PCCP Blog

A new dispenser and scanner system has been developed that creates and screens arrays of different metal oxides, assessing there suitability for photocatalytic water-splitting reactions. The technique operates in a combinatorial fashion and has been used to screen over 3000 unique Bi:M:Cu atomic ratios, where M represents one of 22 post-transition metals.

Of the 22 metals tested, 10 were found to have a M-Cu oxide with higher photochemical activity than CuO, while 10 had a Bi-M-Cu oxide with more activity than CuBi₂O₄. The best performing combination was BiAgCu oxide with the ratio 22:3:11, which produced a photocurrent four times that of CuBi₂O_4. The material was capable of evolving hydrogen from neutral electrolyte solutions under illumination at 0.6V vs RHE when platinum was added as an electrocatalyst.

Read the full details of this fascinating PCCP article:

Screening of transition and post-transition metals to incorporate into copper oxide and copper bismuth oxide for photoelectrochemical hydrogen evolution
Sean P. Berglund, Heung Chan Lee, Paul D. Núñez, Allen J. Bard and C. Buddie Mullins
DOI: 10.1039/C3CP50540E

Scientists in Germany and the USA report a method for measuring pulsed electron paramagnetic resonance (EPR) spectra using a free-electron laser as a radiation source in their Physical Chemistry Chemical Physics (PCCP) article. The high power afforded by the laser enables EPR experiments to be carried out at 240GHz, which significantly enhances the sensitivity of the technique.

The authors of the study have solved the problem of random phase shifts of the free-electron pulse using retrospective data processing, and are able to control phases between pulses, enabling two-pulse experiments that are fundamental to EPR.

Read about this exciting development today:

Phase cycling with a 240 GHz, free electron laser-powered electron paramagnetic resonance spectrometer
Devin T Edwards, Yun Zhang, Steffen J Glaser, Songi Han and Mark Sherwin
DOI: 10.1039/C3CP44492A

This paper from the group of Matthias Arenz at the Nano-Science Center at the University of Copenhagen may prove crucial for comparing catalysts and catalyst matrices for low temperature fuel cells.

In “Pt based PEMFC catalysts prepared from colloidal particle suspensions – a toolbox for model studies” Speder and co-workers demonstrate the applicability of their approach to catalyst fabrication in a model study. The key result is that their catalyst synthesis allow for accurate comparison of different catalyst systems as their procedures are reproducible and yield consistent results.

Fuel cell catalysts on solid supports have been difficult to compare, as the means of their preparation introduce differences, often larger than those variations resulting from the parameter under study. The work summarized in this paper opens a way around this issue, making comparative study feasible. Of this reason alone you should have a look at the paper. On top of that you get the interesting result regarding the anchoring of Pt catalyst particles to the carbon support.

by Dr Thomas Just Sørensen

Read the full details of this HOT PCCP article today:

Pt based PEMFC catalysts prepared from colloidal particle suspensions – a toolbox for model studies
Jozsef Speder, Lena Altmann, Melanie Roefzaad, Marcus Bäumer, Jacob J. K. Kirkensgaard, Kell Mortensen and Matthias Arenz
DOI: 10.1039/C3CP50195G

Japanese scientists have carefully tailored the anion and cation to create of  a new class of ILs which are both strongly hydrophobic and can also hydrogen bond effectively.

The authors found that tetra-n-octylphosphonium paired with ethylphosphonate or n-butylphosphonate were able to form a stable seperate phase after mixing with water while also showing hydrogen bonding characteristics.

This family of ILs could potentially  be used in environmentally friendly separation processes.

Read this exciting PCCP article in full:

Hydrophobic and polar ionic liquids
Yukinobu Fukaya and Hiroyuki Ohno
DOI: 10.1039/C3CP44214D

If you liked this you may also enjoy our recent PCCP themed issue on Interfaces of Ionic Liquids Guest Edited by Professor Frank Endres.

The motivation for this paper from the lab of Douglas B. Chrisey on the formation of silver nanostructures by laser ablation could be either scientific of aesthetic. Although I am sure that Yan and co-workers uses a purely scientific approach, the beauty of the images cannot be denied. Nanoscopic sheets, needles, cubes and stars have been made without any form of surface decoration; simply employing clean water, pure silver and an immensely powerful laser.

Complex silver-nanostructures are commonly prepared by using surfactants to induce a specific shape. Some applications require ‘naked’ silver surfaces, which in turn require alternative routes for preparation of silver structures. By using pulsed laser ablation in liquid the authors of this paper are capable of producing a variety of differently shaped silver-nanostructures, without the aid of additives. The fundamentals behind the parent technique can be found in the book “Pulsed Laser Deposition of Thin Films” by Douglas B. Chrisey and Graham K. Hubler, where the cutting edge is represented by this paper in PCCP:

Generation of Ag–Ag₂O complex nanostructures by excimer laser ablation of Ag in water
Zijie Yan, Ruqiang Bao and Douglas B. Chrisey
DOI: 10.1039/C2CP42668D

by Dr Thomas Just Sørensen

Heterogenic catalysis and the oxidation of carbon monoxide to carbon dioxide would generally not qualify as interesting in my book. But this piece of work from the group of Professor Ib Chorkendorff fascinates me, as does all phenomena where an process appears to be oscillating without external stimulus to do so.

A delicate balance of chemical equilibria is found to be responsible for the oscillations observed by Jensen and co-workers, and in the paper they are able to account for their findings.

They found the oscillations as they were studying the oxidation of CO to CO₂ in an O₂ rich atmosphere. The oxidation is catalysed by platinum; in this work they use Pt-particles of a similar size on a silicon oxide surface. This fact is found to be decisive, as the oscillations only occur if particles are used.

For a full explanation I must refer to:

Self-sustained carbon monoxide oxidation oscillations on size-selected platinum nanoparticles at atmospheric pressure
Robert Jensen, Thomas Andersen, Anders Nierhoff, Thomas Pedersen, Ole Hansen, Søren Dahl and Ib Chorkendorff
DOI: 10.1039/C2CP43684A

by Dr Thomas Just Sørensen