有机光催化剂用于太阳能水分解:分子水平和聚集体水平改性

利用太阳能光解水产氢是实现氢能开发最绿色且可持续的理想技术。为了提高太阳能的转换效率,设计和发展高效、稳定、宽/全光谱响应光催化产氢体系成为关键研究课题。相比于无机半导体,有机半导体具有丰富的π电子和结构可修饰性,使其光学吸收和能带结构易剪裁,光催化路径多样。但低的介电常数造成其载流子迁移率低及迁移距离短。通过有目的地改变有机分子结构,可以轻松地设计和调控有机半导体的能带位置、增加摩尔吸光系数,改善材料对于整个太阳光谱中可见光或红外光的利用;通过功能分子微纳组装或集成,可进一步获得不同组分、维度(0维、1维、2维、3维)、尺寸、晶体学取向的有机光催化剂。有机微纳/复合结构的优异的比表面积、分子排布结构或能级排列结构可进一步提高太阳能的利用率和光生电荷的传输/分离效率,从而提高整体光电转换效率和产氢效率。然而,由于复杂的反应过程和设计困难,整个有机半导体的光催化物理化学过程仍不清楚。在这里,光催化的基本原理从光捕获、光激发电荷分离、表面反应的角度进行了讨论。随后详细总结了有机半导体纳米结构的制备方法包括超分子自组装、再沉淀法、气相沉积法以及其他方法。描述了典型的有机半导体材料,包括苝二酰亚胺、四吡咯化合物、富勒烯、g-C3N4及其他共轭聚合物的微纳结构调控,光物理性质调变及其在光解水产氢中的应用,目的是阐明结构-性质-性能之间的构效关系,从而进一步指导光催化剂的合理设计。重点针对有机半导体存在的问题,介绍了其在光催化产氢应用中改性策略:分子水平上引入不同取代基、基团、原子取代;聚集体水平上调整不同形貌和尺寸、组分和维度、设计多孔结构,从而获得更高效的光催化产氢性能。最后,提出了有机纳米材料在光解水产氢中的关键挑战和未来前景展望。

A robust synthesis route of confined carbyne

The unique mechanical,optical,and electrical properties of carbyne,a one-dimensional allotrope of carbon,make it a highly promising material for various applications.It has been demonstrated that carbon nanotubes(CNTs)can serve as an ideal host for the formation of confined carbyne(CC),with the yield being influenced by the quality of the carbon nanotubes for confinement and the carbon source for carbyne growth.In this study,a robust synthesis route of CC within CNTs is proposed.C70 was utilized as a precursor to provide an additional carbon source,based on its ability to supply more carbon atoms than C60 at the same filling ratio.Multi-step transformation processes,including defect creation,were designed to enhance the yield of CC.As a result,the yield of CC was significantly increased for the C70 encapsulated single-walled CNTs by more than an order of magnitude than the empty counterparts,which also surpasses that of the double-walled CNTs,making it the most effective route for synthesizing CC.These findings highlight the importance of the additional carbon source and the optimal pathway for CC formation,offering valuable insights for the application of materials with high yield.

高度灵活可控的多孔MOF膜用于高效药物释放

具有生物力学和生化活性的敷料在伤口护理和皮肤组织再生中起着至关重要的作用.然而,机械失配和药物释放管理所涉及的问题限制了当前敷料的有效使用.在本工作中,我们报道了一种简单的策略,即采用聚偏二氟乙烯(PVDF)作为底物,通过嵌入不同尺寸的沸石咪唑酸盐框架(ZIF-8)种子,以推动具有均匀蜂窝结构的高柔性金属有机框架(MOF)复合膜的受控生长,用于药物负载和释放.以嵌入的种子为控制中心,形成的多孔膜具有约0.7-3μm的宽孔隙.这种可调节的微尺度孔与ZIF-8中的固有纳米孔不仅可以有效地提高抗炎类药物的负载(姜黄素,CCM),而且还能够快速并可控地释放药物,大大提高了抗菌活性,同时促进细胞生长.其中,在40 nm种子上生长的0.7μm多孔膜的表现优于其他蜂窝膜,与2μm多孔膜(相当于裸PVDF基质)相比,细胞增殖能力提高了约2倍,针对金黄色葡萄球菌(S.aureus)和大肠杆菌(E.coli)的抗菌活性分别提高了5倍和2.4倍,是基底抗菌活性的5倍,这是因为这种最佳孔几何结构具有CCM和Zn2+释放特性的平衡效应.这种可控分层孔阵列膜的独特性质有望真正用于伤口愈合,同时也为生物医学设计提供了新的指导.

