Biradical-Featured Stable Organic-Small-Molecule Photothermal Materials for Highly Efficient Solar-Driven Water Evaporation

With recent progress in photothermal materials, organic small molecules featured with flexibility, diverse structures, and tunable properties exhibit unique advantages but have been rarely applied in solar-driven water evaporation owing to limited sunlight absorption resulting in low solar–thermal conversion. Herein, a stable croconium derivative, named CR-TPE-T, is designed to exhibit the unique biradical property and strong π–π stacking in the solid state, which facilitate not only a broad absorption spectrum from 300 to 1600 nm for effective sunlight harvesting, but also highly efficient photothermal conversion by boosting nonradiative decay. The photothermal efficiency is evaluated to be 72.7% under 808 nm laser irradiation. Based on this, an interfacial-heating evaporation system based on CR-TPE-T is established successfully, using which a high solar-energy-to-vapor efficiency of 87.2% and water evaporation rate of 1.272 kg m⁻² h⁻¹ under 1 sun irradiation are obtained, thus making an important step toward the application of organic-small-molecule photothermal materials in solar energy utilization.     

Nature-Inspired Structure-Engineered TiN/TiO2 Nanotubes Array Toward Solar Desalination Synergy with Photothermal-Enhanced Degradation and Thermoelectric Generation

Solar-driven interfacial evaporation systems are considered as promising technology to alleviate the water scarcity crisis, yet lack of innovative evaporators obstructs further improvement of energy utilization efficiency. Herein, inspired by mangrove, the structure-engineered design is utilized to synthesis multi-level reflection TiN/TiO₂@carbon cloth (CC) nanotubes array. The hollowed TiO₂ nanorods can promote expeditious water transport, while the TiN/TiO₂ array can act as localized surface plasmon resonance (LSPR)-enhanced multi-level reflection structure for solar energy harvesting. The enhanced light absorption capability of the bionic nanostructure is confirmed by finite-difference time-domain (FDTD) simulations. Therefore, the TiN/TiO₂@CC-3 exhibits high evaporation rate of 2.02 kg m⁻² h⁻¹ under 1 solar illumination, which is comparable or better than most of fabric-based evaporators. When applied in wide acid–base (pH 1–13) and salinity range (8–100 ‰) over 15 days, the TiN/TiO₂@CC-3 displays outstanding durability. Furthermore, to expand application scope of the elaborate nanostructure, photothermal-enhanced photocatalysis and thermoelectricity generation applications are evaluated, while these new functionalities are integrated into solar-driven desalination system. The outdoor device exhibits daily water yield of 10.89 kg m⁻², synergy with maximum 200.7 mV output voltage and high dye degradation efficiency, demonstrating flexible applications in multi-functional interfacial evaporation systems according to various requirements.     

Efficient and Full-Spectrum Photothermal Dehydrogenation of Ammonia Borane for Low-Temperature Release of Hydrogen

Efficient hydrogen release from ammonia borane (AB) with a striking hydrogen content (19.6 wt%) via thermolysis provides a promising pathway for on-board applications utilizing hydrogen energy. However, the sluggish kinetics at low temperatures and high energy consumption of thermal dehydrogenation are major obstacles for hydrogen release from AB. Herein, a novel solar-driven strategy for hydrogen production from AB at low temperature is proposed, in which Ti₂O₃ is utilized as a full-spectrum light absorber for photothermal-activating solid-state AB reactants to produce hydrogen. Through a reduction transformation method, nanoscale Ti₂O₃ particles with high chemical stability and narrow band gap are prepared, realizing a rapid production of 2.0 equivalents of hydrogen from AB at ambient temperature, with an excellent recyclable and full-spectrum-responsive photothermal dehydrogenation. Importantly, a record high photothermal activation efficiency of 35% is achieved with nanoscale Ti₂O₃ particles due to an enhanced local photothermal effect contributed by improved light absorption and decreased thermal conduction. Moreover, assisted with CuCl₂ promoter, a release of 2.0 equivalents of hydrogen under 1.0 solar irradiation at 70 °C is successfully achieved, revealing its potential applications in practical vehicles based on proton exchange membrane fuel cells.     

不可逆中冷回热太阳能布雷顿循环系统的优化分析

建立了由太阳能集热器模型和不可逆中冷回热布雷顿循环模型组成的恒温热源条件下太阳能布雷顿循环系统,以系统总效率为目标函数,考虑了高低温侧换热器、回热器和中冷器的热阻损失以及压缩机和涡轮机的不可逆损失,借助数值计算对太阳能集热器的工作温度进行了优化,并分析了主要特征参数对总效率的影响．结果表明：太阳能布雷顿循环系统中存在一个最佳的太阳能集热器工作温度和相应的最大总效率及最大总输出功率;在此基础上,通过优化中间压比可使循环系统的总效率和相应的总输出功率达到双重最大值;系统总效率随着回热器传热有效度和光学效率的增加而提高;系统运行时存在一个最佳的总压比．     

Separation of α-ketoglutaric acid by salting-out extraction coupled with solar-driven distillation

Alpha-ketoglutaric acid (α-KG), as an essential intermediate in biosynthesis and drug synthesis, has a broad application prospect. However, the lower product concentration and impurities in the α-KG production make the downstream separation more complex and costly. In this study, α-KG was separated from biotransformation broth by salting-out extraction (SOE) combined with solar-driven distillation. First, the aqueous two-phase system (ATPS) consisting of acetone/(NH₄)₂SO₄ was selected by comparison. The effects of acetone/(NH₄)₂SO₄ concentration, temperature, α-KG concentration, and pH on the distribution behavior of α-KG in ATPS were investigated. Under the optimized conditions, higher extraction efficiency and purity of α-KG were obtained in the actual biotransformation broth. In addition, solar evaporation was used to achieve preconcentration of the organic phase and salt recovery, significantly reducing energy consumption. The method is environmentally friendly and easy to operate, providing a new idea for separating low concentration products in biosynthesis.     

