Recent scientific investigations have precisely characterized the process of hydrogen spillover, initially identified in 1964, where hydrogen atoms transition from a metallic catalyst to an oxide substrate. These revelations, which attribute the spillover to entropy, have far-reaching implications for the fields of hydrogen storage and activation, and may significantly contribute to the development of clean energy technologies.
A research team spearheaded by Penn State University argues that this newfound understanding could serve as a foundation for enhancements in both hydrogen storage and activation, thereby catalyzing progress in sustainable energy solutions.
The concept of hydrogen spillover is straightforward. It involves small metallic nanoparticles, typically anchored to thermally stable oxides like silica, functioning as catalysts. Catalysts are substances that expedite chemical reactions without undergoing any changes themselves. Normally, these catalytic reactions take place on the reactive—and costly—metal. However, under certain conditions, hydrogen atoms or their equivalents transition from the metal to the oxide surface. These transferred atoms are referred to as “hydrogen spillover.”
Though the phenomenon was initially identified in 1964, it has attracted increased attention recently as a potential medium to harness hydrogen for sustainable energy applications. Bert Chandler, a Penn State professor in Chemical Engineering and Chemistry, notes that while hydrogen spillover has been recognized for almost six decades, it has remained relatively unexplored due to a lack of quantifiable data and an absence of understanding regarding the mechanisms that underlie it. That has now changed.
Through intensive research and analysis, Chandler states that the Penn State-led research team has not only identified how and why hydrogen spillover occurs but has also provided its first quantitative evaluation. These findings were published in the journal Nature Catalysis.
Conventional hydrogen storage involves substantial energy expenditures to maintain the hydrogen at low enough temperatures for it to stay liquid. However, the research team has developed a gold-on-titania system that allows for the efficient and reversible dissociation of hydrogen molecules into individual atoms—a critical step for inducing hydrogen spillover—at elevated temperatures that are less energy-intensive.
The research uncovers that entropy, or the dispersion of energy, drives the spillover process. The team’s findings present valuable insights that could inform the development of new chemistry applications, such as the transformation of atoms for use as clean fuel and hydrogen storage, according to Chandler.
Until now, it had been a general belief that hydrogen spillover required more thermal energy to break the bonds between the hydrogen atom equivalents and the nanoparticle layer. However, the team’s work indicates that weak adsorption is the primary factor, revealing that entropy is the real driving force behind the transition of atoms from the metal to the substrate.
This milestone in scientific research, Chandler states, represents a significant step toward advancing clean energy solutions and exemplifies the self-correcting nature of scientific discovery.
The study was supported by the Department of Energy’s Basic Energy Sciences Program, the National Science Foundation, and the Research Corporation for Science Advancement. The findings were published in Nature Catalysis under the title “The role of surface hydroxyls in the entropy-driven adsorption and spillover of H2 on Au/TiO2 catalysts,” authored by an interdisciplinary team led by Bert D. Chandler on August 10, 2023.
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Frequently Asked Questions (FAQs) about Hydrogen Spillover
What is the main focus of the research discussed in the article?
The main focus of the research is to quantify and understand the mechanism behind the process of hydrogen spillover, a phenomenon where hydrogen atoms transition from a metallic catalyst to an oxide substrate. The study reveals that entropy is the driving force behind this process.
Who led the research team?
The research team was led by Penn State University, with Bert Chandler, a professor in Chemical Engineering and Chemistry, serving as one of the key spokespersons for the study.
What significance does entropy have in hydrogen spillover?
Entropy is identified as the key driving force behind the hydrogen spillover process. It is the dispersion of energy that allows hydrogen atoms or their equivalents to transition from the metal to the oxide substrate. Understanding this can open new avenues for hydrogen storage and activation.
How does this research contribute to clean energy technology?
The study offers substantial insights that could revolutionize the fields of hydrogen storage and activation, thereby contributing to advancements in clean energy technology. Specifically, the research team has developed a gold-on-titania system that allows efficient and reversible dissociation of hydrogen molecules at elevated temperatures, requiring less energy.
Where were the research findings published?
The research findings were published in the journal Nature Catalysis on August 10, 2023.
What are the potential applications of these findings?
The findings have potential applications in the development of new chemistry practices for clean fuel and hydrogen storage. It could also provide a foundation for enhancements in both hydrogen storage and activation, thereby fostering progress in sustainable energy solutions.
Who supported the research?
The research was financially supported by the Department of Energy’s Basic Energy Sciences Program, the National Science Foundation, and the Research Corporation for Science Advancement.
How long did it take for the team to complete the research?
According to Bert Chandler, it took approximately six years of measuring and re-measuring to compile the data and reach the conclusions published in the study.
What challenges have researchers faced in understanding hydrogen spillover until now?
Until this research, the challenges have mainly been a lack of quantifiable data and a clear understanding of the mechanisms that underlie the hydrogen spillover process. Previous researchers could not measure the amount of spillover accurately due to weak adsorption on the oxide masking the actual spillover from the metal.
What does the term ‘fizz adsorption’ mean in the context of this study?
In the study, ‘fizz adsorption’ is a term coined by Bert Chandler to describe the unclear, complex bonding that has made it difficult to ascertain what truly drives hydrogen spillover. The term signifies the fuzzy, sticky bonding that masked the true driving force, which is now identified as entropy.