有机微结构诱导的分级多孔g-C_(3)N_(4)光催化剂

为了保证光催化的高光吸收和电化学动力学,构建分级多孔光催化剂十分必要.类石墨相氮化碳(g-C_(3)N_(4))易于合成、理化性质稳定、稳定性好和带隙合适等优点,特别是其可调的微/纳米结构,使其成为分级多孔光催化剂一个很好的选择.然而,具有层次孔的g-C_(3)N_(4)的简易制备仍然是一个难点.本文中,我们首次用均匀的有机微结构作为软模板,用简单方法制备了分级多孔g-C_(3)N_(4).该有机微纳结构模板是在硫脲前驱体溶液中原位形成的,与g-C_(3)N_(4)相似的π共轭结构使其能够有效修饰g-C_(3)N_(4)的分子结构.结果表明,合成的g-C_(3)N_(4)具有分级的中孔和大孔,比表面积为27.34 m^(2)g^(−1),孔体积为0.18 cm^(3)g^(−1),分别是未改性g-C_(3)N_(4)的6.2倍和9.0倍.这种分级多孔结构有利于电荷/质量传输过程,使其光降解有机污染物能力增强了2.4倍.同时,此光催化剂具有良好的光稳定性,长期使用100分钟后效率仅损失20%.

Microwave heating as a universal method to transform confined molecules into armchair graphene nanoribbons

Armchair graphene nanoribbons(AGNRs)with sub-nanometer width are potential materials for the fabrication of novel nanodevices thanks to their moderate direct band gaps.AGNRs are usually synthesized by polymerizing precursor molecules on substrate surface.However,it is time-consuming and not suitable for large-scale production.AGNRs can also be grown by transforming precursor molecules inside single-walled carbon nanotubes(SWCNTs)via furnace annealing,but the obtained AGNRs are normally twisted.In this work,microwave heating is applied for transforming precursor molecules into AGNRs.The fast heating process allows synthesizing the AGNRs in seconds.Several different molecules were successfully transformed into AGNRs,suggesting that it is a universal method.More importantly,as demonstrated by Raman spectroscopy,aberrationcorrected high-resolution transmission electron microscopy and theoretical calculations,less twisted AGNRs are synthesized by the microwave heating than the furnace annealing.Our results reveal a route for rapid production of AGNRs in large scale,which would benefit future applications in novel AGNRs-based semiconductor devices.

纳米有机半导体光催化剂

近年来,有机半导体因其独特可调的化学结构及光电性质越来越多地被应用于高效可见光催化领域。但是,有机材料本身化学键弱、载流子迁移率低,导致其催化效率低、稳定性差。因此,将有机半导体进行纳米组装及其构建异质结构,得到零维、一维、二维或多元复合纳米有机光催化剂,成为近几年的研究热点。零维粒子尺寸小、比表面积大;一维结构长程有序排列、表面缺陷密度降低;二维结构在增大表面活性位点的同时能最大限度地缩短电荷在材料内部的迁移距离而表现出更高的光生电荷利用率;纳米复合结构的异质界面可以有效促进光生电子-空穴对的分离,因此在提高光催化活性及稳定性方面具有重要意义。同时,纳米有机光催化剂种类丰富,催化机理各不相同,因此被广泛应用于分解水或空气中污染物的光催化领域。本综述中归纳了各类纳米有机光催化剂的制备方法、结构特性以及光催化应用,同时对多种光催化机制进行了介绍,并对其应用前景进行了展望。

Facile synthesis of bimodal macroporous g-C_3N_4/SnO_2 nanohybrids with enhanced photocatalytic activity

