Solar Thermal Conversion Research Articles

3D reconfigurable hydroxylated carbon nanotubes-based water evaporators with long-distance transportation for continuous vapor generation

Utilizing solar-thermal power for water purification through interfacial solar steam generation represents an environmentally friendly approach to secure a clean water source. However, it is still challenging to simultaneously overcome short transport distances, low transport rates, and unsatisfactory solar-thermal energy conversion efficiency, as well as the salt accumulation problem. In this work, three-dimensional (3D) reconfigurable water evaporators are developed based on commercial fabric strings and hydroxylated carbon nanotubes. The specifically designed 3D architecture enables the fabric strings to have a long water transport distance and localized focusing of solar light that benefits the fabrication of 3D evaporators and water isolation with low heat loss. Besides, the hydroxylated carbon nanotubes with strong hydrophilicity as well as their inherent black color show high solar-heat conversion efficiency. A high evaporation rate of 3.234kg m-2h−1 is found and a solar-to-vapor efficiency of 123.21 % is also achieved by using a vertical evaporation structure due to the enlarged surface area allowing absorption of heat from the environment. Meanwhile, the accumulated salts do not block the water transport pathway and they can be easily removed in high-salinity water evaporation by employing the assembled rotating evaporator. The results suggest that the fabric rope is a good platform for exploring highly efficient evaporation structures. Combined with hydroxylated carbon nanotubes, as-designed 3D reconfigurable evaporators are promising for efficient freshwater generation.

Flexibility, malleability, and high mechanical strength phase change composite films for solar-thermal and electro-thermal energy storage

Phase change materials (PCMs) are widely used in a range of energy storage applications due to high latent heat absorption and release capacities during phase change processes. There is still a lot to be done to resolve the inherent leakage, stiffness problems, and poor solar-thermal and electrical-thermal conversion capacities of PCMs to functionalize them. Here, a novel solid-solid phase change material (IGPCM) is created using block copolymerization. The IGPCM has a tunable enthalpy (from 58.16 to 99.60 J g−1) by adjusting the molecular weight of the PEG. The obtained IGPCM10K has high toughness (479.1 MJ/m3), excellent bending and malleability. Since IGPCM10K suffers from poor thermal conductivity, photo responsiveness, and electro-thermal conversion, carbon nanotubes (CNT) can be added to our IGPCM10K in a simple way to improve these issues. The thermal conductivity of IGPCM10K-CNT-3 is improved by 55.6 % compared to IGPCM10K. The photothermal conversion efficiency is 84.9 % at 300 mW/cm2. The electrothermal conversion efficiency is 82.3 % at 12 A. The prepared flexible PCM composites have super toughness, high enthalpy, excellent thermal conductivity, and photo-thermal and electro-thermal conversion capabilities, which will show great potential in future applications.

Full‐Spectrum Light‐Harvesting Solar Thermal Electrocatalyst Boosts Oxygen Evolution

AbstractEnabling high‐efficiency solar thermal conversion (STC) at catalytic active site is critical but challenging for harnessing solar energy to boost catalytic reactions. Herein, we report the direct integration of full‐spectrum STC and high electrocatalytic oxygen evolution activity by fabricating a hierarchical nanocage architecture composed of graphene‐encapsulated CoNi nanoparticle. This catalyst exhibits a near‐complete 98 % absorptivity of solar spectrum and a high STC efficiency of 97 %, which is superior than previous solar thermal catalytic materials. It delivers a remarkable potential decrease of over 240 mV at various current densities for electrocatalytic oxygen evolution under solar illumination, which is practically unachievable via traditionally heating the system. The high‐efficiency STC is enabled by a synergy between the regulated electronic structure of graphene via CoNi‐carbon interaction and the multiple absorption of lights by the light‐trapping nanocage. Theoretical calculations suggest that high temperature‐induced vibrational free energy gain promotes the potential‐limiting *O to *OOH step, which decreases the overpotential for oxygen evolution.

