Easily Repairable and High-Performance Carbon Nanostructure Absorber for Solar Photothermoelectric Conversion and Photothermal Water Evaporation

Intercalation of V2O5 and Polypyrrole into a Graphene Oxide Layer: A Hybrid Multifunctional Photothermal Structure for Efficient Solar Evaporation, Water Purification, Disinfection, and Power Production

Development of a hybrid multifunctional photothermal structure with multifunctional capabilities is deliberated as an effective approach for harvesting abundant solar energy for sustainable environmental applications. Achieving enhanced solar to thermal conversion efficiency utilizing a suitably designed, environmentally compatible thermal management structure however remains a significant challenge. Herein, we report the intercalation of V2O5 and polypyrrole into a graphene oxide layer to design a hybrid photothermal assembly (PPy-V2O5-GO) and its multifunctional proficiencies. The hybrid photothermal structure demonstrated synergistic photothermal conversion, buoyant porous structure sustaining water transmission, and efficient steam release. V2O5 and polypyrrole-intercalated optimized graphene oxide structure attained an evaporation rate of 1.9 kg m-2 h-1 with a conversion efficiency of 92% under 1 sun solar radiation. At maximum, the assembly's surface temperature hit 64 ± 2 °C, suggesting its suitability as a solar water purifier. Outdoor experiments suggest the evaporator assembly's capability to accumulate a total output of 15 kg m-2 over a single day. Cell viability investigations revealed strong antimicrobial properties of PPy-V2O5-GO against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria, eliminating nearly all under 1 sun, making it a potential candidate for photothermal therapy. Furthermore, when combined with a commercial thermoelectric module, the framework displayed exceptional photothermal conversion efficiency, hinting at its potential for electrical power generation. The integration of PPy-V2O5-GO with a Bi2Te3-based thermoelectric module significantly boosted the thermoelectric generator's performance, offering an enhanced power output of 2.8 mW and a high power density of 1.24 mW/cm2, making them suitable for off-grid or remote-area application. Overall, the PPy-V2O5-GO photothermal assembly's stability, lack of leaching, effectiveness in producing pure water from seawater, antimicrobial efficacies, and recyclability make it an excellent choice for sustainable water treatment and power generation.

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.

A lignin-derived carbon dot-upgraded bacterial cellulose membrane as an all-in-one interfacial evaporator for solar-driven water purification

Solar-driven interfacial evaporation has emerged as an efficient approach for wastewater treatment and seawater desalination. New trends demand adaptive technology to develop photothermal membranes with multifunctional features. Herein, we report a robust multi-purpose near-infrared (NIR)-active hydrogel composite (c-BC@N-LCD) from broad-spectrum active nitrogen-doped lignin-derived carbon dots (N-LCDs) covalently cross-linked with a bacterial cellulose (BC) matrix. BC provides adequate porosity and hydrophilicity required for easy water transport while managing heat loss. A commendable evaporation rate (ER) of 2.2 kg m-2 h-1 under one sun (1 kW m-2) is achieved by c-BC@N-LCD. The developed hydrogel system is also found to be efficient for desalination (∼2.1 kg m-2 h-1) and for remediating various pollutants (heavy metal ions, dyes, and pharmaceuticals) from feed water. The efficacy of the membrane remains unaltered by different grades of water, and hence can be adoptable for economically stressed communities living in water-polluted regions as well as those residing in coastal areas.

Plasmon-Enhanced Light Absorption Below the Bandgap of Semiconducting SnS2 Microcubes for Highly Efficient Solar Water Evaporation

Semiconducting materials show high potential for solar energy harvesting due to their suitable bandgaps, which allow the efficient utilization of light energy larger than their bandgaps. However, the photon energy smaller than their bandgap is almost unused, which significantly limits their efficient applications. Herein, plasmonic Pd/SnS2 microcubes with abundant Pd nanoparticles attached to the SnS2 nanosheets are fabricated by an in situ photoreduction method. The as-prepared Pd/SnS2 microcubes extend the light-harvesting ability of SnS2 beyond its cutoff wavelength, which is attributed to the localized surface plasmon resonance (LSPR) effect of the Pd nanoparticles and the 3D structure of the SnS2 microcubes. Pd nanoparticles can also enhance the light absorption of TiO2 nanoparticles and NiPS3 nanosheets beyond their cutoff wavelengths, revealing the universality for promoting absorption above the cutoff wavelength of the semiconductors. When the plasmonic Pd/SnS2 microcubes are integrated into a hydrophilic sponge acting as the solar evaporator, a solar-to-vapor efficiency of up to 89.2% can be achieved under one sun. The high solar-to-vapor conversion efficiency and the broad applicability of extending the light absorption far beyond the cutoff wavelength of the semiconductor comprise the potential of innovative plasmonic nanoparticle/semiconductor composites for solar desalination.

