Archive for the ‘Hot Articles’ Category

Targeting the Powerhouse of the Cell to Fight Cancer

Everyone knows that cancer as a disease is awful, but the side effects of currently utilized chemotherapies have their own horrors. Research into natural products as therapies have found some promising compounds, but they face barriers to practical use in patients. One particular molecule, artesunate (ART), recently showed high potential for anticancer activity when in the presence of iron. Unfortunately, ART has major problems that limit its current applicability, including low solubility in water and high instability in biologically relevant conditions.

One approach to get around these issues is to encapsulate the drug (pun intended) in a nanoparticle-based carrier. A carrier with a hydrophobic interior and hydrophilic exterior can bring higher concentrations of drugs with low solubility into a cell and protect them from deleterious conditions in the body. An additional benefit is the relative ease of incorporating targeting ligands into the particles during synthesis. This allows the drugs to only interact with specific cells or, in this specific case, the mitochondria within cells.

Figure 1. Schematic of the nanoparticle synthesis process complete with targeting ligand molecules. The anticancer agent is activated in the presence of iron.

Researchers in China have prepared approximately 200 nm nanoparticle carriers for ART (Figure 1) using triphenyl phosphonium (TPP) as a mitochondrial targeting ligand. These nanoparticles remained stable in biologically relevant conditions for a week, sufficient for in-vitro studies. The studies showed significant decreases in cancer cell growth when the nanoparticles were used compared to the ART alone. The nanoparticles with TPP on the surface showed the highest efficacy, particularly when coupled with iron treatment to activate the ART.

Figure 2. Images of cells exposed to nanoparticles with (bottom) and without (top) a targeting ligand filled with different fluorescent dyes. The increased brightness corresponds to higher uptake of the nanoparticles by the cells.

To further investigate the cell uptake pathway of the nanoparticles, the researchers added fluorescent dye molecules to the inside of the particles. Once the cells took up and ruptured the nanoparticles, the dyes were released and became visible to the researchers (Figure 2). The fluorescence was twice as great in cells exposed to the nanoparticles treated with the TPP targeting ligand, showing its value for cell uptake. The researchers also used fluorescent dyes that react with reactive oxygen species (ROSs), as their generation is how ART kills cancer cells. The in-vitro studies showed an over three-fold increase in fluorescence from reactions with ROSs which, combined with data showing higher rates of cell death, supports the increased activity of ART when combined with this nanoparticle architecture.

To find out more please read:

A mitochondria targeting artesunate prodrug-loaded nanoparticle exerting anticancer activity via iron-mediated generation of the reactive oxygen species

Zhigang Chen, Xiaoxu Kang, Yixin Wu, Haihua Xiao, Xuzi Cai, Shihou Seng, Xuefeng Wang and Shiguo Chen

Chem. Commun., 2019, 55, 4781 – 4784.

About the blogger:

 

Beth Mundy is a PhD candidate in chemistry in the Cossairt lab at the University of Washington in Seattle, Washington. Her research focuses on developing new and better ways to synthesize nanomaterials for energy applications. She is often spotted knitting in seminars or with her nose in a good book. You can find her on Twitter at @BethMundySci.

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HOT ChemComm articles for March

All of the referee-recommended articles below are free to access until Friday 21st June 2019.

Amperometric monitoring of vesicular dopamine release using a gold nanocone electrode
Nan Zhang, Wei Zhao, Cong-Hui Xu,* Jing-Juan Xu* and Hong-Yuan Chen
Chem. Commun., 2019, 55, 3461-3464
DOI: 10.1039/C9CC01280J, Communication

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Photo-writing self-erasable phosphorescent images using poly(N-vinyl-2-pyrrolidone) as a photochemically deoxygenating matrix
Jinxiong Lin, Shigang Wan, Wenfeng Liu and Wei Lu*
Chem. Commun., 2019, 55, 4299-4302
DOI: 10.1039/C9CC01388A, Communication

 

 

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Selective amidation by a photocatalyzed umpolung reaction
Debasish Ghosh, Rajesh Nandi, Saikat Khamarui, Sukla Ghosh and Dilip K. Maiti*
Chem. Commun., 2019, 55, 3883-3886
DOI: 10.1039/C9CC01079C, Communication

 

 

