Archive for the ‘Subject Areas’ Category

How do Anions Fight Indoor Organic Contaminants?

Indoor air quality is critical to public health. Chronic exposure to indoor organic contaminants (IOCs), including aldehydes and benzene homologues, substantially increases the risk of having respiratory diseases. In recent years, negative air ions (NAIs) have emerged as promising materials to decompose IOCs. NAIs are negatively charged ions generated via ionizing air. However, the limited understanding of the decomposition reaction mechanisms hinders the safety evaluation and wide adoption of NAI-cleaning.

A group of Chinese researchers led by Jin-Ming Lin of Tsinghua University recently demonstrated in ChemComm a powerful tool to unveil the reaction mechanisms. They built a system integrated with an NAI generator, an IOC sprayer and a mass spectrometer (Figure 1). NAIs containing mostly CO3 were produced by the ionization of air. These anions then mixed and reacted with the sprayer-delivered IOCs in front of the mass spectrometer inlet. All species generated during the reactions were directly brought into the mass spectrometer by inert N2 for characterization.

Figure 1. The experimental set-up of the integrated system.

This device revealed real-time reaction kinetics by identifying the reaction intermediates. The mass spectrum of a common IOC, formaldehyde, when reacted with CO3 is presented in Figure 2a. Two pronounced peaks with mass to charge ratios (m/z) of 45.10 and 60.10 were assigned to HCOO and CO3, respectively. Additionally, the 45.10 peak was only detected when formaldehyde was present (Figure 2b). On the basis of these observations, the authors concluded that the major pathway of formaldehyde degradation by CO3was the reaction between CO3 and the α-H atom of the aldehyde group. With identical instrumentation, the authors also proposed how the reactions between CO3 and benzene homologues or esters may proceed.

Figure 2. (a) The mass spectrum of reaction intermediates between CO3 and 10 ppm formaldehyde. (b) The change of peak intensities of m/z = 60.10 and 45.10 peaks with the operation time. Formaldehyde was present during 7.0-14.0 min.

The results obtained by this study could greatly deepen the understanding of NAI-based chemistry. It could also be useful to investigate kinetics of a broad range of other chemical reactions involving charged reactants.

 

To find out more please read:

Real-Time Characterization of Negative Air Ion-Induced Decomposition of Indoor Organic Contaminants by Mass Spectrometry

Ling Lin, Yu Li, Mashooq Khan, Jiashu Sun and Jin-Ming Li

Chem. Commun., 2018, DOI: 10.1039/c8cc05795h

 

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/.

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

MOFS, ZMOFS and Automobiles

Mohamed Eddaoudi and co-workers at KAUST have synthesised a porous metal organic framework (MOF) constructed from carboxylic acid-functionalised imidazole linkers coordinated to yttrium and potassium cations. The researchers classified this material as a zeolite-like MOF (ZMOF) due to its topological resemblance to the naturally occurring zeolite mineral analcime.

The material’s architecture, with cylindrical channels and a pore aperture measuring 3.8 x 6.2 Å, promised utility as a molecular sieve, and the authors showed the ZMOF could be used to sort small chain alkanes based on their level of branching. Linear and mono-branched pentanes and butanes were adsorbed by the material for different lengths of time (linear isomers were retained longer than their branched counterparts) allowing kinetic separation, while the di-branched alkane 2,2,4-trimethylpentane was excluded entirely. The authors anticipate that this material could have practical applications in crude oil refining, to upgrade petroleum into more energy-efficient fuels with reduced emissions.

ZMOF zeolite-like metal organic framework crystal structure with analcime (ana) topology showing channels and pore aperture.

ZMOF crystal structure with analcime (ana) topology showing channels and pore aperture.

The petroleum used to power internal combustion engines consists of a mixture of low molecular weight, linear and branched alkanes. The research octane number (RON) is a standard measure of petroleum performance, and indicates how much pressure a fuel can withstand before self-igniting (knocking) in the engine. High compression engines, which are more energy efficient and release less emissions than regular engines, require high RON fuels.

The RON increases with the proportion of branched alkanes, so can be improved by supplementing fuels with branched isomers obtained by catalytic isomerisation. This process generates a mixture of linear and branched alkanes, so the desired products must be isolated via fractional distillation, which is energy intensive. This creates a dilemma: high RON fuels are more energy efficient, but their energy-intensive production reduces the net benefit.

