Water and its interactions with other substances are essential to human life. However, understanding the structure of liquid water and its hydrogen-bonding networks has been a challenge.
　　According to previous studies, all oxygen atoms in water trimers, tetramers, and pentamers with cyclic minimum-energy structures exist in a two-dimensional (2D) plane. In contrast, water hexamers have noncyclic three-dimensional (3D) structures. Therefore, the water hexamer was long considered to be the smallest water droplet with a 3D hydrogen-bonding network.
　　This understanding has now changed due to work by Chinese scientists.
　　A research team led by Prof. JIANG Ling and Prof. YANG Xueming from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences, in collaboration with Prof. LI Jun from Tsinghua University, has now revealed that the noncyclic 3D structure of water clusters begins to exist with pentamers at low finite temperatures.
　　Scientists discover three-dimensional structure in smaller water droplet. (Image by ZHANG Bingbing and Yu Yong)
　　The study was published in Proceedings of the National Academy of Sciences of the United States of America (PNAS) on June 15.
　　Profs. JIANG and YANG developed a method of infrared spectroscopy of neutral clusters based on a tunable vacuum ultraviolet free electron laser (VUV-FEL). This method creates a new paradigm for the study of vibrational spectra of a wide variety of neutral clusters that could not be studied before.
　　They measured IR spectra of size-selected neutral water clusters using the VUV-FEL-based IR scheme. Distinct new OH stretch vibrational fundamentals observed in the 3500-3600 cm-1 region of (H2O)5 provide unique spectral signatures indicating the formation of a noncyclic pentamer.
　　Prof. LI's team carried out quantum chemical studies to understand the structural and spectral changes in these clusters. A three-center two-electron (3c2e) model was proposed to describe the bonding nature of the hydrogen-bonding network of water clusters.
　　The results revealed that the striking spectral change in the OH stretch region could be attributed to the appearance of 3D hydrogen-bonding networks in pentamers at finite temperature, suggesting that water clusters exhibit a noncyclic 3D structure beginning with pentamers, not hexamers, as previously thought.
　　The scientists' findings provide a consistent picture of the structural diversity of the hydrogen-bonding networks that are responsible for the major structural features and properties of water in the condensed phase. (Text by ZHANG Bingbing and Yu Yong)

　　Strong metal–support interactions (SMSI) describes the phenomenon that platinum group metals (PGMs) supported on reducible oxides lose their capability to adsorb small molecule after high-temperature reduction. SMSI has significant influence on the activity, selectivity and stability of catalysts.
　　Scientists discovered a few novel SMSI effects of gold and PGMs nanocatalysts. However, whether SMSI can form on single-atom catalysts (SACs) or not remains unclear.
　　Recently, Prof. QIAO Botao and Prof. ZHANG Tao's group from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences discovered that SMSI could occur on TiO2-supported Pt single atoms but at a much higher reduction temperature than that for Pt nanoparticles (NPs).
　　Furthermore, the suppression of CO adsorption on Pt single atoms, different from that of Pt NPs, originated from coordination saturation rather than the physical coverage.
　　Pt single atoms vs NPs: difference in strong-metal support interactions. (Image by HAN Bing and GUO Yalin)
　　The researchers prepared Pt/TiO2 catalyst by a modified photochemical method, consisting of both Pt single atoms and NPs. They found that Pt NPs lost adsorption ability at 250 °C reduction. In contrast, CO adsorption on Pt single atoms only disappeared completely at reduction at as high as 600 °C. The followed 300 °C re-oxidation could restore CO adsorption on both NPs and single atoms.
　　They performed low-energy ion scattering (LEIS) to detect the change of surface Pt atoms and demonstrated that Pt single atoms neither were encapsulated nor sank into the support after high temperature reduction.
　　Theoretical calculations showed that the reason for Pt single atoms losing their adsorption capacity was coordination saturation (18-electron rule) rather than the physical coverage of Pt atoms by the support. According to this finding they demonstrated that in hydrogenation of 3-nitrostyrene, the single-atom sites played a major role while the contribution of NP sites was negligible by selectively encapsulating the NPs sites.
　　The study not only demostrates for the first time that the SMSI between Pt single atoms and TiO2 support can occur, but also reveals the difference of SMSI in single atoms and NPs.
　　These findings help us deeply understand SMSI effect, and provide an effective approach to study catalytic active centers and tuning catalytic performance. 
　　The study was published as a hot paper in Angewandte Chemie International Edition. It was supported by the National Natural Science Foundation of China, National Key Projects for Fundamental Research and Development of China, Strategic Priority Research Program of the Chinese Academy of Sciences, Liaoning Revitalization Talents Program and DNL Cooperation Fund, CAS.
　　Moreover, this paper was dedicated to the 70th anniversary of Dalian Institute of Chemical Physics, Chinese Academy of Sciences. (Text by HAN Bing and GUO Yalin)

