An artificial photosynthetic system that directly produces fuels from sunlight could provide an approach to scalable energy storage and a technology for the carbon-neutral production of high-energy-density transportation fuels. A variety of designs are currently being explored to create a viable artificial photosynthetic system, and the most technologically advanced systems are based on semiconducting photoelectrodes. Here, I discuss the development of an approach that is based on an architecture, first conceived around a decade ago, that combines arrays of semiconducting microwires with flexible polymeric membranes. I highlight the key steps that have been taken towards delivering a fully functional solar fuels generator, which have exploited advances in nanotechnology at all hierarchical levels of device construction, and include the discovery of earth-abundant electrocatalysts for fuel formation and materials for the stabilization of light absorbers. Finally, I consider the remaining scientific and engineering challenges facing the fulfilment of an artificial photosynthetic system that is simultaneously safe, robust, efficient and scalable.
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Verne, J. The Mysterious Island (Pierre Jules-Hetzel, 1874).
Ciamician, G. The photochemistry of the future. Science 36, 385–394 (1912).
Capra, F. You Can't Take It With You (Columbia Pictures, 1938).
Eisenberg, A. The answer is (artificially) blowing in the wind. The New York Times (21 May 2011).
Regalado, A. Reinventing the leaf: artificial photosynthesis to create clean fuel. Scientific American (1 October 2010).
Long, J. C. S. & John, M. California's Energy Future: The View to 2050 (California Council on Science and Technology, 2011).
Lewis, N. S. & Crabtree, G. Basic Research Needs for Solar Energy Utilization (United States Department of Energy, 2005).
Bard, A. J. & Fox, M. A. Artificial photosynthesis: solar splitting of water to hydrogen and oxygen. Acc. Chem. Res. 28, 141–145 (1995).
Lewis, N. S. & Nocera, D. G. Powering the planet: chemical challenges in solar energy utilization. Proc. Natl Acad. Sci. USA 103, 15729–15735 (2006).
Walter, M. G. et al. Solar water splitting cells. Chem. Rev. 110, 6446–6473 (2010).
Lewis, N. S. Research opportunities to advance solar energy utilization. Science 351, http://dx.doi.org/10.1126/science.aad1920 (2016).
Shapiro, H. T. Overview and Summary of America's Energy Future: Technology and Transformation (National Academies Press, 2010). Explores technology pathways for transforming energy supply and use in the United States.
Wasielewski, M. R. Energy, charge, and spin transport in molecules and self-assembled nanostructures inspired by photosynthesis. J. Org. Chem. 71, 5051–5066 (2006).
Wasielewski, M. R. Self-assembly strategies for integrating light harvesting and charge separation in artificial photosynthetic systems. Acc. Chem. Res. 42, 1910–1921 (2009).
Duan, L. et al. A molecular ruthenium catalyst with water-oxidation activity comparable to that of photosystem II. Nat. Chem. 4, 418–423 (2012).
Alibabaei, L., Sherman, B. D., Norris, M. R., Brennaman, M. K. & Meyer, T. J. Visible photoelectrochemical water splitting into H2 and O2 in a dye-sensitized photoelectrosynthesis cell. Proc. Natl Acad. Sci. USA 112, 5899–5902 (2015).
Concepcion, J. J., House, R. L., Papanikolas, J. M. & Meyer, T. J. Chemical approaches to artificial photosynthesis. Proc. Natl Acad. Sci. USA 109, 15560–15564 (2012).
Swierk, J. R. et al. Metal-free organic sensitizers for use in water-splitting dye-sensitized photoelectrochemical cells. Proc. Natl Acad. Sci. USA 112, 1681–1686 (2015).
Han, Z. & Eisenberg, R. Fuel from water: the photochemical generation of hydrogen from water. Acc. Chem. Res. 47, 2537–2544 (2014).
Han, Z., Qiu, F., Eisenberg, R., Holland, P. L. & Krauss, T. D. Robust photogeneration of H2 in water using semiconductor nanocrystals and a nickel catalyst. Science 338, 1321–1324 (2012).
Maeda, K. & Domen, K. Photocatalytic water splitting: recent progress and future challenges. J. Phys. Chem. Lett. 1, 2655–2661 (2010).
Kudo, A. & Miseki, Y. Heterogeneous photocatalyst materials for water splitting. Chem. Soc. Rev. 38, 253–278 (2009).