Solar Selectivity of Silver Nanoparticles Modified Copper Oxide Nanocomposite Thin Films Prepared by Facile Chemical Oxidation Method

AbstractSilver nanoparticles modified copper oxide nanocomposite thin films (Ag‐CuO NC TFs) and pristine CuO TF were successfully synthesized on copper substrates using a chemical oxidation route. X‐ray diffractometry (XRD) characterization of Ag‐CuO NC TFs revealed the formation of monoclinic crystal structured CuO. Scanning electron microscopy (SEM) images showed a star‐like grain morphology of the Ag‐CuO NC TFs. Energy dispersive X‐ray spectroscopy (EDX) analysis ascertained the presence of anticipated elements without impurities. Fourier transform infrared spectroscopy (FTIR) investigation confirmed the presence of Ag NPs on CuO in the Ag‐CuO NC TFs. Raman spectroscopy examination indicated the presence of a spinel structure with vibrational and tetrahedral sites. UV‐Vis‐NIR reflectance analysis demonstrated that Ag‐CuO NC TFs with 2.0 wt.% Ag NPs exhibited solar absorptance of 72.39 %, thermal emittance of 4.3 %, and a highest solar selectivity of 16.83 among the prepared thin films. These results suggest that the Ag‐CuO NC TFs could be promising candidates for use as solar selective absorbers in solar thermal energy conversion devices.

Perylene diimide-derived supramolecules-modified graphene sponge as a high-efficiency solar steam generator

Generating steam using solar energy appears to be an effective approach to obtaining clean water, especially from salty water and wastewater, since the sun is a natural and constant source. Compared to many methods, studies in solar steam generation have accelerated due to being highly efficient, sustainable, and low-cost. Graphene sponges (GrSs), possessing structural flexibility and effective photothermal activity, are widely used for this purpose. However, the hydrophobic character of these materials limits their effectiveness in solar steam generators. At this point, we prepared perylene diimide-derived supramolecules (PDI) modified three-dimensional (3D) gradient hydrophobic GrS (PDI/GGrS) as the highly efficient solar thermal converter for the generation of clean water. PDI allowed us to achieve perfect absorption of broad-band sunlight and GGrS facilitated water transport through channels of sponge structure. As a result, PDI/GGrS has achieved a high water evaporation rate of 3.5 kg h−1 m−2 with a superior solar thermal conversion efficiency of up to 90 %. This study can provide new possibilities for harvesting solar energy by producing clean water from seawater, wastewater, and even acidic/alkali solutions.

Fe3O4 nanostructure films as solar-thermal conversion materials for ammonia synthesis.

Here, we report that black photothermal materials elevate solar heating temperatures across high solar absorption and low infrared radiation. Fe3O4 nanostructure films can be heated to 350 °C under light irradiation, and this system shows effective visible-light-driven ammonia synthesis production of 3677 μg g-1 h-1 under gas-solid phase catalysis without noble metals.

Preparation and thermal stability research of oxalic acid dihydrate-glutaric acid/PAMPS phase change gel for solar thermal energy utilization

Thermal energy storage technology based on phase change materials (PCMs) can address the temporal and spatial mismatches in solar thermal energy conversion, thereby enhancing solar energy utilization efficiency. However, the liquid flow and poor thermal reliability of PCMs limit their large-scale application in solar thermal systems. In this study, we employ a simple “one-pot method” to prepare a form-stable and thermally reliable oxalic acid dihydrate-glutaric acid/poly 2-Acrylamido-2-methyl-1-propanesulfonic acid (OAD-GA/PAMPS) phase change gel. The OAD-GA/PAMPS phase change gel melts at 64.5 °C with a phase change enthalpy of 193.6 kJ/kg, the tensile strength is 7.707 MPa, and the compressive strength is 16.940 MPa. By incorporating 5 wt% BN particles, the thermal conductivity of OAD-GA/PAMPS phase change gel reaches 0.63 W/(m·K). After 200 heating-cooling cycles, the phase change temperature of the OAD-GA/PAMPS phase change gel remains nearly unchanged, and the phase change enthalpy decreases by only 5.7 %. The photo-thermal conversion efficiency of the OAD-GA/PAMPS phase change gel is 82.7 %. The high thermal reliability and photo-thermal conversion efficiency of the OAD-GA/PAMPS phase change gel makes it suitable for solar thermal energy storage applications.