The development of renewable energies such as wind energy and solar energy is limited by their inherently random and intermittent nature.However, the vanadium flow battery (VFB) offers a cost- and energy-efficient, long-life energy storage technology that can store and smoothly output power from renewable energies.The VFB energy storage system mainly comprises the stack, the electrolyte, and systems for pipeline, battery management and energy conversion. Among these components, the stack plays a crucial role. Therefore, increasing the stack's power density and reducing its cost will further accelerate the industrialization of VFB technology.A research group led by Prof. LI Xianfeng from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences has developed a new generation of VFB stack technology that offers low cost and high power density.The group's test results showed stack energy efficiency exceeding 81%. The stack ran at a constant power of 30 kW and showed no capacity decay after 100 cycles.New generation of vanadium flow battery stack technology offers low cost and high power density. (Image by SHI Dingqin)"The stack assembly process was improved by applying weldable, porous ionic conductive membranes that we developed," said Prof. LI.Laser welding technology was used in the stack assembly for the first time. It not only improved the reliability of the stack, but also achieved automation of the stack assembly, decreased the use of sealing materials, and reduced the cost of the stack."This new VFB stack technology not only maintains the high power density of conventional stacks, but also reduces total cost by 40% compared to conventional stacks," said Prof. LI.The membranes used in conventional VFB stacks are mainly commercial perfluorosulfonic acid membranes characterized by high cost and relatively poor ion selectivity.In contrast, the weldable, porous ionic conductive membranes adopted in this new generation of VFB stack technology can improve ionic selectivity and increase the capacity retention of the electrolyte. This type of membrane costs much less than perfluorosulfonic acid membranes. (Text by SHI Dingqin and WU Jine) 

　　Understanding and exploiting the environment of extraterrestrial bodies is a central objective of planetary science. The gas giants, such as Jupiter, Saturn, Uranus and Neptune, are rich in molecular chemistry and remain the target of prolonged scientific study.
　　Same as Earth, these planets orbits the sun with its own eccentricity and obliquity leading to seasonal variations in incident solar and thus a cycling chemical composition with latitudinal and altitudinal variations in the abundances of the various molecular constituents.
　　Recently, Prof. YUAN Kaijun and Prof. YANG Xueming’s group from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences, in cooperation with Prof. Michael N. R. Ashfold from the University of Bristol and Prof. Christopher S. Hansen from the University of New South Wales, revealed the new dissociation channels in the ethane photochemistry by using Dalian Coherent Light Source (DCLS).
　　The absorption of near-infrared solar radiation by methane (CH4) is an important contributor to heating the upper atmospheres (stratospheres) of these planets. CH4 contributes less to stratospheric cooling, however, which is more reliant on emission from ethane (C2H6) and acetylene (C2H2).
　　Understanding the balance and interplay between CH4 and C2H6/C2H2 is central to understanding the atmospheric dynamics of the gas giants. Therefore, the photodissociation of ethane have been studied systematically based on DCLS.
　　The VUV photochemistry of ethane, which is an important constituent in the atmospheres of the gas giants, has been studied in the wavelength range from 112nm to 126 nm by using the free electron laser (FEL) and multi-mass imaging detection methods. The scientists demonstrated contributions from at least five primary photofragmentation pathways yielding CH2, CH3 and/or H atom products from ethane following VUV excitation.
　　These results point to several shortcomings in the description of ethane photochemistry used in contemporary models of the atmospheres of the gas giants and help rationalize hitherto unexplained aspects of the ethane/acetylene ratios observed in the Cassini-Huygens fly-by of Jupiter.
　　The results were published in Chemical Science. It was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, the Chemical Dynamics Research Center, and the National Natural Science Foundation of China. (Text by CHANG Yao)
　　The CH3, CH2 and H atom elimination channels in the photodissociation of ethane. (Image by CHANG Yao)

