Photo and Electrochemical Investigations of Solution Processable Molecules and Materials for the Hydrogen Evolution Reaction

摘要

Sustainable hydrogen production photoelectrochemically or photocatalytically is a desirable process that has the potential to allow hydrogen to be utilized as a carbon free fuel. In order for this method to become commercially viable, scientific advances must be made on current technologies. Sustainable hydrogen production photocatalytically is projected to be more cost effective than hydrogen production photoelectrochemically, however significant scientific studies need to made and its future is uncertain. We envision a system of molecular electrocatalysts and colloidal photosensitizers for hydrogen production via photocatalysis. In Chapter 2, a library of molecular electrocatalysts are synthesized and their ability to perform hydrogen evolution electrocatalytically is explored. These molecules are found to be competent hydrogen evolution catalysts in nonaqueous solvents, albeit with high overpotentials. The parent metalloligand's ability to be a nucleophile toward a variety of cations lead us to study its interactions with CdSe in Chapter 3. In this Chapter, an electrochemical method for analyzing the equilibrium interactions between CdSe nanocrystals and small molecules is investigated. This technique is demonstrated as a useful tool for analyzing catalyst-photosensitizer interactions which is an important qualification for understanding efficient photocatalysis. Preliminary data is shown to support oxidation state binding preference to CdSe nanocrystals for the molecules described in Chapter 3.;Non-precious metal hydrogen evolution catalysts that are durable and solution processable would help increase the cost effectiveness of photoelectrochemical hydrogen production. In Chapters 4 and 5, colloidally-synthesized WSe 2 in the 1T and 2H polytype forms respectively, are investigated as electrocatalysts for the hydrogen evolution reaction. In Chapter 4, in order to improve the activity of the 1T WSe2, the effects of a ligand removing chemical agent, Meerwein's reagent, are investigated. In Chapter 5, the colloidally synthesized 2H WSe2 is also investigated for the hydrogen evolution reaction. For this material, in addition to the ligand removal chemistry mentioned above, a facile electrochemical activation in aqueous conditions has been observed. This activation step increases the activity to be on par to the 1T WSe2 discussed in Chapter 4.