Conclusion: A Promising Future for AP

So far this summer, I have worked on a few projects and had some promising results.  The paper we submitted received comments from reviewers, and I have been conducting new experiments to answer and fulfill their questions and comments. We hope that the paper will be published by the end of the summer.  In addition, I am diligently attempting to get some clean crystals for one of the cobalt complexes I wrote about in a past blog.  So far, this summer has been a very productive and promising journey.   I love having the opportunity to do full time research since, during the school year, I have very limited time to do chemistry research with all of my classes.  This way, I can dive deep into my chemistry research, and make larger dents in pushing my project forward.  I am planning on doing my honors thesis on this family of cobalt complexes, so I appreciate the jump start to senior year honors research.  I also received a summer research grant last year, and have been grateful to participate in the Charles Center Summer Research program each year.

Synthesis and Analysis of a family of Cobalt Complexes for AP

After submitting the paper, I began working on novel cobalt-based catalysts for proton reduction.  These catalysts are valuable due to their cost-effective reagents.  So far, we have synthesized two of the three cobalt complexes.  Structurally, the complexes look very similar to each other, with the exception of electron withdrawing/electron donating groups that will affect activity and efficiency.  The electron withdrawing groups pull electron density away from the metal center, which, in theory, will facilitate the reduction of the complex due to the more positive character of the center.  The electron donating groups may worsen efficiency, but also have the potential to increase activity.  I have been synthesizing these complexes and running electrochemical experiments on them in order to measure their catalytic activity.  The synthesis itself is very straightforward, since it is a one pot synthesis, in air, that refluxes for only two hours.  Then, the solution is filtered, and the concentrate can be used to crystallize out the complex with a slow diffusion crystallization technique.

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Humic Acid Studies & Lake Water Studies – Varying Conditions

Humic acid is a cost-effective and green substance made of organic waste.  It does not have much use as is, but green chemistry research has gone into harnessing humic acid, since it is in such high abundance.  Humic acid has the potential to be used as a sacrificial electron donor instead of triethylamine (TEA) in our photocatalytic system.  So, I have been conducting experiments to utilize triethylamine in our test tubes.  I also performed experiments to measure the quenching of our catalyst with humic acid.  Unfortunately, no hydrogen was produced in our photocatalytic system when humic acid was incorporated instead of TEA.  I varied concentration of the humic acid in the test tube to no avail.  So, I took a trip to our dear Lake Matoaka to see if I could find lake water with a very small amount of humic acid that would hopefully act as a natural electron donor.  The rationale behind using lake water is accented by the fact that we have had success using lake water and TEA in our photocatalytic systems.  Unfortunately, the humic acid in the water was not effective.  The humic acid idea is tabled for now, but it is possible in the future that it will be incorporated into photocatalytic systems under different conditions in the future.

Artificial Photosynthesis: Optimization of proton reduction catalysis

My name is Ryan DiRisio, and I am a junior at the College majoring in chemistry.

If the Earth continues to rely on fossil fuels as our primary energy source, there will be severe consequences in the environment: global average temperature will increase, extreme weather will occur more frequently, and the ocean will acidify, destroying ecosystems.  In order to combat this, alternative energies are being developed.  Solar energy has shown promise, since it is almost universal in its availability.  However, traditional photovoltaics are expensive and inefficient, especially when attempting to store the harvested energy in batteries.  One novel approach to solar energy Artificial Photosynthesis (AP).  The point of AP is to mimic Nature; in traditional photosynthesis, a plant is irradiated, prompting a splitting of water into protons and oxygen gas.  The electron released from this reaction is then used to reduce NADP+ to NADP.  This, effectively, stores energy in the form of a chemical bond.  In a traditional AP scheme, water is split into protons and hydrogen gas, as in traditional photosynthesis.  Then, however, the proton is reduced to hydrogen gas.  This hydrogen produced can then be ignited as a carbon-neutral energy source, producing water vapor as a by-product.  In our lab, we focus on the reductive side of AP.  In our proton reduction setup, we irradiate a photosensitizer, sacrificial electron donor, catalyst, ethanol, and water with light and measure the amount of hydrogen produced over time to gauge activity and robustness.  Over the summer, I will be continuing this research through the optimization of our experimental setup.  I will accomplish this through varying photosensitizers and catalysts, as well as adjusting the concentrations of the components to maximize activity.

Conclusion

The past seven weeks have been extremely productive and interesting.  I had no idea how quick the seven weeks would go, how I would hone my skills to be a productive member of the lab, and how I would make a dent in the project that I have been working on since January.  While my project is fickle, and the seven weeks flew by, I feel that I have learned extremely valuable and practical lab experience for my time left as an undergraduate and beyond.  Practical chemical knowledge is essential to being a chemist; drawing mechanisms in organic chemistry class is not the same as performing the reaction yourself.  I made mistakes this summer, there were ups and downs to my research, and I found out what it feels like to work full time.  I also had success in my project, had liquid nitrogen ice cream with the entire chemistry department, and enjoyed lab bonding activities.  I am excited to start the school year with more practical experience under my belt, but I am also excited to keep improving, and to keep learning, and to keep making mistakes, so that I can grow as a person and as a chemist.