Solar-thermal Conversion Performance Research Articles

Influence of particle morphology on solar thermal conversion performance and sensible heat storage capacity: A case study of TiO2@Go binary nanofluid

Photothermal catalytic hydrogen production driven by the full spectrum of outdoor solar radiation, represents a highly promising and efficient approach for hydrogen generation. This method is widely anticipated by researchers due to its potential to enhance photon utilization efficiency at the reaction source. However, limited attention has been devoted to the variations in photothermal conversion performance of particle reaction suspensions caused by objective fluctuations of solar irradiation, especially when the morphology of the nanostructure changes, which is a crucial factor for practical applications in hydrogen production. Based on this bottleneck, we prepared the typical photo-responsive TiO2@Go composite with varied dimensions (i.e., nanosphere TiO2@Go, nanorod TiO2@Go, nanosheet TiO2@Go) as research models, and systematically investigated their thermal conversion and sensible heat conversion performance under different working conditions. The results showed that at low nanofluid concentration, nanosphere TiO2@Go and nanosheet TiO2@Go exhibit better sensible heat conversion. As the particle concentration increases, the sensible heat conversion efficiency of all nanofluids decreases. It can also be found that the latent heat conversion efficiency tends to increase with the increase of concentration, but the nanorod TiO2@Go show the opposite, which should be closely related to the uniformity of the particle size in different directions. In addition, for the sensible heat storage properties of nanofluids, smaller particle size and abundant porosity due to particles aggregation were found to be more beneficial for varied shapes. The underlying functional mechanisms were elucidated associated with the analysis of particle structures, interfacial properties, and optical characteristics. We contend that our research could provide valuable insights for the large-scale implementation of solar photothermal hydrogen production and a reasonable selection of photothermal material morphology for outdoor working conditions.

Double-layered phase change material microcapsules with enhanced solar thermal conversion performance and fire safety for buildings

Building energy saving is directly related to resource utilization optimization and residential comfort, which is important for the environment and production. At present, building energy saving is developing towards green, recyclable, and low-risk directions. Phase change materials, as effective energy storage materials, can pollution-freely regulate room temperature. Regarding the leakage, phase change materials are encapsulated into microcapsules. However, the flammability and slow thermal response of phase change material microcapsules hinder their application in building materials. Herein, novel double-layered phase change material microcapsules (D-MPCMs), with the inner poly melamine tetramethylene phosphonium sulfate (PMTMPS) shell layers and outer polydopamine (PDA) shell layers, are prepared by in-situ polymerization method, which are filled into epoxy resin (EP) coatings. This study is the first to use cross-linked flame retardants as the shells of microcapsules. The outer PDA shell layer improves the flame retardancy of microcapsules while overcoming the problem of slow thermal response rate. Thermogravimetric analysis and differential scanning calorimeter tests are considered to explore the thermal stabilities and properties of the resultant microcapsules. Results demonstrate that D-MPCMs have a residual mass of 10.8 % more at 600 ℃ and a faster thermal response rate. The study shows that the addition of the PDA shell layers not only reduces the total heat release from 64.29 MJ/m2 to 45.01 MJ/m2 but also enhances the solar thermal conversion performance which gives potential in the process solar energy storage design and fire safety design in actual building application of epoxy resin coatings.

Phase change materials encapsulated in graphene hybrid aerogels with high thermal conductivity for efficient solar-thermal energy conversion and thermal management of solar PV panels

Phase change materials (PCMs) have a wide range of applications in latent heat storage and thermal management. However, their practical use is hindered by high leakage rates and low thermal conductivity. To address these issues, polyvinyl alcohol/carboxylated carbon nanotubes/graphene hybrid aerogels (PCG) were carbonized at high temperatures to obtain polyvinyl alcohol/carboxylated carbon nanotubes/graphene carbon aerogels (cPCG). Polyethylene glycol (PEG) was then encapsulated within cPCG to form cPCG@PEG shape-stabilized PCMs (SSPCMs). These cPCG@PEG SSPCMs demonstrated excellent thermal conductivity (0.843 W•m-1•K-1) and superior solar-thermal conversion performance (91.8%). Additionally, the latent heat of cPCG@PEG showed a minimal decrease even after 100 melt-crystallization cycles. An experimental setup was designed to regulate the temperature of solar photovoltaic (PV) panels using cPCG@PEG. The results indicated that cPCG@PEG effectively managed the temperature of solar PV panels under varying light conditions. This study presents a novel approach for enhancing the application of porous PCMs in solar energy utilization and thermal management of equipment.