Tan, M. X. et al. in Progress in Inorganic Chemistry (ed. Karlin, K. D.) 21–144 (John Wiley & Sons, 1994).
Gerischer, H. Kinetics of oxidation–reduction reactions on metals and semiconductors. I. General remarks on the electron transition between a solid body and a reduction-oxidation electrolyte. Z. Phys. Chem. 26, 223–247 (1960).
Gerischer, H. Kinetics of oxidation–reduction reactions on metals and semiconductors. III. General remarks on the electron transition between a solid body and a reduction-oxidation electrolyte. Z. Phys. Chem. 27, 48–79 (1961).
Memming, R. Semiconductor Electrochemistry (Wiley-VCH, 2000).
Spurgeon, J. M. & Lewis, N. S. Proton exchange membrane electrolysis sustained by water vapor. Energy Environ. Sci. 4, 2993–2998 (2011).
Xiang, C., Chen, Y. & Lewis, N. S. Modeling an integrated photoelectrolysis system sustained by water vapor. Energy Environ. Sci. 6, 3713–3721 (2013).
Fujishima, A. & Honda, K. Electrochemical photolysis of water at a semiconductor electrode. Nature 238, 37–38 (1972). First report of unassisted, light-driven water splitting by a semiconducting electrode.
Wrighton, M. S., Wolczanski, P. T. & Ellis, A. B. Photoelectrolysis of water by irradiation of platinized n-type semiconducting metal oxides. J. Solid State Chem. 22, 17–29 (1977).
Wrighton, M. S. et al. Strontium-titanate photoelectrodes. Efficient photoassisted electrolysis of water at zero applied potential. J. Am. Chem. Soc. 98, 2774–2779 (1976).
Rocheleau, R. E. & Miller, E. L. Photoelectrochemical production of hydrogen: engineering loss analysis. Int. J. Hydrogen Energy 22, 771–782 (1997).
Luttmer, J. D. & Trachtenberg, I. Performance predictions for solar-chemical converters based on photoelectrochemical I–V curves. J. Electrochem. Soc. 132, 1312–1315 (1985).
Bolton, J. R., Strickler, S. J. & Connolly, J. S. Limiting and realizable efficiencies of solar photolysis of water. Nature 316, 495–500 (1985). For water splitting, this analysis estimates practical efficiencies of ∼10% for single-absorber systems and ∼16% for dual-absorber systems.
Singh, M. R., Papadantonakis, K. M., Xiang, C. X. & Lewis, N. S. An electrochemical engineering assessment of the operational conditions and constraints for solar-driven water-splitting systems at near-neutral pH. Energy Environ. Sci. 8, 2760–2767 (2015).
Jin, J. et al. An experimental and modeling/simulation-based evaluation of the efficiency and operational performance characteristics of an integrated, membrane-free, neutral pH solar-driven water-splitting system. Energy Environ. Sci. 7, 3371–3380 (2014).
Hernandez-Pagan, E. A. et al. Resistance and polarization losses in aqueous buffer-membrane electrolytes for water-splitting photoelectrochemical cells. Energy Environ. Sci. 5, 7582–7589 (2012).
Xiang, C., Papadantonakis, K. M. & Lewis, N. S. Principles and implementations of electrolysis. Mater. Horiz. 3, 169–173 (2016).
Licht, S. et al. Efficient solar water splitting, exemplified by RuO2-catalyzed AlGaAs/Si photoelectrolysis. J. Phys. Chem. B 104, 8920–8924 (2000).
Khaselev, O. & Turner, J. A. A monolithic photovoltaic-photoelectrochemical device for hydrogen production via water splitting. Science 280, 425–427 (1998).
Khaselev, O., Bansal, A. & Turner, J. A. High-efficiency integrated multijunction photovoltaic/electrolysis systems for hydrogen production. Int. J. Hydrogen Energy 26, 127–132 (2001).
Appleby, A. J. Photocell device for evolving hydrogen and oxygen from water. US patent 4643817 (1987).
Appleby, A. J. et al. An amorphous silicon-based one-unit photovoltaic electrolyzer. Energy 10, 871–876 (1985).
Rocheleau, R. E., Miller, E. L. & Misra, A. High-efficiency photoelectrochemical hydrogen production using multijunction amorphous silicon photoelectrodes. Energy Fuels 12, 3–10 (1998).
