Spectrum Tailored Defective 2D Semiconductor Nanosheets Aerogel for Full‐Spectrum‐Driven Photothermal Water Evaporation and Photochemical Degradation

Abstract

The wide spectral range of the solar flux with undesirable diffused energy distribution remains a substantial impediment to the high-efficiency utilization of the whole spectrum. Here, inspired by the spectrally selective sunlight utilization of plants, a spectrum-tailored solar harnessing aerogel is conceived. It is composed of oxygen vacancy (O v) defect-rich semiconductor HNb 3 O 8 (D-HNb 3 O 8) nanosheets and polyacrylamide (PAM) framework to perform all-in-one photochemical and photothermal full solar energy conversion. The aerogel selectively utilizes the whole solar spectrum, in which high energy ultraviolet (UV) photon is converted into high redox potential electron-hole pairs, while low energy visible-near infrared (NIR) photons are transformed into heat. The designed solar absorber-polymer composite shows energy harnessing-conversion capability with desired heat insulation, reactant enrichment, rapid mass diffusion and capillary pumping characteristics, thus realizing a high efficient steam generation and photochemical activity. This cooperative photochemical and photothermal solar energy conversion, at respective optimal working spectrum, holds great promise for optimizing and maximizing the solar energy utilization, as well as opening up opportunities to explore simultaneous multifunctional usage of solar energy.

Biomimetic Ultra‐Black Sponge Derived from Loofah and Co‐MOF for Long‐Term Solar‐Powered Vapor Generation and Desalination

“…The efficiency calculated according to the energy loss analysis and the efficiency calculated according to the efficiency calculation formula (Experimental Section) can be considered as matching within the error range. The water evaporation rate and photothermal conversion efficiency of BUBS are higher than those of most recently reported photothermal materials, including plasmonic materials, [ 26,57 ] semiconductors, [ 27,28,58–60 ] carbon materials, [ 36,40,61–64 ] polymers, [ 65,66 ] and MXene [ 49,52 ] (Figure 4f and Table S1, Supporting Information).…”

“…Solar‐powered vapor generation and desalination, which is an economical strategy that mainly utilizes solar energy and ultra‐black materials with efficient light absorption and photothermal conversion properties in solar band, is used to powerfully accelerate the evaporation of water and collect water and thereby solve the crises of drinking water shortage and water pollutions. [ 18–21 ] In the last few years, some evaporators based on different photothermal materials such as metal nanoparticles, [ 22–26 ] semiconductors, [ 27–30 ] polymers, [ 31–35 ] carbon materials, [ 36–48 ] and MXene [ 49–52 ] have been reported. However, most evaporators with high water evaporation rates and photothermal conversion efficiencies have some limitations in practical application scenarios, such as the use of expensive metals (Au and Ag) to enhance light absorption and photothermal conversion, strict and complex preparation processes to achieve microstructural control, and poor durability when used for solar‐powered desalination.…”

Photothermal Devices for Sustainable Uses Beyond Desalination

“…Reproduced with permission. [ 20 ] Copyright 2020, Wiley‐VCH; c) a photothermal evaporator coupled with a SERS substrate. Reproduced with permission.…”

“…For example, Yang et al developed an all‐in‐one device in which the high‐energy ultraviolet light was utilized in photocatalytic reactions, whereas the low‐energy visible‐to‐near‐infrared light was transformed to heat for photothermal evaporation (Figure 1b). [ 20 ] The heat generated from the photothermal materials can not only drive the evaporation but also facilitate the photocatalytic reactions by heating the surrounding medium, because most of the chemical reactions can be accelerated at an elevated temperature. [ 25 ] Such design demonstrates the photothermal synergistic effects for higher solar energy utilization.…”

“…For example, a photothermal evaporator decorated with a photocatalyst can be applied in wastewater treatment for both evaporation and contaminate degradation. [20] Combined with hygroscopic materials, the photothermal evaporator can capture moisture from the environment and produce clean water through a condensation-evaporation cycle. [21] Moreover, the latent heat, [22] temperature or salt concentration gradient, [10,23] as well as the water flow during evaporation, can drive an energy-generation process along with desalination, acquiring both freshwater and electricity simultaneously.…”