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A free radical alkylation of quinones with olefins
Shuai Liu, Tong Shen, Zaigang Luo and Zhong-Quan Liu*
Chem. Commun., 2019, 55, 4027-4030
DOI: 10.1039/C9CC01704F, Communication

 

 

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Probing transient non-native states in amyloid beta fiber elongation by NMR
Jeffrey R. Brender, Anirban Ghosh, Samuel A. Kotler, Janarthanan Krishnamoorthy, Swapna Bera, Vanessa Morris, Timir Baran Sil, Kanchan Garai, Bernd Reif, Anirban Bhunia* and Ayyalusamy Ramamoorthy*
Chem. Commun., 2019, 55, 4483-4486
DOI: 10.1039/C9CC01067J, Communication

 

 

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A nickel(II)-catalyzed asymmetric intramolecular Alder-ene reaction of 1,7-dienes
Wen Liu, Pengfei Zhou, Jiawen Lang, Shunxi Dong,* Xiaohua Liu and Xiaoming Feng*
Chem. Commun., 2019, 55, 4479-4482
DOI: 10.1039/C9CC01521C, Communication

 

 

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1+1>2: Bridging Constituents in Hetero-Structured Hydrogen Evolution Photocatalysts

Solar-driven water reduction is a sustainable method to acquire hydrogen fuel. An indispensable component of this reaction is the photocatalyst which drives spontaneous hydrogen gas evolution from water when illuminated. Hetero-structured materials consisting of two or more catalysts stand out as promising hydrogen evolution catalysts, due to the combined advantages of their constituents (e.g. enhanced light-absorption capability). Unfortunately, the weak adhesion between different components is the Achilles heel of conventional hetero-structured photocatalysts. It impedes electron transport from the photocatalysts to the nearby water molecules, hindering the catalytic activity.

A research group led by Xiao Xiao and Jian-Ping Zou from Nanchang Hangkong University of China has demonstrated a solution to the aforementioned challenge. They firmly connected two photocatalysts – Pt-loaded carbon nitride (CN) and the covalent organic framework CTF-1 – via amide bonds, resulting in a new type of hetero-structured photocatalyst, CN/CTF-1, which exhibited a hydrogen evolution rate approximately 3 times faster than those of conventional hetero-structured photocatalysts made of weakly bound CN and CTF-1.

The researchers adopted a two-step method to synthesize CN/CTF-1. They first reacted CTF-1 sheets with 4-aminobenzoic acid to graft carboxylic groups onto the surfaces of the CTF-1 sheets. A subsequent amide condensation between the amine groups of the CN and the carboxyl groups on the CTF-1 bridged the two components. The amide groups serve as electron transport pathways and facilitate the movement of photo-excited electrons from CTF-1 to CN (Figure 1a) which liberates hydrogen gas.

The covalent amide “bridges” gave CN/CTF-1 a fast hydrogen production rate. Quantitatively, when irradiated with a 300 W Xe lamp at 160 mW/cm2, CN/CTF-1 produced ~4 mmol H2 per gram of CN/CTF-1 after 4 h (0.85 mmol H2 h-1 gcatalyst-1), whereas under identical conditions, weakly adhered CN and CTF-1 sheets as well as a physical mixture of CN and CTF-1 all achieved H2 evolution rates of ~1 mmol H2 per gram of photocatalyst (0.30 mmol H2 h-1 gcatalyst-1) (Figure 1b).

Figure 1. (a) (Pt-loaded) CN sheets are covalently bound to CTF-1 sheets via amide bonds. These covalent bonds serve as electron transport “bridges” that facilitate the diffusion of photo-excited electrons from CTF-1 to CN. (b) H2 evolution rates of four photocatalysts: 1 – covalently bound CN/CTF-1; 2 and 3 –  weakly adhered CN and CTF-1; 4 – a physical mixture of CN and CTF-1.

The covalent bonding strategy is applicable to other coupling reactions such as the Friedel-Crafts reaction. This general method could create a new paradigm for designing and synthesizing high-performance hetero-structured photocatalysts.

 

To find out more please read:

A General Strategy via Chemically Covalent Combination for Constructing Heterostructured Catalysts with Enhanced Photocatalytic Hydrogen Evolution

Gang Zhou, Ling-Ling Zheng, Dengke Wang, Qiu-Ju Xing, Fei Li, Peng Ye, Xiao Xiao, Yan Li, and Jian-Ping Zou

Chem. Commun., 2019, 55, 4150-4153

About the blogger:

Tianyu Liu obtained his Ph.D. (2017) in Chemistry from University of California, Santa Cruz in the United States. He is passionate about scientific communication to introduce cutting-edge research to both the general public and scientists with diverse research expertise. He is a blog writer for Chem. Commun. and Chem. Sci. More information about him can be found at http://liutianyuresearch.weebly.com/.