Waste to functions: Construction of a novel solar-thermal conversion material based on sludge-derived carbon dots via Ca-in-situ-functionalization for efficient solar-driven water evaporation

Solar interface water evaporator (SIWE) based on waste-derived carbon dots (CDs) are highly promising for large-scale production applications in the future, due to their low-cost, eco-friendly, and tunable structure and properties. However, there are still obstacles, including limited performance, blind selection of waste materials, and unknown underlying mechanisms between waste properties and the physicochemical properties of derived CDs. In this study, a novel CDs-based wooden SIWE derived from paper mill sludge (PMS) was constructed (called ESCDs-wood). Under 1 sun, ESCDs rapidly heated up from 15.6 °C to 53.5 °C and reached stability within 10 mins. The solar-thermal conversion efficiency of ESCDs was as high as 137.58 %, and the ESCDs-wood achieved a high evaporation rate of 2.94 kg m-2h−1. Moreover, the ESCDs-wood cost about $9 to complete 1 m2 evaporation. Meanwhile, the ESCDs-wood exhibited long-term stability, after 20 cycles, its solar-thermal conversion efficiency and water evaporation rate remained at 84.21 % and 85.03 % of the initial test, respectively. Moreover, the Ca-doping was found to be a key factor in effectively enhancing the solar-thermal conversion and the thermal stability of ESCDs, and the exact role of Ca-doping on the solar-thermal conversion performance enhancement of CDs was validated and revealed. Therefore, this study not only constructed a cost-effectiveness, high performance, sustainability, chemical-free, and eco-friendly SIWE, but also innovatively proposed the functionalization mechanism of Ca-doping for CDs and thus provided a new sight for the targeted regulation and design of CDs.

Multiple shearing-induced high alignment in polyethylene/graphene films for enhancing thermal conductivity and solar-thermal conversion performance

The simultaneous achievement of ordered alignment for fillers and polymer matrix is highly desired in polymer-based thermally conductive composites, but it is still extremely challenging. Herein, we put forward a layer-by-layer scraping (LbLS) method to simultaneously arrange ultra-high molecular weight polyethylene (UHPE) chains and graphene nanoplates (GNP) into a highly oriented structure. When UHPE/GNP gel suffering the strong shearing effect during LbLS process, the inner UHPE chains and GNP were dragged and orderly arranged along shearing direction, and these oriented structures were retained after rapidly drying by distillation. After layer-by-layer stacking, nacre-like UHPE/GNP films with tightly layered structure were obtained. By adjusting the scraping gap from 200 to 50 μm, the oriented structure can be effectively reinforced with the Herman orientation factors f increasing from 0.83 to 0.88 for GNP and 0.75 to 0.82 for UHPE chains. The highly ordered structure can form a tight and oriented thermal conduction network with low interfacial thermal resistance in plane. The LbLS composite film thus significantly enhanced the in-plane thermal conductivity up to 28.88 W/mK, compared with traditional solution casting film (9.63 W/mK). Moreover, the highly oriented structure can significantly increase the solar-thermal conversion performance (58.1 °C@100 mW/cm2) by improving its light absorption ability comparing to that of solution casting film. Besides, the mechanical strength and toughness that depend on the filler and chain alignment were effectively increased by the oriented structure.

