Self-Adaptive Solar-Thermal System With Moss-Like Surface for Efficient Energy Utilization.

Abstract

In order to achieve high-efficiency solar utilization, inspired by the "black carpet effect" of moss population in cold regions, a self-adaptive Janus solar-thermal system with the solar-thermal conversion-conduction-storage-loss control ability is designed. The solar-thermal system features a composite phase change material (CPCM) thermal storage base and a moss-like switchable solar-thermal surface. This surface is constructed from graphene skeletons containing graphene/polydopamine/MXene heterostructures and MXene secondary nano-porous structures. High-efficiency solar-thermal conversion (98.1%) is realized in this surface, due to the interlayer carrier interaction at the heterostructure, as proved by femtosecond transient absorption spectroscopy (fs-TAS), Raman and photoluminescence (PL) spectroscopies, and multiscale calculations, along with the multiple reflections and absorption in porous structures. The converted thermal energy is then rapidly conducted (26.5 W/(m·K)) and stored (236.7 J/g) in the CPCM base. At night, the moss-like surface with ultralow thermal conductivity of 0.03 W/(m·K) and emissivity of 0.2 greatly restrains the thermal loss to the external environment, thereby achieving long-term thermal management (13.3 times longer than that without the system). This study utilized a systematic bioinspired design strategy for preparing the high-performance solar-thermal system, which possesses broad potential for long-term solar utilization.