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Using Carbon to Make a Better Solar Cell

Maybe I’m stating the obvious, but solar cells are incredibly complex devices with more components than just the light absorber.

While the focus on the active layer by chemists looking to develop new materials is understandable, in order to truly create next-generation solar cells the other components of the architecture must be improved.  Creating the crack-resistant or resilient layers necessary for functional flexible solar cells is a major challenge currently being addressed. These new materials and approaches also need to work within the general framework of fabrication techniques used for the other layers – ideally at low temperature and solution processible.

An often-neglected piece of the puzzle is the electrode. Electrodes are traditionally composed of a thin metal layer, which is often vapor deposited at high temperatures and low pressures. This class of electrodes is expensive, susceptible to degradation, and can damage the critical hole transport or active layers. One emerging alternative is carbon-based electrodes, applied as pastes. These low-cost, highly stable, and hydrophobic materials are attractive given their compatibility with emerging photovoltaic technologies, particularly perovskites. Their broad application has been limited by the necessity of toxic solvents to create the pastes, but researchers in China have developed a low-temperature, highly conductive carbon paste that can be screen printed onto perovskite solar cells without using toxic solvents.

Fabrication schematic and cross sectional SEM for a perovskite solar cell with a carbon electrode

Figure 1. (a) Fabrication schematic for perovskite solar cells with carbon electrodes and hole transport layers. (b) Cross sectional SEM image of a device.

Not only are the solvents more environmentally friendly compared to those previously used, they also increase the mechanical strength of the final film and, under fabrication conditions, do not damage the perovskite active layer or organic hole transport layer. While the hole transport layer isn’t strictly necessary to create a working device, it has been shown to increase the champion efficiency from 11.7% to 14.55%. This is likely due to poor contact between the perovskite and carbon electrode, which the thin hole transport layer (PEDOT:PSS) helps remedy.

Carbon-based electrode undergoing a bending test and sheet resistivity data

Figure 2. (a) A sample undergoing a bending test. (b) The electrode sheet resistance before and after 100 bends.

The most exciting aspect of these electrodes is their resilience when subjected to a bending test. After 100 bends, the researchers saw no visible film damage or increase in the sheet resistance when compared to the initial sample. Actual flexible solar cells fabricated and studied did show a decrease in performance after 1,000 bends, but this was attributed to known robustness issues in the base ITO layer. This work with carbon-based electrode materials could lead to simpler manufacturing for fabricating perovskite solar cells at a commercial level.

 

To find out more please read:

A low-temperature carbon electrode with good perovskite compatibility and high flexibility in carbon based perovskite solar cells

Shiyu Wang, Pei Jiang, Wenjian Shen, Anyi Mei, Sixing Xiong, Xueshi Jiang, Yaoguang Rong, Yiwen Tang, Yue Hu & Hongwei Han

Chem. Commun., 2019, 55, 2765-2768

This article is also part of the Chemical CommunicationsPerovskites‘ themed collection.

About the blogger:

 

Beth Mundy is a PhD candidate in chemistry in the Cossairt lab at the University of Washington in Seattle, Washington. Her research focuses on developing new and better ways to synthesize nanomaterials for energy applications. She is often spotted knitting in seminars or with her nose in a good book. You can find her on Twitter at @BethMundySci.

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HOT ChemComm articles for February

All of the referee-recommended articles below are free to access until Friday 24th May.

