Reduced graphene oxide aerogel with the dual-cross-linked framework for efficient solar steam evaporation

Development Status of Solar-Driven Interfacial Steam Generation Support Layer Based on Polymers and Biomaterials: A Review

With the increasing shortage of water resources and the aggravation of water pollution, solar-driven interfacial steam generation (SISG) technology has garnered considerable attention because of its low energy consumption, simple operation, and environmental friendliness. The popular multi-layer SISG evaporator is composed of two basic structures: a photothermal layer and a support layer. Herein, the support layer underlies the photothermal layer and carries out thermal management, supports the photothermal layer, and transports water to the evaporation interface to improve the stability of the evaporator. While most research focuses on the photothermal layer, the support layer is typically viewed as a supporting object for the photothermal layer. This review focuses on the support layer, which is relatively neglected in evaporator development. It summarizes existing progress in the field of multi-layer interface evaporators, based on various polymers and biomaterials, along with their advantages and disadvantages. Specifically, mainly polymer-based support layers are reviewed, including polymer foams, gels, and their corresponding functional materials, while biomaterial support layers, including natural plants, carbonized biomaterials, and other innovation biomaterials are not. Additionally, the corresponding structure design strategies for the support layer were also involved. It was found that the selection and optimal design of the substrate also played an important role in the efficient operation of the whole steam generation system. Their evolution and refinement are vital for advancing the sustainability and effectiveness of interfacial evaporation technology. The corresponding potential future research direction and application prospects of support layer materials are carefully presented to enable effective responses to global water challenges.

A Lotus Seedpods-Inspired Interfacial Solar Steam Generator with Outstanding Salt Tolerance and Mechanical Properties for Efficient and Stable Seawater Desalination

Interfacial solar steam generators (ISSGs) can capture solar energy and concentrate the heat at the gas-liquid interface, resulting in efficient water evaporation. However, traditional ISSGs have limitations in long-term seawater desalination processes, such as limited light absorption area, slow water transport speed, severe surface salt accumulation, and weak mechanical performance. Inspired by lotus seedpods, a novel ISSG (rGO-SA-PSF) is developed by treating a 3D warp-knitted spacer fabric with plasma (PSF) and combining it with sodium alginate (SA) and reduces graphene oxide (rGO). The rGO-SA-PSF utilizes a core-suction effect to achieve rapid water pumping and employs aerogel to encapsulate the plasma-treated spacer yarns to create the lotus seedpod-inspired hydrophilic stems, innovatively constructing multiple directional water transport channels. Simultaneously, the large holes of rGO-SA-PSF on the upper layer form lotus seedpod-inspired head concave holes, enabling efficient light capture. Under 1 kW m-2 illumination, rGO-SA-PSF exhibits a rapid evaporation rate of 1.85 kg m-2  h-1 , with an efficiency of 96.4%. Additionally, it shows superior salt tolerance (with no salt accumulation during continuous evaporation for 10 h in 10% brine) and self-desalination performance during long-term seawater desalination processes. This biomimetic ISSG offers a promising solution for efficient and stable seawater desalination and wastewater purification.

Carbon nanofiber reinforced carbon aerogels for steam generation: Synergy of solar driven interface evaporation and side wall induced natural evaporation

Solar-based interface evaporation (SIE) is a green, efficient and cost-effective technique to harvest fresh water. 3D solar evaporators show their unique advantages in gaining energy from environment and hence possess a higher evaporation rate than 2D evaporators. However, much effort is still required to develop mechanically robust and superhydrophilic 3D evaporators with strong water transportation capability and salt-rejection performance, and at the same time reveal how they gain energy from environment via the natural evaporation. In this work, a novel carbon nanofiber reinforced carbon aerogel (CNFA) is prepared for the SIE. The CNFA has a high light absorption up to 97.2% and outstanding photothermal conversion performance. The heteroatom doping and hierarchically porous structure endow the CNFA with superhydrophilicity and thus powerful water transportation capability and salt rejection performance. Benefiting from synergy of the SIE and side wall induced natural evaporation, the CNFA evaporator exhibits a high evaporation rate and efficiency (as high as 3.82 kg m^-2h^-1 and 95.5%, respectively) with long-term stability and durability. The CNFA can also work normally in high-salinity and corrosive seawater. This study demonstrates a new method to fabricate all-carbon aerogel solar evaporators and provides insights for the effective thermal management during the interface evaporation.

All-Weather Freshwater and Electricity Simultaneous Generation by Coupled Solar Energy and Convection

Integrating solar evaporation-driven desalination and electricity production has emerged as a promising approach to alleviate energy crisis and freshwater scarcity. However, there remain huge challenges to achieve high water productivity and steady power generation efficiency. Herein, a compact evaporation-induced water-electricity co-generation device was proposed using a bio-waste squid ink sphere-based cellulose fabric as an evaporator and a silicon nanowires array-based evaporation-driven moist-electric generator. The efficient localized solar thermal heating of the photothermal component leads to significant enhancement in freshwater yield, and the latent heat of vapor condensation is recycled to promote the electricity generation. More notably, the device is capable of harvesting wind energy toward all-weather water and power generation. The fabricated device demonstrated a high evaporation rate of 2.17 kg m^-2 h^-1 with a collection rate of 66.7% and a maximum output voltage of 1.48 V under one sun illumination with a wind speed of 4 m s^-1. The outdoor experiments display a maximum water evaporation rate of 1.84 kg m^-2 h^-1 with a maximum output voltage of 1.35 V even on cloudy days. Such superior performance of a comprehensive device has great potential for sustainable and practical application in freshwater and electricity generation.