It is of vital importance to construct highly interconnected,macroporous photocatalyst to improve its efficiency and applicability in solar energy conversion and environment remediation.Graphitic-like C_3N_4(g-C_3N_4),as an analogy to two-dimensional(2D)graphene,is highly identified as a visible-lightresponsive polymeric semiconductor.Moreover,the feasibility of g-C_3N_4 in making porous structures has been well established.However,the preparation of macroporous g-C_3N_4 with abundant porous networks and exposure surface,still constitutes a difficulty.To solve it,we report a first facile preparation of bimodal macroporous g-C_3N_4 hybrids with abundant in-plane holes,which is simply enabled by in-situ modification through thermally treating the mixture of thiourea and SnCl_4(pore modifier)after rotary evaporation.For one hand,the formed in-plane macropores endow the g-C_3N_4 system with plentiful active sites and short,cross-plane diffusion channels that can greatly speed up mass transport and transfer.For another,the heterojunctions founded between g-C_3N_4 and SnO_2 consolidate the electron transfer reaction to greatly reduce the recombination probability.As a consequence,the resulted macroporous gC_3N_4/SnO_2 nanohybrid had a high specific surface area(SSA)of 44.3 m^2/g that was quite comparable to most nano/mesoporous g-C_3N_4 reported.The interconnected porous network also rendered a highly intensified light absorption by strengthening the light penetration.Together with the improved mass transport and electron transfer,the macroporous g-C_3N_4/SnO_2 hybrid exhibited about 2.4-fold increment in the photoactivity compared with pure g-C_3N_4.Additionally,the recyclability of such hybrid could be guaranteed after eight successive uses.

Biomimetic albumin-modified gold nanorods for photothermo-chemotherapy and macrophage polarization modulation

Nanotechnology-based photothermal therapy has attracted great attention in the past decade. Nevertheless, photothermal therapy has some inherent drawbacks, such as the uneven heat production and limited laser penetration, often leading to insufficient treatment outcomes. Here, we developed a combination strategy to improve cancer therapy. The biomimetic albumin-modified gold nanorods(AuNRs) were prepared with incorporation of paclitaxel(PTX). This therapeutic system was characterized by several features. First, the albumin modification enhanced the biocompatibility and colloidal stability. Second, the surface-coated albumin promoted cellular uptake via the albumin-binding protein pathway. Third, PTX was incorporated via hydrophobic interaction between PTX and the albumin lipophilic domain. Fourth, the system can be used for combined photothermo-chemotherapy for yielding synergistic effects. The antitumor activity of the system was evaluated both in vitro and in vivo using the HCT116 colon cancer cell and tumor model. The combination therapy was found with an enhanced treatment efficiency and no obvious side effect. Most importantly, the thermal effect was also discovered with the ability to modulate the tumor microenvironments and suppress the macrophages polarization towards the M2 pro-tumor phenotype. It could be a mechanism for photothermal immunotherapy. The combination strategy and the system provide a potential method for cancer therapy.

Bacterial anti-adhesion surface design:Surface patterning,roughness and wettability:A review

Bacterial adhesion and biofilm formation impose a heavy burden on the medical system. Bacterial adhesion on implant materials would induce inflammation and result in implant failure. The adhesion of bacteria on food-processing and handling equipment may lead to food-borne illness. To reduce and even prevent bacterial adhesion, some bacterial anti-adhesion surface designs have been developed. However,the effect of some surface properties(including surface patterning, roughness and wettability) on bacterial adhesion has not been systematically summarized. In this review, a comprehensive overview of bacterial anti-adhesion surface design is presented. Modifying the surface pattern and roughness could reduce the contact area between bacteria and surfaces to weaken the initial adhesion force. Fabricating superhydrophobic surface or modifying hydrophilic functional groups could hinder the bacterial adhesion. The analysis and discussion about influencing factors of bacterial anti-adhesion surfaces provide basic guidelines on antibacterial surface design for future researches.

Facile fabrication of three-dimensional interconnected nanoporous N-TiO_2 for efficient photoelectrochemical water splitting

Three-dimensional （3D） interconnected porous architectures are expected to perform well in photoelectrochemical （PEC） water splitting due to their high specific surface area as well as favourable porous properties and interconnections. In this work, we demonstrated the facile fabrication of 3D interconnected nanoporous N-doped TiO2 （N-TiO2 network） by annealing the anodized 3D interconnected nanoporous TiO2 （TiO2 network） in ammonia atmosphere. The obtained N-TiO2 network exhibited broadened light absorption, and abundant, interconnected pores for improving charge separation, which was supported by the reduced charge transfer resistance. With these merits, a remarkably high photocurrent density at 1.23 V vs. reversible hydrogen electrode （RHE） was realized for the N-TiO2 network without any co-catalysts or sacrificial reagents, and the photostability can be assured after long term illumination. In view of its simplicity and efficiency, this structure promises for perspective PEC applications.

