Photocatalytic Conversion of Biomass to High Value Chemicals(2/3)

With increasing awareness of environmental protection for our planet and the needs for energy transition, the utilization of renewable energies and enhancement of energy efficiency are critical. It is clear that from the Technology Roadmap published by International Energy Agency, in 2050 hydrogen and fuel cells will be the key low-carbon technologies. From this perspective, hydrogen must be produced from non-fossil resources. Photocatalytic hydrogen production from water is one of the options. However, oxygen production directly from water splitting is not kinetically favorable. Here, we propose a photoelectrochemical (PEC) system to perform a selective oxidation of biomass-derived chemicals. Hydrogen is produced at the cathode and valuable chemicals are synthesized at the anode, increasing both the efficiency and selectivity of solar-to-chemical conversion. Unfortunately, most photocatalyst materials suffer from low efficiency due to the limited range of light absorption, high electron-hole recombination rates, and low reaction kinetics at the active sites, making PEC system difficult to compete with traditional production process. The keys to enhanced solar-to-chemical conversion are the optimization of the photoanode and the photocathode, band engineering to match the redox potentials of biomass conversion reactions, and understanding of the reaction mechanism. In this three-year project, our approach to solving these problems involves the following strategies:1. Optimization of the photoanode and the photocathode, including n-type and p-type absorber, protection layer, and co-catalyst.2. Investigation of charge-transfer mechanism of photo-generated carriers: charge transport impedance studies using electrochemical methods (EIS/IMPS/IMVS) and charge transport dynamics using time-resolved techniques (transient absorption)3. Construction of in-situ and operando analysis system.4. Understanding of the selective chemical reaction kinetics and mechanism.