Model Materials and Reactor Systems for Artificial Leaves in Solar Energy Conversion Applications

Abstract

Artificial leaves mimic natural photosynthesis processes to convert solar energy into chemical products, including fuels and raw materials. The innovation and utilization of artificial leaves require fundamental studies of materials and reaction mechanisms, along with the development and engineering of scalable reaction platforms. To address these aspects, this study adopts two innovative research approaches for the development of artificial leaves: (1) fundamental studies on materials using model heterostructures and (2) applied design and development of reaction systems. The first two research chapters present research using well-defined, high-quality Cu2O thin film prepared via pulsed laser deposition as model metal oxide heterostructures. The effects of lattice interactions on the intrinsic crystalline and electronic structures of Cu2O are systematically investigated via two strategies: 1. different lattice mismatch configurations on distinct substrates, and 2. different domains on the same substrate. The third research chapter investigates the effects of lattice interactions on the structural evolutions of model heterostructures during solar energy conversion reactions. First, advanced in-situ and operando characterization techniques for thin film model structures are developed. Then, the changes in crystalline and electronic structures are monitored during reactions. Lattice interaction-dependent and crystallographic direction-dependent behaviors were revealed to provide insights into fundamental reaction phenomena and propose design strategies for advanced solar conversion materials. The fourth research chapter studies the design and operation strategies of solar concentrators for photocatalysis and develops a scalable, low-cost photoreactor using quartz wool as the 3D photocatalyst support. A reaction system is constructed as the model platform to study the operational parameters of artificial leaves and propose strategies to build and operate net-energy-positive solar-to-fuel conversion systems. These fundamental and applied studies provide innovative research and development strategies for advancing energy conversion materials and engineering scalable reaction systems. The findings and strategies developed in this research can contribute to the future realization of artificial leaves for solar energy conversions.