Plasmonic Gold Nanoparticle as Multifaceted Probe for Tissue Imaging
Yu-Hong Cheng, Toby Siu-Chung Tam, Siu-Leung Chau, Samuel Kin-Man Lai, Ho-Wai Tang, Chun-Nam Lok, Ching-Wan Lam and Kwan-Ming Ng*
Chem. Commun., 2019, 55, 2761-2764
DOI: 10.1039/C9CC00356H, Communication

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One-Pot, Modular Approach to Functionalized Ketones via Nucleophilic Addition/Buchwald-Hartwig Amination Strategy
Jorn de Jong, Dorus Heijnen, Hugo Helbert and Ben L. Feringa*
Chem. Commun., 2019, 55, 2908-2911
DOI: 10.1039/C8CC08444K, Communication

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Soft Self-assembled Sub-5 nm Scale Chessboard and Snub-Square Tilings with Oligo(para-phenyleneethynylene) Rods
Constance Nürnberger, Huanjun Lu, Xiangbing Zeng, Feng Liu,* Goran Ungar,* Harald Hahn, Heinrich Lang, Marko Prehm and Carsten Tschierske*
Chem. Commun., 2019, 55, 4154-4157
DOI: 10.1039/C9CC00494G, Communication

 

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Dual-Wavelength Lasing from Organic Dye Encapsulated Metal-Organic Framework Microcrystals
Yue Zhang, Haiyun Dong, Yuan Liu, Chunhuan Zhang, Fengqin Hu* and Yong Sheng Zhao*
Chem. Commun., 2019, 55, 3445-3448
DOI: 10.1039/C8CC10232E, Communication

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Hybridization Chain Reaction-Based Nanoprobe for Cancer Cell Recognition and Amplified Photodynamic Therapy
Mengyi Xiong, Qiming Rong, Gezhi Kong, Chan Yang, Yan Zhao, Feng-Li Qu,* Xiao-Bing Zhang* and Weihong Tan
Chem. Commun., 2019, 55, 3065-3068
DOI: 10.1039/C8CC10074H, Communication

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Synthesis of Renewable Acetic Acid from CO2 and Lignin over Ionic Liquid-Based Catalytic System
Huan Wang, Yanfei Zhao, Zhengang Ke, Bo Yu, Ruipeng Li, Yunyan Wu, Zhenpeng Wang, Juanjuan Han and Zhimin Liu*
Chem. Commun., 2019, 55, 3069-3072
DOI: 10.1039/C9CC00819E, Communication

 

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A Battery Cathode with a Bee Pupa-Filled Honeycomb Structure

Increasing the volumetric energy densities of batteries is essential for improving the durability of portable electronics and the operating ranges of electric vehicles. One way to improve energy density is to enlarge the mass fraction of active materials in battery electrodes; however, the degree of enhancement remains limited. This limitation results from the densification of the electrodes when the mass fraction increases, making electron transport and ion diffusion throughout the electrodes sluggish. These drawbacks lower the utilization efficiency of the overall electrode materials.

A team of scientists from China and the United States has recently addressed the aforementioned challenges. Specifically, they synthesized a 3D cathode of carbon-coated Li2MnSiO4 (Li2MnSiO4/C) with a structure mimicking a honeycomb filled with bee pupas (Fig. 1). This lithium-ion battery cathode possesses a high mass fraction of 90% (of overall electrode mass) as well as a volumetric energy density as high as 2443 Wh/dm3.

The uniquely structured electrodes were prepared through a hard-template method (Fig. 1). Using polystyrene particles, silica surface coating, and Li2MnSiO4 precursor infiltration, the authors synthesized a carbon-coated Li2MnSiO4 honeycomb scaffold with each cavity filled with a carbon-coated Li2MnSiO4 particle. This architecture differed from previously reported 3D structures, which typically had a large portion of voids, and enabled an ultrahigh active-material mass loading of 90 wt.%. Additionally, the gaps between the scaffold and the particles functioned as ion-diffusion channels, and the carbon coatings served as electron-transport expressways. These characteristics effectively addressed the problem of sluggish ion diffusion and electron transport.

Figure 1. The synthesis procedures of the BPFH-shaped Li2MnSiO4/C electrode. The green particles and yellow scaffold represent polystyrene spheres and the silica coating, respectively.

Due to the facilitated electron transport and ion diffusion, the Li2MnSiO4/C electrode with a bee pupa-filled honeycomb (BPFH) structure (Fig. 2a) exhibited an outstanding charge-storage performance. Specifically, it delivered a high volumetric capacity of 643 mAh/cm3 at a current density of 0.1 C, corresponding to a volumetric density of 2443 Wh/dm3. This volumetric capacity was approximately two times higher than that of a Li2MnSiO4/C honeycomb lattice without any Li2MnSiO4 particles (Fig. 2b). After 100 consecutive charge-discharge cycles, the BPFH-shaped Li2MnSiO4/C electrode retained a volumetric capacity of 328 mAh/cm3 (Fig. 2c).

