Carbon-supported nano tungsten bronze aerogels with synergistically enhanced photothermal conversion performance: Fabrication and application in solar evaporation

Abstract

Solar interfacial evaporation is an effective and sustainable strategy to solve the shortage of fresh water. Nowadays, fully converting the near-infrared light with significant thermal effect, and reducing the energy loss in evaporation stage are the key factors to achieve higher evaporation rate. Herein, the nano cesium tungsten bronze (Cs0.32WO3) with exceptional near-infrared absorption property was loaded on reduced graphene oxide-carbon nanotubes (rGO-CNTs) composite aerogel, drastically enhancing the evaporation efficiency from 61.0% to 85.9%, which can be explained by the remarkable synergistic effect between rGO-CNTs and nano Cs0.32WO3 in improving the photothermal conversion performance. As a result, the solar evaporators assembled by the fabricated rGO-CNTs-Cs0.32WO3 aerogels and corn straw grooves achieved an evaporation rate of 1.93 kg m−2 h−1, exceeding the previously-investigated carbon aerogels/foams, natural plants and tungsten-based compound systems. The characterization results reveal that the loading of nano Cs0.32WO3 contributes to the partial restoration of π-conjugated structure in rGC, increasing solar absorption and the corresponding thermal energy released by the lattice vibration. Meanwhile, the oxygen vacancies and carrier density of Cs0.32WO3 nanoparticles increase after compositing with rGC, which further enhances the local surface plasma resonances (LSPR) effect. Significantly, the hydrophilic functional groups and excellent wettability of composite aerogel and corn straw play crucial effect in accelerating water transport, activating water molecules and reducing evaporation energy consumption. In a word, the unique construction of rGO-CNTs-Cs0.32WO3 aerogels presents a novel approach for the design of solar-driven freshwater production system, the application expansion of nano tungsten bronze and carbon aerogels.