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

Wouter Vijselaar, Pieter Westerik, Janneke Veerbeek, Roald M. Tiggelaar, Erwin Berenschot, Niels R. Tas, Han Gardeniers (Corresponding Author), Jurriaan Huskens* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

46 Citations (Scopus)
49 Downloads (Pure)

Abstract

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%.

Original languageEnglish
Pages (from-to)185-192
Number of pages8
JournalNature energy
Volume3
Issue number3
DOIs
Publication statusPublished - Mar 2018

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