Figure 2. (a and b) Scanning electron microscopy images of (a) the BPFH-shaped Li2MnSiO4/C electrode and (b) the Li2MnSiO4/C scaffold. (c) The capacities and the Coulombic efficiencies of the two electrodes during 100 charge-discharge cycles.

The demonstrated BPFH architecture could be extended to other materials for the synthesis of battery electrodes with both high mass fractions of active materials and outstanding volumetric energy densities.

 

To find out more please read:

A Bee Pupa-Infilled Honeycomb Structure-Inspired Li2MnSiO4 Cathode for High Volumetric Energy Density Secondary Batteries

Jinyun Liu, Xirong Lin, Huigang Zhang, Zihan Shen, Qianqian Lu, Junjie Niu, Jinjin Li and Paul V. Braun

Chem. Commun., 2019, 55, 3582-3585

About the blogger:

Tianyu Liu obtained his Ph.D. (2017) in Chemistry from University of California, Santa Cruz in the United States. He is passionate about scientific communication to introduce cutting-edge research to both the general public and scientists with diverse research expertise. He is a blog writer for Chem. Commun. and Chem. Sci. More information about him can be found at http://liutianyuresearch.weebly.com/.

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HOT ChemComm articles for January

All of the referee-recommended articles below are free to access until Monday 1st April.

Remote control of electronic coupling – modification of excited-state electron-transfer rates in Ru(tpy)2-based donor–acceptor systems by remote ligand design
Yusen Luo, Jens H. Tran, Maria Wächtler, Martin Schulz, Kevin Barthelmes, Andreas Winter, Sven Rau, Ulrich S. Schubert and Benjamin Dietzek*
Chem. Commun., 2019, 55, 2273-2276
DOI: 10.1039/C8CC10075F, Communication

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A rhodium-catalysed Sonogashira-type coupling exploiting C–S functionalisation: orthogonality with palladium-catalysed variants
Milan Arambasic, Manjeet K. Majhail, Robert N. Straker, James D. Neuhaus and Michael C. Willis*
Chem. Commun., 2019, 55, 2757-2760
DOI: 10.1039/C9CC00092E, Communication

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Hexagonal perovskite derivatives: a new direction in the design of oxide ion conducting materials
Sacha Fop,* Kirstie S. McCombie, Eve J. Wildman, Janet M. S. Skakle and Abbie C. Mclaughlin*
Chem. Commun., 2019, 55, 2127-2137
DOI: 10.1039/C8CC09534E, Feature Article

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Combined experimental and theoretical study of long-range H–F interactions in α-fluoro amides
Elena Cosimi, Nils Trapp, Marc-Olivier Ebert* and Helma Wennemers*
Chem. Commun., 2019, 55, 2253-2256
DOI: 10.1039/C8CC09987A, Communication

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Mechanised lubricating silica nanoparticles for on-command cargo release on simulated surfaces of joint cavities
Xiaolong Tan, Yulong Sun, Tao Sun and Hongyu Zhang*
Chem. Commun., 2019, 55, 2593-2596
DOI: 10.1039/C8CC10069A, Communication

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A sub-100 °C aluminum ion battery based on a ternary inorganic molten salt
Jie Wang, Xu Zhang, Weiqin Chu, Shiqi Liu and Haijun Yu*
Chem. Commun., 2019, 55, 2138-2141
DOI: 10.1039/C8CC09677E, Communication

 

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Saving Organic Electrodes in Lithium-Ion Batteries

Organic compounds with conjugated electron structures are emerging as promising Li-ion battery cathodes due to their high capacity and environmental benignity. To make these cathodes practically feasible, organic electrodes are typically incorporated with metal ions to boost their energy densities. The addition of metal ions, however, usually jeopardizes the structural integrity of the electrodes and shortens battery lifetime.

Recently, three groups of Chinese researchers demonstrated that increasing the electrolyte concentration could effectively prolong the lifespan of metal-incorporated organic cathodes. The researchers studied cuprous tetracyano-quinodimethane (CuTCNQ), a Cu2+-containing organic Li-ion battery cathode, and observed its significantly improved cycling stability in a 7 M LiClO4 electrolyte compared to a 1 M electrolyte. This work was published recently in ChemComm.

