This project focuses on understanding aqueous interfaces of Earth abundant and nontoxic transition metal sulfides to engineer a cost-effective photo-electrocatalytic CO2 reduction system. The biggest roadblock to making scalable the sun-light powered synthesis of carbonaceous fuels from CO2 and water is the lack of a catalysts which is simultaneously efficient, cheap, and environmentally benign. The development of such a catalyst is hindered by the infancy of the mechanistic understanding of the proton-coupled multiple electron transfers involved into the CO2 reduction beyond CO and formate. The proposed interdisciplinary research will bridge this knowledge gap by systematically studying for the first time copper and iron sulfide minerals as novel and cheap photocatalytic materials. A novel molecular cocatalytic approach is suggested to overcome the thermodynamic and kinetic limitations of CO2 reduction towards energy-dense fuels. The objective is to determine the mechanisms of the reaction dependence on molecular cocatalysts at the interfaces and in bulk electrolyte, with the ultimate goal to develop more sustainable and efficient photosynthetic systems. Towards this ambitious goal, a team from Columbia University will study for the first time the multiscale physics and chemistry driving artificial photosynthesis of carbonaceous fuels by iron and copper sulfides, using advanced operando FTIR and Raman spectro-electrochemical, (photo)electrochemical, and theoretical (e.g., Density Fuction Theory) methods.
The new more efficient photosynthetic systems based on copper and iron sulfides developed during the research will be a practical step towards scaling up renewable energy. It will lead to novel scalable strategies for the rational design of the interfaces of metal sulfides with water. Apart from artificial photosynthesis, this outcome can find application in immobilizing radionuclides in environmental remediation, as well as in mineral processing (selective separation) of sulfide minerals, in the design of greener chemicals. In addition, this knowledge will broaden our understanding of biogeochemical process including processes in acid-mine drainage, cycling of iron and cupper in deep oceans, and eventually the origin of life. The general results of the research and the new methodology will be included in the PI's undergraduate/graduate level courses.
