Omnidirectional, Broadband Light Absorption in a Hierarchical Nanoturf Membrane for an Advanced Solar‐Vapor Generator

Abstract

Solar‐thermal materials have been intensively studied in the context of production and localization of thermal energy, targeting an industry level application. Although photonic and optical strategies for enhancing light absorption have increased the efficiency of photo excitation/conversion into thermal energy, most of them have several limitations such as large area fabrication, thermal stability and broadband/omnidirectional light absorption. In this study, a gold‐coated hierarchical nanoturf membrane (Au/h‐Nanoturf membrane) incorporated with randomly distributed high aspect ratio (AR) nanostructures and micro‐through holes is proposed. The Au/h‐Nanoturf has peculiar black structures that provide advantages in forming a membrane with a large area and in absorbing broadband solar light spectrum. Furthermore, the membrane is combined with micro‐cone array which makes it exhibit exceptionally omnidirectional light absorption properties. Using computational analysis, it is confirmed that the micro‐cone array substantially contributes to the omnidirectional solar absorption irrespective of the wavelength. The optimized structural parameters for the maximum efficiency of the solar‐thermal materials are also found. The prepared solar‐vapor generator with the optimized structural features exhibits 91% average conversion efficiency under one sun condition. The efficiency is sustainable for up to four weeks. The highly efficient and omnidirectional broadband‐absorbing solar‐thermal membrane can be readily employed, targeting an industry level application.

Design of a Separated Solar Interfacial Evaporation System for Simultaneous Water and Salt Collection

“…The Co 2p peak is attributed to Co 2p 3/2 (780.5 eV) and Co 2p 1/2 (796.0 eV) of Co 3 O 4 , and the N 1s peak is attributed to −NH + – (400.7 eV), −NH– (399.9 eV), and N– (397.8 eV) groups of Ppy. , The Co and N elements are uniform on the surface of the Ppy@Co 3 O 4 @Al sheet (Figure S6). The Ppy@Co 3 O 4 @Al sheet has high sunlight absorption (∼97%) in the 300–2500 nm wavelength range (Figure f), due to the synergistic effect of the inherent high light absorption of Ppy and the Co 3 O 4 nanoplate array. ,, The Ppy@Co 3 O 4 @Al sheet also shows excellent photothermal performance, as its upper surface temperature can increase quickly to 90.4 °C in 3 min under 1 sun (Figures g and S7).…”

“…The Ppy@Co 3 O 4 @Al sheet has high sunlight absorption (∼97%) in the 300−2500 nm wavelength range (Figure 2f), due to the synergistic effect of the inherent high light absorption of Ppy and the Co 3 O 4 nanoplate array. 44,52,53 The Ppy@Co 3 O 4 @Al sheet also shows excellent photothermal performance, as its upper surface temperature can increase quickly to 90.4 °C in 3 min under 1 sun (Figures 2g and S7).…”

Solar Water Evaporation Toward Water Purification and Beyond

“…Different material and structural design principles are developed for energy management to reduce heat losses for effective water vaporization. Interfacial evaporation is demonstrated to concentrate heat energy at the air/liquid interface to decrease heat losses, which requires floating solar water evaporators to isolate the evaporation surface from bulk water. , Moreover, fast water transport from the bulk water to the evaporation surface could be achieved by constructing one-dimensional (1D), two-dimensional (2D), or 3D water pathways. ,, Introducing thermal insulation configurations with low thermal conductivity on the top or bottom surface of water evaporators could further decrease heat losses. , …”

Towards highly salt-rejecting solar interfacial evaporation: Photothermal materials selection, structural designs, and energy management

“…Therefore, it is crucial for humans to explore environmentfriendly energy to relieve freshwater shortage [1]. Among the various energy sources in the world, such as wind energy, tidal energy, geothermal energy, and solar energy, the solar energy is one of the most clean, abundant, and easily available energy resource on earth [2,3]. The efficient utilization of solar energy is of great significance to relieve environmental pollution and global energy stress.…”