METAL COCATALYST TUNING FOR IMPROVED PHOTOCATALYTIC EFFICIENCY

The solar-driven photocatalytic splitting of water into hydrogen and oxygen is a potential source of clean and renewable fuels. Typically the semiconductor photocatalysts are modified with cocatalysts, often noble metals, to improve electron-hole separation and act as an active site for hydrogen formation. These cocatalysts play an essential role in reactions such as water splitting, as they offer lower activation potentials for hydrogen evolution, and greatly enhance the photocatalytic activity. In light of the cocatalyst significance, and motivated by cost reduction considerations, we explored means for its optimal utilization. Advancements in the art of manipulating matter on the nanometric scale enabled us to strategically correlate architecture with activity. We focus on decoupling the effects of composition, size, amount, and overall morphology on the efficiency.

In particular, we provide evidence that for a multi electron reaction such as hydrogen reduction, the photocatalyst design should only include a single cocatalytic site per each segment of the semiconductor capable of light excitation. This is to insure that intermediates are formed at close proximity. We are currently exploring the effect of the size of the metal nanoparticle and the role it plays in dictating the interfacial charge-transfer processes. We believe that this fundamental understanding of the cocatalyst role will be significant to the design of hydrogen fuel inspire photocatalysts.