Fueling the Zero-Carbon Future through Earth Abundant Catalysts
Technical advancements, government policy, private sector progress, and individual choices all must come together to help reduce energy consumption and carbon output. At the right time and place, certain actions can serve as catalysts to achieve real change toward achieving these goals.
When conditions are right, electrocatalysts can do the same for chemical reactions. At the core, a catalyst saves energy in any process it is present in. Catalysis is essential for the chemical industry, a major contributor to 90% of all industrial chemicals produced. Over 30% of the global GDP depends on catalysis.
In addition to relying heavily on fossil fuels for energy, today’s infrastructure requires fossil fuels for chemical inputs to supply the carbon, hydrogen, and power needed to produce the majority of items that we use in our daily lives. The finite supply of fossil fuels, and the CO2 emissions they produce create a need for a cleaner, more stable energy source. Earth-abundant electrocatalysis can fill this need by enabling the creation of clean fuel from captured CO2 and H2O.
For example, creating fuel products from H2O and CO2 molecules requires catalysts to perform very different tasks. H2O molecules must be split through electrolysis, while CO2 needs to be activated and selectively converted into higher carbon chain products.
By combining the resulting carbon in CO2 and hydrogen from H2O, catalysts and renewable electricity can be used to create just about any fuel imaginable. If we use these abundant materials as carbon and hydrogen sources and rely on renewables instead of fossil fuels for energy, we can begin to move toward a circular energy economy. Abundant and effective catalysts are crucial to scale this type of production, feed into carbon-neutral energy infrastructure, and fulfill the promising outlook on electrocatalysis. This circular energy economy powered by renewables and catalysis is the vision that JCDREAM is working toward.
Currently, the most popular catalysts come from the platinum group on the periodic table. Platinum group metals (PGMs) are a group of six elements that are both structurally and chemically similar. They are platinum, palladium, rhodium, iridium, ruthenium, and osmium. PGMs are highly valued for their wide range of applications. These metals are found in products we use every day, in the catalytic converter of your car, the medications you take, and countless electronic devices. They also play an important role in fertilizer production that has helped to sustain exponential population growth in the 20th century.
Because of their efficacy in so many applications, PGMs are in high demand. This demand has escalated to the point that mining alone does not supply enough to meet these needs. According to the U.S. Geological Survey, recycled platinum, palladium, and rhodium obtained from jewelry, electronics, and catalytic converters provided up to 24% of global platinum and palladium supply and about 27% of global rhodium supply in 2011.
The U.S. Geological Survey’s 2014 Platinum Group Elements Fact Sheet describes why it is so difficult to locate productive deposits of PGMs for mining:
- The Earth’s upper crust contains only about 0.0005 parts per million (ppm) platinum.
- The average grade of platinum-group elements (PGEs) in ores mined for their PGE concentrations ranges from 5 to 15 ppm.
- In most rocks, platinum-group minerals range in size from less than a micron to a few hundred microns in diameter, so the presence of PGEs must be confirmed by laboratory analysis.
- Over 100 minerals contain PGEs as an essential component.
Already, this is an issue of mismatched supply and demand. Growth in the world’s consumption of goods and technology and a push toward cleaner energy supply put even more stress on the supply chain of PGMs.
So again, we need to work on stabilizing the supply chain through recycling and pursuing alternatives. Part of what makes PGMs so challenging is the difficulty of substitution, but difficulty does not mean it is impossible. Thankfully many other more common transition metals like iron or nickel can be altered to achieve equal or better efficacy than PGMs by precisely modifying their electronic and/or chemical structures.
Professor Yuehe Lin of Washington State University has made significant strides in earth-abundant catalysts by creating a Nickel-Iron nanofoam for splitting water that is more effective than the typical Iridium oxide currently in use commercially.
Significant work is already being done to increase efficiency, find alternatives, and generally use catalysis to create cleaner energy streams. In Washington State alone, there are several scientists making impressive strides in the field. For example, in a new project funded by JCDREAM, Professor Yong Wang is working with major industry partner ADM to develop novel carbon-neutral fuels using earth-abundant catalysts.
One hurdle to overcome when using non-precious metals in lieu of PGMs is the formation of metal oxides – commonly known as rust. Rusting slows important chemical reactions and lowers the efficiency of catalysts. WSU Professors Jean-Sabin McEwen and Yong Wang have made progress in preventing this from happening to iron-based catalysts used in bio-based fuel production in order to maintain higher levels of efficiency.
Another opportunity is pursuing more efficient use of PGMs, and single atoms of PGMs have been found to be even more effective than bulk material. Using these catalysts as single atoms allows us to stretch our resources. Work by the same team at WSU has successfully demonstrated that single atoms of platinum strategically placed on copper oxide are able to replace bulk platinum in vehicle catalytic converters, which prevent carbon monoxide emissions in our gasoline-powered cars.
Formic acid – as being explored by OCO Inc – can be used as fuel in a circular CO2 energy economy. It has a chemical formula of HCOOH – or quite literally H2 + CO2 – and can be used as a fuel in certain fuel cell systems. Typically, the production of H2 from formic acid required palladium catalysts, but work by Su Ha has replaced the precious metal with molybdenum, a much more abundant resource.
These advances – and many more to come – can be implemented in the pursuit of cleaner fuels and ways to consume fuels more efficiently. Catalysis researchers in Washington are showing how there are various angles from which we can tackle this issue. Recycling, substitution with earth-abundant alternatives, and efficiency improvements for PGMs will all help to balance the supply and demand of these critical metals and vastly improve the supply reliability for catalysts.
On November 10th, 2020, JCDREAM is hosting Dr. Jean-Sabin McEwen and Dr. Steve Ciatti for talks on how we can use electrocatalysts to meet the energy needs of heavy-duty transportation in the pursuit of decarbonization. Ciatti is a Principal Engineer at PACCAR and will bring the industry perspective from the PACCAR Technical Center where they have worked tirelessly to electrify or otherwise reduce the carbon impact of their trucks. McEwen brings a wealth of knowledge in catalysis for sustainability and will share how much of the research in catalysis offers promising solutions to these problems, and how to address the issue of scale.