G. Charles Dismukes - Research
Earth-abundant catalysts for the Carbon Dioxide Reduction Reaction
We develop selective and robust catalysts that electrochemically convert carbon dioxide (CO2) into sustainable chemical feedstocks and could ultimately be coupled to the recycling of environmental CO2. The catalysts employed are transition metal phosphide and their doped derivatives that form distinct crystalline structure types, enabling selection of chemical reactivity towards desired products including high molecular weight solid polymers. Selecting the catalyst’s elemental composition and crystal structure allows for tuning of the chemical, physical, and electrical properties to achieve the best match with desired product and application.
Perovskite-based oxyhydrides as nitrogen fixation catalysts
Production of ammonia (NH3) continues to increase to satisfy ever-growing global demand. Most industrial production processes are still based on the 100-year-old Haber-Bosch process which requires temperatures of >400 °C and 150-200 atm of pressure to overcome slow dissociation of N2. These harsh reaction conditions have led to NH3 production accounting for 2% of global energy consumption and 1% of global greenhouse gas production. New catalysts that can lower energy requirement and carbon footprint of this process are of interest. Recently, a new class of perovskite-based oxyhydrides (AMO3-xHx; A2MO4-xHx) have been discovered and it has been demonstrated that N3–/H– substitution can be achieved in these compounds by heating under N2 flow. This ability to break the N2 triple bond at ambient pressures makes perovskite oxyhydrides candidates for NH3 production catalysts.
Heterogeneous Water Oxidizing Catalysts from Inert Transition Metal Oxide Spinels
Manganese oxides occur naturally as minerals in at least 30 different crystal structures, providing a rigorous test system to explore the significance of atomic positions on the catalytic efficiency of water oxidation. We chose to systematically compare eight synthetic oxide structures containing Mn(III) and Mn(IV) only, with particular emphasis on the five known structural polymorphs of MnO2. We have adapted literature synthesis methods to obtain pure polymorphs and validated their homogeneity and crystallinity by powder X-ray diffraction and both transmission and scanning electron microscopies.
Molecular Catalysts for Water Oxidation
The development of sustainable catalysts that use materials of high natural abundance and long-term stability is a major goal of this project. Our research is closely linked to the discovery of the catalytic CaMn4O5 site for photosynthetic water oxidation. Armed with nature's emerging blueprint for design of a water oxidation enzyme, we are synthesizing bioinspired inorganic complexes and materials for use in hybrid photoelectrochemical cells as water splitting catalysts. Our proposed mechanism for photosynthetic water oxidation serves as the guiding principle for catalyst design.