Multi-3D hierarchical biomass-based carbon particles absorber for solar desalination and thermoelectric power generator

Abstract

To meet challenges of the global energy crisis and the freshwater resources shortage, the interfacial solar-to-steam conversion (ISSC) system was developed quickly in recent years. The photothermal materials play an important role in the ISSC system. We are devoted to developing a unique photothermal material integrating multiple 3D design philosophy both at macroscopic and microscopic levels by employing the cost-effective and widespread resources like straw, rose and coffee grounds, for carbonization as solar absorbers. The biomass-based carbonized particles (CPs) possess three major advantages: (1) wide size-distribution is accessible to form 3D porous rough surface of absorber layer to enhance ability of light absorption; (2) the pristine hierarchical microstructure could absorb nearly all the incident light; (3) the intrinsic vascular bundles with pores on their lumen walls provide a rapid and omnidirectional transport for water and steam escape. A high-efficient solar steam device was fabricated based on the absorber material with its internal 3D micro textures and external 3D architectures. Under the illumination of 1 sun, the photothermal conversion efficiency of straw, rose and coffee CPs can reach 93.4 %, 92.8 % and 76 %, respectively. Simultaneously, a high-efficient solar thermoelectric generator (STEG) is made by coating CPs on a commercial thermoelectric generator and the maximum power of STEG can reach 538.0 μW. Such scalable biomass-based photothermal materials and high-grade thermoelectric conversion capability could be applied to the water purification and the electricity production.