Form-stable phase change composites with multistage pores based on black phosphorus nanosheets/PVA aerogel for efficient solar photothermal conversion

The development of the form-stable Phase Change Materials (FPCMs) with excellent solar-thermal conversion performance is crucial for sustainable solar energy utilization. However, the leakage of organic phase change materials limits its practical application. Herein, we reported a novel multistage porous aerogel fabricated from black phosphorus (BP) nanosheets, polyvinyl alcohol (PVA) and carbonized kapok (CK) fibers by a solution blending method. The aerogel was directly dipped in molten hexadecanol as the phase change material. The results showed that the HD/PVA-BP30 had a phase change temperature of 55 °C, latent heat of phase change of 164.3 kJ/kg. After 100 melting/freezing cycle, the phase change composite leaks only 0.38 %. The mechanical properties of PVA-BP30 exhibited a compressive strength of 1.04 MPa at 80 % strain, and the mechanical strength of the aerogel increased with increasing BP content. The addition of BP also enhanced the photothermal conversion (73.6 %) under 1 sun illumination. The prepared HD/PVA-BP30 have the characteristics of the suitable phase change temperature, excellent melting/freezing cycle reliability, strong mechanical properties, and anti-leakage properties. Therefore, the reported FPCMs are anticipated to have great potential for solar water heater utilization in bath water.

Modified mica-supported phase change materials for efficient solar thermal conversion and thermal energy management

To improve the solar thermal conversion performance of composite phase change materials and further practical applications, the rational design and realization of excellent thermal properties, electrical properties, shape stability, and fast response to solar energy are essential. Three-dimensional layered composite phase change materials loaded with paraffin wax were prepared by vacuum impregnation method using polyethylene glycol grafted nanocellulose modified mica as the carrier. The prepared materials exhibited high bulk resistivity (1.47 × 1013 Ω cm), excellent thermal conductivity (1.3 W/m K), outstanding solar energy conversion efficiency (98.3%), good thermal stability and reusability. It was noteworthy that the thermal conductivity of the composite was improved by 619.05% compared to pure paraffin. The three-dimensional layered structure of directional stacking and the polyethylene glycol-linked heat transfer channels greatly improved the thermal conductivity of the composite phase change material. These findings provide ideas for designing innovative materials that combine energy storage and other functional properties.

A high thermal conductive composite phase change film for flexible solar/electro-thermal energy conversion

The applications of phase change materials (PCMs) in solar energy utilization, wearable thermal management and electro-thermal energy storage make it urgent to develop flexible PCMs with high thermal conductivity, electrical conductivity, morphological stability, and solar absorption capacity. Herein, we successfully fabricated a flexible multi-functional composite PCM film by adopting interwoven carbonized bamboo fibers (CBF) as the electrical and thermal conductive framework, with the introduction of polyvinylidene fluoride (PVDF) as the binder to enhance strength and flexibility and flexibility and paraffin as the thermal storage material. Besides, the introduction of Ti3C2Tx as a photon capturer and heating molecule further improved the solar-thermal conversion capability. The composite PCM films exhibited considerable flexibility, favorable thermal storage capacity (>103.6 J/g), and excellent long-term cycling stability. The interwoven electrical and thermal conductive skeleton endowed the flexible phase change films with satisfying electro-thermal conversion capacity and improving thermal conductivity, which further resulted in a promising solar-thermal conversion performance and remarkable Joule heating effect. The as-prepared flexible composite PCM films with excellent solar/electro-thermal conversion responses would be suitable smart materials for future wearable thermal management application.

Efficient solar thermal energy utilization and storage based on phase change materials stabilized by MOF@CuO composites

Solar thermal conversion technology employing phase change composites is an available strategy for solar thermal energy utilization and storage. In this work, a novel metal-organic framework (MOF)-based phase change composites were successfully constructed through vacuum impregnation method. The stearic acid (SA) was served as phase change materials, and the SA-modified MOF (HS) with CuO derived from MOF (HS@CuO composites) was assembled to be support materials, which composed the SA/HS@CuO phase change composites. HS@CuO composites could well prevent the SA leakage over phase change point and endowed the phase change composites outstanding form stability (SA loading rate: 71.8 %) and thermal storage ability (ΔHm: 158.24 J/g). Furthermore, the SA/HS@CuO possessed greatly strengthened thermal conductivity (improved by 3.8 times over SA) and extraordinary solar thermal conversion performance (η: 95.9 %). These results powerfully suggest that the innovative phase change composites own promising potentials in not only solar energy utilization and development but also thermal storage and management fields.

