A research team led by HAN Keli from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences synthesized lead-free direct band gap double perovskite nanocrystals (NCs) with bright dual-color emission. Their findings were published in J. Am. Chem. Soc..
　　Lead-based perovskite NCs with near-unity photoluminescence quantum efficiency (PLQE) and tunable emission in the visible region are potentially applied for various optoelectronic applications, such as light emitting diodes, lasing, and photodetectors. Unfortunately, the toxicity of Pb is often considered as a drawback, leading to the efforts of finding a possible replacement.
　　PLQE of Cs2AgInxBi1-xCl6 (x=0, 0.25, 0.5, 0.75 and 0.9) NCs and the PL image under UV light. (Image by YANG Bin)
　　The researchers synthesized a series of lead-free double perovskite NCs that is Cs2AgInxBi1-xCl6(x = 0, 0.25, 0.5 0.75 and 0.9), that could be tuned from the indirect bandgap (x = 0, 0.25 and 0.5) to the direct bandgap (x = 0.75 and 0.9). Direct-bandgap NCs exhibited 3 times greater absorption cross-section, lower sub-bandgap trap states, and larger than 5 times PLQE compared with those observed for indirect bandgap NCs (Cs2AgBiCl6). A PLQE of 36.6% for direct bandgap NCs was comparable to those observed for lead-perovskite NCs in the violet region.
　　They conducted the spectroscopic characterizations of the double perovskite NCs by using femtosecond transient absorption spectroscopies. It was found that the indirect band gap NCs exhibted prominet sub-band gap trapping precesses while which was negligible for direct band gap NCs.
　　The design of lead-free direct bandgap perovskite NCs with superior optical properties opens the door for high performance lead-free perovskite optoelectronic devices.
　　This work was supported by the National Natural Science Foundation of China.（Text by YANG Bin）

　　The unprecedented boom of portable and wearable electronics has stimulated the demand for microscale energy storage devices with various properties, especially flexibility, tailored performance according to actual situations and seamless integration with existing electronics industry systems.
　　Planar micro-supercapacitors (MSCs), consisting of two adjacent electrodes separated by a separator-free interspace on a single substrate, could substantially simplify integration process and avoid possibility of multilayer delamination under bending states in comparison with conventional stacked geometry. However, cost-effective and scalable fabrication of integrated MSCs is still unsolved.
　　A research group led by WU Zhong-Shuai and BAO Xinhe et al. from the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences (CAS), in collaboration with researchers from the Institute of Metal Research, CAS, developed rapid and scalable fabrication of ultrahigh-voltage integrated micro-supercapacitors (IMSCs) with designable shapes and superior flexibility.
　　Schematic of screen-printing fabrication of IMSCs; Photographs of IMSCs with various geometries and diverse integration; Photograph of letter-shaped IMSCs powering 3 liquid crystal displays. (Image by SHI Xiaoyu and HOU Xiaocheng)
　　Through elaborated selection and optimization of active material, conducting additive and polymer binder, the scientists prepared highly stable and conducting graphene-based ink with outstanding rheological, electrical and electrochemical properties.
　　With assistance of a universal, cost-effective, industrially applicable screen-printing strategy, they demonstrated fast and scalable fabrication of graphene-based planar IMSCs, with shape diversity, aesthetic versatility, and outstanding flexibility.
　　More importantly, by using the highly conductive ink as current collectors, microelectrodes and interconnects simultaneously, they directly screen-printed IMSCs consisting of hundreds of individual MSCs on arbitrary substrates in several seconds.
　　The resulting IMSCs are free of metal current collectors and interconnects as well as separators, and exhibit exceptional electrical double-layer capacitive behaviors and remarkable flexibility.
　　Notably, the output voltage and capacitance of IMSCs are readily adjustable through connection in well-defined arrangements of MSCs. As a proof of concept, a tandem energy storage pack of IMSCs with 130 MSCs can output a recorded voltage exceeding 100 V, demonstrative of superior modularization and performance uniformity.
　　This work exhibits great potential for scalable fabrication and integration of other planar energy storage devices, such as hybrid capacitors and batteries.
　　This work was published online entitled “Ultrahigh-voltage integrated micro-supercapacitors with designable shapes and superior flexibility” in Energy & Environmental Science.
　　This work was supported by the National Natural Science Foundation of China, the National Key R&D Program of China, the Natural Science Foundation of Liaoning Province, and the Dalian National Laboratory For Clean Energy (DNL), CAS, etc.(Text by SHI Xiaoyu and HOU Xiaocheng)

