The Catalyst Review February 2020 - 17

EXPERIMENTAL
well as in oxygen reduction reactions, was demonstrated by citrate
nanoparticles. Moreover, their efficiency was only half the efficiency
of a platinum catalyst, which significantly exceeds the gold analogue
in cost. The study of the structures showed that gold nanoparticles
with citrate lost some of their ligands, while nanoparticles with
cetyltrimethylammonium bromide (CTAB) and mercaptoundecanoic
acid (MUA) remained almost unchanged. This may be due to the
different strength of the bonds between gold and organic ligands. To
test the stability, which is one of the most important characteristics
of the catalysts, all samples were tested for 12 hours under a
voltage that significantly exceeded the optimum. All nanoparticles
retained their structure after testing; moreover, gold nanoparticles
with citrate improved their electrocatalytic characteristics. This
may indicate that new types of catalysts will work effectively under
continuous operation. Due to the stability of the new catalysts,
these have an interesting potential to be employed in industry in
the future. The ligand exchange method developed by the chemists
can find application in the synthesis of catalysts with predetermined
properties suitable for renewable hydrogen-based energy sources.
Source: PhysOrg, 2/4/2020.
Chemistry Finding Could Make Solar Energy More Efficient...
Scientists for the first time have developed a single molecule that can absorb sunlight efficiently and also act as a catalyst to
transform solar energy into hydrogen. This new molecule collects energy from the entire visible spectrum and can harness more
than 50% more solar energy than current solar cells can. The researchers outlined their findings in a study published today in Nature
Chemistry. The research team was led by Claudia Turro, a chemistry professor and director of The Ohio State University Center for
Chemical and Biophysical Dynamics. The researchers showed, for the first time, that it is possible to collect energy from the entire
visible spectrum of sunlight - including low-energy infrared, a part of the solar spectrum that previously had been difficult to
collect - and transform it, quickly and efficiently, into hydrogen. Most previous attempts to collect solar energy and turn it into
hydrogen have focused on the higher-energy wavelengths of sunlight - think ultraviolet rays, for example. Previous attempts also
have relied on catalysts that are built from two or more molecules. But energy is lost in the exchange, making those multi-molecule
systems less efficient. The few attempts that relied on a single-molecule catalyst were also inefficient, Turro said, in part because
they did not collect energy from the full visible spectrum of sunlight, and in part because the catalysts themselves degraded quickly.
Turro's research team figured out how to make a catalyst out of just one molecule - a form of the element rhodium - which means
less energy is lost, she said. And they figured out how to collect energy from infrared to ultraviolent - the entire visible spectrum.
The system this research team designed is nearly 25 times more efficient with low-energy near-infrared light than previous singlemolecule systems operative with ultraviolet photons, according to the study. In the study, the researchers used LEDs to shine light
onto acid solutions containing the active molecule. When they did, they found that hydrogen was produced. Source: Ohio State
University, 1/20/2020.
Catalytic Protocells Get Zingy...
In a new study published in the journal Nature Communications, an international research team, led by University of Bristol
chemists, used two different types of catalysts to develop a new type of artificial cell capable of decomposing hydrogen peroxide and
generating oxygen. The team used a ruthenium-based inorganic catalyst in the form of a synthetic enzyme (synzyme) as a membrane
structuring agent to generate copious amounts of oxygen bubbles that they then exploited to construct synzyme-driven buoyant
microcapsules. In addition, the natural enzyme horseradish peroxidase was captured inside the protocells so that the synthetic and
biological catalysts competed for hydrogen peroxide present in the solution. The team used the antagonistic arrangement of the
two catalysts to implement a rudimentary chemical signalling pathway between members of an artificial protocell community that
were dispersed in solution or trapped within small droplets. Professor Marcella Bonchio, from the University of Padua, said: "As the
ruthenium-based catalyst has significant potential in bio-inspired catalysis, it seems feasible that communities of synzyme protocells
could provide a step towards synthetic metabolic networks based on light-activated stimuli." Professor Stephen Mann from the
University of Bristol's School of Chemistry, added: "Our results highlight a new type of catalytic micro-compartment with multifunctional activity and provide a step towards the development of protocell reaction networks." Source: EurkeAlert!, 1/8/2020.
The Catalyst Review

February 2020

The Catalyst Review February 2020

Table of Contents for the Digital Edition of The Catalyst Review February 2020