The authors envisaged an energy-efficient strategy for increasing the RON of petroleum fuels: A low RON fuel is pumped into the engine, where it encounters a separation chamber consisting of ZMOF-based membranes. The membrane excludes and redirects di-branched alkanes, which have a very high RON, to the internal combustion engine. The low RON fraction, consisting of mono-branched and linear alkanes, passes through the ZMOF pores to undergo further reforming processes downstream. In other words: low RON fuels go in, but high RON fuels are combusted.

Scheme showing how ZMOF materials could be used to upgrade gasoline by separating alkanes based on their level of branching. zeolite-like metal organic framework petroleum reforming

Scheme showing the RON of common small-chain alkanes and the use of ZMOF membranes in upgrading gasoline by separating alkanes based on their level of branching

In this work the authors show the potential of ZMOFs to maximise the energetic potential and reduce emissions of petroleum based fuels, while also offering a glimpse of the more general strategy of energy-efficient separations of chemically-similar molecules using tailored materials.

To find out more please read:

Upgrading gasoline to high octane number using zeolite-like metal organic framework molecular sieve with ana-topology

M. Infas H. Mohideen, Youssef Belmabkhout, Prashant M. Bhatt, Aleksander Shkurenko, Zhijie Chen, Karim Adil, Mohamed Eddaoudi.
Chem. Commun., 2018, 54, 9414-9417
DOI: 10.1039/c8cc04824j

About the author

Zoë Hearne is a PhD candidate in chemistry at McGill University in Montréal, Canada, under the supervision of Professor Chao-Jun Li. She hails from Canberra, Australia, where she completed her undergraduate degree. Her current research focuses on transition metal catalysis to effect novel transformations, and out of the lab she is an enthusiastic chemistry tutor and science communicator.

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

Marbles, Microreactions and Magic Tricks

The reaction vessel is a fixed variable behind every innovative chemical synthesis, material or catalyst. It may be as simple as a round bottom flask or as complex as a single cell, as large as an industrial batch reactor or as small as a test tube.

Yujun Feng and co-workers, at Sichuan University in China, study a different kind of reaction vessel: water droplets. The droplets are ‘liquid marbles’, composed of microlitre volumes of water with fine hydrophobic particles covering their surface. Liquid marbles can be used as reaction vessels to manipulate small liquid volumes, avoiding the use of specialised microfluidics equipment. In this communication the authors show that carbon dioxide can trigger coalescence of droplets containing multiple reagents, in order to perform microscale chemistry. This research could be useful for developing high-throughput assays for procedures that would benefit from remotely controlled induction such as very fast or hazardous reactions.

The authors synthesised CO2-responsive particles composed of a mixture of polystyrene and PDEA: a methacrylate polymer bearing tertiary amine ancillary groups. The amine is vital to the properties of the polymer: when deprotonated the powder is hydrophobic, but exposure to carbon dioxide renders the polymer hydrophilic by transforming the amine into an ammonium bicarbonate salt. Liquid marbles were synthesised with a patch of CO2-responsive polymer powder. The rest of the marble was coated in lycopodium, a moss spore with hydrophobic properties that is not CO2-responsive (trivia: the high fat content of lycopdoium makes it a great flash powder, used by magicians since the middle ages).

A) Liquid marbles with white hydrophobic/hydrophilic CO2-responsive patches and pink (dyed) lycopodium powder. B) Coalescence of two liquid marbles upon CO2 carbon dioxide exposure within one minute. C) Coalescence schematic

A) Liquid marbles with white CO2-responsive patches and pink (dyed) lycopodium powder. B) & C) Photos and schematic of coalescence between two liquid marbles upon CO2 exposure

To realise CO2-induced chemistry, two liquid marbles containing different chemical reagents are placed side by side with the CO2-responsive powder positioned at the interface of the two marbles. Upon exposure to CO2 the responsive powder becomes hydrophilic and disperses into the aqueous solution within the two marbles, causing them to coalesce and the reagents to react within a single vessel. The authors performed several reactions using this method, all with distinct colour changes for rapid analysis: redox (persulfate and iodide, permanganate and persulfate), complexation (starch and iodine), substitution (bromine water and phenol) and chemiluminescence (luminol, peroxide and ferricyanide).