　　More than 350 million tonnes of lower olefins are produced per year through the steam cracking of hydrocarbons. It consumes lots of energy to separate large quantities of chemical mixtures into pure accounts.
　　The efficient removal of alkyne impurities to produce polymer-grade lower olefins remains challenging.
　　A research team led by Prof. JIANG Ling from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences, in collaboration with Prof. LI Landong from Nankai University and Prof. YANG Sihai from the University of Manchester, reported a strategy to control the pore interior of faujasite (FAU) zeolites and thus improve chemoselective alkyne/olefin separations. The results were published in Science.
　　They revealed that the reversible, chemoselective binding of alkynes on open Ni(II) sites confined in Faujasite (FAU) zeolites enables the efficient production of polymer-grade lower olefins under ambient conditions.
　　Under ambient conditions, Ni@FAU showed exceptional adsorption of alkynes and efficient separations of acetylene/ethylene, propyne/propylene and butyne/1,3-butadiene mixtures with unprecedented dynamic separation selectivities of 100, 92, and 83, respectively.
　　Prof. JIANG’s group developed an infrared photodissociation spectroscopy for in-situ and sensitive detection of key reaction intermediates. The adsorption species in C2H2- and C2H4- loaded Ni@FAU were identified by infrared photodissociation spectroscopy.
　　Their results indicated that by confining atomically dispersed Ni(II) sites into the FAU zeolite channels, the discrimination between alkyne and olefin binding was amplified in Ni@FAU, which enabled the production of polymer-grade olefins under conditions relevant to practical processes.
　　Combining its facile synthesis at large scale and excellent stability, the Ni@FAU sorbent offers a potential practical solution to the challenging alkyne/olefin separations.
　　The above work was supported by the National Natural Science Foundation of China. (Text and Image by WANG Chong)
　　Adsorption isotherms of C2H2 and C2H4 for Ni@FAU (Left). Mass spectra of species produced by pulsed laser vaporization of the Ni@FAU target (Right). (Image by WANG Chong)

　　Lignin is the aromatic polymer fragment of lignocellulose, which is the richest renewable aromatic carbon source in nature. The depolymerization of lignin and the preparation of a wide variety of aromatic compounds can be achieved through lignin cleavage.
　　However, most current depolymerized strategies utilize species such as active hydrogen (H) and oxygen (O) to obtain value-added aromatics from lignin. Since the lignin itself contains only carbon (C), H and O, the product composition from lignin is limited to C, H and O.
　　The future bio-refinery demands a broad spectrum of fine chemicals, especially those containing elements other than C, H and O.
　　Heteroatom-containing compounds have emerged as powerful reagents to participate in the novel bond cleavage in lignin; meanwhile, the obtained heteroatom-containing aromatics extend the application of lignin-derived products.
　　A group led by Prof. WANG Feng from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) reviewed the recent advances in the lignin C–C and C–O bond cleavages induced by heteroatoms X (N, Si, I and Li), which could generate functionalized products containing C–X and O–X bonds.
　　The review article was published in Chemical Society Reviews.
　　Heteroatom-containing reagents triggered the catalytic cleavage of lignin linkages and functionalization of products simultaneously. (Image by LI Hongji)
　　Catalytic depolymerization methods have been investigated using various nitrogen reagents (including amines, hydroxylamine, imine and azide), silanes and lithium iodide. These heteroatom X (N, Si, S and Li)-containing reagents triggered the cleavage of lignin C–C and C–O bonds and contributed to formation of C–X and O–X bonds in products.
　　The functionalization with heteroatoms onto lignin derived aromatics provides valuable properties for further upgrading of lignin monomers in many applications such as in the polymer, agriculture, pharmaceutical, material and chemical industries.(Text by LI Hongji)