Yamada, Y. et al. One chip photovoltaic water electrolysis device. Int. J. Hydrogen Energy 28, 1167–1169 (2003).
Licht, S. et al. Over 18% solar energy conversion to generation of hydrogen fuel; theory and experiment for efficient solar water splitting. Int. J. Hydrogen Energy 26, 653–659 (2001).
Kocha, S. S., Montgomery, D., Peterson, M. W. & Turner, J. A. Photoelectrochemical decomposition of water utilizing monolithic tandem cells. Sol. Energy Mater. Sol. Cells 52, 389–397 (1998).
Cox, C. R., Lee, J. Z., Nocera, D. G. & Buonassisi, T. Ten-percent solar-to-fuel conversion with nonprecious materials. Proc. Natl Acad. Sci. USA 111, 14057–14061 (2014).
Reece, S. Y. et al. Wireless solar water splitting using silicon-based semiconductors and earth-abundant catalysts. Science 334, 645–648 (2011).
Abdi, F. F. et al. Efficient solar water splitting by enhanced charge separation in a bismuth vanadate-silicon tandem photoelectrode. Nat. Commun. 4, 2195 (2013).
Minguzzi, A., Fan, F.-R. F., Vertova, A., Rondinini, S. & Bard, A. J. Dynamic potential–pH diagrams application to electrocatalysts for water oxidation. Chem. Sci. 3, 217–229 (2012).
Newman, J. Scaling with Ohm's law: wired vs. wireless photoelectrochemical cells. J. Electrochem. Soc. 160, F309–F311 (2013).
Bockris, J. O. M., Dandapani, B., Cocke, D. & Ghoroghchian, J. On the splitting of water. Int. J. Hydrogen Energy 10, 179–201 (1985).
Maiolo, J. R., Atwater, H. A. & Lewis, N. S. Macroporous silicon as a model for silicon wire array solar cells. J. Phys. Chem. C 112, 6194–6201 (2008).
Kayes, B. M., Atwater, H. A. & Lewis, N. S. Comparison of the device physics principles of planar and radial p–n junction nanorod solar cells. J. Appl. Phys. 97, 114302 (2005).
Maiolo, J. R. et al. High aspect ratio silicon wire array photoelectrochemical cells. J. Am. Chem. Soc. 129, 12346–12347 (2007).
Kayes, B. M. et al. Growth of vertically aligned Si wire arrays over large areas (>1 cm2) with Au and Cu catalysts. Appl. Phys. Lett. 91, 103110 (2007). In this work, Si microwires are grown using vapour–liquid–solid techniques employing either Au or Cu catalysts. Au is deleterious to the performance of Si, whereas Cu is less so and can be removed via gettering.
Plass, K. E. et al. Flexible polymer-embedded Si wire arrays. Adv. Mater. 21, 325–328 (2009).
Kelzenberg, M. D. et al. Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications. Nat. Mater. 9, 239–244 (2010).
Kelzenberg, M. D. et al. High-performance Si microwire photovoltaics. Energy Environ. Sci. 4, 866–871 (2011).
Putnam, M. C. et al. Si microwire-array solar cells. Energy Environ. Sci. 3, 1037–1041 (2010).
Audesirk, H. A., Warren, E. L., Ku, J. & Lewis, N. S. Ordered silicon microwire arrays grown from substrates patterned using imprint lithography and electrodeposition. ACS Appl. Mater. Interfaces 7, 1396–1400 (2015).
Boettcher, S. W. et al. Energy-conversion properties of vapor-liquid-solid-grown silicon wire-array photocathodes. Science 327, 185–187 (2010).
Coridan, R. H. et al. Methods for comparing the performance of energy-conversion systems for use in solar fuels and solar electricity generation. Energy Environ. Sci. 8, 2886–2901 (2015). The ideal regenerative cell efficiency is a half-cell performance metric, appropriate when evaluating either a photoanode or photocathode that is not capable of driving a reaction unassisted.
Boettcher, S. W. et al. Photoelectrochemical hydrogen evolution using Si microwire arrays. J. Am. Chem. Soc. 133, 1216–1219 (2011).
Spurgeon, J. M., Walter, M. G., Zhou, J., Kohl, P. A. & Lewis, N. S. Electrical conductivity, ionic conductivity, optical absorption, and gas separation properties of ionically conductive polymer membranes embedded with Si microwire arrays. Energy Environ. Sci. 4, 1772–1780 (2011).
