Emerging investigator series: the rise of nano-enabled photothermal materials for water evaporation and clean water production by sunlight

Abstract

This frontier reviews impressive progresses of nano-enabled solar-driven water evaporation and clean water production made in the past 4 years.

Harnessing Solar‐Driven Photothermal Effect toward the Water–Energy Nexus

“…H v is determined by the vaporization temperature of the water/air interface (2453 kJ kg −1 at 20 °C and 2265 kJ kg −1 at 100 °C), and H s is dependent on the specific heat of water (c water = 4.186 kJ kg −1 °C −1 ) and its temperature change. Several previous reviews have briefly summarized the diverse solar absorber materials and device designs of steam generators, [13,23,[26][27][28][29]111] whereas we will mainly focus on the latest representative strategies for enhancing water evaporation efficiency in the following part. In aim to minimize heat losses and boost conversion efficiency, an insulating and hydrophilic porous supporter has been integrated into the floating system to avoid the direct contact between photothermal materials and bulk water, as shown in Figure 3a, which has been regarded as the next generation solar-driven water evaporation device.…”

“…[23,24] First, solar-driven photothermal effect can be directly used or integrated into other water purification technologies. Given that most of the regions with high water shortage have abundant solar energy resources, these emerging photothermal applications show great potential to utilize solar energy to directly solve the issue of water shortage and improve the overall resilience of the water-energy nexus.…”

“…[23,[26][27][28][29] However, these previously published review articles are limited to the specific topic of solar steam generation, and thus there is still no comprehensive review focusing on the latest progress and future development trend of all the solardriven low-energy water purification/harvesting technologies. [23,[26][27][28][29] However, these previously published review articles are limited to the specific topic of solar steam generation, and thus there is still no comprehensive review focusing on the latest progress and future development trend of all the solardriven low-energy water purification/harvesting technologies.…”

Fast‐Growing Field of Interfacial Solar Steam Generation: Evolutional Materials, Engineered Architectures, and Synergistic Applications

“…In the reflectance of absorber surface (orange dotted line upon the water), the advance of nanotechnology has largely decreased the reflectance of the conventional materials (black copper foam, graphite, carbon powder etc.). The reason is that the micro‐nano structured design can increase the number of reflection and refraction probability on the surface of absorbers and enhance absorption …”

“…[12,13] The optical studies on ISSG device mainly focus on how the device indirectly enhances the total energy of light converted into heat by enhancing the absorbance of sunlight (long orange solid line in Figure 2). [13] An ideal ISSG device with regard to light absorbing path management and control generally needs to be constructed with light absorbance materials with a high absorbance capacity toward sunlight (within the spectrum 0.2-2.5 mm), such as plasmonic materials (e.g., Au nanoparticle, Ag nanoparticle, and Al nanoparticle) [9,14,15] and carbon-based materials (e.g., graphene, graphdiyne, and reduced graphene). [9,12] In terms of the optical-thermal conversion principle of plasmonic materials, they form surface plasmon resonances through metal electrons and incident light waves.…”