A multifunctional biphasic water splitting catalyst tailored for integration with high-performance semiconductor photoanodes


Artificial photosystems are advanced by the development of conformal catalytic materials that promote desired chemical transformations, while also maintaining stability and minimizing parasitic light absorption for integration on surfaces of semiconductor light absorbers. Here, we demonstrate that multifunctional, nanoscale catalysts that enable high-performance photoelectrochemical energy conversion can be engineered by plasma-enhanced atomic layer deposition. The collective properties of tailored Co3O4/Co(OH)2 thin films simultaneously provide high activity for water splitting, permit efficient interfacial charge transport from semiconductor substrates, and enhance durability of chemically sensitive interfaces. These films comprise compact and continuous nanocrystalline Co3O4 spinel that is impervious to phase transformation and impermeable to ions, thereby providing effective protection of the underlying substrate. Moreover, a secondary phase of structurally disordered and chemically labile Co(OH)2 is introduced to ensure a high concentration of catalytically active sites. Application of this coating to photovoltaic p+n-Si junctions yields best reported performance characteristics for crystalline Si photoanodes.

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Figure 1: Electrocatalytic properties of CoOx films as a function of deposition temperature.
Figure 2: Structural characterization of catalysts by transmission electron microscopy.
Figure 3: Compositions and chemical states of tailored CoOx catalyst layers.
Figure 4: Electrochemical characterization of chemical transformations of CoOx catalysts.
Figure 5: Photoelectrochemical and stability characteristics of high-performance CoOx/Si photoanodes.


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We thank H. Frei for valuable scientific discussions. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the US Department of Energy under Award Number DE-SC0004993. PE-ALD and TEM were performed at the Molecular Foundry, supported by the US Department of Energy (DOE), Office of Basic Energy Sciences, Scientific User Facilities Division, under contract DE-AC02-05CH11231. XANES and EXAFS experiments were performed at the Stanford Synchrotron Radiation Lightsource (Beamline 7.3), operated under contract DE-AC02-05CH11231. Soft X-ray reflectivity and scattering experiments were performed at the Advanced Light Source (Beamline, under contract DE-AC02-05CH11231. L.H.H. acknowledges financial support from the Alexander von Humboldt Foundation.

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The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript.

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Correspondence to Ian D. Sharp.

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Yang, J., Cooper, J., Toma, F. et al. A multifunctional biphasic water splitting catalyst tailored for integration with high-performance semiconductor photoanodes. Nature Mater 16, 335–341 (2017). https://doi.org/10.1038/nmat4794

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