　　Biomass can serve as a renewable source for both energy and carbon. ABE (acetone, n-butanol, and ethanol) fermentation broth as a biomass-derived source of fuels and chemicals has received a lot of attention for several decades. However, the crude fermentation broth contains low concentrations of oxygenates, limiting its practical applications.
　　Thus, it is pivotal to develop a highly efficient water-resistant catalyst to directly and selectively convert crude aqueous oxygenate mixtures to value-added chemicals; water-immiscible ones (easy separation after reaction) are especially of great importance. However, the efficiency and selectivity of the transformation process for biomass-derived intermediates remains a major techno-economic challenge.
　　Prof. WANG Feng from the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences, and his colleagues from Peking University, recently reported an efficient and novel catalytic method for the conversion of aqueous biomass fermentation broth to a water-immiscible product. Their finding is published in Nature Communications (DOI: 10.1038/s41467-018-07593-0).
　　They developed a strategy capable of transforming ~70% of carbon in an aqueous ABE fermentation mixture to 4-heptanone (4-HPO), catalyzed by tin-doped ceria (Sn-ceria) with a selectivity as high as 86%. While Sn-ceria is a versatile catalyst for dehydrogenation, the Guerbet alcohol reaction, condensation, and esterification reactions, all these reactions, involving acid-base catalysis and redox ones, relay and generate 4-HPO with high selectivity(Fig.(A)). 4-HPO is a value-added intermediate and can be used to produce jet fuel and fine chemicals (Fig. (B)).
　　(A) Proposed reaction pathways leading to 4-HPO. (B) 4-HPO utilization.(Image by WANG Yehong)
　　Furthermore, water, which is detrimental to the reported catalysts for ABE conversion, was beneficial for producing 4-HPO. The excellent catalytic performance of tin-doped ceria is due to the highly dispersed tin species and oxygen vacancies of ceria.
　　"This strategy offers a route for highly efficient organic carbon utilization," said WANG. "It can potentially integrate biological and chemical catalysis platforms for the robust and highly selective production of value-added chemicals."
　　The research was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, the National Key R&D Program of China, and the Natural Science Foundation of China. This work is also dedicated to the 70th anniversary of Dalian Institute of Chemical Physics, CAS. (Text by WANG Yehong)

　　Recently, scientists from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences discovered that metformin could lead to metabolic reprogramming by passing AMPKα. Their finding was published in Metabolism-Clinical and Experimental.
　　Metformin Ampkα-independently increases Glysolysis and AMP/ATP ratio, decreases TCA cycle and NAD/ NADH ratio. While, metformin Ampkα-dependently increases p-ACC activation. (Image by QI Huan and WANG Ting)
　　Metformin is widely used as a hypoglycemic drug due to its desirable safety and surprising therapeutic efficacy for type 2 diabetes (T2D). Also, metformin has been linked to reduced incidence of cancer among diabetics who take this medicine. Thus, metformin has gained considerable attention as a potential anticancer agent.
　　AMP-activated protein kinase (AMPK), a heterotrimeric complex composed of α, β and γ subunits, plays a critical role in many biological processes, including metabolism, cell growth, autophagy and apoptosis. However, whether AMPK? contributes to such effects of metformin remains controversial.
　　The scientists found that metformin treatment obviously suppressed tricarboxylic acid (TCA) cycle, elevated lactate production and reduced the energy state by passing AMPK? via performing integrative metabolomics analyses to systematically examine the effects of metformin on metabolic pathways in Ampka1 wild type (WT) and knock-out (KO) mouse embryonic fibroblast (MEF) cells. Moreover, the replenishment of glutamine or sodium pyruvate could both reverse metformin-induced growth inhibition. And based on three-dimensional colony formation assays, metformin was also found to remarkably inhibit clonogenicity of HCC cell lines in an AMPKα-independent manner.
　　This study provides a new insight for the clinical application of metformin.
　　This study was supported by the National Key Research and Development Program of China, National Natural Science Foundation of China grants, Innovation program of science and research from the DICP, CAS and the 100 Talents Program of Chinese Academy of Sciences. (Text by QI Huan and WANG Ting)

　　Recently, Prof. ZHOU Yongjin from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences was invited to deliver a commentary about current status and prospects of synthesizing natural and non-natural terpenoids by using synthetic biology and directed evolution.
　　This commentary first introduced and discussed the research article about non-natural terpenoids biosynthesis, which was published in the same issue by Prof. Sotirios C. Kampranis from the University of Copenhagen in Denmark.
　　Then it pointed out that synthetic biology could not only improve the synthesis efficiency of natural terpenoids, it could also be used to expand the nature product portfolio by synthesizing non-natural compounds, which would provide more options for drug discovery and even high-quality biofuels.
　　Moreover, the commentary proposed a focus on future research directions, including obtaining more other terpenoids, further improving selectivity without sacrificing enzyme catalytic efficiency, and systematically constructing microbial cell factories for enhanced production.
　　Published in Nature Chem Biol., this commentary paper will draw attention from academia and industry to further explore the potential and challenges of synthetic biology. (Text by YANG Shan)
　　Synthesis of non-natural terpenoids (Image by ZHOU Yongjin)