MnO2 decorated double-shell microencapsulated phase change materials for photothermal conversion and storage

Solar energy is considered as a renewable energy source, but it still exists imbalance between energy supply and energy consumption. Although phase change materials (PCMs) can supply an effective way to improve solar energy utilization efficiency with the help of their excellent energy storage capacity, their poor solar-thermal conversion performance significantly reduces energy storage capacity and seriously restricts their applications in solar energy utilization fields. Herein, this work innovatively prepared MnO2-decorated double-shell microencapsulated PCMs using electrochemical adsorption and redox methods to cover a second compact shell of MnO2 on the first polymeric shell, which integrate the advantages of organic and inorganic shell materials with multi-functions and broaden the wide-spread applications of PCMs. The MnO2-decorated double-shell endows the microencapsulated PCMs with multi-functions and broadens their wide-spread applications. The excellent electrochemical and optical performances of MnO2 shell provide the microencapsulated PCMs with a high light-to-heat conversion efficiency of 93 %, and also endow the composite PCMs with a specific capacitance of 364 F/g. Meanwhile, phase change enthalpy of the microencapsulated PCMs is in the range of 133.56–152.71 J/g. These results confirm that the MnO2-decorated double-shell microencapsulated PCMs have a considerable potential in solar energy utilization and electrochemical fields.

Characterization of high-temperature figure of merit for solar-thermal absorbers

The figure of merit (FOM) is a widely used metric to characterize the solar-thermal conversion performance of solar absorber layers. Many of previous works have reported FOMs estimated from the radiative properties measured at room temperature. However, advanced concentrated solar power (CSP) plants operate at very high temperatures (∼750°C), which can strongly affect the absorber’s radiative properties. The present work proposes using a 1-D conduction-based reference bar technique to directly measure the converted thermal energy to determine the FOM at high absorber temperatures (≳750°C) while operating under a large solar concentration (∼1200× suns). Using the finite difference method, we carefully analyze several key parameters influencing the design of the experimental setup, such as temperature distribution, material properties, heat loss, and sensor accuracy. In addition, a rigorous uncertainty analysis is incorporated into the FOM to ascertain the confidence level of the result. We validate this new technique on a custom-built tungsten reference bar with an oxidized Inconel 625 solar-thermal absorber. A good agreement between the model and the experiment shows the reliability of the FOM measurement with a well-defined uncertainty. The same method can be implemented to measure the high-temperature FOM of most surface or volumetric solar absorbers for CSP.

The dynamic stability of silicone oil-based MWCNT nanofluids under high-temperature, high-flux irradiation, and shear-flow conditions

Nanofluid-based volumetric-type solar collectors have emerged as a promising technique for solar thermal applications. However, achieving the long-term stability of nanofluids under high-temperature, high-flux irradiation, and shear-flow conditions is still challenging. Herein, we propose a facile method to stabilize silicon oil-based multi-walled carbon nanotube (MWCNT) nanofluids via shear flow. The effects of shear flow on the stability of nanofluids are experimentally evaluated. Results indicate that the shearing force can break up the clusters. Once achieving a dynamic equilibrium between cluster formation and cluster breakage, the instability of nanofluids can be controlled within 7.3% for the heating temperature range 140 °C–180 °C. Besides, the shear-flow stabilized nanofluids can keep dynamic stability and maintain high solar thermal conversion performance with an efficiency reduction of within 7% after cyclic tests under irradiation of 19 Sun for 24 h. The proposed method offers a practical path for stabilizing nanofluids under harsh conditions.

