Hierarchical Graphene Foam for Efficient Omnidirectional Solar–Thermal Energy Conversion

Efficient solar–thermal energy conversion is essential for the harvesting and transformation of abundant solar energy, leading to the exploration and design of efficient solar–thermal materials. Carbon‐based materials, especially graphene, have the advantages of broadband absorption and excellent photothermal properties, and hold promise for solar–thermal energy conversion. However, to date, graphene‐based solar–thermal materials with superior omnidirectional light harvesting performances remain elusive. Herein, hierarchical graphene foam (h‐G foam) with continuous porosity grown via plasma‐enhanced chemical vapor deposition is reported, showing dramatic enhancement of broadband and omnidirectional absorption of sunlight, which thereby can enable a considerable elevation of temperature. Used as a heating material, the external solar–thermal energy conversion efficiency of the h‐G foam impressively reaches up to ≈93.4%, and the solar–vapor conversion efficiency exceeds 90% for seawater desalination with high endurance.     

Multilayer Polypyrrole Nanosheets with Self‐Organized Surface Structures for Flexible and Efficient Solar–Thermal Energy Conversion

Converting solar energy into concentrated heat is very appealing for various applications. Polypyrrole (PPy) is known to possess excellent photothermal property with low thermal conductivity, and thus is an ideal candidate for solar–thermal energy conversion. However, solar–thermal materials based on PPy or other conducting polymers still exhibit limited energy conversion efficiency due to the lack of effective light‐trapping schemes. Here, it is demonstrated that multilayer PPy nanosheets with spontaneously formed surface structures such as wrinkles and ridges via sequential polymerization on paper substrates can dramatically enhance broadband and wide‐angle light absorption across the full solar spectrum, leading to an impressive solar–thermal conversion efficiency of 95.33%. The intriguing solar–thermal properties and structural features of multilayer PPy nanosheets can be used for solar heating and photoactuators. Meanwhile, when used for solar steam generation, the measured efficiency could achieve ≈92% under one sun irradiation. The hierarchically multilayer structure is mechanically flexible and robust, holding great potential for practical solar energy utilization. This study provides a simple and straightforward approach toward engineering light‐weight and thermally insulating polymers into efficient solar–thermal materials for emerging solar energy‐related applications.     

Solution‐Processed All‐Ceramic Plasmonic Metamaterials for Efficient Solar–Thermal Conversion over 100–727 °C

Low‐cost and large‐area solar–thermal absorbers with superior spectral selectivity and excellent thermal stability are vital for efficient and large‐scale solar–thermal conversion applications, such as space heating, desalination, ice mitigation, photothermal catalysis, and concentrating solar power. Few state‐of‐the‐art selective absorbers are qualified for both low‐ ( < 200  ° C) and high‐temperature ( > 600  ° C) applications due to insufficient spectral selectivity or thermal stability over a wide temperature range. Here, a high‐performance plasmonic metamaterial selective absorber is developed by facile solution‐based processes via assembling an ultrathin ( ≈ 120 nm) titanium nitride (TiN) nanoparticle film on a TiN mirror. Enabled by the synergetic in‐plane plasmon and out‐of‐plane Fabry–Pérot resonances, the all‐ceramic plasmonic metamaterial simultaneously achieves high, full‐spectrum solar absorption (95%), low mid‐IR emission (3% at 100  ° C), and excellent stability over a temperature range of 100–727  ° C, even outperforming most vacuum‐deposited absorbers at their specific operating temperatures. The competitive performance of the solution‐processed absorber is accompanied by a significant cost reduction compared with vacuum‐deposited absorbers. All these merits render it a cost‐effective, universal solution to offering high efficiency (89–93%) for both low‐ and high‐temperature solar–thermal applications.     