CuTCNQ in a typical diluted electrolyte of 1 M LiClO4 exhibited unsatisfactory stability. Its first-cycle charging capacity reached ~180 mAh/g, but it dropped appreciably to 23 mAh/g after the first discharging process (Figure 1a). Concurrently, the electrolyte turned from clear to yellow (Figure 1b), due to the dissolution of TCNQ. These observations unequivocally showed the rapid disintegration of CuTCNQ in diluted electrolytes.

Figure 1. (a) The first-cycle charge-discharge profile of CuTCNQ in a liquid electrolyte containing ethylene carbonate (EC), propylene carbonate (PC) and 1 M LiClO4 (1 M LiClO4-EC/PC). (b) Photographs showing the electrolyte color before and after the first charge-discharge cycle.

CuTCNQ was found to be more stable in electrolytes with concentrations higher than 1 M. When the LiClO4 concentration increased to 3 M, 5 M and 7 M, the specific capacities of CuTCNQ retained after 50 consecutive charge-discharge cycles were ~25 mAh/g, ~70 mAh/g, and ~110 mAh/g, respectively (Figure 2a). All of these capacities were higher than that of CuTCNQ in 1 M LiClO4 after the same cycle number (<10 mAh/g). Additionally, the electrolytes experienced nearly no color change, suggesting little TCNQ was dissolved (Figure 2b).

The elevated stability of CuTCNQ correlates to the formation of Li+-ClO4 ion pairs in concentrated electrolytes (Figure 2c). With increasing LiClO4 concentration, Li+ and ClO4 tend to form ion pairs that coordinate with solvent molecules. Solvent-coordination reduces the number of free solvent molecules that can dissolve TCNQ, thus minimizing the dissolution of TCNQ.

Figure 2. (a) The cycling stability performances of CuTCNQ with electrolytes with different LiClO4 concentrations. (b) Photographs showing the electrolyte color before and after 50 charge-discharge cycles at different LiClO4 concentrations. (c) Li+ and ClO4- form solvent-coordinated ion pairs in super-concentrated electrolytes (e.g., 7 M).

This work provides a facile approach to mitigate the capacity fading of CuTCNQ. The strategy may be extended to stabilize other metal-incorporated organic cathodes in Li-ion batteries.

To find out more please read:

Sustainable Cycling Enabled by A High-Concentration Electrolyte for Lithium-Organic Batteries

Ying Huang, Chun Fang, Wang Zhang, Qingju Liu and Yunhui Huang

Chem. Commun., 2019, 55, 608-611

About the blogger:

Tianyu Liu obtained his Ph.D. (2017) in Chemistry from University of California, Santa Cruz in the United States. He is passionate about scientific communication to introduce cutting-edge research to both the general public and scientists with diverse research expertise. He is a blog writer for Chem. Commun. and Chem. Sci. More information about him can be found at http://liutianyuresearch.weebly.com/.

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HOT ChemComm articles for November

All of the referee-recommended articles below are free to access until Friday 18th January.

Naphthalene and perylene diimides – better alternatives to fullerenes for organic electronics?
Agnieszka Nowak-Król, Kazutaka Shoyama, Matthias Stolteb and Frank Würthner
Chem. Commun., 2018, 54, 13763-13772
DOI: 10.1039/C8CC0764OE, Highlight

Naphthalene and perylene diimides; alternatives to fullerenes in organic electronics.

 

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A single-atom Fe–N4 catalytic site mimicking bifunctional antioxidative enzymes for oxidative stress cytoprotection
Wenjie Ma, Junjie Mao, Xiaoti Yang, Cong Pan, Wenxing Chen, Ming Wang, Ping Yu, Lanqun Mao and Yadong Li
Chem. Commun., 2019, Advance Article
DOI: 10.1039/C8CC08116F, Communication

Catalytic site mimicking bifunctional antioxidative enzymes

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Si(bzimpy)2 – a hexacoordinate silicon pincer complex for electron transport and electroluminescence
Margaret Kocherga, Jose Castaneda, Michael G. Walter, Yong Zhang, Nemah-Allah Saleh, Le Wang, Daniel S. Jones, Jon Merkert, Bernadette Donovan-Merkert, Yanzeng Li, Tino Hofmann and Thomas A. Schmedake
Chem. Commun., 2018, 54, 14073-14076
DOI: 10.1039/C8CC07681B, Communication

Hexacoordinate silicon pincer complexes; applications in electron transport and electroluminescence.

