3D carbonized grooved straw with efficient evaporation and salt resistance for solar steam generation

Interdisciplinary Hybrid Solar-Driven Evaporators: Theoretical Framework of Fundamental Mechanisms and Applications

The global water and energy crisis seems to be mitigated with promising prospects of emerging interdisciplinary hybrid solar-driven evaporator technology (IHSE). However, the lack of numeric standards for comparison between enormously reported systems and the synergistic effects of interdisciplinary hybridization remains a significant challenge. To entice researchers from various domains to collaborate on the design of a system for realistic, large-scale applications, this study provides a comprehensive overview of the interdisciplinary approaches to IHSE from the domains of physics, chemistry, materials science, and engineering, along with their guiding principles and underlying challenges. First, an in-depth analysis of IHSE with the basic scientific foundations and current advancements in recent years is discussed. Then, the physical principles/scientific principles alongside the overall system improvement enhancement techniques at the macro and micro scale are highlighted. Furthermore, the review analyzes the impact of significant physical factors that alter or restrict the efficiency of IHSE, as well as their connection and potential regulation. In addition, a comprehensive study of emerging sustainable applications for insight into the design and optimization of IHSE is provided for scientists from different fields. Lastly, the current challenges and future perspectives of interdisciplinary IHSE for large-scale applications are emphasized.

Novel Sponge-Based Carbonaceous Hydrogel for a Highly Efficient Interfacial Photothermal-Driven Atmospheric Water Generator

A high-performance atmospheric water generator based on continuous adsorption-desorption of liquid hygroscopic agents was constructed by applying interfacial photothermal evaporation technology to the field of atmospheric water harvesting. A three-dimensional carbon-containing sponge hydrogel photothermal conversion material with a porous channel structure was designed, which was prepared from melamine foam (MF) and carbon black (CB) cross-linked by sodium alginate (SA). The results showed that the evaporation rate of CB/SA@MF in pure water was 1.90 kg·m-2·h-1, and the photothermal conversion efficiency could reach 85.0%. The multistage pore structures and water transport channels in the A4 configuration device provided an excellent structural basis for material salt resistance and liquid hygroscopic agent regeneration. Using sponge-based CB/SA@MF hydrogel photothermal composites as the evaporation interface and liquid hygroscopic salts as the air-water trapping agent, an interfacial photothermal-driven atmospheric water generator successfully absorbed water at night and produced water during the day. Its water production could reach 2.84 kg·m-2·d-1. The cost of the atmospheric water generator was only $12, and the water quality obtained after 5 cycle tests met WHO/GB 5749-2022. This research was designed to collect fresh water from the air, bringing convenience to inland arid regions as well as remote and scattered areas with limited power resources.

Salt Resistant PPy/MXene Flexible Waffle Type Fabric for Efficient Solar Evaporation and Water Purification Production

In recent years, with the development of solar seawater desalination technology, many solar evaporators are affected by precipitated salts during the evaporation process, which can reduce efficiency. In this work, flexible fabrics made of polypyrrole (PPy)/MXene are obtained by impregnating the prepared PPy ink onto waffle like fabrics. The combination of PPy and fabric greatly improves the water absorption and evaporation performance of the fabric. The average evaporation rate of this structure is 1.43 kg m-2 h-1, and the average evaporation efficiency under a single light source is 85.13%. After a 15-h testing cycle and a total of 8 cycles, lasting nearly 120 h, the performance of the device remained stable. The structural characteristics of waffle fabric, based on the Marangoni thermal effect, make it possible to suppress salt precipitation during evaporation, avoiding large salt particles covering the evaporation surface and reducing efficiency. This experiment successfully demonstrated long-term stable water evaporation, providing new ideas for the development of fabric evaporators.