Scalable, “Dip‐and‐Dry” Fabrication of a Wide‐Angle Plasmonic Selective Absorber for High‐Efficiency Solar–Thermal Energy Conversion

A galvanic‐displacement‐reaction‐based, room‐temperature “dip‐and‐dry” technique is demonstrated for fabricating selectively solar‐absorbing plasmonic‐nanoparticle‐coated foils (PNFs). The technique, which allows for facile tuning of the PNFs' spectral reflectance to suit different radiative and thermal environments, yields PNFs which exhibit excellent, wide‐angle solar absorptance (0.96 at 15°, to 0.97 at 35°, to 0.79 at 80°), and low hemispherical thermal emittance (0.10) without the aid of antireflection coatings. The thermal emittance is on par with those of notable selective solar absorbers (SSAs) in the literature, while the wide‐angle solar absorptance surpasses those of previously reported SSAs with comparable optical selectivities. In addition, the PNFs show promising mechanical and thermal stabilities at temperatures of up to 200 °C. Along with the performance of the PNFs, the simplicity, inexpensiveness, and environmental friendliness of the “dip‐and‐dry” technique makes it an appealing alternative to current methods for fabricating selective solar absorbers.     

Creating Graphitic Carbon Nitride Based Donor‐π–Acceptor‐π–Donor Structured Catalysts for Highly Photocatalytic Hydrogen Evolution

Conjugated polymers with tailored donor–acceptor units have recently attracted considerable attention in organic photovoltaic devices due to the controlled optical bandgap and retained favorable separation of charge carriers. Inspired by these advantages, an effective strategy is presented to solve the main obstructions of graphitic carbon nitride (g‐C₃N₄) photocatalyst for solar energy conversion, that is, inefficient visible light response and insufficient separation of photogenerated electrons and holes. Donor‐π–acceptor‐π–donor polymers are prepared by incorporating 4,4′‐(benzoc 1,2,5 thiadiazole‐4,7‐diyl) dianiline (BD) into the g‐C₃N₄ framework (UCN‐BD). Benefiting from the visible light band tail caused by the extended π conjugation, UCN‐BD possesses expanded visible light absorption range. More importantly, the BD monomer also acts as an electron acceptor, which endows UCN‐BD with a high degree of intramolecular charge transfer. With this unique molecular structure, the optimized UCN‐BD sample exhibits a superior performance for photocatalytic hydrogen evolution upon visible light illumination (3428 µmol h^?1 g^?1), which is nearly six times of that of the pristine g‐C₃N₄. In addition, the photocatalytic property remains stable for six cycles in 3 d. This work provides an insight into the synthesis of g‐C₃N₄‐based D‐π–A‐π–D systems with highly visible light response and long lifetime of intramolecular charge carriers for solar fuel production.     

Holey Reduced Graphene Oxide Coupled with an Mo2N–Mo2C Heterojunction for Efficient Hydrogen Evolution

An in situ catalytic etching strategy is developed to fabricate holey reduced graphene oxide along with simultaneous coupling with a small‐sized Mo₂N–Mo₂C heterojunction (Mo₂N–Mo₂C/HGr). The method includes the first immobilization of H₃PMo₁₂O₄₀ (PMo₁₂) clusters on graphite oxide (GO), followed by calcination in air and NH₃ to form Mo₂N–Mo₂C/HGr. PMo₁₂ not only acts as the Mo heterojunction source, but also provides the Mo species that can in situ catalyze the decomposition of adjacent reduced GO to form HGr, while the released gas (CO) and introduced NH₃ simultaneously react with the Mo species to form an Mo₂N–Mo₂C heterojunction on HGr. The hybrid exhibits superior activity towards the hydrogen evolution reaction with low onset potentials of 11 mV (0.5 m H₂SO₄) and 18 mV (1 m KOH) as well as remarkable stability. The activity in alkaline media is also superior to Pt/C at large current densities (>88 mA cm^?2). The good activity of Mo₂N–Mo₂C/HGr is ascribed to its small size, the heterojunction of Mo₂N–Mo₂C, and the good charge/mass‐transfer ability of HGr, as supported by a series of experiments and theoretical calculations.     