Investigation on the optimal performance and design parameters of an irreversible solar-driven Braysson heat engine

An irreversible solar-driven Braysson thermal engine has been investigated, in which finite rate heat transfer with the radiation–convection mode from the high-temperature reservoir to the heat engine and the convection mode from the heat engine to the heat sink, and irreversible adiabatic processes are taken into account. Based on the thermodynamic analysis method, the analytic expressions of the power output and efficiency of the Braysson heat engine are derived. By using numerical value calculation, the effects of the isobaric temperature ratio, internal irreversibility parameter, temperature ratio of the thermal reservoirs as well as the allocation parameters involving the heat-transfer coefficients, and areas on the performance characteristics of the Braysson heat engine are analysed and discussed in detail. The results obtained in this paper are more general than the related conclusions published in the literature and may provide some parameter design reference for solar-driven heat engines.     

Multifunction ZnO/carbon hybrid nanofiber mats for organic dyes treatment via photocatalysis with enhanced solar-driven evaporation

ZnO-based photocatalytic materials have received widespread attention due to their usefulness than other photocatalytic materials in organic dye wastewater treatment. However, its photocatalytic efficiency and surface stability limit further applicability. This paper uses a one-step carbonization method to prepare multifunctional ZnO/carbon hybrid nanofiber mats. The carbonization creates a π-conjugated carbonaceous structure of the mats, which prolongs the electron recovery time of ZnO nanoparticles to yield improved photocatalytic efficiency. Further, the carbonization reduces the fiber diameter of the carbon hybrid nanofiber mats, which quadruples the specific surface area to yield enhanced adsorption and photocatalytic performance. At the same time, the prepared nanofiber mats can increase the evaporation rate of water under solar irradiation to a level of 1.46 kg·m⁻²·h⁻¹ with an efficiency of 91.9%. Thus, the nanofiber mats allow the facile incorporation of photocatalysts to clean contaminated water through adsorption, photodegradation, and interfacial heat-assisted distillation mechanisms.     

面向水处理与有机溶剂回收的太阳能界面蒸发系统与材料

海水淡化是缓解全球淡水资源短缺的重要途径,但传统海水淡化技术受限于过大的能源消耗,而太阳能界面蒸发技术因高蒸发效率、可持续性和低成本等优点引起了人们极大的关注。太阳能界面蒸发技术利用光热转换材料将光捕获并高效地转化为热能,随之将热量传递给水分子将其蒸发收集而实现净化。本文综述了近年太阳能界面蒸发系统结构设计的演变,总结了新兴的光热材料如金属基等离子体材料、碳基材料、半导体材料、生物质材料等在海水淡化、污水处理等方面的研究,并基于系统设计理念提出了太阳能蒸发技术应用于有机溶剂纯化领域的可能性。在此基础上,对太阳能界面蒸发技术的前景和面临的挑战进行了总结,提出了太阳能界面蒸发技术与蒸汽发电、光催化、光解水产氢等多种技术的耦合。     

不可逆太阳能热泵系统集热器的最佳工作温度

基于有限时间热力学理论和集热器的线性热损模型，研究了热阻及工质内部不可逆性对太阳能热泵系统优化性能的影响，导出了系统的总性能系数及集热器的最佳工作温度。所得结论可为实际太阳能热泵系统的优化设计提供新的理论。     

Confinement Capillarity of Thin Coating for Boosting Solar-Driven Water Evaporation

Realizing ultrathin water and generating an abundant water/air interface in the interconnected pores of photothermal materials is an effective way to boost the solar-driven water evaporation rate, but still a great challenge. Herein, confinement capillarity (CC) of photothermal thin coating on porous sponge for significantly enhancing the solar-driven water evaporation is proposed. The thin coating is composed of abundant agminated black/hydrophilic nanoparticles (BHNPs), and the channels among the BHNPs can generate strong capillarity for water transportation. Water can be spontaneously limited and transported among the agminated nanoparticles, rather than fill in the interconnected pores of the sponge. Thus, ultrathin water layer can be realized on the outer/inner surface of the sponge skeleton, without precisely controlling water supply. The thin water layer can not only expose as much evaporation area as possible by increasing the vapor escape channel, but also prevent solar energy to heat excess water. Thanks to the CC, the rate of solar steam generation can be greatly improved. Moreover, the photothermal material with CC can maintain its high evaporation rate during the whole day, and can remove the salt during night time, highlighting its recyclability and anti-salt-accumulation property. Moreover, the CC can be readily scaled up for practical applications.