Haussener, S. et al. Modeling, simulation, and design criteria for photoelectrochemical water-splitting systems. Energy Environ. Sci. 5, 9922–9935 (2012).
Ardo, S., Park, S. H., Warren, E. L. & Lewis, N. S. Unassisted solar-driven photoelectrosynthetic HI splitting using membrane-embedded Si microwire arrays. Energy Environ. Sci. 8, 1484–1492 (2015).
Yahyaie, I. et al. Characterization of the electrical properties of individual p-Si microwire/polymer/n-Si microwire assemblies. J. Phys. Chem. C 115, 24945–24950 (2011).
Cho, C. J., O'Leary, L., Lewis, N. S. & Greer, J. R. In situ nanomechanical measurements of interfacial strength in membrane-embedded chemically functionalized Si microwires for flexible solar cells. Nano Lett. 12, 3296–3301 (2012).
Gallant, B. M., Gu, X. W., Chen, D. Z., Greer, J. R. & Lewis, N. S. Tailoring of interfacial mechanical shear strength by surface chemical modification of silicon microwires embedded in Nafion membranes. ACS Nano 9, 5143–5153 (2015).
McDonald, M. B., Ardo, S., Lewis, N. S. & Freund, M. S. Use of bipolar membranes for maintaining steady-state pH gradients in membrane-supported, solar-driven water splitting. ChemSusChem 7, 3021–3027 (2014).
Vargas-Barbosa, N. M., Geise, G. M., Hickner, M. A. & Mallouk, T. E. Assessing the utility of bipolar membranes for use in photoelectrochemical water-splitting cells. ChemSusChem 7, 3017–3020 (2014).
McDonald, M. B. & Freund, M. S. Graphene oxide as a water dissociation catalyst in the bipolar membrane interfacial layer. ACS Appl. Mater. Interfaces 6, 13790–13797 (2014).
Shaner, M. R. et al. Photoelectrochemistry of core–shell tandem junction n–p+-Si/n-WO3 microwire array photoelectrodes. Energy Environ. Sci. 7, 779–790 (2014).
Liu, C., Tang, J. Y., Chen, H. M., Liu, B. & Yang, P. D. A fully integrated nanosystem of semiconductor nanowires for direct solar water splitting. Nano Lett. 13, 2989–2992 (2013).
Chen, Y., Sun, K., Audesirk, H., Xiang, C. & Lewis, N. S. A quantitative analysis of the efficiency of solar-driven water-splitting device designs based on tandem photoabsorbers patterned with islands of metallic electrocatalysts. Energy Environ. Sci. 8, 1736–1747 (2015).
McCrory, C. C. L. et al. Benchmarking hydrogen evolving reaction and oxygen evolving reaction electrocatalysts for solar water splitting devices. J. Am. Chem. Soc. 137, 4347–4357 (2015).
Liu, P. & Rodriguez, J. A. Catalysts for hydrogen evolution from the [NiFe] hydrogenase to the Ni2P(001) surface: the importance of ensemble effect. J. Am. Chem. Soc. 127, 14871–14878 (2005).
Popczun, E. J. et al. Nanostructured nickel phosphide as an electrocatalyst for the hydrogen evolution reaction. J. Am. Chem. Soc. 135, 9267–9270 (2013).
Popczun, E. J., Read, C. G., Roske, C. W., Lewis, N. S. & Schaak, R. E. Highly active electrocatalysis of the hydrogen evolution reaction by cobalt phosphide nanoparticles. Angew. Chem. Int. Ed. 126, 5531–5534 (2014).
McEnaney, J. M. et al. Amorphous molybdenum phosphide nanoparticles for electrocatalytic hydrogen evolution. Chem. Mater. 26, 4826–4831 (2014).
McEnaney, J. M. et al. Electrocatalytic hydrogen evolution using amorphous tungsten phosphide nanoparticles. Chem. Commun. 50, 11026–11028 (2014).
Callejas, J. F. et al. Electrocatalytic and photocatalytic hydrogen production from acidic and neutral-pH aqueous solutions using iron phosphide nanoparticles. ACS Nano 8, 11101–11107 (2014).
Saadi, F. H. et al. CoP as an acid-stable active electrocatalyst for the hydrogen-evolution reaction: electrochemical synthesis, interfacial characterization and performance evaluation. J. Phys. Chem. C 118, 29294–29300 (2014).