Engineering Supramolecular Polymer Conformation for Efficient Carbon Nanotube Sorting

Supramolecular polymer sorting is a promising approach to separating single‐walled carbon nanotubes (CNTs) by electronic type. Unlike conjugated polymers, they can be easily removed from the CNTs after sorting by breaking the supramolecular bonds, allowing for isolation of electronically pristine CNTs as well as facile recycling of the sorting polymer. However, little is understood about how supramolecular polymer properties affect CNT sorting. Herein, chain stoppers are used to engineer the conformation of a supramolecular sorting polymer, thereby elucidating the relationship between sorting efficacy and polymer conformation. Through NMR and UV–vis spectroscopy, small‐angle X‐ray scattering (SAXS), and thermodynamic modeling, it is shown that this supramolecular polymer exhibits ring–chain equilibrium, and that this equilibrium can be skewed toward chains by the addition of chain stoppers. Furthermore, by controlling the stopper–monomer ratio, the sorting yield can be doubled from 7% to 14% without compromising the semiconducting purity (>99%) or properties of sorted CNTs.     

Recent Advances in n‐Type Polymers for All‐Polymer Solar Cells

All‐polymer solar cells (all‐PSCs) based on n‐ and p‐type polymers have emerged as promising alternatives to fullerene‐based solar cells due to their unique advantages such as good chemical and electronic adjustability, and better thermal and photochemical stabilities. Rapid advances have been made in the development of n‐type polymers consisting of various electron acceptor units for all‐PSCs. So far, more than 200 n‐type polymer acceptors have been reported. In the last seven years, the power conversion efficiency (PCE) of all‐PSCs rapidly increased and has now surpassed 10%, meaning they are approaching the performance of state‐of‐the‐art solar cells using fullerene derivatives as acceptors. This review discusses the design criteria, synthesis, and structure–property relationships of n‐type polymers that have been used in all‐PSCs. Additionally, it highlights the recent progress toward photovoltaic performance enhancement of binary, ternary, and tandem all‐PSCs. Finally, the challenges and prospects for further development of all‐PSCs are briefly considered.     

Conjugated Donor–Acceptor Terpolymers Toward High‐Efficiency Polymer Solar Cells

The development of conjugated alternating donor–acceptor (D–A) copolymers with various electron‐rich and electron‐deficient units in polymer backbones has boosted the power conversion efficiency (PCE) over 17% for polymer solar cells (PSCs) over the past two decades. However, further enhancements in PCEs for PSCs are still imperative to compensate their imperfect stability for fulfilling practical applications. Meanwhile development of these alternating D–A copolymers is highly demanding in creative design and syntheses of novel D and/or A monomers. In this regard, when being possible to adopt an existing monomer unit as a third component from its libraries, either a D′ unit or an A′ moiety, to the parent D–A type polymer backbones to afford conjugated D–A terpolymers, it will give a facile and cost‐effective method to improve their light absorption and tune energy levels and also interchain packing synergistically. Moreover, the rationally controlled stoichiometry for these components in such terpolymers also provides access for further fine‐tuning these factors, thus resulting in high‐performance PSCs. Herein, based on their unique features, the recent progress of conjugated D–A terpolymers for efficient PSCs is reviewed and it is discussed how these factors influence their photovoltaic performance, for providing useful guidelines to design new terpolymers toward high‐efficiency PSCs.     

RAFT聚合技术在聚合物分子设计领域的应用研究进展

总结了近十年来可逆加成-断裂链转移聚合技术的制备方法在聚合物分子设计领域的研究进展。首先介绍该方法在制备窄分子量分布的均聚物方面的应用,比较了该方法在溶液和乳液体系中的特点,同时介绍了该方法在制备无规和交替共聚物方面的应用,并着重介绍了制备特殊链结构的共聚物,如嵌段,星形,接枝以及梯度共聚物方面的研究进展。并对今后的研究重点和应用前景作了展望。