联产混合电解水策略实现节能电化学制氢的最新进展

随着全球能源需求增长和环境污染加剧,发展可持续能源减少对化石燃料(如石油、天然气和煤炭等)的消耗成为实现人类社会可持续发展的关键.氢能因其能量密度高、燃烧无污染、应用形式多样被认为是最理想的替代能源.电解水制氢包括阴极析氢反应(HER)和阳极析氧反应(OER),具有绿色环保、生产灵活和纯度高等特点,是理想的绿色生产技术之一.然而,阳极电解水产氧反应动力学缓慢,导致阴极的产氢效率低.此外,在电解水过程中,会产生高氧化性的过氧化氢(H_(2)O_(2)),降低电解水膜的寿命,阻碍电解水技术的实际应用.因此,亟待开发新型高效、稳定且具有高附加值的电解水催化剂.目前,电化学整体水分解(OWS)制氢技术存在安全风险、投资回报低、阳极OER动力学慢和电能消耗大等问题,将阳极氧化反应与混合电解水(HWE)装置中的HER相结合,借助热力学较好的电氧化反应取代缓慢的传统OER反应协同产氢,可以有效克服传统电解水的产率不足,解决污染排放和生物质回收问题.本文综述了协同电催化用于联产氢气和低能耗、高法拉第效率高价值产品的催化剂结构设计,揭示不同协同电催化系统的催化途径和意义,以实现更高效、零碳排放的目标.首先,介绍了HWE系统的发展现状,重点关注各种富氢物质的协同电解,例如酒精、生物质衍生物、葡萄糖和在阳极形成的高附加值化学品.与传统阳极OER工艺相比,有机/生物质底物小分子的OER表现出较低的热力学需求,降低产氢能耗.随后,详细介绍了基于阴极HER和阳极OER协同电解反应、协同催化HWE高效电极/电催化剂的合理设计,以实现高催化活性、高选择性和良好的电化学稳定性.重点讨论了新型电极/电催化剂设计、活性改进以及结构-催化活性关系提升的合成策略.再后,讨论了基于有机/生物质小分子协同HWE系统电催化的代表性研究进展和突破,强调了其在促进可持续低压制氢方面的重要作用,并回顾了近年来HWE的研究突破,同时,对一些可行性分析和机理探索进行比较,为制氢提供了新的研究方向.最后,提出了协同电催化制氢面临的挑战并展望未来的研究方向.综上,大多数电催化剂存在催化活性低、稳定性差等问题,要实现可持续、经济高效和清洁的产氢技术,仍有很多方面需要进一步的深入研究.本文综述了高效多功能HWE系统发展现状和催化剂结构设计,为电解水制氢和高附加值产品的节能联产提供一定的参考.

Ultrafast Electron Transfer in All-Small-Molecule Photovoltaic Blends Promoted by Intermolecular Interactions in Cyanided Donors

Cyano substitution has been established as a viable approach to optimize the performance of all-small-molecule organic solar cells.However,the effect of cyano substitution on the dynamics of photo-charge generation remains largely unexplored.Here,we report an ultrafast spectroscopic study showing that electron transfer is markedly promoted by enhanced intermolecular charge-transfer interaction in all-small-molecule blends with cyanided donors.The delocalized excitations,arising from intermolecular interaction in the moiety of cyano-substituted donor,undergo ultrafast electron transfer with a lifetime of∼3 ps in the blend.In contrast,some locally excited states,surviving in the film of donor without cyano substitution,are not actively involved in the charge separation.These findings well explain the performance improvement of devices with cyanided donors,suggesting that manipulating intermolecular interaction is an efficient strategy for device optimization.

One-Pot Synthesis of Tetraarylpyrrolo[3,2-b]pyrrole Dopant-Free Hole-Transport Materials for Inverted Perovskite Solar Cells

Four organic smallmolecule hole transport materials(D41, D42,D43 and D44) of tetraarylpyrrolo[3,2-b]pyrroles were prepared. They can be used without doping in the manufacture of the inverted planar perovskite solar cells. Tetraarylpyrrolo[3,2-b]pyrroles are accessible for one-pot synthesis.D42, D43 and D44 possess acceptor-π-donor-π-acceptor structure, on which the aryl bearing substitutes of cyan, fluorine and trifluoromethyl, respectively. Instead, the aryl moiety of D41 is in presence of methyl with a donor-π-donor-π-donor structure. The different substitutes significantly affected their molecular surface charge distribution and thin-film morphology, attributing to the electron-rich properties of fused pyrrole ring. The size of perovskite crystalline growth particles is affected by different molecular structures,and the electron-withdrawing cyan group of D42 is most conducive to the formation of large perovskite grains. The D42 fabricated devices with power conversion efficiency of17.3% and retained 55% of the initial photoelectric conversion efficiency after 22 days in dark condition. The pyrrolo[3,2-b]pyrrole is efficient electron-donating moiety for hole transporting materials to form good substrate in producing perovskite thin film.

