Spatial decoupling of light absorption and catalytic activity of Ni–Mo-loaded high-aspect-ratio silicon microwire photocathodes

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A solar-driven photoelectrochemical cell provides a promising approach to enable the large-scale conversion and storage of solar energy, but requires the use of Earth-abundant materials. Earth-abundant catalysts for the hydrogen evolution reaction, for example nickel–molybdenum (Ni–Mo), are generally opaque and require high mass loading to obtain high catalytic activity, which in turn leads to parasitic light absorption for the underlying photoabsorber (for example silicon), thus limiting production of hydrogen. Here, we show the fabrication of a highly efficient photocathode by spatially and functionally decoupling light absorption and catalytic activity. Varying the fraction of catalyst coverage over the microwires, and the pitch between the microwires, makes it possible to deconvolute the contributions of catalytic activity and light absorption to the overall device performance. This approach provided a silicon microwire photocathode that exhibited a near-ideal short-circuit photocurrent density of 35.5 mA cm−2, a photovoltage of 495 mV and a fill factor of 62% under AM 1.5G illumination, resulting in an ideal regenerative cell efficiency of 10.8%.

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  1. 1.

    Walter, M. G. et al. Solar water splitting cells. Chem. Rev. 110, 6446–6473 (2010).

  2. 2.

    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).

  3. 3.

    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).

  4. 4.

    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).

  5. 5.

    Battaglia, C., Cuevas, A. & De Wolf, S. High-efficiency crystalline silicon solar cells: status and perspectives. Energy Environ. Sci. 9, 1552–1576 (2016).

  6. 6.

    Vijselaar, W., Elbersen, R., Tiggelaar, R. M., Gardeniers, H. & Huskens, J. Photo-electrical characterization of silicon micropillar arrays with radial p/n junctions containing passivation and anti-reflection coatings. Adv. Energy Mater. 7, 1601497 (2016).

  7. 7.

    Chen, Y. K., Sun, K., Audesirk, H., Xiang, C. X. & 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).

  8. 8.

    Elbersen, R. et al. Controlled doping methods for radial p/n junctions in silicon. Adv. Energy Mater. 5, 1401745–1401753 (2015).

  9. 9.

    Elbersen, R., Vijselaar, W., Tiggelaar, R. M., Gardeniers, H. & Huskens, J. Effects of pillar height and junction depth on the performance of radially doped silicon pillar arrays for solar energy applications. Adv. Energy Mater. 6, 1501728 (2016).

  10. 10.

    Nickel Plating Handbook Vol. 1, 80 (Nickel Institute, Toronto, Canada, 2014).

  11. 11.

    McKone, J. R. et al. Evaluation of Pt, Ni, and Ni–Mo electrocatalysts for hydrogen evolution on crystalline Si electrodes. Energy Environ. Sci. 4, 3573–3583 (2011).

  12. 12.

    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).

  13. 13.

    Hoare, J. P. Boric-acid as a catalyst in nickel plating solutions. J. Electrochem. Soc. 134, 3102–3103 (1987).

  14. 14.

    Fan, C., Piron, D. L., Sleb, A. & Paradis, P. Study of electrodeposited nickel–molybdenum, nickel–tungsten, cobalt–molybdenum, and cobalt–tungsten as hydrogen electrodes in alkaline water electrolysis. J. Electrochem. Soc. 141, 382–387 (1994).

  15. 15.

    Podlaha, E. J. & Landolt, D. Induced codeposition. I. An experimental investigation of Ni–Mo alloys. J. Electrochem. Soc. 143, 885––892 (1996).

  16. 16.

    Podlaha, E. J. & Landolt, D. Induced codeposition. II. A mathematical model describing the electrodeposition of Ni–Mo alloys. J. Electrochem. Soc. 143, 893–899 (1996).

  17. 17.

    Podlaha, E. J. & Landolt, D. Induced codeposition. III. Molybdenum alloys with nickel, cobalt, and iron. J. Electrochem. Soc. 144, 1672–1680 (1997).

  18. 18.

    Chen, Y., Shen, J. & Chen, N. X. The effect of Mo atoms in ternary nitrides with eta-type structure. Solid State Commun. 149, 121–125 (2009).

  19. 19.

    Mishima, Y., Ochiai, S. & Suzuki, T. Lattice parameters of Ni(γ), Ni3Al(γ′), and Ni3Ga(γ′) solid solutions with the additions of transition and B-subgroup elements. Acta Metallurgica 33, 1161–1196 (1985).

