % for methylene blue. Significantly, the composite material demonstrates exceptional electromagnetic shielding capability, yielding a total shielding effectiveness exceeding 40 dB. The composite system also demonstrated outstanding thermal and cycling stability, with a negligible latent heat loss of merely 1.9 % even after undergoing 500 thermal cycles. This work proposes a pragmatic methodology to accomplish the functional integration of PCMs. [Display omitted] •Design and preparation of a new multi-layer composite phase change material.•Introduced biochar framework as supporting material.•Introduced a multifunctional interface for CuS/ZnO modified carbon mesh.