Photocatalytic hybrid nanorod designed for improved charge transfer

Conversion of solar energy to fuels such as hydrogen is attracting enormous interest in light of the increasing energy demand and fossil fuel supplies depletion, in addition to issues such as global warming and air pollution. Considering these concerns, energy to fuel conversion via photocatalysis has been widely investigated. Despite intensive global research, producing efficient and stable photocatalysis systems remains a great challenge. Hydrogen generated from solar-driven water-splitting has the potential to be a clean, sustainable and abundant energy source. An important advancement towards rendering hydrogen more accessible was accomplished in our lab. Nearly 100% photon-to-hydrogen production efficiency was recorded by utilizing nanoparticle-based photocatalysts, composed of Pt-tipped CdSe@CdS rods. While this structure was found to be highly active for hydrogen production, it is not suitable for overall water-splitting as it is encumbered by photochemical instability, the Achilles heel of CdS. Unfortunately, prolonged irradiation of its suspensions leads to photocorrosion, thus requiring a sacrificial donor for hydrogen evolution from the water. It was demonstrated that successful mediation of holes away from the CdS based catalysts afford the structure the desired photochemical stability. In fact, this step is considered the bottleneck of the process. Hence, we have designed and successfully produced a novel hybrid nanorod photosensitizer structure that is envisioned to improve hole removal. Analogously to the record efficient Pt-tipped CdSe@CdS rods, these nanoheterostructures combine CdS and CdSe semiconductors for improved charge separation, in a controlled and variable spatial arrangement. Yet, in this new design, the CdSe is fully exposed to facilitate hole scavenging to a redox shuttle, or to an electrode substrate. In this poster, we will present our synthetic efforts devoted to completing the photocatalytic system, and studies on the structure-properties relationship. We believe building an integrated functional system would be an important milestone towards direct solar to fuel conversion.