The authors show in this paper that innovations in chemistry needn’t be limited to reactions themselves; the vessel we choose can broaden what is possible on a practical level. On a completely impractical note, remotely controlled microreactions in liquid marbles sounds like a magic trick, resonant with the lycopodium flash powder covering their surface.

To find out more please read:

CO2-triggered microreactions in liquid marbles 

Xinjie Luo, Hongyao Yin, Xian’e Li, Xin Su, Yujun Feng.
Chem. Commun., 2018, Advance Article
DOI: 10.1039/c8cc01786g

About the author

Zoë Hearne is a PhD candidate in chemistry at McGill University in Montréal, Canada, under the supervision of Professor Chao-Jun Li. She hails from Canberra, Australia, where she completed her undergraduate degree. Her current research focuses on transition metal catalysis to effect novel transformations, and out of the lab she is an enthusiastic chemistry tutor and science communicator.

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

ChemComm Poster Prize winner for the 2nd Early Career Researchers Meeting of the RSC–Macrocyclic and Supramolecular Chemistry Group

Dr Guillaume De Bo (left) presenting the ChemComm prize to Alexander Elmi (right).

The 2nd Early Career Researchers Meeting of the RSC-Macrocyclic and Supramolecular Chemistry (RSC-MASC) Group took place on 27th July 2018 at the University of Manchester, UK. This one-day symposium was organised by Dr. Guillaume De Bo (University of Manchester) and was attended by PhD students and post-doctoral researchers within the supramolecular field.

The meeting consisted of fifteen selected talks from submitted abstracts, and all attendees were invited to present a poster. The day ended with a plenary lecture by Professor Anthony Davis (University of Bristol) on ‘Biomimetic Carbohydrate Recognition:  The Host-Guest Chemistry of Carbohydrates in Water’.

ChemComm was proud to sponsor this successful symposium. Alexander Elmi (University of Edinburgh) received the ChemComm poster prize for his poster entitledUnderstanding Aromatic Stacking Interactions In Solution’.

 

Congratulations Alexander from everyone at ChemComm!

 

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

An enzymatic Rube Goldberg machine: a bioluminescent switch for the detection of uracil DNA-glycosylase

A team of researchers from Shandong Normal University in Jinan, China, have developed a highly sensitive and label-free assay for the detection of uracil-DNA glycosylase, a DNA repair enzyme that removes uracil from DNA molecules. Uracil is an RNA base, and when uracil appears in DNA through deamination of cytosine or misincorporation during DNA synthesis, the error can have mutagenic consequences.

Diminished activity of uracil-DNA glycosylase has been linked to a number of disease states including human immunodeficiency and Bloom syndrome, an inherited disorder associated with an increased risk of cancer (among other symptoms). Developing sensitive methods to quantify uracil-DNA glycosylase would enable early diagnosis of such conditions and improve understanding of the DNA-repair machinery. As a proof-of-concept, the researchers showed that this method could quantify the enzyme in the cell lysate of HeLa cancer cells.

Their method reminds me of Rube Goldberg machines, which achieve a task via a series of connected, mechanical steps. Completion of one step triggers the start of another: such as a line of falling dominos hitting a marble that, in turn, rolls down a track. In this work the action of one enzyme returns a product that is the preferred substrate of another enzyme. At the risk of deviating slightly, one of the more spectacular examples of a Rube Goldberg machine is seen in the music video for OK GO’s ‘this too shall pass’, a single-take shoot of a warehouse sized machine, featuring rolling cars, swinging pianos, flowing water and rolling billiard balls, all to perform the task of (spoiler alert) blasting the band members in the face with coloured paint.

The label-free strategy for detecting uracil-DNA glycosylase results in a bioluminescent signal via tricyclic signal amplification

The strategy starts with the action of uracil-DNA glycosylase and ends with a bioluminescent signal via a cascade of enzymatic reactions

The authors’ strategy involves a series of sequential steps employing seven different enzymes and three nucleic acid probes. It begins with a double stranded DNA probe containing one rogue uracil base: the perfect bait for uracil-DNA glycosylase. The action of this enzyme and two others, in a process involving base excision, DNA backbone cleavage and the addition of thymine-rich sequences, produces a large quantity of single-stranded DNA molecules with long thymine-rich tails. These molecules hybridise with adenine-rich RNA probes to generate RNA-DNA duplexes. An enzyme digests the RNA portion, releasing adenosine monophosphate monomers, which are converted to adenosine triphosphate (ATP), a required energy input to activate firefly luciferase. Luciferase catalyses the oxidation of luciferin to form oxyluciferin, accompanied by a large bioluminescent signal. Thus, uracil-DNA glycosylase is detected with 1-2 orders of magnitude more sensitivity than state-of-the-art fluorescent and luminescent assays.

