High‐Performance Solar Steam Device with Layered Channels: Artificial Tree with a Reversed Design

Abstract

Solar steam generation, combining the most abundant resources of solar energy and unpurified water, has been regarded as one of the most promising techniques for water purification. Here, an artificial tree with a reverse‐tree design is demonstrated as a cost‐effective, scalable yet highly efficient steam‐generation device. The reverse‐tree design implies that the wood is placed on the water with the tree‐growth direction parallel to the water surface; accordingly, water is transported in a direction perpendicular to what occurs in natural tree. The artificial tree is fabricated by cutting the natural tree along the longitudinal direction followed by surface carbonization (called as C‐L‐Wood). The nature‐made 3D interconnected micro‐/nanochannels enable efficient water transpiration, while the layered channels block the heat effectively. A much lower thermal conductivity (0.11 W m−1 K−1) thus can be achieved, only 1/3 of that of the horizontally cut wood. Meanwhile, the carbonized surface can absorb almost all the incident light. The simultaneous optimizations of water transpiration, thermal management, and light absorption results in a high efficiency of 89% at 10 kW m−2, among the highest values in literature. Such wood‐based high‐performance, cost‐effective, scalable steam‐generation device can provide an attractive solution to the pressing global clean water shortage problem.

Multifunctional Solar Waterways: Plasma‐Enabled Self‐Cleaning Nanoarchitectures for Energy‐Efficient Desalination

“…The continuously increasing demands for economic development and increasing pollution lead to severe water scarcity in a growing portion of the world. [7][8][9][10][11][12][13][14][15] However, the state-of-the-art water desalination devices still suffer from several issues in energy efficiency, long-term performance, salt fouling, light blocking, and clean water collection in real-world applications. [3][4][5] A recent report combining solar harvesting and heat localization for evaporation achieved a relatively high energy efficiency over 85%, [6] opening up new opportunities for efficient solar desalination.…”

Systematic Study of the Effects of System Geometry and Ambient Conditions on Solar Steam Generation for Evaporation Optimization

“…The preparation process and cost of solar evaporators can therefore be greatly simplified and reduced, which is of great significance to future large-scale applications. [27,30] Hydrophilicity is widely accepted as a desirable characteristic for solar evaporators because water at the base can be delivered promptly up to the top hot region, making evaporation efficient and sustainable. The highly rich mesostructure of balsa wood contributes to its super low density and good mechanical performance.…”

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

“…[85] Inspired by this technology, many researchers used some common, abundant, and low-cost organic porous materials (e.g., foam, [67,[86][87][88] lotus seedpods, [89] wood, [64] bamboo, [90] and cotton [66] ) to readily fabricate different photothermal convertors. [85] Inspired by this technology, many researchers used some common, abundant, and low-cost organic porous materials (e.g., foam, [67,[86][87][88] lotus seedpods, [89] wood, [64] bamboo, [90] and cotton [66] ) to readily fabricate different photothermal convertors.…”

“…[93] As a consequence, the effective and common solution is to reduce the contact area to minimize the conductive and radiative heat from the evaporation surface. Until now, a series of low thermal conductivity materials have been exploited as the insulating supporter, including polyethylene membrane (0.448 W m −1 K −1 ), [48] cotton (0.04 W m −1 K −1 ), [66] wood (0.11-0.36 W m −1 K −1 ), [64,122] polystyrene foam (≈0.04 W m −1 K −1 ), [65] and plant fiber sponges (0.103 W m −1 K −1 ), [123] and electrospun polyvinylidene fluoride (PVDF) layers ( Figure 5a). In this special structure, the bottom carbon foam is thermally insulating to reduce heat losses to the underlying bulk water, and the top exfoliated graphite layer acts as the solar absorber.…”

“…In this special structure, the bottom carbon foam is thermally insulating to reduce heat losses to the underlying bulk water, and the top exfoliated graphite layer acts as the solar absorber. [64] Apart from above-mentioned two-layer structure, diverse 3D bulk solar absorbers with low thermal conductivity and moderate thickness can also act as the photothermal convertor, as well as prevent heat losses to the bulk water, such as synthetic polymer foam (0.057 W m −1 K −1 ), [124] GO aerogel (0.047-0.035 W m −1 K −1 ), [63] silica/Au gel, [44] and polymer hydrogel. [110] Since then, the introduction of the insulating porous supporters has been considered as the most effective method to reduce heat losses and realize thermal management.…”