The mechanism of enhanced photothermal conversion of low-dimensional plasmonic nanofluids with LFPs resonance

Solar-thermal utilization is one of the important ways of energy utilization at present and in the future. Nanofluids play a key role in photothermal conversion. In this work, the low-dimensional plasmonic TiN/MWCNTs nanofluids were firstly proposed. The photothermal conversion properties of low-dimensional plasmonic nanofluids was systematically investigated. The analytical results indicated that the heat transfer and optical properties of plasmonic nanofluids were significantly enhanced. Specifically, thanks to the expanded light absorption by the LSPR of nano-TiN and the enhanced thermal transport by its low-frequency phonon (LFP) resonance with MWCNTs, the photothermal conversion efficiency can reach 68.1% with 10 ppm TiN/MWCNTs nanofluids, which was 22.9% higher than that of the MWCNTs nanofluids. And the photothermal conversion efficiency of TiN/MWCNTs nanofluids (40 ppm) reached 76.4%. Furthermore, through the simulation and experimental results, this paper explained the mechanism of the enhanced solar-thermal conversion performance of nanofluids from the perspective of phonon heat transfer.

Phytic acid–decorated κ-carrageenan/melanin hybrid aerogels supported phase change composites with excellent photothermal conversion efficiency and flame retardancy

Organic phase change materials (PCMs) have been widely applied to thermal energy storage systems; however, poor solar–thermal conversion performance, high flammability, and liquid leakage issues considerably limit their practical application in efficient solar energy utilization. Herein, phytic acid–decorated melanin/κ-carrageenan aerogels (PMCAs) with excellent solar–thermal effect and satisfactory flame retardancy were developed using the cationic induction method. Then, form-stable PCM composites (PMPCMs) were fabricated by integrating molten n-octacosane into PMCAs through vacuum impregnation. The PMCAs effectively supported n-octacosane and avoided liquid leakage during the solar–thermal storage process owing to their strong surface tension and capillary force. The PMPCMs exhibited considerably high encapsulated efficiency (up to 97.73%), satisfactory thermal storage ability (246.7–257.7 J/g), and excellent thermal reliability. The introduction of natural melanin (natural photothermal conversion compound) and phytic acid (bio-based phosphorus-rich compound) significantly enhanced the solar–thermal conversion efficiency (from 61.7% to 89.4%) and flame retardancy of the PMPCMs. Thus, the synthesized form-stable composites possess tremendous potential for solar energy utilization.

Preparation of carbon nanotube/cellulose hydrogel composites and their uses in interfacial solar-powered water evaporation

Cellulose extracted from corncobs, a bulk agricultural waste product, by a solvent at −12 °C, was composited with carbon nanotubes (CNTs) with excellent light absorption properties to construct CNT/cellulose hydrogel composites. Taking advantage of the superior water retention ability and degradability of cellulose hydrogels, and the high-efficiency solar-thermal conversion performance, excellent mechanical properties and biocompatibility of CNTs, CNT/cellulose hydrogel composites are used in water purification by interfacial solar-powered evaporation. The effects of the addition of CNTs on the solar energy absorption, mechanical properties and interfacial solar-thermal water evaporation efficiency of the composites were investigated. With an optimum CNT content of 0.2 wt.%, the composite had an average evaporation rate of ~1.52 kg m−2 h−1 and a solar-steam conversion efficiency about 92%. After continuous evaporation in seawater for 8 h, the evaporation rate of the composite remained at about 1.37 kg m−2 h−1 without salt precipitation, indicating its strong resistance to salt. The quality of the purified water was superior to the WHO and EPA standards for drinking water. When the composite was used in concentrated acid/alkaline aqueous systems, dye wastewater and heavy metal ion polluted water, the evaporation rates remained in the range of 1.30-1.40 kg m−2 h−1, and the solar-steam conversion efficiencies reached 80%-86%. The retention rates for both organic pollutants and salt were as high as 99.9%, confirming the evaporation stability of the composite. This work indicates that an evaporator based on the CNT/cellulose hydrogel composite has broad application prospects in the fields of seawater desalination and industrial wastewater purification.