Unlike conventional Rube Goldberg machines, which are characterised by unnecessary complexity, in this ‘enzymatic Rube Goldberg machine’ each step has a specific purpose and serves to amplify the signal of the last. This is dubbed ‘tricyclic cascade signal amplification’ and it enables highly sensitive detection of the enzyme.

To find out more please read:

Label-free and high-throughput bioluminescence detection of uracil-DNA glycosylase in cancer cells through tricyclic cascade signal amplification

Yan Zhang, Qing-nan Li, Chen-chen Li, Chen-yang Zhang.
Chem. Commun., 2018, 54, 6991-6994
DOI: 10.1039/c8cc03769h

About the author

Zoë Hearne is a PhD candidate in chemistry at McGill University in Montréal, Canada, under the supervision of Professor Chao-Jun Li. She hails from Canberra, Australia, where she completed her undergraduate degree. Her current research focuses on transition metal catalysis to effect novel transformations, and out of the lab she is an enthusiastic chemistry tutor and science communicator.

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

ChemComm poster prize winner at the 16th Symposium for Host-Guest and Supramolecular Chemistry

The 16th Symposium for Host-Guest and Supramolecular Chemistry was held on 2 – 3 June 2018 at the Tokyo University of Science in Japan.

This annual symposium covers all aspects of the chemical sciences related to molecular recognition and supramolecular chemistry, including the discussion of topics around intermolecular interactions. The event included a special lecture by Dr Shigeki Sasaki and invited lectures by Dr Takashi Hayashi and Dr Katsuhiko Ariga.

ChemComm is delighted to announce that the ChemComm poster prize was awarded to Hiroshi Koganezawa from the Tokyo University of Science for a poster entitled ‘Synthesis of [2]Rotaxanes with Spirofluorene and Pyrrole Moieties’.

Well done Hiroshi from everyone at ChemComm!

 

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

Better Make It A Double

Synthesizing nanomaterials consisting of two-particle pairs, or dimers, is no longer a headache. Hongyu Chen and coworkers from Nanjing Tech University, China recently developed a protocol that can produce gold dimers with a record high yield. This breakthrough is published in Chem. Commun.

Dimers are suitable platforms to study the effects of particle-particle interactions on the electrical and optical properties of the constituent materials. Unfortunately, no conventional synthesis methods to exclusively produce dimers from single particles have been successful. This is because of the uncontrollable particle-aggregation rate that leads to the formation of multi-particle clusters. Therefore, how to couple single particles into dimers without triggering their further aggregation has become a tough nut to crack.

Chen and coworkers found a solution by developing a polymer-assisted method that generates gold dimers with high yield. Firstly, they encapsulated individual gold nanoparticles with polymer shells made of polystyrene-b-poly(acrylic acid). Under optimized conditions, the gold nanoparticles were mostly coupled into dimers (Figure 1), achieving a dimer yield of 65%. This is the highest dimer yield achieved for one-step synthesis methods.

Figure 1. (a) A transmission electron microscopy (TEM) image of the polymer-encapsulated gold single particles. (b) A TEM image and (c) a scanning electron microscopy image of the synthesized gold dimers. All scale bars are 200 nm.

The key to this success is due to three factors: temperature, solvent composition and acid concentration. All these factors can change the strength of the repulsion force among the polymer shells. The force must be meticulously tuned to a level that is weak enough to induce 1-to-1 coupling, but strong enough to prevent 1-to-multiple or multiple-to-multiple aggregation. Through a set of control experiments, the authors identified the optimal conditions to be 60 oC, dimethylformamide/water (v/v)=6:1 and 5 mM of hydrochloric acid.

The method demonstrated herein could be extended to other particles. It may also inspire versatile synthesis strategies towards complex nanostructures with high selectivity.