Genetically-engineered“all-in-one”vaccine platform for cancer immunotherapy

An essential step for cancer vaccination is to break the immunosuppression and elicit a tumor-specific immunity.A major hurdle against cancer therapeutic vaccination is the insufficient immune stimulation of the cancer vaccines and lack of a safe and efficient adjuvant for human use.We discovered a novel cancer immunostimulant,trichosanthin(TCS),that is a clinically used protein drug in China,and developed a well-adaptable protein-engineering method for making recombinant protein vaccines by fusion of an antigenic peptide,TCS,and a cell-penetrating peptide(CPP),termed an"allin-one"vaccine,for transcutaneous cancer immunization.The TCS adjuvant effect on antigen presentation was investigated and the antitumor immunity of the vaccines was investigated using the different tumor models.The vaccines were prepared via a facile recombinant method.The vaccines induced the maturation of DCs that subsequently primed CD8^(+)T cells.The TCS-based immunostimulation was associated with the STING pathway.The general applicability of this genetic engineering strategy was demonstrated with various tumor antigens(i.e.,legumain and TRP2 antigenic peptides)and tumor models(i.e.,colon tumor and melanoma).These findings represent a useful protocol for developing cancer vaccines at low cost and time-saving,and demonstrates the adjuvant application of TCSdan old drug for a new application.

Inorganic Nanotube/Organic Nanoparticle Hybrids for Enhanced Photoelectrochemical Properties

Inorganic/organic nanohybrids composed of arrayed TiO_2 nanotubes（Ti NTs）/porphyrin nanoparticles（NPs） have been fabricated via a wet chemical approach. The inorganic component, particularly the arrayed one-dimensional（1D） nanostructures, provides high charge-carrier mobility and rapid charge transport. The organic component exhibits extensive visible light absorption and good solution processability. Additionally, the geometric restraint by supramolecular assembly renders an improved photostability. A combination of these two components could thus allow for an efficient solar energy conversion. In this work, a colloid of porphyrin NPs prepared by a solvent exchange method is coated on anodic Ti NTs by means of a dip-coating treatment to form inorganic/organic hybrids. The hybrids exhibit an improvement on solar absorption and a significant enhancement on photocurrent generation at a small bias compared with individual component. Herein, the inorganic/organic nanohybrids are proved to be excellent photoanodes highly responsive to visible light and thus pave a way to discover new inorganic/organic assemblies for high-performance optoelectronic applications, as well as for device integration.

Visible-light responsive organic nano-heterostructured photocatalysts for environmental remediation and H2 generation

The ease of molecular design and functionalization make organic semiconductors(OSCs)unit the electronic,chemical and mechanical benefits with a material structure.The easily tunable optoelectronic properties of OSCs also make it promising building blocks and thereby provide more possibilities in photocatalytic applications.So far,organic nanostructures have gained great impetus and found wide applications in photocatalytic organic synthesis,remediation of water and air,as well as water splitting into hydrogen.But they still suffer from low charge separation and sunlight absorption efficiencies.Accordingly,many strategies have been explored to address these issues,and one of the most effective solutions is to develop nano-heterostructures.To give an impulse for the developments of this field,this review attempts to make a systematic introduction on the recent progress over the rational design and fabrication of organic nano-heterostructured photocatalysts,including the types of organic semiconductor/semiconductor(OSC/SC),organic semiconductor/metal(OSC/M),organic semiconductor/carbon(OSC/C),and OSC-based multinary nano-heterostructures.The emphasis is placed on the structure/property relationships,and their photocatalytic purposes in environmental and energy fields.At last,future challenges and perspectives for the ongoing development of OSC materials and their use in high-quality optoelectronic devices are also covered.

Organic photocatalysts:From molecular to aggregate level

Organic semiconductors(OSCs)have the advantages of tunable molecular structures,suitable band gaps,and exceptional optoelectronic properties.The π-π stacking ability of OSCs also leads to appealing molecular stacking structure,function,and stability.So far,organic photocatalysts have engaged in homogeneous or heterogeneous photocatalysis in the form of free molecules,supported molecules,or nanostructures.Meanwhile,researches on organic photocatalysts have expanded from small organic molecules to the organic macromolecules,as well as their various nanostructures and nanocomposites including isolated zero-dimensional(0D),one-dimensional(1D),two-dimensional(2D),three-dimensional(3D)nanostructures,and their combinations.Therefore,many versatile strategies have been explored to improve photocatalytic ability and practicality either from molecular synthetic modification,crystal,or interface engineering.In this review,we first discuss the photophysical and photochemical processes of organic photocatalysts that govern the ultimate photocatalytic efficiency;we then summarize different forms of organic photocatalysts,their rational design strategies,and mechanistic pathways,as well as their applications in H_(2) evolution,CO_(2) reduction,and environmental purification,aiming to highlight the structure/property relationships;we lastly propose ongoing directions and challenges for future development of organic photocatalysts in real use.

