Enhancement of solar vapor generation by a 3D hierarchical heat trapping structure

Abstract

Solar vapor generation is an efficient way to use solar energy for seawater desalination and sewage purification. The efficient utilization of solar-generated heat is a critical and hot topic for developing one-sun driven highly efficient solar vapor generation devices. Here, we reported a three-dimensional graphene-based hive (GBH) solar evaporator that can ensure efficient heat utilization by hierarchical heat trapping and efficient heat localization and reflux as well as long-term heat storage. As a result, a significant efficiency improvement (∼9%) was demonstrated in the 3D GBH evaporator from the initial 1.95 kg m⁻² h⁻¹ (corresponding to an energy efficiency of ∼85%) to the subsequent 2.13 kg m⁻² h⁻¹. In addition, the GBH evaporator exhibited an excellent water evaporation performance under discontinuous irradiation that is 81% of that achieved by continuous solar irradiation for one hour at 1 kW m⁻². The promising 3D hierarchical design offers efficient heat trapping, localization, and reflux as well as long-term heat storage which make it easy to develop highly efficient solar vapor generation devices for sunny and cloudy days.