New research advances clean energy solutions

Ring-shaped molecules known as porphyrins have potential as effective catalyst

September 3, 2021

Meeting society’s growing energy needs has become a daunting challenge for humanity. Demands for energy are expected to nearly double by the year 2050, while the effects of climate change, caused by the burning of fossil fuels, are already wreaking havoc in the form of droughts, wildfires, floods and other disasters.

Gary Moore, a researcher at Arizona State University's Biodesign Center for Applied Structural Discovery and ASU's School of Molecular Sciences thinks chemistry will play a vital role in the development of clean solutions to the world’s mounting energy dilemma. Gary Moore and his colleagues describe the use of ring-shaped molecules known as porphyrins, seen in this graphic. Such molecules, among the most abundant pigments in nature, are noted for their ability to speed up or catalyze chemical reactions, including important reactions occurring in living systems. They are useful components for the design of artificial photosynthetic systems. Cover graphic for the journal by Jason Drees Download Full Image

In new research appearing on the cover of the journal ChemElectroChem, Moore and his colleagues describe the use of ring-shaped molecules known as porphyrins. Such molecules, among the most abundant pigments in nature, are noted for their ability to speed up or catalyze chemical reactions, including important reactions occurring in living systems.

Among these reactions is the conversion of radiant energy from the sun into chemical energy stored in molecular bonds, a process exploited by plants and photosynthetic microbes. This chemical energy can then be used to fuel the organism’s metabolism, through the process of cellular respiration.

Researchers like Moore hope to take a page from nature’s playbook, creating synthetic analogs to natural processes of photosynthesis. The new study describes a synthetic diiron-containing porphyrin and explores its potential as an effective catalyst.

Gary Moore is a researcher at the Biodesign Center for Applied Structural Discovery. Photo by Biodesign Institute

“Rather than exploiting the products of natural photosynthesis, we can be inspired by our knowledge of photosynthesis to pioneer new materials and technologies with properties and capabilities rivalling those of their biological counterparts,” Moore said.

Porphyrins, and their structurally related analogs, are found in abundance across the biological world. They act to bind a range of metal ions to perform far-flung cellular tasks. Chlorophyll molecules, for example, bind magnesium (a crucial chemical stage in plant photosynthesis), while heme – an iron-containing porphyrin — helps organize molecular oxygen and carbon-dioxide transport and provides the necessary electron-transport chains essential for cellular respiration. Because of their commanding role in life processes, porphyrin abnormalities are responsible for a range of serious diseases.

Porphyrins can also be used as catalysts in synthetic devices known as electrochemical cells, which convert chemical energy into electrical energy, or vice versa. Although radiant energy from the sun may be stored within conventional types of batteries, such applications are limited by their low-energy densities compared with fuels used for modern transportation.

Moore’s efforts to design artificial photosynthetic systems could provide a valuable piece of the renewable energy puzzle, producing “non-fossil-based” fuels as well as a range of beneficial commodities.

Such devices would allow the capture and storage of solar energy for use when and where it is needed and can be constructed using chemicals that are far cheaper and more abundant than the materials currently in use for conventional solar energy applications.

The paper has been selected for the cover of the current issue of the journal, with a descriptive graphic produced by Jason Drees, multimedia developer lead at ASU, and is part of a special collection dedicated to Professor Jean-Michel Savéant.

Richard Harth

Science writer, Biodesign Institute at ASU


ASU researchers bring a new twist to 2D magnets

September 3, 2021

The discovery of graphene — a single layer of graphite, also known as charcoal — revolutionized our understanding of low-dimensional materials and unraveled their potential for applications in quantum technologies.

We now have a library of 2D materials with outstanding capabilities. Thanks to their weak chemical bonding, it is also possible to combine different types of 2D materials — like 2D Lego bricks — to engineer unique properties. Left: Top view of two types of orientations of Cr-trihalide bilayer materials. Right: Moiré pattern emerges when two layers are twisted with respect to each other. This creates a moiré field and can lead to skyrmions. Figure adapted with permission from Nano Lett. 2021, 21, 15, 6633-6639. Copyright 2021 American Chemical Society Download Full Image

One of the new editions to the catalog of properties available in 2D materials is magnetism: Utilizing and manipulating magnetism is crucial for quantum applications.

A team of researchers from ASU shows in a recent manuscript published in Nano Letters, titled "Moiré Skyrmions and Chiral Magnetic Phases in Twisted CrX3 (X = I,Br, and Cl) Bilayers," that twisting two-dimensional magnets such as Cr-trihallides can lead to new magnetic phenomena such as skyrmions. Skyrmions are hedgehog-like arrays of magnetic moments with potential applications in memory devices.

“Twisting two-dimensional materials lead to large-scale structures called moiré patterns. Moiré patterns can significantly modify the properties of materials and give rise to new emergent phases,” said Antia Botana, an assistant professor in the Department of Physics. “Skyrmions have been sought after for a long time in 2D magnets. We are excited to show that Cr-based trihalides can be platform to realize them.”

“Employing complementary approaches is crucial to address complex phenomena in varying length scales,” said Onur Erten, an assistant professor in the Department of Physics. “It would not be possible to conduct this project without the combined expertise of both groups.”

Botana and Erten emphasize the key role of the graduate students in this project. This work is supported by National Science Foundation, Division of Materials Research Award No. DMR 1904716.

Kiersten Moss

Marketing Assistant, Department of Physics