A Recyclable Energy Storage Wood Composite with Photothermal Conversion Properties for Regulating Building Temperature

AbstractAddressing the challenges of energy storage liquid leakage and long‐term stability in energy storage is crucial for achieving sustainable energy efficiency. In this study, polymethyl methacrylate (PMMA) is innovatively employed as an encapsulation film on the surface of the wood‐based phase change material, resulting in a recyclable wood‐based composite energy storage material (PPW). A novel energy storage liquid (PCMs) composed of lauric acid (LA), capric acid (CA), and polyethylene glycol (PEG) is immersed in the pretreated porous wood frame through vacuum impregnation. The PCMs imparted a phase change temperature of 21.0 °C, which is close to human comfort levels, and a high energy storage efficiency of 31.6 J g−1 to the PPW. Additionally, the PCMs provided the PPW with a photothermal conversion efficiency of 29.3%. Even after 200 freeze‐thaw cycles, the energy storage properties of the PPW remained nearly unchanged. Therefore, utilizing PMMA as an effective encapsulation material is a viable approach to prevent leakage of the phase change solution and enhance the recyclability of the PPW. Furthermore, the transparency of PMMA preserves the natural appearance of the wood, thereby broadening the application potential of PPW in residential buildings, thermal energy storage, and solar thermal conversion systems.

Enhanced thermal conductivity of wood-based phase change materials with copper for thermal management and solar-thermal conversion

Polyethylene glycol (PEG) has been regarded as a promising thermal management material for next-generation building materials due to its high energy storage density and phase change performance. However, its practical application has been limited by some issues such as easily leakage and low thermal conductivity. In this work, a high-thermal-conductivity wood-based composite phase change material (Cu-DW/PEG) was fabricated by impregnating copper (Cu) precursor solution and PEG into delignified wood (DW). The incorporation of Cu nanoparticles increased the thermal conductivity of Cu-DW/PEG by 105 % and 64 % compared to pure PEG and DW/PEG composite, respectively. This also endow the Cu-DW/PEG good photo-thermal conversion capability, achieving a conversion efficiency of 76.5 %. Meanwhile, the Cu-DW/PEG exhibits relatively high latent heat (132.93 J/g), good shape stability and thermal cycling stability. Considering these excellent performances, the Cu-DW/PEG is a promising material for thermal management, building energy conservation, and solar thermal harvesting.

Tree-like 3D GNP-rPN composite structure for solar-thermal evaporation and photocatalytic degradation of antibiotic wastewater

To realize high-yield and long-term purification of wastewater containing antibiotic ciprofloxacin hydrochloride (CIP) and seawater, a tree-like 3D GNP-rPN solar-driven water evaporation and photocatalysis evaporator is developed by preparing and assembling GO/NPDI/PVA (GNP) hydrogel (canopy) and rGO/PU/NPDI (rPN) foam (trunk). The “tree-like” evaporation and photocatalysis evaporator design in this work has the following three characteristics: First of all, graphene oxide (GO) and reduced graphene oxide (rGO) sheets broaden the light absorption range of the photocatalyst perylene imide nanowires (NPDI), which facilitates absorption of more sunlight; secondly, GO and rGO adsorb pollutants in water and provide them to NPDI for catalytic degradation under sunlight irradiation because of their huge specific surface area; thirdly, the excellent photothermal conversion ability of GO and rGO converts solar energy into heat energy, thus facilitating the catalytic degradation of CIP by NPDI. Thanks to the reduced enthalpy of water evaporation by GNP hydrogel, the sufficient top-down water supply, the superior photocatalytic performance of NPDI nanowires, and the efficient solar light absorption and solar-thermal energy conversion of the GO sheets and NPDI nanowires, the resultant GNP-rPN evaporation and photocatalysis system achieves an average water evaporation rate of 2.84 kg m−2 h−1 and a CIP degradation efficiency of 74.04 % within 1 h under 1-sun irradiation. The GNP-rPN system exhibits an optimal degradation efficiency of 74.04 % for a CIP solution with an initial concentration of 10 mg/L within 1 h of irradiation, reaching a degradation efficiency of 96.37 % after 4 h, demonstrating its effectiveness in purifying antibiotic-laden wastewater.