A modified kapok fiber based phase change composite for highly-efficient solar-thermal conversion

Phase change material (PCM) has attracted considerable attention as thermal energy management technology for thermal storage. However, the low thermal conductivity and poor solar-thermal conversion performance severely limit their further practical applications. Herein, we successfully design a novel form-stable polyethylene glycol (PEG)-kapok fiber (KF)@Ti3C2Tx nanosheets phase change composite with favorable thermal conductivity (0.630 W/mK) and outstanding solar-thermal conversion efficiency (98.49%). The Ti3C2Tx on KF could offer more thermally conductive channels, thus greatly improve the thermal conductivity of PEG PCM. The strong solar absorption of Ti3C2Tx and the black surface of the composite conjointly resulted in the highly efficient solar-thermal conversion procedure. When the as-prepared composite exposed to sunlight, the surface temperature could reach over 90 °C in just 10 min. This work could not only exhibit the great potential of PEG-KF@Ti3C2Tx in thermal energy management, but also provide a new and efficient way for high solar-thermal conversion.

Concentrated solar power tower systems coupled locally with spectrally selective coatings for enhancement of solar-thermal conversion and economic performance

Tower receivers in next-generation concentrated solar power towers (SPTs) face an increasing challenge to suppress the massive radiation heat loss associated with an elevated operating temperature. Negative thermal-flux regions (NTRs) exist in tower receivers owing to the high but uneven temperature and solar concentration ratio on their surfaces. Spectrally selective coatings on NTRs are proposed in this study to reduce the radiation heat loss and thus improve the solar-thermal conversion efficiency of tower receivers. Four coatings, namely, black Cr, Ag film, and ideal coatings with cutoff wavelengths of 2.5 and 1.5 μm, are investigated to evaluate the compatibility and effectiveness of coatings with diverse spectral selectivities to improve NTR solar-thermal conversion performance. The Dunhuang 10 MWe SPT plant using a binary salt as the heat transfer fluid was selected for the study. A novel spectral heat transfer model of the tower receiver and an economic assessment model of the Dunhuang SPT plant were established and verified by the experimental results. These results showed that the spectral coatings locally coupled on NTRs were effective in regulating NTR radiation properties and reducing radiation heat loss, thus improving the thermal performance of the tower receiver. The tower receiver efficiencies with Ag and ideal coating (cutoff wavelength of 1.5 μm) were significantly improved by 6.92% and 12.03%, respectively, compared to that of a prototype receiver. The novel receiver based Dunhuang SPT plant harvested an annual power output improvement of 5.8% and levelized cost of energy reduction of 5.6%.

Solar-thermal conversion performance of heterogeneous nanofluids

Nanofluids have excellent optical and thermal properties and show great potential for applications in direct absorption solar collectors (DASCs). However, due to the preparation process or force interaction, the non-uniform distribution of NP radii (r) and volume fraction (fv) in heterogeneous nanofluids may affect the solar-thermal conversion performance. In this work, we established a multiscale model based on the finite element method (FEM) coupled with the Monte Carlo (MC) method to investigate the solar-thermal conversion performance of heterogeneous nanofluids. Results show that the non-uniform distribution of r has little effect on the solar-thermal conversion performance due to the weak scattering and strong absorption properties of NPs in dilute nanofluids. The non-uniform distribution of fv has great effect on the local heating flux distribution in the heterogeneous nanofluid, which would affect the collector efficiency (ηcol) due to the different surface heat losses. And a superior ηcol can be achieved at a downward-gradient distribution of r and fv compared with uniform or upward-gradient distributions. This work develops an effective method to evaluate the solar-thermal conversion performance of heterogeneous nanofluids and provides a promising strategy by tuning the distribution of r and fv to enhance the solar collector performance.