 

To find out more please read:

Controllable Oligomerization: Defying Step-Growth Kinetics in the Polymerization of Gold Nanoparticles

Xuejun Cheng, Gui Zhao, Yan Lu, Miao Yan, Hong Wang and Hongyu Chen

Chem. Sci., 2018, DOI: 10.1039/C8CC03424A

 

About the blogger:

Tianyu Liu obtained his Ph.D. (2017) in Physical 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/.

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

ChemComm poster prize winner at the 2018 European Materials Research Society Spring Meeting

The 2018 European Materials Research Society (EMRS) Spring Meeting was held from the 18th – 22nd June in the Strasbourg Convention Centre in France.

The EMRS Spring Meeting is the society’s major conference and covers all aspects of materials science including energy and environment, biomaterials, semiconductors, nanomaterials, functional materials, and materials processing and characterization. It offers on average 25 topical symposia and is widely recognised as being of the highest international significance, with approximately 2,500 attendees every year.

ChemComm is proud to announce that the ChemComm poster prize was awarded to Dr Manal Alkhamisi from the University of Nottingham (School of Physics and Astronomy) for ‘The Growth and Fluorescence of Phthalocyanine Monolayers and Thin Films on Hexagonal Boron Nitride’. Manal was awarded the prize by ChemComm Associate Editor Steven De Feyter.

Well done Manal!

 

ChemComm Associate Editor Steven De Feyter (left) awarding the poster prize to Dr Manal Alkhamisi (right)

 

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

Come for the colour changing crystals, stay for the science

Synthesis of copper bimetallic complexes from imidazolyl ligands, and the solvatochromic materials formed upon crystallization and solvent guest-exchange. The solvatochromic behaviour was quantified with visible-region diffuse reflectance spectra.

Synthesis of copper bimetallic complexes from imidazolyl ligands, and the solvatochromic materials formed upon crystallization and solvent guest-exchange. The solvatochromic behaviour was quantified with visible-region diffuse reflectance spectra.

During the first inorganic chemistry course I took during my undergraduate degree, our professor started the class by passing around some mineral samples, promising us that if we pursued the chemistry of metals we could work with beautifully coloured crystals every day. At the time, colour seemed like such a trite detail amongst the complexity of the subject. Why would you choose a field of study based on something so simple? Well, after a PhD dominated by pale yellow oils, I think I get it now.

Nikolayenko and Barbour at the University of Stellenbosch in South Africa bring us colour! The authors synthesised organometallic copper complexes, which crystallise to form porous single crystals that drastically change colour upon absorption of various solvents. The authors investigated the solvatochromic mechanism using X-ray crystallography, EPR, UV-visible spectroscopy and DFT calculations. Solvatochromic materials are not just made to look pretty; they have potential to be used as sensitive, selective and recyclable sensors to detect solvent vapours with useful applications in industrial process risk management, chemical threat detection and environmental monitoring.

The researchers synthesised a series of complexes comprised of a bidentate ligand with 2-methylimidazolyl groups coordinated to copper(II) ions. The complexes stack to form channels in the crystal, capable of trapping solvent molecules to give different coloured crystals: DMSO and THF-containing crystals are green (λmax = 574 nm and 540 nm, respectively), those containing acetonitrile are red (λmax = 624 nm), and crystals trapping acetone, ether and pentane are yellow (λmax = 588), orange (λmax = 598 nm) and red/brown (λmax = 592 nm), respectively.

The authors revealed a correlation between the size of the solvent guest, coordination geometry of the copper complex, and the ligand field splitting. Small guests such as acetonitrile minimally perturb the metallocyclic framework, preserving a rhombic ligand field geometry (large δxy of g values in the EPR spectrum), small ligand d-orbital splitting and red-shifted optical spectra. Large guests such as THF have the opposite effect, giving ligand field geometries approaching tetragonal (small δxy), large ligand field d-orbital splitting and blue-shifted optical spectra.

By delving into the complexity beneath a seemingly simple phenomenon, Nikolayenko, Barbour and their co-workers have shown using a series of single-crystal complexes that there is nothing simple about colour (and nothing trite about detail).

To find out more please read:

Supramolecular solvatochromism: mechanistic insight from crystallography, spectroscopy, and theory

Varvara I. Nikolayenko, Lisa M. van Wyk, Orde Q. Munro, Leonard J. Barbour.
Chem. Commun., 2018, Advance Article
DOI: 10.1039/c8cc02197j

About the author

Zoë Hearne is a PhD candidate in chemistry at McGill University in Montréal, Canada, under the supervision of Professor Chao-Jun Li. She hails from Canberra, Australia, where she completed her undergraduate degree. Her current research focuses on transition metal catalysis to effect novel transformations, and out of the lab she is an enthusiastic chemistry tutor and science communicator.