Compact multilayer selective absorbers based on amorphous carbon for solar-thermal conversion

In addressing the energy crisis and climate change, environmentally sustainable materials and structures with heightened absorption and enhanced photothermal conversion efficiency are urgently demanded. In this study, a series of ultrabroadband, omnidirectional, and near-perfect solar radiation absorbers based on amorphous carbon (a-C) were fabricated by magnetron sputtering. These absorbers, featuring 4, 6, and 8-layer compact multilayer thin film structures, exhibited measured absorption of 96.8 %, 96.5 %, and 96.6 % in the range of 300–2500 nm, respectively. The high absorption efficiency delves into the synergistic effects of intrinsic absorption of a-C and enhanced absorption through thin film interference. Through microstructure analysis, the reduced absorption compared to design originates from the optical thickness mismatch caused by the unstable growth rate of a-C. In addition, the absorbers show very slight variations in absorption within 40° and maintain a high absorption of more than 80 % in the incident angle of 60°. For samples with different air annealing temperatures from 100 to 250 °C, the microstructure, morphology, and optical properties were systematically investigated. The appearance of oxygen channels due to surface defects or voids leads to the oxidation reaction of the diffused Ti atoms at high temperature. Notably, the proposed absorber can be fabricated by a lithography-free method, paving a way for large-area application of a-C.

The effect of ultrasonic waves on the structure, morphology, and thermal conductivity of graphene oxide as nanofluids for direct absorption solar collector application

This research aims to explore how ultrasonic waves affect the structure and morphology of graphene oxide (GO) as a nanofluid, influencing its thermal conductivity (TC), stability, and photo-thermal conversion properties. GO was rapidly synthesized under ultrasonic bath irradiation using modified and improved Hummers' methods. Ultrasonic irradiation creates different structural and morphological defects in the GO that depend on the sonication time. The relationship between the exposure time to ultrasound and the creation of structural and morphological defects in graphene oxide nanosheets was investigated using UV–Vis, FTIR, Raman spectroscopies, AFM, and TEM analysis. The study examined how the structure and morphology of graphene oxide nanosheets affect the thermophysical and photo-thermal conversion properties of nanofluids by comparing heat transfer and stability. The simultaneous characterizing of the structure and morphology indicates that TC and stability are related to the sonication time. Indirect sonication with low intensity can carefully control the oxidation reaction of GO. Sonication for 30 min creates GO nanosheets that yield stable nanofluids with a 32.31 % enhancement in TC, with no extra treatment needed. This particular nanofluid has excellent photo-thermal conversion properties thanks to its high optical absorption, good stability, and thermal conductivity. This can increase the solar-thermal conversion efficiency (η) up to 72.5 %, making it a promising candidate for use as the working fluid in direct absorption solar collectors (DASCs)

Dual-dielectric Fabry-Perot film for visible-infrared compatible stealth and radiative heat dissipation

Multiband camouflage of space satellite to against advanced detection has attracted rising attention. However, the combination of compatible camouflage and radiative heat dissipation for space satellite still remains challenging, which requires low visibility and selective thermal emission in a dark and deep cold background. In this work, a dual dielectric Ge/SiO2 layer embedded Fabry-Perot multilayer film (W/Ge/SiO2/W/SiO2) is proposed for space stealth and heat dissipation. Ge and SiO2 films with appropriate thickness are designed to realize high visible absorption and spectra selective IR emission, simultaneously. The optimized multilayer film achieves a high absorbance (α = 0.983) in visible light (0.38–0.80 μm) for visible stealth, low emissivity (ε3–5 μm = 0.038; ε8–14 μm = 0.200) in atmospheric windows for infrared stealth, and relative high emissivity outside the atmospheric windows (ε5–8 μm = 0.487) for radiative heat dissipation. The simulation results indicate that the coupling of tunneling effect in ultrathin metallic W film and Fabry-Perot resonant is the main contribution to the excellent absorptivity and emissivity tunability. The proposed dual spacers embedded Fabry-Perot multilayer film paves a new way for multispectral camouflage of space satellite and other applications such as solar-thermal conversion, thermal management, energy saving, and detective technologies.

