CAREER: Rational Design, Synthesis and Understanding of Heteronanostructures as Photoelectrodes for Water Splitting

Boston College, Chestnut Hill MA

Investigators

Abstract

TECHNICAL SUMMARY: The performance of advanced energy conversion devices, including that for solar water splitting, is ultimately connected to the design of the electrode materials at the nanoscale. Current research in this area is limited by how much one can tailor the intrinsic properties of existing materials and the slow progress in discovering novel materials. Supported by the Solid State and Materials Chemistry program within the Division of Materials Research, this proposal will address the challenge by designing, preparing and understanding a new class of nanonet-based materials. The project will build on the PI's past success in making nanostructures with heterogeneous interfaces by studying combinations that include TiSi2 nanonets, which are unique two-dimensional nanostructures discovered by the PI's lab that offer suitably high surface areas and high conductivities, and a variety of oxide semiconductors such as TiO2, WO3 and Fe2O3. Specifically, the PI aims at solving the problems of poor charge diffusion within these oxides. The improved charge collection will reduce the undesired accumulation of photogenerated charges and thereby increase the photon-to-electron-conversion efficiencies. The study will focus on understanding how the electronic properties of nanostructures are influenced by their morphologies and compositions. Experimental techniques to be employed include chemical vapor deposition (for the creation of TiSi2 nanonets), atomic layer deposition (for the conformal coating of oxide semiconductors around the nanonets), various electrochemical methods, and a host of structural characterization procedures. These experiments will produce information on the crystallinity, the electronic property and the chemical property of the nanostructures, which will be essential to not only water splitting but also a number of related energy conversion and storage processes where charge transport plays an important role. NON-TECHNICAL SUMMARY: The ability to harvest solar energy and use it directly to produce hydrogen by splitting water has the potential to meet the energy needs without a negative impact on the environment. Due to the lack of suitable materials, this research is currently progressing at a slow pace. The proposed project will introduce a fundamentally new design that may advance the field significantly and make solar water splitting practical. The key to this design is a unique two-dimensional nanonet structure the PI's lab has discovered. When combined with oxide semiconductors, the nanonets can provide a dedicated charge transport pathway that should enable high-efficiency solar water splitting. The research efforts will be augmented by a fully integrated novel education program that aims at disseminating information on clean energy technology. The outreach program will take advantage of the popularity of Boston College's football games. The PI's team will participate in the FanFest event, which attracts a large number of alumni and visitors including K-12 students, by demonstrating how clean energy can be produced and used. A summer program will also be established to invite one to two science teachers each year from local high schools to conduct research on the proposed topics and gain hands-on experience which they will be able to share with their students.