Tag: catalysts

Tender X-rays show how one of nature’s strongest bonds breaks

Tender X-rays show how one of nature’s strongest bonds breaks

Short flashes of an unusual kind of X-ray light at SwissFEL and SLS bring scientists closer to developing better catalysts to transform the greenhouse gas methane into a less harmful chemical. The result, published in the journal Science, reveals for the first time how carbon-hydrogen bonds of alkanes break and how the catalyst works in this reaction.

Methane, one of the most potent greenhouse gases, is being released into the atmosphere at an increasing rate by livestock farming as well as the continuing unfreezing of permafrost. Transforming methane and longer-chain alkanes into less harmful and in fact useful chemicals would remove the associated threats, and in turn make available a huge feedstock for the chemical industry. However, transforming methane necessitates as a first step the breaking of a C-H bond, one of the strongest chemical linkages in nature.

Forty years ago, molecular metal catalysts were discovered that can easily split C-H bonds. The only thing found to be necessary was a short flash of visible light to “switch on” the catalyst and – bafflingly – the strong C-H bonds of alkanes passing nearby were easily broken almost without using any energy. Despite the importance of this so-called C-H activation reaction, it has remained unknown how that catalyst performs this function. Now, experiments at Swiss FEL and SLS have enabled a research team led by scientists at Uppsala University to directly watch the catalyst at work and reveal how it breaks the C-H bonds.

Read more on the PSI website

Image: An X-ray flash illuminates a molecule

Credit: University of Uppsala / Raphael Jay

How a record-breaking copper catalyst converts CO2 into liquid fuels

How a record-breaking copper catalyst converts CO2 into liquid fuels

Researchers at Berkeley Lab, collaborating with CHESS scientists at the PIPOXS beamline, have made the first real-time movies of copper nanoparticles as they evolve to convert carbon dioxide and water into renewable fuels and chemicals. Their new insights could help advance the next generation of solar fuels.

Since the 1970s, scientists have known that copper has a special ability to recycle carbon dioxide into valuable chemicals and fuels. But for many years, scientists have struggled to understand how this common metal works as an electrocatalyst, a mechanism that uses energy from electrons to chemically transform molecules into different products.

Now, a research team led by Lawrence Berkeley National Laboratory (Berkeley Lab) has gained new insight by capturing the world’s first real-time movies of copper nanoparticles (copper particles engineered at the scale of a billionth of a meter) as they convert CO2 and water into renewable fuels and chemicals: ethylene, ethanol, and propanol, among others. The work was reported in the journal Nature.

“This is very exciting. After decades of work, we’re finally able to show – with undeniable proof – how copper electrocatalysts excel in CO2 reduction,” said Peidong Yang, a senior faculty scientist in Berkeley Lab’s Materials Sciences and Chemical Sciences Divisions who led the study. Yang is also a professor of chemistry and materials science and engineering at UC Berkeley. “Knowing why copper is such an excellent electrocatalyst brings us steps closer to turning CO2 into new, renewable solar fuels through artificial photosynthesis.”

Read more on the CHESS website

Image: Artist’s rendering of a copper nanoparticle as it evolves during CO2 electrolysis: Copper nanoparticles (left) combine into larger metallic copper “nanograins” (right) within seconds of the electrochemical reaction, reducing CO2 into new multicarbon products.

Credit: Yao Yang/Berkeley Lab

Building better catalysts to close the carbon dioxide loop

Building better catalysts to close the carbon dioxide loop

The best way to stave off the worst effects of climate change is to reduce CO2 emissions around the world. And one way to do that, says Zhongwei Chen, a professor in the Department of Chemical Engineering at the University of Waterloo, is to capture the CO2 and convert it into other useful chemicals, such as methanol and methane for fuels. Stopping emissions at the source, and further reducing future ones by replacing CO2-producing fuels with cleaner ones “…is a way to close the circle,” Chen says.

In order to turn CO2 into methanol, you need a catalyst to jump-start the electrochemical reaction. Traditionally, these catalysts have either been made out of precious metals like gold or palladium, or base metals like copper or tin. However, they are expensive and break down easily, hindering large-scale implementation. “Right now we can’t meet industrial requirements,” says Chen, who holds a Canada Research Chair. “So we are trying to design catalysts with better activity, selectivity, and durability.”