Analysis of solar absorption, degradation mechanism and thermal stability in air environments for SS/TiB2/Al2O3 spectrally selective absorber coating

The quest for high solar-thermal conversion efficiency and thermal stability is a significant challenge in the development of high-efficiency spectrally selectivity absorber coatings. A key aspect of this challenge is the creation of air-stabilized coatings, particularly crucial for scenarios involving unexpected vacuum loss or applications of concentrating solar power systems in air environments. In our study, TiB2 films own excellent spectral selectivity and thermal stability at air environment. In pursuit of revealing the absorption mechanism of the coating, the optical constants, absoption and transmission of the single TiB2 layer were measured. The result of analysis display that the TiB2 layer contribute the bulk of the sunlight absorption. Reflectance spectra of the SS/TiB2/Al2O3 coating was succeeding simulated by CODE software with the optical constant to fit the experimental spectra, which confirms the results obtained by spectroscopic ellipsometry. The solar-thermal conversion efficiency of the as-deposited coating could reach 88.9 % of 100 suns at 500 °C. After annealing at 300–500 °C, the absorbance and emittance of the coating change slightly. But after annealing at 600 °C, the changing surface morphology, increasing surface roughness, and oxidation reaction of TiB2 resulted in a decrease in the optical performance of the coating.

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.

Interfacial enhancement enables highly conductive reduced graphene oxide-based yarns for efficient electromagnetic interference shielding and thermal regulation

Although the coating of conductive graphene onto commercial yarns is promising for scalable production, the resulting conductive yarns are susceptible to the coating detachment, causing reduced conductivity and poor stability. Herein, we propose a scalable and cost-effective interfacial enhancement strategy for fabricating highly conductive yarns with satisfactory mechanical properties by modifying polyamide yarns with polyethyleneimine to enhance their interaction with graphene oxide (GO) sheets and subsequently reducing the GO component with hydroiodic acid. Because the enhanced interfacial interactions of the polyethyleneimine-modified polyamide yarns with the GO sheets improve the loading of GO and the coating stability, the resultant yarns can withstand bending, embroidering, sewing and weaving, maintaining an extraordinary conductivity of 4.7 × 103 S m−1 after 10000-cycle bending. The conductive textiles woven by the yarns reach an excellent electromagnetic interference (EMI) shielding effectiveness of 66.7 dB at the thickness of 0.615 mm along with superior hydrophobicity, satisfactory air permeability, and high electrothermal and solar-thermal energy conversion performances. The EMI shielding effectiveness of the textile is well maintained even after 5000-cycle bending, demonstrating its satisfactory stability. This work demonstrates an interfacial enhancement strategy for the large-scale fabrication of multifunctional yarns that hold great promise for EMI shielding, personal thermal regulation, and deicing applications.

Bioinspired Spectrally Selective Phase‐Change Composites for Enhanced Solar Thermal Energy Storage

AbstractIntegrating solar thermal conversion with phase change materials (PCMs) offers a promising pathway for continuous thermal energy generation with a zero‐carbon footprint. However, substantial infrared radiation losses at elevated temperatures often hinder the efficiency of such integrated systems. Inspired by the thermoregulation mechanisms of polar bears, this work introduces composite PCMs with spectrally selective absorption to enhance solar thermal energy storage efficiency. These composite phase change materials (CPCMs), featuring densely packed SiC ceramic grains with high porosity, exhibit a thermal conductivity of up to 14 W m−1 K−1 and an energy storage density of 195.1 kJ kg−1. The incorporation of nanoparticle‐coated foil induces a plasmonic effect that increases solar absorptivity to 90.57% and reduces infrared emissivity from 71.94% to 7.47%. Consequently, the solar thermal storage efficiency is significantly increased from 54.56% to 81.65% at 500 K, effectively addressing the challenges associated with high‐temperature solar thermal storage. Additionally, the low infrared emissivity of the c (PNC), combined with the inherent heat absorption properties of PCMs, enables infrared stealth functionality. These multifunctional CPCMs demonstrate considerable potential for advancing high‐temperature solar thermal storage technologies and other heat‐related applications.

Anisotropic MXene@polydopamine- and Dialdehyde Carboxymethyl Cellulose-Modified Collagen Aerogel Supported Form-Stable Phase Change Composites for Light-To-Heat Conversion and Energy Storage.