季铵化介孔碳纳米球的合成及其在体内协同光热抗菌治疗

<p indent="0mm">Photothermal antimicrobial therapy (PTT) has more advantages than traditional antimicrobial therapy. Photothermal conversion nanomaterials can convert optical energy into thermal energy for killing bacteria under near-infrared light. Compared with antibiotic therapy, PTT has several advantages, such as broad-spectrum antimicrobial performance, spatiotemporal specificity, minimally invasive, and deep tissue penetration, and does not cause bacterial resistance. Nevertheless, the therapeutic effect of PTT monotherapy is not ideal because it is often accompanied by side effects, such as thermal injury. To overcome this shortcoming, synergistic photothermal therapy has attracted extensive research interests. This study first synthesized mesoporous carbon nanospheres (MCNs) with commendable solar-thermal conversion performance and uniform size. Then, carboxy-rich MCNs (CMCNs) were obtained by heating in a mixed acid solution. Subsequently, polyethyleneimine (PEI) was covalently grafted onto the surface of CMCNs using the 1-ethyl-3-(3-dimethyl aminopropyl)-carbodiimide (EDC) and N-hydroxysuccinimide (NHS) coupling reaction. Finally, quaternized mesoporous carbon nanospheres (CMCN-QAC) was obtained using a quaternization reaction. The morphology and crystalline forms of MCNs were analyzed using scanning electron microscopy and X-ray diffraction. The photothermal conversion performance of CMCNs was evaluated using an infrared thermal imager. It was found that the photothermal conversion performance of CMCNs was related to the material concentration and the 808-nm near-infrared laser irradiation power intensity. Moreover, photothermal stability experiments were conducted, and the results show that the CMCNs has stable photothermal conversion performance and stability. Next, the spread plate method and live/dead staining experiments were conducted to study the synergistic photothermal antibacterial effect of CMCN-QAC<italic> in vitro</italic>. The MBC value of CMCN-QAC was 60-μg/mL under 1.5-W/cm² 808-nm near infrared (NIR) laser for <sc>10 min.</sc> Finally, to investigate the synergistic photothermal therapy of CMCN-QAC <italic>in vivo</italic>, we established a mouse model of wound infection induced by <italic>Escherichia coli</italic>. The <italic>in vitro</italic> and <italic>in vivo</italic> results showed that the CMCN-QAC+NIR group exhibited the best therapeutic effect and high biocompatibility, indicating that CMCN-QAC has great potential to serve as a novel synergistic photothermal antimicrobial nanomaterial to treat bacterial infections.

All-Day Freshwater Harvesting by Selective Solar Absorption and Radiative Cooling.

Solar interfacial evaporation for freshwater harvesting has received attention recently due to its high evaporation rate and environmental friendliness. Traditional interfacial evaporation mostly uses black porous polymers to absorb solar radiation and transport water which involve high thermal radiation loss to the environment and heat conduction loss to the bulk water. In addition, the freshwater collection ratio is usually lower than the solar evaporation ratio due to the high temperature of the condensation surface under solar irradiation, and no freshwater can be harvested at night due to the absence of sunlight. Here, we design an all-day freshwater-harvesting device using a solar-selective absorber (SSA) and sky radiative cooling. The prepared SSA with a high solar absorptance of 0.92 and a mid-infrared thermal emittance of 0.11 provides a great solar-thermal conversion performance (87.1% vs 51.4% for the black porous polymer at 25 °C) by minimizing the thermal radiation loss, and a hollow structure is also used to reduce the conductive heat loss, resulting in a high solar evaporation rate (1.23 vs 0.79 kg m-2 h-1 for the black porous polymer). In addition, a transparent radiative cooling polymer after plasma treatment is used for freshwater collection by enhancing the solar transmittance (0.92) and mid-infrared thermal emittance (0.91 at 25 °C). A theoretical freshwater collection rate of 0.044 kg m-2 h-1 is achieved at night-time. Outdoor results show that the all-day water harvesting is 0.87 kg m-2. This strategy to achieve all-day water collection by coupling with the SSA and transparent radiative cooling has potential application in the field of desalination and freshwater harvesting in tropical desert areas.