Effect of electron-withdrawing units on triphenylamine-based small molecules for solution-processed organic solar cells

Organic small molecules （TPA-BT3T, TPA-PT3T, and TPA-DFBT3T） using triphenylamine as a donor unit, terthiophene as a bridge, and benzo-2,1,3-thiadiazole （BT）, [1,2,5]thiadiazolo[3,4-e]pyridine （PT） or 5,6-difluorobenzo[c][1,2,5]thiadiazole （DFBT） as an acceptor unit were designed and synthesized through Suzuki coupling reactions. These molecules exhibited good thermal stability with decomposition temperatures over 380℃ and broad absorption from 300 to 700 nm. Photovoltaic devices were fabricated with these small molecules as donors and PC71BM as an acceptor. The TPA-BT3T based devices exhibited a power conversion efficiency of 2.89%, higher than those of the TPA-PT3T- and TPA-DFBT3T-based devices （1.34% and 1.54% respectively）. The effects of electron-withdrawing units on absorption, energy level, charge transport, morphology, and photovoltaic properties also were investigated.

Utilization of unmodified gold nanoparticles in colorimetric detection

This review begins with an overview of the appealing properties and various applications of gold nanoparticles, and briefly summarizes recent advances in using unmodified gold nanoparticles to detect different kinds of targets including nucleic acids, proteins, metal ions and small organic molecules. The key point to the unmodified gold nanoparticle-based visual detection assay is to control dispersion and aggregation of colloidal nanoparticles by targets of interest, which usually relies on affinities between gold nanoparticles and targets. The degree of dispersion or aggregation can be visualized through the change of the solution color or the precipitation of nanoparticles from the solution. Thus, the existence of the target molecules can be trans-lated into optical signals and monitored by the naked eye conveniently. Finally, some future prospects of this research field are given.

Ultraviolet-activated long-lived room-temperature phosphorescence from small organic molecule-doped polymer systems

Long-lived organic room-temperature phosphorescent(RTP)materials have attracted widespread attention because of their fantastic properties and application prospects.The current methods for developing RTP materials are mainly based on the synthesis of new chromophore molecules and crystallization engineering.However,there are great challenges in the preparation of new chromophore molecules and the use of crystalline materials.Herein,dynamic stimulus-responsive long-lived RTP systems with various emission colors are realized by doping organic chromophore molecules into polymer matrix prepared from vinyl acetate and acrylic acid.Through UV light irradiation,the growth process of long-lived RTP phenomena can be observed for up to 10 s.In particular,the phosphorescence intensity,lifetime,afterglow brightness,and quantum yield of one representative film(P2-M2)increase by 155,262,414,and 8 times after the irradiation,respectively.The unique photophysical phenomena are ascribed to the oxygen consumption characteristics of the polymer matrix under UV irradiation.Meanwhile,the information storage devices are prepared with these RTP systems.This work provides a strategy for achieving small organic molecule-doped polymer RTP systems that are easy to prepare,low-cost,and widely adaptable.

Fluorescent nanoparticles for chemical and biological sensing

Fluorescent nanoparticles (NPs), including quantum dots (QDs), dye-doped NPs, and rare earth-based NPs, etc., have been a major focus of research and development during the past decade. The impetus behind such endeavors can be attributed to their unique chemical and optical properties, such as bright fluorescence, high photostability, large Stocks shift and flexible processability. The introduction of fluorescent NPs into analytical chemistry has opened up new venues for fluorescent analysis. In this review, we focus on the developments and analytical applications of fluorescent NPs in the chemical and biological sensing of pH, ions, organic compounds, small biological molecules, nucleic acids, proteins, virus and bacteria. The review also points out the in vitro and in vivo imaging application of fluorescent NPs at the cell and body levels. Meanwhile, the ad- vantages of NPs brought field of sensing and signal transductions are also discussed.

