Solar water splitting is a highly desirable approach to solving the challenge associated with the need for clean energy. However, in order to be an economically competitive and sustainable energy source, environmentally benign, earth-abundant and highly efficient materials are desired. Fitting these requirements, hematite is a promising candidate offering a suitable band gap (2.0-2.2 eV) and exceptional stability under water splitting conditions. Despite such desirable characteristics, short minority carrier diffusion lengths and sluggish charge transfer kinetics at the solid-electrolyte interface render challenges in achieving high efficiency solar fuels production with hematite. Atomic layer deposition (ALD) is uniquely suited to addressing each of the challenges presented. Two ALD-based approaches to mitigating these issues will be presented: 1) decoupling light absorption and carrier diffusion lengths through nanostructured photoelectrode architectures, and 2) interfacing ultra-thin oxygen evolution catalysts to the surface of hematite. A three-fold photocurrent enhancement was observed when utilizing new photoelectrode architectures, while less than one monolayer of Co-catalyst resulted in a 100-200 mV cathodic shift in the water oxidation potential.

All-inclusive atomic layer deposition approach to solar water splitting

245th National Meeting (2013)

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