Caban-Acevedo, M. et al. Efficient hydrogen evolution catalysis using ternary pyrite-type cobalt phosphosulphide. Nat. Mater. 14, 1245–1251 (2015).
Roske, C. W. et al. Comparison of the performance of CoP-coated and Pt-coated radial junction n+p-silicon microwire-array photocathodes for the sunlight-driven reduction of water to H2(g). J. Phys. Chem. Lett. 6, 1679–1683 (2015).
Warren, E. L., McKone, J. R., Atwater, H. A., Gray, H. B. & Lewis, N. S. Hydrogen-evolution characteristics of Ni–Mo-coated, radial junction, n+p-silicon microwire array photocathodes. Energy Environ. Sci. 5, 9653–9661 (2012).
Shaner, M. R., McKone, J. R., Gray, H. B. & Lewis, N. S. Functional integration of Ni–Mo electrocatalysts with Si microwire array photocathodes to simultaneously achieve high fill factors and light-limited photocurrent densities for solar-driven hydrogen evolution. Energy Environ. Sci. 8, 2977–2984 (2015).
Ding, Q. et al. Designing efficient solar-driven hydrogen evolution photocathodes using semitransparent MoQxCly (Q = S, Se) catalysts on Si micropyramids. Adv. Mater. 27, 6511–6518 (2015).
Aspnes, D. E. & Heller, A. Photo-electrochemical hydrogen evolution and water-photolyzing semiconductor suspensions — properties of platinum group metal catalyst semiconductor contacts in air and in hydrogen. J. Phys. Chem. 87, 4919–4929 (1983).
Walczak, K. et al. Modeling, simulation, and fabrication of a fully integrated, acid-stable, scalable solar-driven water-splitting system. ChemSusChem 8, 544–551 (2015).
Chen, Y., Xiang, C., Hu, S. & Lewis, N. S. Modeling the performance of an integrated photoelectrolysis system with 10× solar concentrators. J. Electrochem. Soc. 161, F1101–F1110 (2014).
Hu, S., Xiang, C., Haussener, S., Berger, A. D. & Lewis, N. S. An analysis of the optimal band gaps of light absorbers in integrated tandem photoelectrochemical water-splitting systems. Energy Environ. Sci. 6, 2984–2993 (2013). Pairing a material with a 1.6–18 eV bandgap with Si in a tandem structure gives a theoretical solar-to-hydrogen efficiency limit of 25–30% if the semiconductors are near the Shockley–Queisser efficiency limit and state-of-the-art catalysts are used.
Haussener, S., Hu, S., Xiang, C., Weber, A. Z. & Lewis, N. S. Simulations of the irradiation and temperature dependence of the efficiency of tandem photoelectrochemical water-splitting systems. Energy Environ. Sci. 6, 3605–3618 (2013).
Chen, Y., Hu, S., Xiang, C. & Lewis, N. S. A sensitivity analysis to assess the relative importance of improvements in electrocatalysts, light absorbers, and system geometry on the efficiency of solar-fuels generators. Energy Environ. Sci. 8, 876–886 (2015).
Kline, G., Kam, K. K., Canfield, D. & Parkinson, B. A. Efficient and stable photoelectrochemical cells constructed with WSe2 and MoSe2 photoanodes. Solar Energy Mater. 4, 301–308 (1981).
Fan, F.-R. F., White, H. S., Wheeler, B. L. & Bard, A. J. Semiconductor electrodes. 31. Photoelectrochemistry and photovoltaic systems with n- and p-type WSe2 in aqueous solution. J. Am. Chem. Soc. 102, 5142–5148 (1980).
Kautek, W. & Gerischer, H. The photoelectrochemistry of the aqueous iodide/iodine redox system at n-type MoSe2 electrodes. Electrochim. Acta 26, 1771–1778 (1981).
Kam, K. K. & Parkinson, B. A. Detailed photocurrent spectroscopy of the semiconducting group VI transition metal dichalcogenides. J. Phys. Chem. 86, 463–467 (1982).
Levy-Clement, C., Heller, A., Bonner, W. A. & Parkinson, B. A. Spontaneous photoelectrolysis of HBr and HI. J. Electrochem. Soc. 129, 1701–1705 (1982).
