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

Abstract

Designing ultra‐black materials with strong and broadband light absorption and efficient photothermal conversion properties is of great importance in many fields, including camouflage, catalysis, thermal therapy, and solar energy conversion. The West African Gaboon viper (Bitis rhinoceros), a master of camouflage, features black spots on its dorsal scales. The crest‐ridge structure in its black scales has been proven to be a typical antireflection structure. Herein, an artificial biomimetic ultra‐black sponge (BUBS) that imitates the crest‐ridge structure in the black scales of B. rhinoceros is successfully fabricated through growth of vertically aligned carbon nanosheet arrays derived from cobalt‐based metal–organic framework (Co‐MOF) on a loofah sponge. The vertically aligned carbon nanosheet arrays result in enhanced broadband light absorption (up to 97.08% on average) and photothermal conversion (equilibrium temperature of 80.7 °C under 1 sun illumination) of BUBS. Benefiting from its efficient light absorption and photothermal conversion, the BUBS is incorporated into solar‐powered vapor generation and desalination devices. The BUBS shows a higher water evaporation rate and efficiency of 1.93 kg m−2 h−1 and 98.5%, respectively, compared with other state‐of‐the‐art devices under 1 sun illumination. Furthermore, the BUBS also shows continuous and high water evaporation rates and excellent salt‐rejection in various brines, ensuring its potential application in solar‐powered desalination.

Over 11 kg m–2 h–1 Evaporation Rate Achieved by Cooling Metal–Organic Framework Foam with Pine Needle-Like Hierarchical Structures to Subambient Temperature

“…Furthermore, in order to collect the water steam, a combination of a glass cover and a Petri dish was used (Figure S12). The electrical conductivities (Figure b) of the collected water decreased by several orders of magnitude compared with those of original brines and within the conductivity of drinking water and city water . The collected water steam becomes clear compared with the original turbid seawater (Figure S13).…”

“…The electrical conductivities (Figure 4b) of the collected water decreased by several orders of magnitude compared with those of original brines and within the conductivity of drinking water and city water. 11 The collected water steam becomes clear compared with the original turbid seawater (Figure S13). The contents of Na + , Mg 2+ , K + , and Ca 2+ in the collected water steam are below 0.73 mg L −1 and are all lower than the safe contents defined by standards set by the World Health Organization, demonstrating the excellent solar desalination ability of the biface evaporator.…”

“…In the last several years, solar-powered water purification technology based on solar energy and ultrablack photothermal materials has aroused a lot of interest due to its great potential to alleviate the drinking water crisis without extra energy input. − Until now, many ingenious designs have been made toward the improvement of evaporation rates and efficiencies of evaporators ,,,− More recently, the emergence of three-dimensional (3D) evaporators facilitates the evaporation rates and efficiencies improve manifold compared to two-dimensional (2D) evaporators. Through structure design, 3D evaporators can not only reduce diffuse reflection and energy loss but also obtain energy from the warm ambient conditions.…”

Composite Polyelectrolyte Photothermal Hydrogel with Anti-biofouling and Antibacterial Properties for the Real-World Application of Solar Steam Generation

“…In recent years, solar steam generation via an air/water interfacial heat scheme has been realized as a favorable method with high solar energy utilization efficiency to accelerate evaporation for clean water production. − Generally, in such a process, photothermal evaporators harvest solar energy and convert it into heat energy, which is localized in the air/water interface to weaken the heat losses and improve the steam generation capacity . Numerous ingenious photothermal evaporators made of optimized photothermal materials with thermal management have been utilized to speed up water evaporation and to enhance energy efficiency for freshwater production. − …”

Ultrablack Poly(vinyl alcohol)‐Graphite Composite Xerogel with Vertically Arranged Pores for Highly Efficient Solar Steam Generation and Desalination

“…In the past few years, some efficient evaporators based on different ultrablack materials such as metal nanoparticles, [23][24][25] semiconductors, [26][27][28] carbon materials, [29][30][31][32][33][34] polymers, [35][36][37] and others [38][39][40][41][42] have been reported. However, there are still one or more disadvantages of these evaporators in practical application, such as the use of expensive metals, the strict and complex chemical synthesis process to achieve high absorbance, synthesis process involving high temperature and pressure, and poor durability.…”