Collaborative Research: New Anodic Catalysts for Water Oxygen Evolution Using Hybrid Solid-State Materials

California Institute Of Technology, Pasadena CA

Investigators

Abstract

The development of large-scale non-fossil sources of energy is arguably science and engineering's most important goal. The proposed project will address a key process for scaled use of sunlight, the electrocatalytic oxidation of water. Electrocatalysts are materials that make electrically-driven chemical reactions proceed faster, more efficiently, and/or with less input of electricity. This project will involve discovery of new catalytic materials for efficient electrochemical oxidation of water to produce hydrogen (H2) and oxygen (O2). The produced dihydrogen can be used directly as a fuel to produce electricity in hydrogen fuel cells or as a reactant to upgrade low-grade carbon-containing compounds to high-value fuels and chemicals. The project will address a critical step in a sustainable process for converting solar energy to chemical energy, thus alleviating dependence on fossil resources. A key aspect of this effort is to elucidate details and understanding of catalyst performance that would not be possible without the synergistic use of both experimental and computational interrogation. A major challenge for the scaled use of electrocatalytic processes for the use of green energy to produce hydrogen from water is the development of robust anodic materials that catalyze rapid and long-lived water oxidation. The proposed research is focused on the development of new carbon-supported materials to gain fundamental understanding of electrocatalytic water oxidation, especially with a focus on the ability to integrate well-defined molecular catalyst structures into conducting solid materials. Through a collaborative effort that involves groups in molecular catalysis (Gunnoe, Machan), nanomaterials (Zhang), theory and computational modeling (Goddard), carbon materials and catalyst characterization (Heumann), and benchmarking and mechanistic studies (Spanos) including in situ EPR spectroscopy (Schnegg), a strategy to develop and optimize molecular catalysts with ligand functionality to enhance electrocatalytic water oxidation, incorporate these molecular units into conducting carbon-based materials, and to study their efficacy and mechanism will be implemented. To achieve these goals, three objectives will be pursued: Objective 1. Increased understanding of the design of capping arene ligands to optimize performance of hybrid electrocatalysts, including multi-nuclear transition metal molecular precursors, for water oxidation based on Co or Fe metals. Objective 2. Develop design principles for pyridine-alkoxide ligands to optimize performance of hybrid electrocatalysts, with a focus on generating multi-nuclear transition metal molecular precursors, for the OER based on Cu and Co. Objective 3. Understand the impact of the carbon support on the activity and stability of the catalyst active site. Also, the project will also involve educational outreach to primarily undergraduate institutions (PUIs) to increase interest among students from diverse backgrounds in careers as scientists and engineers. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.