　　Shuttling stoppers: Cross-section scanning electron microscopy image of exfoliated graphene (EG)/Co(OH)2 interlayer/polypropylene(PP) separator. (Image by Journal of Physics: Energy)
　　Sulphur has recently proved a cheap and competitive partner for lithium ion batteries with an energy density of 2600 Wh/kg, in theory. In practice lithium-sulphur batteries have suffered from low cycling lifetimes attributed to the polysulphide ions shuttling to and from the electrodes during charge and discharge. Now researchers at the Dalian Institute of Chemical Sciences, the Chinese Academy of Science, have developed a hybrid interlayer combining graphene and Co(OH)2 nanosheets that prevents sulphide movement and enhances use of the sulphide ions to improve the battery capacity and cyclability.
　　Reporting their results in the first issue of the Journal of Physics: Energy Zhong-Shuai Wu and colleagues highlight the electrical insulation of elemental sulphur and the discharge products Li2S/Li2S2, as a challenge for optimizing performance, as well as the sulphide ion shuttling, which alongside volumetric expansion and lithium dendrite formation diminish the cycling lifetime.
　　Zhong-Shuai Wu (Image by physicsworld)
　　Interlayer innovations
　　Other groups have previously experimented with modifying the separator – a standard battery component between cathode and anode – with nonpolar carbon materials to prevent the sulphide ion shuttling. However, the interactions between sulphide ions and those modified separators were too weak to effectively block their diffusion. Wu and colleagues get around this with the hybrid interlayer they coat on the separator because the Co(OH)2 nanosheets are polar and so increase chemical interactions with the sulphides, while the graphene nanosheets serve as a physical barrier for preventing the diffusion and migration of the dissolved polysulfides. The high functionality of the graphene and Co(OH)2 nanosheets with a strong synergistic effect for suppressing the shuttle effect also allows low mass loading of just 0.20 mg cm-2.
　　“The EG [exfoliated graphene] sheets in hybrid interlayer can serve as a polysulfides physical barrier and electrical conductive network to increase the reuse of polysulfide trapped while the polar Co(OH)2 nanosheets can fulfil the role of chemical adsorption of polysulfides,” they explain in their report. “As a consequence, high-capacity Li-S batteries with 918 mAh/g at 0.5 C, accompanied with exceptional rate capability (677 mAh/g at 5 C) and stable cycle stability (565 mAh/g after 300 cycles at 0.5 C), are achieved.”
　　Tannic WS2 enhancements: (a) Schematic representation for effective exfoliation and modification of pristine WS2 with tannic acid assistant. (b) and (c) Schematic illustration of polysulfide species on the graphene mixed with ta-WS2 and pristine WS2, respectively. (Image by Journal of Physics: Energy) 
　　Optimizing reaction rates
　　Da-Wei Wang at the University of New South Wales in Australia and Xin Tan at Australian National University and colleagues also report results of research focused on polysulphide batteries in the first issue of Journal of Physics: Energy. They suggest, “Although substantial effort has been devoted to the improvement of LIBs [lthium ion batteries] and various vigorous studies toward further development still continue, the present Li-ion technologies cannot fulfil the ever-increasing requirements of the modern society, because of the limited energy density and expensiveness in the large-scale applications.”
　　They add that the main barrier to uptake for polysulphide organic battery systems is the cost and flammability, which has prompted a lot of effort to make organic polysulphide systems that operate with an aqueous-based electrolyte. This has in turn led to frustrations with “sluggish” reaction rates. Wang and Tan and their colleagues tackle this with a conducting graphene support decorated with hydrophilic WS2 nanosheets exfoliated using tannic acid. In their report they highlight that as well as enabling efficient exfoliation of WS2 nanosheets, the tannic acid modifies them to enhance the hydrophilic properties thereby improving the electrocatalytic activity of the WS2 and boosting the battery reaction rates.
　　“The incorporation of tannic acid imposed the collective interactions between polysulfide and the WS2 nanosheets via the hydrophilic molecules and the polar surfaces,” they explain in their report. “With a 0.5 M Li2S2 electrolyte, the graphene and modified WS2 mixture gave an areal specific capacity of 0.37 mA h/cm2, compared to 0.27 mA h/cm2 for the pure graphene.”
　　Full details of both papers are available in the first issue of Journal of Physics: Energy. (physicsworld)