Progress in small-molecule luminescent materials for organic light-emitting diodes

Organic light-emitting diodes （OLEDs） have been extensively studied since the first efficient device based on small molecular luminescent materials was reported by Tang. Organic electroluminescent material, one of the centerpieces of OLEDs, has been the focus of studies by many material scientists. To obtain high luminosity and to keep material costs low, a few remarkable design concepts have been developed. Aggregation-induced emission （AIE） materials were invented to overcome the common fluorescence-quenching problem, and cross-dipole stacking of fluorescent molecules was shown to be an effective method to get high solid-state luminescence. To exceed the limit of internal quantum efficiency of conventional fluorescent materials, phosphorescent materials were successfully applied in highly efficient electroluminescent devices. Most recently, delayed flu- orescent materials via reverse-intersystem crossing （RISC） from triplet to singlet and the ＂hot exciton＂ materials based on hy- bridized local and charge-transfer （HLCT） states were developed to he a new generation of low-cost luminescent materials as efficient as phosphorescent materials. In terms of the device-fabrication process, solution-processible small molecular lumi- nescent materials possess the advantages of high purity （vs. polymers） and low procession cost （vs. vacuum deposition）, which are garnering them increasing attention. Herein, we review the progress of the development of small-molecule luminescent materials with different design concepts and features, and also briefly examine future development tendencies of luminescent materials.

New frontiers of N-heterocyclic carbene catalysis

N-heterocyclic carbene （NHC） is both a family of strong o-donor ligands for transition metals and a privileged class of organocatalysts with synthetic potential that rivals popu- lar amine and phosphoric acid catalysts. NHC was found as a key catalytic species in thiamine diphosphate catalyzed biochemical reactions [1]. However, due to their inherent chemical instability, free NHCs had not been isolated until 1991 by Ardungo et al. [2]. Since then, the use of chiral NHC as a versatile organocatalyst has enjoyed tremendous advances and has helped to transform modem synthetic chemistry. There are over 2000 research papers dealing with both ＂N-heterocyclic carbene＂ and ＂Catalysis＂ in the past 15 years [3].

A series of dithienobenzodithiophene based small molecules for highly efficient organic solar cells

Three acceptor-donor-acceptor （A-D-A） small molecules DCAODTBDT, DRDTBDT and DTBDTBDT using dithieno[2,3-d：2＇,3＇-d＇]benzo[1,2-b：4,5-b＇]dithiophene as the central building block, octyl cyanoacetate, 3-octylrhodanine and thiobarbituric acid as the end groups were designed and synthesized as donor materials in solution-processed photovoltaic cells （OPVs）. The impacts of these different electron withdrawing end groups on the photophysical properties, energy levels, charge carrier mobility, morphologies of blend films, and their photovoltaic properties have been systematically investigated. OPVs device based on DRDTBDT gave the best power conversion efficiency （PCE） of 8.34%, which was significantly higher than that based on DCAODTBDT （4.83%） or DTBDTBDT （3.39%）. These results indicate that rather dedicated and balanced consideration of absorption, energy levels, morphology, mobility, etc. for the design of small-molecule-based OPVs （SM-OPVs） and systematic investigations are highly needed to achieve high performance for SM-OPVs.

Design,synthesis and properties of novel organic small molecule photovoltaic materials based on diketopyrrolopyrrole-fluorene

Two novel organic small molecule donor materials(FLU),TDPP and(DFLU)_(2)TDPP based on diketopyrrolopyrrole-fluorene were designed and synthesized successfully.The D-D-π-A-π-D-D type molecule(DFLU)_(2)TDPP was constructed based on the D-π-A-π-D type molecule(FLU)_(2)TDPP by a backbone extension strategy.The optical absorption,electrochemistry and photovoltaic properties of the two novel materials were investigated in detail.Both(FLU)_(2)TDPP and(DFLU)_(2)TDPP show narrow energy gaps of1.71 and 1.64 eV,respectively.Compared to(FLU)_(2)TDPP,the photovoltaic device based on(DFLU)_(2)TDPP/PC_(71)BM exhibited a higher power conversion efficiency of 2.27%due to its excellent optical absorption,narrow band gap and balanced carrier mobility.This study indicates that skeleton extension strategy is an effective strategy to broaden the molecular absorption range and improve device performance.