New Nanophotonics Approaches for Enhancing the Efficiency and Stability of Perovskite Solar Cells

Over the past decade, the power conversion efficiency (PCE) of perovskite solar cells (PSCs) has experienced a remarkable ascent, soaring from 3.8% in 2009 to a remarkable record of 26.1% in 2023. Many recent approaches for improving PSC performance employ nanophotonic technologies, from light harvesting and thermal management to the manipulation of charge carrier dynamics. Plasmonic nanoparticles and arrayed dielectric nanostructures have been applied to tailor the light absorption, scattering, and conversion, as well as the heat dissipation within PSCs to improve their PCE and operational stability. In this review, it is begin with a concise introduction to define the realm of nanophotonics by focusing on the nanoscale interactions between light and surface plasmons or dielectric photonic structures. Prevailing strategies that utilize resonance-enhanced light-matter interactions for boosting the PCE and stability of PSCs from light trapping, carrier transportation, and thermal management perspectives are then elaborated, and the resultant practical applications, such as semitransparent photovoltaics, colored PSCs, and smart perovskite windows are discussed. Finally, the state-of-the-art nanophotonic paradigms in PSCs are reviewed, and the benefits of these approaches in improving the aesthetic effects and energy-saving character of PSC-integrated buildings are highlighted.

Unidirectionally Structured Magnetic Phase-Change Composite Based on Carbonized Polyimide/Kevlar Nanofiber Complex Aerogel for Boosting Solar-Thermo-Electric Energy Conversion

To realize highly efficient solar-thermo-electric energy conversion for clean electricity power generation, we have developed a new type of unidirectionally structured magnetic phase-change composite comprising a carbonized polyimide (C-PI)/Kevlar nanofiber (KNF) complex aerogel as a 3D carbon skeleton porous supporting material, CoFe2O4 nanoparticles as a magnetic additive, polyethylene glycol (PEG) as a phase-change material, and polypyrrole as a photothermal absorption coating layer. The as-fabricated C-PI/KNF complex aerogel exhibits a unidirectional microstructure, high porosity, robust skeleton frame, ultralight weight, and high thermal conductance. Featured with such unique structure and characteristics, the complex aerogel can offer an effective heat and electron transfer method to ensure highly efficient solar-thermal conversion and photothermal energy storage of the developed composite. The developed composite exhibits a high latent heat capacity of over 150 J g-1, outstanding shape stability along with a low leakage of 0.2 wt %, good thermal cycling stability, and high photothermal conversion efficiency of 84.8%. Based on the Seebeck effect, a solar thermoelectric generation system (STEGS) was constructed with the hot side coupled with the developed composite and the cold side immersed in air and ice water. Under 2.0 kW m-2 solar irradiation, the developed STEGS in ice water obtained maximum output voltage and current of 259.7 mV and 27.1 mA, respectively, which are significantly higher than those in air. The output power of the developed STEGS in an ice water environment is 50.6% higher than that in air under 4.0 kW m-2 solar irradiation. More importantly, the developed STEGS in ice water continuously generated output voltage and current for about 810 s without solar irradiation thanks to the latent heat release by the PEG component within the developed composite. In addition, the introduction of magnetic CoFe2O4 can accelerate solar-thermal conversion through periodic electron motion by the Néel relaxation or Brownian relaxation. This resulted in an increase in the maximum output voltage and current by 13.7 and 11.5%, respectively, under an alternating magnetic field as a result of the magnetism-accelerated solar-thermo-electric conversion. This study offers an innovative approach for developing PCM-based advanced functional materials for solar energy utilization in clean and sustainable electricity generation.

Three-Dimensional Spiral Evaporator with Side Channels for Efficient Solar-Driven Water Purification

Solar evaporators have the advantages of not consuming fossil fuels, being environmentally friendly, and nonpolluting, offering a promising sustainable method to obtain fresh water and alleviate the worldwide freshwater shortage crisis. In this work, we report that high-performance solar evaporators can be facilely fabricated by processing a cost-effective polypyrrole (PPy)-coated nonwoven fabric (PCNF) into a three-dimensional (3D) spiral structure and introducing side channels for vapor escape. The coated PPy layer ensures excellent photothermal properties and the chemical stability of the evaporator. Meanwhile, the as-created spiral structure of the evaporator can significantly increase the effective evaporation area and harvest energy from the environment, greatly stimulating the evaporation. The side opening channels can effectively facilitate the escape of vapor generated inside the 3D spiral structure, avoid the internal vapor accumulation, and ultimately promote the evaporation of the inner surface, leading to a boost of the evaporation performance. Combining these features, the resulting evaporator exhibits an ultrahigh evaporation rate of 3.26 kg m-2 h-1 and an energy efficiency of 138% under 1-sun irradiation. More importantly, we show that this evaporator can also be used to collect fresh water from soil and sand, demonstrating its great applicability for obtaining potable water in arid areas.

