Photocatalytic Hydrogen Production on Semiconductor-Based Catalysts: Roles of Co-catalysts and Surface Junctions

This lecture presents recent progress made in photocatalytic hydrogen production utilizing solar energy and fundamental understanding of photocatalysis and photochemical reactions on semiconductor-based photocatalysts. The concerns about the depletion of fossil fuel reserves and the pollution caused by continuously increasing energy demands make hydrogen an attractive energy source. Solar energy is the primary source for clean and renewable energy alternative. Photocatalytic hydrogen production using solar energy is a promising process for renewable energy production, considered as an efficient strategy to eventually realize hydrogen economy. Semiconductor materials are believed to be the most promising components for photocatalysts, so the discovery and synthesis of novel semiconductor materials are crucial for the development of advanced photocatalysts. To convert solar energy efficiently to chemical energy, much attention has been paid to reducing charge recombination and improving solar energy conversion efficiency. Our recent results demonstrate that the formation of surface phase junction and hetero-junction on semiconductor catalysts can significantly enhance the activity in photocatalytic hydrogen production. By mimicking the photosynthesis, loading spatially separated dual cocatalysts for oxidation and reduction on semiconductor nanoparticles can obviously avoid the charge recombination and consequently increase the photocatalytic activity. A recent progress made in photocatalytic hydrogen production shows that a quantum yield up to 93% can be achieved for Pt-PdS/CdS catalysts where the dual co-catalysts, Pt and PdS nanoparticles are deposited on CdS. These findings provide a strategy to develop highly active photocatalysts for hydrogen production