Organic semiconductor nanostructures:optoelectronic properties,modification strategies,and photocatalytic applications

Organic semiconductors(OSCs)possess diverse chemical structures and tailored optoelectronic properties via simple chemical modifications,so increasing use of them are found in efficient visible-light photo-catalysis.However,the weak chemical bonds and the poor charge behavior(e.g.,low concentration of free charge carriers,low carrier mobility)intrinsic in them,always incur quite limited stability and efficiency.Therefore,the assembly of them into refined nanostructures or nanocomposites is usually proposed to enhance their optoelectronic properties,as well as the photocatalytic efficiency and reliability.Zero-dimensional(0D)nanoparticles are low in size and hence high specific surface area(SSA);One-dimensional(1D)nanostructures are usually arranged in an orderly long range thus leading to low surface defect density and increased carrier mobility;Two-dimensional(2D)nanostructures are particularly capa-ble of enhancing the photogenerated charge utilization because of their large reaction sites and shortened charge transport length.Furthermore,the building of heterogeneous interfaces in the nanocomposites can effectively facilitate the special charge separation.All these highlight the importance of organic nanos-tructures in improving the photocatalytic activity and stability.Therefore,organic semiconductor nanostructures(OSNs)have been increasingly used in the photocatalytic water splitting into H_(2) and O_(2),CO_(2) reduction,pollutant decomposition,disinfection,etc.In this review,we first examine the important optoelectronic properties of OSNs that govern the photocatalytic processes;we then analyze different classes of OSNs and their mechanistic pathways,with an emphasis on the structure-property relationships;we also introduced various photocatalytic applications of OSNs;we lastly propose the challenges and future outlook in real use.

A skin-like stretchable colorimetric temperature sensor

Wearable and stretchable physical sensors that can conformally contact on the surface of organs or skin provide a new opportunity for human-activity monitoring and personal healthcare. Particularly, various attempts have been made in exploiting wearable and conformal sensors for ther- mal characterization of human skin. In this respect, skin- mounted thermochromic films show great capabilities in body temperature sensing. Thermochromic temperature sensors are attractive because of their easy signal analysis and optical recording, such as color transition and fluorescence emission change upon thermal stimuli. Here, desirable mechanical properties that match epidermis are obtained by physical crosslinking of polydiacetylene （PDA） and transparent elas- tomeric polydimethylsiloxane （PDMS） networks. The result- ing PDA fdm displayed thermochromic and thermo- fluorescent transition temperature in the range of 25-85℃, with stretchability up to 300% and a skin-like Young＇s mod- ulus of -230 kPa. This easy signal-handling provides excellent references for further design of convenient noninvasive sen- sing systems.

Enhancing control over the degradation behavior of zinc alloy via MOF coating

Zinc and its alloys provide a scalable alternative to the list of biodegradable metals due to its moderate degradation rates and biocompatible degradation products.However,one of the challenges impeding their clinical applications is the uncontrollable and unstable interfacial reactions between zinc implants and the corrosive media.In this study,we report a facile synthesis of metal-organic framework(MOF)nanocrystal coating with tunable thickness on the high-strength Zn-0.8Li alloy matrix for controlled corrosion.The as-obtained dense and uniform MOF nanocrystals form a strong connection with the zinc matrix via coordination bond so as to maintain the mechanical properties,and meantime provide highly rough surfaces exhibiting tunable wettability.The varied MOF coating thus regulate the interface structure between the zinc matrix and corrosive media to control the degradation behavior.Excellent antibacterial activity and biocompatibility are also achieved because of the unique topology morphologies,surface superhydrophilicity,as well as the dynamic Zn^(2+)release.This study sheds valuable lights on the design of MOF-functionalized metal implants for practical use and also triggers extensive applications of MOF in biomaterials.