A droplet friction/solar-thermal hybrid power generation device for energy harvesting in both rainy and sunny weathers

Photovoltaic device is highly dependent on the weather, which is completely ineffective on rainy days. Therefore, it is very significant to design an all-weather power generation system that can utilize a variety of natural energy. This work develops a water droplet friction power generation (WDFG)/solar-thermal power generation (STG) hybrid system. The WDFG consists of two metal electrodes and a candle soot/polymer composite film, which also can be regarded as a capacitor. Thus, the capacitor coupled power generation (C-WDFG) device can achieve a sustainable and stable direct-current (DC) output under continuous dripping without external conversion circuits. A single device can produce an open-circuit voltage of ca.0.52 V and a short-circuit current of ca.0.06 mA, which can be further scaled up through series or parallel connection to drive commercial electronics. Moreover, we demonstrate that the C-WDFG is highly compatible with the thermoelectric device. The excellent photothermal performance of soot/polymer composite film can efficiently convert solar into heat, which is then converted to electricity by the thermoelectric device. Therefore, this C-WDFG/STG hybrid system can work in both rainy and sunny days.

Shape-Stable Hybrid Emulsion Gel with Sodium Acetate Trihydrate and Paraffin Wax for Efficient Solar Energy Storage and Building Thermal Management

Organic-inorganic composite phase change materials (PCMs) are promising in the fields of solar energy storage and building thermal management. However, combining inorganic with organic PCMs meets a great challenge. In the current work, a shape-stable hybrid emulsion gel (EGel/GO) is developed via Pickering emulsion polymerization, which seamlessly combines sodium acetate trihydrate (SAT) in the water phase with paraffin wax (PW) in the oil phase. The polymer dual-phase cross-linking in EGel/GO forms a supporting framework that effectively enhances the material's shape stability, slows the loss of crystalline water in hydrates, and reduces supercooling. The addition of graphene oxide (GO) enhances EGel/GO-0.5's optical absorption properties, resulting in photothermal conversion efficiency as high as 89.1%. Furthermore, EGel/GO not only has high latent heat of 225.08 J/g but also has almost no leakage and no phase separation. The Pickering emulsion polymerization method paves a broad avenue for combining organic with inorganic PCMs, which is an ideal choice for the effective utilization of solar energy and building energy storage.

Constructing of efficient interface solar evaporator: In-situ colloid foaming strategy for solar desalination and visible light response sewage purification

The shortage of drinking water has become a global problem, coastal cities can make full use of abundant seawater resources by desalination technology to ease the contradiction between supply and demand. However, fossil energy consumption contradicts the goal of reducing carbon dioxide emissions. Currently, researchers favor interfacial solar desalination devices relying only on clean solar energy. Based on the structure optimization of the evaporator, a kind of device composed of a superhydrophobic BiOI (BiOI-FD) floating layer and CuO polyurethane sponge (CuO sponge) is constructed in this paper, with its design advantages presented in the following two aspects: 1. The novel BiOI-FD photocatalyst in the floating layer reduces the surface tension and realizes the degradation of the enriched pollutants, ensuring the device to achieve solar desalination and inland sewage purification; 2. CuO sponge can inhibit salt crystallization and realize the combination of the water transport and photothermal layers. Particularly, the photothermal evaporation rate of the interface device reached 2.37 kg m^-2 h^-1.The novel interface evaporator design will bring a new solution for solar desalination, sewage treatment and large-scale application.

Three-Dimensional Mirror-Assisted and Concave Pyramid-Shaped Solar-Thermal Steam Generator for Highly Efficient and Stable Water Evaporation and Brine Desalination

Although significant advances have been achieved in developing solar-driven water evaporators for seawater desalination, there is still room for simultaneously enhancing water evaporation efficiency, salt resistance, and utilization of solar energy. Herein, for the first time, we demonstrate a highly efficient three-dimensional (3D) mirror-assisted and concave pyramid-shaped solar-thermal water evaporation system for high-yield and long-term desalination of seawater and brine water, which consists of a 3D concave pyramid-shaped solar-thermal architecture on the basis of polypyrrole-coated nonwoven fabrics (PCNFs), a 3D mirror array, a self-floating polystyrene foam layer, and a tail-like PCNF for upward transport of water. The 3D concave pyramid-shaped solar-thermal architecture enables multiple solar light reflections to absorb more solar energy, while the 3D mirror-assisted solar light enhancement design can activate the solar-thermal energy conversion of the back side of the concave pyramid-shaped PCNF architecture to improve the solar-thermal energy conversion efficiency. Crucially, selective accumulation of the precipitated salts on the back side of the concave pyramid-shaped architecture is realized, ensuring a favorable salt-resistant feature. The 3D mirror-assisted and concave pyramid-shaped solar-driven water evaporation system achieves a record high water evaporation rate of 4.75 kg m^-2 h^-1 under 1-sun irradiation only and exhibits long-term desalination stability even when evaporating high-salinity brine waters, demonstrating its great applicability and reliability for high-yield solar-driven desalination of seawater and high-salinity brine water.