Tenne, R. & Wold, A. Passivation of recombination centers in n-WSe2 yields high efficiency (>14%) photoelectrochemical cell. Appl. Phys. Lett. 47, 707–709 (1985).
Kubiak, C. P., Schneemeyer, L. F. & Wrighton, M. S. Visible light driven generation of chlorine and bromine. Photooxidation of chloride and bromide in aqueous solution at illuminated n-type semiconducting molybdenum diselenide and molybdenum disulfide electrodes. J. Am. Chem. Soc. 102, 6898–6900 (1980).
McKone, J. R., Pieterick, A. P., Gray, H. B. & Lewis, N. S. Hydrogen evolution from Pt/Ru-coated p-type WSe2 photocathodes. J. Am. Chem. Soc. 135, 223–231 (2013).
Lewerenz, H. J., Ferris, S. D., Doherty, C. J. & Leamy, H. J. Charge collection microscopy on p-WSe2: recombination sites and minority carrier diffusion length. J. Electrochem. Soc. 129, 418–423 (1982).
Parkinson, B. A., Furtak, T. E., Canfield, D., Kam, K.-K. & Kline, G. Evaluation and reduction of efficiency losses at tungsten diselenide photoanodes. Faraday Discuss. 70, 233–245 (1980).
Schoppel, H. R. & Gerischer, H. Cathodic reduction of Cu–I oxide electrodes as example for reduction mechanism of semiconductor crystal. Ber. Bunsen-Ges. Phys. Chem. 75, 1237–1239 (1971).
Xiang, C. X. et al. 820 mV open-circuit voltages from Cu2O/CH3CN junctions. Energy Environ. Sci. 4, 1311–1318 (2011).
Gerischer, H. On the stability of semiconductor electrodes against photodecomposition. J. Electroanal. Chem. Electrochem. 82, 133–143 (1977).
Chen, S. & Wang, L.-W. Thermodynamic oxidation and reduction potentials of photocatalytic semiconductors in aqueous solution. Chem. Mater. 24, 3659–3666 (2012).
Berglund, S. P., Flaherty, D. W., Hahn, N. T., Bard, A. J. & Mullins, C. B. Photoelectrochemical oxidation of water using nanostructured BiVO4 films. J. Phys. Chem. C 115, 3794–3802 (2011).
Seabold, J. A. & Choi, K. S. Efficient and stable photo-oxidation of water by a bismuth vanadate photoanode coupled with an iron oxyhydroxide oxygen evolution catalyst. J. Am. Chem. Soc. 134, 2186–2192 (2012).
Abdi, F. F. & van de Krol, R. Nature and light dependence of bulk recombination in Co-Pi-catalyzed BiVO4 photoanodes. J. Phys. Chem. C 116, 9398–9404 (2012).
Seabold, J. A. & Choi, K. S. Effect of a cobalt-based oxygen evolution catalyst on the stability and the selectivity of photo-oxidation reactions of a WO3 photoanode. Chem. Mater. 23, 1105–1112 (2011).
Coridan, R. H., Arpin, K. A., Brunschwig, B. S., Braun, P. V. & Lewis, N. S. Photoelectrochemical behavior of hierarchically structured Si/WO3 core–shell tandem photoanodes. Nano Lett. 14, 2310–2317 (2014).
Klahr, B., Gimenez, S., Fabregat-Santiago, F., Bisquert, J. & Hamann, T. W. Electrochemical and photoelectrochemical investigation of water oxidation with hematite electrodes. Energy Environ. Sci. 5, 7626–7636 (2012).
Klahr, B. M. & Hamann, T. W. Current and voltage limiting processes in thin film hematite electrodes. J. Phys. Chem. C 115, 8393–8399 (2011).
Lopes, T. et al. Hematite photoelectrodes for water splitting: evaluation of the role of film thickness by impedance spectroscopy. Phys. Chem. Chem. Phys. 16, 16515–16523 (2014).
Morrison, S. R. The Chemical Physics of Surfaces (Springer, 1990).
Hu, S. et al. Thin-film materials for the protection of semiconducting photoelectrodes in solar-fuels generators. J. Phys. Chem. C 119, 24201–24228 (2015).
Chen, Y. W. et al. Atomic layer-deposited tunnel oxide stabilizes silicon photoanodes for water oxidation. Nat. Mater. 10, 539–544 (2011).
Scheuermann, A. G. et al. Design principles for maximizing photovoltage in metal-oxide-protected water-splitting photoanodes. Nat. Mater. 15, 99–105 (2016).
