by Julia Acquavita ’22
On Monday, November 12, the Ruane Center for the Humanities hosted a lecture by Dr. Harry B. Gray titled, “Powering the Planet: How to Solve 21st Century Problems in Sustainability.”
This presentation was made possible by the Jean Dreyfus Lectureship for Undergraduate Institutions. Providence College was one of five primarily undergraduate institutions chosen to receive a 2017 grant from the Camille and Henry Dreyfus Foundation, which supports chemistry and biochemistry research and education.
Through this grant, the Ruane Center for the Humanities was able to host this presentation by Dr. Gray.
Dr. Gray serves as the Arnold O. Beckman Professor of Chemistry at the California Institute of Technology & Founding Director of the Beckman Institute.
For 60 years, Gray has dedicated much of his time and effort to studying and addressing fundamental problems in inorganic chemistry, photochemistry, and electron transfer chemistry.
During his lecture, Gray discussed how his years of studying led him to find a solution to power the planet, despite the looming problem of a lack of resources.
Gray started his lecture by discussing solar energy. He noted that we do get plenty of energy from sunlight; however, it is vital to be able to convert and store this sunlight efficiently.
“Storage is the critical point here,” said Gray, further explaining that through the splitting of water with sunlight, we can achieve this storage.
Gray wrote a paper entitled “Powering the Planet With Solar Fuel” that highlighted this discovery and the idea that a solar water-splitter is more than 10x more efficient than natural photosynthesis is in capturing sunlight to synthesize foods from carbon dioxide and water.
John Turner, Gray’s colleague, created this solar water-splitter. However, there seemed to be a problem with Turner’s initial creation, which caused Gray look for and soon find another solution. Turner’s water-splitter cost a fortune, since its main foundation was the incorporation of platinum.
Gray vowed that he would build one with elements that were cheap and earth-abundant, such as iron, nickel, and cobalt. With this in mind, he began to design a system that included a semiconductor.
This semiconductor had the purpose of separating holes for oxygen and electrons for hydrogen, allowing for the splitting of water into hydrogen and oxygen.
Despite this progress, Gray emphasized the key challenge he and his team would face when carrying out the production of the solar water-splitter. First, the system must be efficient. Second, the system must be scalable with no platinum. Third, the system must be robust, even though stability is a major challenge in this situation.
Gray’s study involved a great deal of interplay between theoreticians and experimentalists, as he endured a long process of redoing and improving experiments over and over again until he reached the perfect system.
Despite challenges Gray faced, he was able to persevere and succeed in creating a catalyst to replace Turner’s platinum one. From this, he stimulated a worldwide effort to create catalysts containing cobalt, iron, and nickel.
However, Gray and his colleagues faced yet another problem: the problem of needing to connect seawater to oxygen due to the limited supply of pure water.
Gray jokingly noted, “Sunlight, nitrogen, seawater, that’s all we have folks!” when explaining the importance of such a discovery that would solve this seawater oxygen evolution. “We are looking for the world’s best water oxidation catalyst, and the nickel-iron catalyst is by far the best.”
Towards the end of Gray’s lecture, he addressed the global impact his solar water-splitter system would have on the environment.
He explained that the splitting of seawater will allow for the use of hydrogen as fuel. The reduction of carbon dioxide to water and then the splitting of this water to make oxygen can be used to work towards life on Mars. We can also split nitrogen to create ammonia and food.
Therefore, Gray’s system and discovery will serve as a vital element to the sustainability of our planet, having an immense impact on the world’s environment, and its fuel, materials, and food.