Nickel-Induced Dual Carbon Networks Encapsulating Phase Change Materials for Photothermal Conversion and Storage

Bifunctional phase change materials (PCMs) with efficient energy storage and photothermal conversion capabilities have tremendous potential to be applied in advanced thermal management. However, classical organic PCMs with high latent heat are challenged by poor light harvesting, low thermal conductivity, and leakage risks. Here, we design a unique dual-carbon network with Ni nanoparticles (NPs), confined carbon nanotubes (CNTs) shuttling in carbon honeycombs (CH), namely, CH@Ni-CNTs, to encapsulate paraffin wax (PW) that can facilitate the light capture and photothermal conversion dynamics. Benefiting from the physical adsorption of the hierarchical porous structure, the obtained PW/CH@Ni-CNTs composite PCMs show a high phase change enthalpy of 131.0 J g^-1 and long-lasting thermal stability of up to 300 heating-cooling cycles. Moreover, an outstanding photothermal energy conversion efficiency of 96.9% is achieved due to the synergistic effect of the dual carbon network and confined Ni NPs. The CNTs shuttled CH network affords multiple reflection chambers and a thermal conductive pathway, while the localized surface plasmon resonance (LSPR) effects of Ni NPs concentrate the incident light energy to generate and accelerate the transport of active "hot electron", thus collectively contributing to the excellent photothermal properties of the composite PCMs. This study presents a bifunctional Ni-induced dual-carbon network system for the controllable preparation of composite PCMs, and it sheds light on the photothermal conversion mechanisms.