  20. 20.

    Schultz, O., Mette, A., Hermle, M. & Glunz, S. W. Thermal oxidation for crystalline silicon solar cells exceeding 19% efficiency applying industrially feasible process technology. Prog. Photovoltaics 16, 317–324 (2008).

  21. 21.

    Benick, J., Zimmermann, K., Spiegelman, J., Hermle, M. & Glunz, S. W. Rear side passivation of PERC-type solar cells by wet oxides grown from purified steam. Prog. Photovoltaics 19, 361–365 (2011).

  22. 22.

    Mack, S. et al. Properties of purified direct steam grown silicon thermal oxides. Sol. Energy Mater. Sol. Cells 95, 2570–2575 (2011).

  23. 23.

    Garcia-Esparza, A. T. & Takanabe, K. A simplified theoretical guideline for overall water splitting using photocatalyst particles. J. Mat. Chem. A 4, 2894–2908 (2016).

  24. 24.

    Westerik, P. J. et al. Sidewall patterning — a new wafer-scale method for accurate patterning of vertical silicon structures. J. Micromech. Microeng. 28, 015008 (2017).

  25. 25.

    Green, M. A. Accuracy of analytical expressions for solar cell fill factors. Solar Cells 7, 337–340 (1982).

  26. 26.

    Kim, J. H. et al. Hetero-type dual photoanodes for unbiased solar water splitting with extended light harvesting. Nat. Commun. 7, 13380 (2016).

  27. 27.

    Vermaas, D. A., Sassenburg, M. & Smith, W. A. Photo-assisted water splitting with bipolar membrane induced pH gradients for practical solar fuel devices. J. Mat. Chem. A 3, 19556–19562 (2015).

  28. 28.

    Veldhuizen, L. W., Vijselaar, W. J. C., Gatz, H. A., Huskens, J. & Schropp, R. E. I. Textured and micropillar silicon heterojunction solar cells with hot-wire deposited passivation layers. Thin Solid. Films 635, 66–72 (2017).

  29. 29.

    Hale, G. M. & Querry, M. R. Optical constants of water in the 200-nm to 200-μm wavelength region. Appl. Opt. 12, 555–563 (1973).

  30. 30.

    Boettcher, S. W. et al. Photoelectrochemical hydrogen evolution using Si microwire arrays. J. Am. Chem. Soc. 133, 1216–1219 (2011).

  31. 31.

    Huang, Z. et al. Ni12P5 nanoparticles as an efficient catalyst for hydrogen generation via electrolysis and photoelectrolysis. ACS Nano 8, 8121–8129 (2014).

  32. 32.

    Bao, X. Q., Fatima Cerqueira, M., Alpuim, P. & Liu, L. Silicon nanowire arrays coupled with cobalt phosphide spheres as low-cost photocathodes for efficient solar hydrogen evolution. Chem. Commun. 51, 10742–10745 (2015).

  33. 33.

    Lv, C. et al. Silicon nanowires loaded with iron phosphide for effective solar-driven hydrogen production. J. Mat. Chem. A 3, 17669–17675 (2015).

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The Netherlands Organization for Scientific Research (NWO) is acknowledged for financial support (FOM projects 13CO12-1 and 13CO12-2, and MESA+ School for Nanotechnology grant 022.003.001). A. Milbrat and G. Mul are acknowledged for assistance with the gas chromatography measurements.

Author information


  1. Molecular NanoFabrication, MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands

    • Wouter Vijselaar
    • , Janneke Veerbeek
    •  & Jurriaan Huskens
  2. Mesoscale Chemical Systems, MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands

    • Pieter Westerik
    • , Roald M. Tiggelaar
    • , Erwin Berenschot
    • , Niels R. Tas
    •  & Han Gardeniers
  3. NanoLab Cleanroom, MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands

    • Roald M. Tiggelaar


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W.V., P.W., J.V. and E.B. performed the experimental work, W.V., P.W., N.R.T. and R.M.T. planned the project and performed the data analysis, W.V., H.G. and J.H. conceived the idea, and all authors contributed to the writing of the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Han Gardeniers or Jurriaan Huskens.

Supplementary information

  1. Supplementary Information

    Supplementary Figures 1–17, Supplementary Tables 1–5, Supplementary Discussion and Supplementary References