Hu, S. et al. Amorphous TiO2 coatings stabilize Si, GaAs, and GaP photoanodes for efficient water oxidation. Science 344, 1005–1009 (2014). Amorphous TiO 2 coatings up to 140 nm thick conduct anodic current, but only when Ni is deposited at the TiO 2 /electrolyte interface.
Lichterman, M. F. et al. Stabilization of n-cadmium telluride photoanodes for water oxidation to O2(g) in aqueous alkaline electrolytes using amorphous TiO2 films formed by atomic-layer deposition. Energy Environ. Sci. 7, 3334–3337 (2014).
McDowell, M. T. et al. The influence of structure and processing on the behavior of TiO2 protective layers for stabilization of n-Si/TiO2/Ni photoanodes for water oxidation. ACS Appl. Mater. Interfaces 7, 15189–15199 (2015).
McDowell, M. T. et al. Improved stability of polycrystalline bismuth vanadate photoanodes by use of dual-layer thin TiO2/Ni coatings. J. Phys. Chem. C 118, 19618–19624 (2014).
Shaner, M. R., Hu, S., Sun, K. & Lewis, N. S. Stabilization of Si microwire arrays for solar-driven H2O oxidation to O2(g) in 1.0 M KOH(aq) using conformal coatings of amorphous TiO2 . Energy Environ. Sci. 8, 203–207 (2015).
Hu, S. et al. Electrical, photoelectrochemical and photoelectron spectroscopic investigation of the interfacial transport and energetics of amorphous TiO2/Si heterojunctions. J. Phys. Chem. C 120, 3117–3129 (2015).
Mei, B. et al. Crystalline TiO2: a generic and effective electron-conducting protection layer for photoanodes and -cathodes. J. Phys. Chem. C 119, 15019–15027 (2015).
Sun, K. et al. Stable solar-driven water oxidation to O2(g) by Ni-oxide-coated silicon photoanodes. J. Phys. Chem. Lett. 6, 592–598 (2015).
Mei, B. et al. Iron-treated NiO as a highly transparent p-type protection layer for efficient Si-based photoanodes. J. Phys. Chem. Lett. 5, 3456–3461 (2014).
Sun, K. et al. Sputtered NiOx films for stabilization of p+n-InP photoanodes for solar-driven water oxidation. Adv. Energy Mater. 5, 1402276 (2015).
Sun, K. et al. Stable solar-driven oxidation of water by semiconducting photoanodes protected by transparent catalytic nickel oxide films. Proc. Natl Acad. Sci. USA 112, 3612–3617 (2015).
Lichterman, M. F. et al. Direct observation of the energetics at a semiconductor/liquid junction by operando X-ray photoelectron spectroscopy. Energy Environ. Sci. 8, 2409–2416 (2015).
Verlage, E. et al. A monolithically integrated, intrinsically safe, 10% efficient, solar-driven water-splitting system based on active, stable Earth-abundant electrocatalysts in conjunction with tandem III–V light absorbers protected by amorphous TiO2 films. Energy Environ. Sci. 8, 3166–3172 (2015).
Zhou, X. et al. Interface engineering of the photoelectrochemical performance of Ni-oxide-coated n-Si photoanodes by atomic-layer deposition of ultrathin films of cobalt oxide. Energy Environ. Sci. 8, 2644–2649 (2015).
The work described herein was enabled by support from the National Science Foundation Center for Chemical Innovation, the Department of Energy Office of Basic Energy Sciences, the Air Force Office of Scientific Research, the Department of Energy through the Joint Center for Artificial Photosynthesis, and the Gordon and Betty Moore Foundation, as acknowledged in the individual publications referenced herein, as well as for partial salary support for N.S.L. that enabled the preparation of this manuscript. M. McDowell and K. Papadantonakis are acknowledged for assistance in preparation of this manuscript. A special acknowledgment is extended to the enthusiastic, talented and dedicated cohort of graduate students, post-doctoral fellows, collaborators and colleagues for their extraordinary, enabling contributions to this research effort, as acknowledged in the publications described and referenced herein.
The author declares no competing financial interests.
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Lewis, N. Developing a scalable artificial photosynthesis technology through nanomaterials by design. Nature Nanotech 11, 1010–1019 (2016). https://doi.org/10.1038/nnano.2016.194
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