Read more on the CLS website

Image: Chithra Karunakaran on the SM beamline at the Canadian Light Source

Credit: David Stobbe

Arranging gold nanoparticles precisely in three dimensions

Arranging gold nanoparticles precisely in three dimensions

Metal nanoparticles have a wide variety of applications many of which stem from the fact that extremely small particles a few nanometres to  10’s of nanometres in diameter can have very different properties from those of the same material at a larger scale (a nanometre is just a billionth of a metre). Such particles are used as catalysts, coloring agents and can even  make antibacterial coatings. Some effects are due to the pattern of the particles and the spacing between them, but these are very difficult to control and particles are typically used in solution where they randomly move around like motes of dust in the air.   

In the current work, scientists based at the Bionanoscience and Biochemistry Laboratory at the Malopolska Centre of Biotechnology (MCB), Jagiellonian University showed that an artificial protein structure, a hollow sphere called a TRAP-cage, was able to act as a scaffold and provide regular-spaced points of attachment for small gold nanoparticles. “TRAP-cage is itself tiny, but at around 15 nm in diameter is still big enough to attach multiple  gold nanoparticles” explained Jonathan Heddle the head of the lab, “The protein cage is made of 12 rings, so overall it looks a little like a 12-sided dice – a dodecahedron.”  The researchers showed that there are spaces equivalent to the corners of the dodecahedron that offer just the right environment to snugly fit the gold nanoparticles inside. As a result, instead of randomly floating around, the particles appear to be constrained into a fixed three-dimensional pattern. It is hoped that the ability to arrange metal nanoparticles in this way may be developed further to produce new materials with useful properties.

Read more on the SOLARIS website

Image: The structure of the protein cage (purple) with three of the embedded gold nanoparticles highlighted (yellow) 

Credit: Jonathan Heddle

Nonprecious transition metal nitrides as efficient oxygen reduction electrocatalysts for alkaline fuel cells

Nonprecious transition metal nitrides as efficient oxygen reduction electrocatalysts for alkaline fuel cells

CHEXS users have discovered a class of nonprecious metal derivatives that can catalyze fuel cell reactions about as well as platinum, at a fraction of the cost. A critical part of the fuel cell is the oxygen reduction reaction, an infamously sluggish process that is traditionally sped up by platinum and other precious metals. Now, in a new paper appearing in the journal Science Advances, a team lead by Héctor Abruña (the Émile M. Chamot Professor of Chemistry and Chemical Biology at Cornell University), have reported a new cobalt nitride catalyst material with near identical efficiency to platinum while costing 475 times less (as of February 2022). Carbon-supported cobalt nitride (Co3N/C) achieved a record-high peak power density among reported nitride cathode catalysts of 700 mW cm−2 in alkaline membrane electrode assemblies. The material was demonstrated to remain stable below 1.0V potentials inside working fuel cells, using operando x-ray spectroscopy at the PIPOXS beamline. Operando XANES and EXAFS (A,B) show dramatic changes in valence and bond lengths for potentials above 1V, while below 1V the material remains stable (C,D).

Read more on the CHESS website

New 12 T magnet strengthens energy and magnetism research

New 12 T magnet strengthens energy and magnetism research

Electron paramagnetic resonance (THz-EPR) at BESSY II provides important information on the electronic structure of novel magnetic materials and catalysts. In mid-January 2022, the researchers brought a new, superconducting 12-T magnet into operation at this end station, which promises new scientific insights.

At the THz-EPR end station, unique experimental conditions are provided through a combination of coherent THz-light from BESSY II and high magnetic fields. These capabilities have now been extended by a new superconducting 12 T magnet, acquired through funding from the BMBF network project “ERP-on-a-Chip” and HZB.

Read more on the HZB website

Image: Exhausted but happy: f.l.t.r. – K. Holldack (HZB), A. Schnegg (MPI CEC Mülheim, HZB), T. Lohmiller (HZB, HUB), D. Ponwitz (HZB) after the successful commissioning of the new 12T magnet (green).