Hierarchical Ti3C2Tx MXene@Honeycomb nanocomposite with high energy efficiency for solar water desalination

The utilization of solar-driven interfacial evaporation holds immense promise in enhancing energy efficiency and establishing sustainable methods for seawater desalination and water purification. While designing the materials to achieve high evaporation efficiency, the tuning of materials with porosity and surface chemistry is very crucial. Novel sustainable materials are of great importance for solar water desalination applications since clean water production is utmost important in the current era. There exists a lack of exploration in modifying the surface wettability states of solar evaporators to expedite the vapor generation rates. In this study, we showcase a hydrophilic Ti3C2Tx MXene-coated carbonized honeycomb (CHC) (Ti3C2Tx MXene@CHC) nanocomposite-based hexagonal-shaped evaporator surface. This is the first-time report on the effective utilization of hierarchical CHC for the preparation of solar absorber comprising of Ti3C2Tx MXene@CHC nanocomposite, particularly for the solar water desalination. The Ti3C2Tx MXene@CHC nanocomposite evaporator achieves an impressive water evaporation rate of 1.6 kg m-2 h-1 with 90% efficiency under 1 sun illumination. The augmented thickness of the water layer in the hydrophilic surface of the Ti3C2Tx MXene@CHC nanocomposite helps in facilitating the rapid escape of water molecules. The relatively elongated contact lines in the hydrophobic region simultaneously ensure substantial water evaporation, significantly enhancing the water desalination process. The Ti3C2Tx MXene@CHC nanocomposite exceeds stringent quality benchmarks, signaling its potential for solar water desalination.

Efficient Solar Steam Generation by Multiscale Photothermal Structures Derived from Cactus Stems

Solar steam generation (SSG) is a promising technique that may find applications in seawater desalination, sewage treatment, etc. The core component for SSG devices is photothermal materials, among which biomass-derived carbon materials have been extensively attempted due to their low cost, wide availability, and diversified microstructures. However, the practical performance of these materials is not satisfactory because of the multifaceted structural requirements for photothermal materials in SSG scenarios. In this work, cactus stems, which possess abundant and multiscaled pores for simultaneous sunlight gathering and water evaporation, are applied as the photothermal structure for SSG devices after mild heat treatment. Consequently, the SSG device based on the carbonized cactus stems delivers high performance (an absorption rate of 93.7% of the solar spectrum, an evaporation rate of 2.02 kg m-2 h-1, and an efficiency of 91.4% under one solar irradiation). We anticipate that the material can be a potential candidate for efficient SSG devices and may shed light on the sustainable supply of water.

Natural down fiber-reinforced and polypyrrole-modified silk fibroin composite aerogel for efficient solar steam generation toward seawater desalination and wastewater treatment

Poor mechanical properties and low photothermal efficiency of silk fibroin (SF)-based aerogels are current challenges that need to be addressed. Herein, SF composite aerogel was developed to enhance the mechanical properties through physical interpenetration of natural down fiber (Df) and hydrogen bonds formed among SF, Df, and polypyrrole (PPy) and to improve the evaporation performance via in-situ polymerization of PPy. The resultant Df/PPy@SF aerogel showed significant improvement of compressive stress (194.29 kPa), which was 6.96 times than that of SF aerogel (27.91 kPa), and also good compression resiliency. Furthermore, due to uniform distribution of PPy and high porosity of 95.27 %, Df/PPy@SF aerogel possessed high light absorbance of 99.87 % and low thermal conductivity (0.043 W·m-1·K-1). Thus, the Df/PPy@SF aerogel evaporator demonstrated high evaporation rates of 2.12 kg·m-2·h-1 for 3.5 wt% saline water, 2.04-2.15 kg·m-2·h-1 for various dye water, and 2.10 kg·m-2·h-1 for actual dye wastewater. Moreover, the developed aerogel exhibited evaporation stability and outstanding salt-resistance when treating seawater due to continuous water supply by superhydrophilic porous aerogel. Therefore, these findings demonstrate the excellent performance of Df/PPy@SF aerogel and will inspire further research on developing natural fiber-reinforced aerogels for use in the fields of solar water evaporation, energy, and other related applications.