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Maintaining homogeneity during a sol–gel transition by an autocatalytic enzyme reaction
Santanu Panjaa and Dave J. Adams
Chem. Commun., 2019, Advance Article
DOI: 10.1039/C8CC08501C, Communication

Autocatalytic enzyme reactions in sol-gel transitions; maintaining homogeneity.

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Desferrioxamine:gallium-pluronic micelles increase outer membrane permeability and potentiate antibiotic activity against Pseudomonas aeruginosa
Max Purro, Jing Qiao, Zhi Liu, Morgan Ashcraft and May P. Xiong
Chem. Commun., 2018, 54, 13929-13932
DOI: 10.1039/C8CC08134D, Communication

Micelles increase outer membrane permeability and provide antibiotic activity against Pseudomonas aeruginosa.

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Unbalanced MOF-on-MOF growth for the production of a lopsided core–shell of MIL-88B@MIL-88A with mismatched cell parameters
Dooyoung Kim, Gihyun Lee, Sojin Oh and Moonhyun Oh
Chem. Commun., 2019, Advance Article
DOI: 10.1039/C8CC08456D, Communication

MOF-on-MOF growth; MIL-88B@MIL-88A.

 

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Shrinking the Size of Hydrogen Evolution Catalysts by Carbon Coating

Hydrogen gas is a zero-emission energy resource promising to replace diminishing fossil fuels. The electrolysis of water is a sustainable way to acquire hydrogen gas, but this non-spontaneous process demands electricity to proceed. Therefore, hydrogen evolution reaction (HER) catalysts are used to reduce the energy cost or overpotential of the electrolysis.

Researchers are pursuing ultrafine nanoparticles as HER catalysts due to their high catalytic activity. For example, the HER catalytic activities of Ru nanoparticles are reportedly 100-200% higher than those of bulk Ru catalysts. Unfortunately, the preparation of well-dispersed nanoparticles is challenging because nanoparticles are prone to aggregate together.

Recently in ChemComm, Fuqiang Chu, Yong Qin and coworkers from Changzhou University, China addressed the challenge. They utilized a Ru-based coordination complex and cyanuric acid as the reactants, and synthesized high-performance HER catalysts composed of ~2 nm Ru nanoparticles uniformly dispersed on graphene sheets. During the thermal annealing step in the synthesis, the ligands of the complex and the cyanuric acid both decompose to nitrogen-doped carbon shells covering the as-formed Ru nanoparticles. These shells serve as spacers that prevent particle aggregation (Figure 1).

Figure 1. An illustration of the synthesis of carbon-coated Ru ultrafine nanoparticles on graphene sheets. Tris(2,2′-bipyrindine) ruthenium dichloride is the precursor of the Ru nanoparticles.

In both the acidic and the alkaline electrolytes, the 2 nm Ru particles (RuNC-2) display lower overpotentials and higher current densities than the 5 nm Ru particles (Figure 2) without the carbon coating (RuNC-5). Remarkably, the 2 nm particles showed comparable performance to the benchmark Pt catalyst in the acidic electrolyte (the red and black curves in Figure 2a).

Figure 2. Linear sweep voltammograms of ~3 nm Pt nanoparticles (PtNC), 2 nm Ru nanoparticles (RuNC-2) and 5 nm Ru nanoparticles (RuNC-5) in (a) 0.5 M H2SO4 and (b) 1 M KOH aqueous solutions.

The concept of the in-situ generation of protective coatings could inspire the synthesis of other ultra-small nanoparticles to potentially push the HER catalytic performance to new heights.

 

To find out more please read:

An Ultrafine Ruthenium Nanocrystal with Extremely High Activity for the Hydrogen Evolution Reaction in Both Acidic and Alkaline Media

Yutong Li, Fuqiang Chu, Yang Liu, Yong Kong, Yongxin Tao, Yongxin Li and Yong Qin

Chem. Commun., 2018, DOI: 10.1039/c8cc08276f

 

About the blogger:

Tianyu Liu obtained his Ph.D. (2017) in Chemistry from University of California, Santa Cruz in the United States. He is passionate about scientific communication to introduce cutting-edge research to both the general public and scientists with diverse research expertise. He is a blog writer for Chem. Commun. and Chem. Sci. More information about him can be found at http://liutianyuresearch.weebly.com/.

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