 

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

Pt3Ni-Coated Palladium Nano-branches Outperformed Pt in Catalyzing Ethanol Oxidation

Researchers in China recently developed a new Pd-based catalyst that outperformed Pt, the benchmark catalyst for electrochemical oxidation of ethanol. This catalyst, synthesized by a one-pot chemical reduction method, consists of branched Pd nanocrystals coated with thin Pt3Ni shells.

The ethanol oxidation reaction (EOR) is a typical anode reaction that drives the energy output from fuel cells. Due to its intrinsically slow kinetics, the reaction requires proper EOR catalysts to facilitate the oxidation. Pt-based materials are highly active in promoting EOR, but the scarcity of Pt leads to high costs and demands efficient methods to recycle these materials. In addition, the instable catalytic activity of Pt significantly reduces the lifetime of EOR catalysts containing Pt. Clearly, developing inexpensive EOR catalysts with comparable performance to Pt is meaningful for the affordability and durability of fuel cells.

A research team led by Shuifen Xie at Huaqiao University and Shenzhen Research Institute of Xiamen University in China, have demonstrated a one-pot chemical reduction method of a novel EOR catalyst. This catalyst is made of Pt3Ni-coated Pd nanocrystals as shown in Figure 1. There are three main advantages for this catalyst over the benchmark Pt: Firstly, the core material Pd is more affordable. Secondly, the ultrathin Pt-alloy coating, Pt3Ni, contains relatively less Pt and is reported to exhibit high EOR catalytic activity. Thirdly, the little lattice mismatch between Pt and Pd allows seamless integration of the two metals that is beneficial to preserve the structural integrity and ensure excellent durability.

Figure 1. (a) The schematic illustration showing the key steps of the one-pot chemical reduction method. The catalyst is formed via consecutive reduction of Pd2+, Pt2+ and Ni2+ to Pd nano-branches, Pt nanoparticles and Pt3Ni coatings, respectively. (b) A TEM image of a representative morphology of a branched nanocrystal. (c) Elemental mappings depict that Pt and Ni elements exist mainly in the shell while Pd is in the core.

Electrochemical characterizations revealed that the catalytic performance of the Pt3Ni-coated Pd nanocrystals outperformed those of two commercial catalysts: Pt/C (Pt particles supported on activated carbon) and Pd black (a fine powder elemental Pd). Figure 2a compares the linear-sweep voltammograms of the three samples. The synthesized catalyst showed appreciably enhanced oxidation current at potentials beyond 0.4 V vs. RHE. The histograms in Figure 2b clearly display that the mass activity and the specific activity of the synthesized nanocrystals are the highest. The authors ascribed the superior performance to the high surface area (42.50 m2 g-1), the ultrathin Pt3Ni coating with its {111} crystal planes exposed, and the core-shell configuration.

Figure 2. (a) Linear-sweep voltammograms of the synthesized catalyst (Pd@Pt3Ni/C), Pt/C and Pd black. (b) The comparison of mass activity (i.e. oxidation current normalized to the masses of the catalysts) and specific activity (i.e. oxidation current normalized to the areas of the catalysts) of Pd@Pt3Ni/C, Pt/C and Pd black.

This work signifies the feasibility of Pd-based nano-catalysts as alternatives to Pt towards catalyzing EOR. It is also expected to encourage the effort in developing a diverse array of inexpensive and high-performance catalysts for other reactions pertaining to fuel cells, including but not limited to oxidation of fuels other than ethanol and oxygen reduction reactions.

To find out more please read:

One-Pot Synthesis of Pd@Pt3Ni Core-Shell Nanobranches with Ultrathin Pt3Ni{111} Skins for Efficient Ethanol Electrooxidation

Yuanyuan Wang, Wei Wang, Fei Xue, Yong Cheng, Kai Liu, Qiaobao Zhang, Maochang Liu and Shuifen Xie

Chem. Commun., 2018, DOI: 10.1039/c8cc02816h

About the blogger:

Tianyu Liu obtained his Ph.D. (2017) in Physical 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/.

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)