As a renewable alternative heat source, the inherently intermittent feature of solar energy needs to be coordinated by reliable energy conversion and storage systems for utilizing the most abundant solar energy. Phase change materials (PCMs) are supposed to be advanced mediums for storing a great deal of heat generated by solar light. However, PCMs cannot effectively absorb and utilize solar energy due to leakage, low photothermal conversion efficiency, and poor thermal conductivity. Herein, we developed a collagen-based aerogel modified by dialdehyde carboxymethyl cellulose and polydopamine-modified two-dimensional transition-metal carbide/nitride (MXene@PDA) through bidirectional freeze-drying technology for supporting PCMs, which exhibited anisotropy in structure and properties. In particular, the thermal conductivity of the aerogel was 0.0871 W/(m·K) in the axial direction and 0.0504 W/(m·K) in the radial direction, demonstrating its anisotropic thermal insulation performance. Moreover, the final aerogel composite PCMs had been obtained via impregnating the obtained aerogel supporting matrix into polyethylene glycol (PEG) and hydrophobic treatment of polydimethylsiloxane, which exhibited outstanding solar-thermal conversion ability, good thermal storage capacity, advanced leakage-proof property, and antifouling performance. The loading rate of PEG was as high as 92.2%, and the melting enthalpy was 132.6 J/g. Most importantly, the water contact angle was evaluated to be 156.8°, indicating its superior antifouling performance. This material has intensive application prospects in the fields of solar energy collection, conversion, and storage.

Achieving highly interfacial evaporation rate and continuous salt resistance simultaneously via multi-dimensional composite biomimetic evaporator

In response to the global freshwater crisis, various measures have been proposed. Solar-driven interfacial photoevaporation is gaining attention because its environmentally friendly and energy-efficient. However, challenges such as low solar-thermal conversion efficiency and low evaporation rates continue to hinder the advancement of solar photoevaporation technology. Inspired by Tamarisk, we proposed a multistage reflective structure using a hydrothermal method, increasing the carbon cloth (CC) surface area. Numerical simulations indicate that the plasmon resonance effect of the composites could effectively enhance the light absorption properties of the structures. Subsequently, a polyvinyl alcohol-phytic acid (PVA-PA) hydrogel was integrated with the composites to achieve effective separation of the evaporation layer from the water transport layer, thereby minimizing the interfacial light evaporation material. The PVA-PA/MnO2@CC evaporation system demonstrates excellent thermal management performance. Both experimental and simulation results confirm that the system can localize the heat obtained from photothermal conversion at the water–air interface. Additionally, the Marangoni effect, induced by the temperature gradient in the evaporation system, facilitates the transport of water in the PVA-PA hydrogel to the interface through microscopic holes. The evaporator exhibited an evaporation rate of 3.190 kg m-2h−1 in deionized water, with an evaporation efficiency of 94.1 %. Even under high-concentration brine conditions, the evaporation rate remained high, and during continuous evaporation in high-concentration brine, the surface showed no significant salt accumulation. In summary, this work combines two-dimensional carbon cloth with three-dimensional hydrogel, and incorporates metal oxides onto the carbon cloth surface to further enhance its light-trapping ability. By synthesizing the advantages of both materials, the performance of the evaporator is significantly improved.

Ultrablack surface with omnidirectional high absorption.

Black surface plays an important role in solar-thermal conversion systems and space optical systems. Despite the significant efforts in developing a black surface with strong broadband absorption, realizing scalable omnidirectional high absorption ultrablack surfaces remains challenging. Here, we report an ultrablack surface based on a structural black paint (SBP), realized by femtosecond (fs) laser fabrication of high aspect ratio microstructure mold followed by mold transferring on black paint coating. The SBP exhibits extremely low hemispheric reflectance (R < 1.2%) in the solar spectrum at a normal incident angle; even at an 80° incident angle, the SBP also has good anti-reflection performance (R < 9%). Based on such properties, we further show the enhanced solar-thermal performance over commercial black paints. Our approach holds promises for scalable and cost-effective manufacturing of ultrablack surface, with potential applications in solar-thermal conversion efficiency improvement and space optical system stray light suppression.