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Published September 1, 2019 | Supplemental Material
Journal Article Open

Integration of electrocatalysts with silicon microcone arrays for minimization of optical and overpotential losses during sunlight-driven hydrogen evolution


Microstructured photoelectrode morphologies can advantageously facilitate integration of optically absorbing electrocatalysts with semiconducting light absorbers, to maintain low overpotentials for fuel production without producing a substantial loss in photocurrent density. We report herein the use of arrays of antireflective, high-aspect-ratio Si microcones (μ-cones), coupled with light-blocking Pt and Co–P catalysts, as photocathodes for H_2 evolution. Thick (∼16 nm) layers of Pt or Co–P deposited onto Si μ-cone arrays yielded absolute light-limited photocurrent densities of ∼32 mA cm^(−2), representing a reduction in light-limited photocurrent density of 6% relative to bare Si μ-cone-array photocathodes, while maintaining high fill factors and low overpotentials for H_2 production from 0.50 M H_2SO_4(aq). The Si μ-cone arrays were embedded in a flexible polymeric membrane and removed from the Si substrate, to yield flexible photocathodes consisting of polymer-embedded arrays of free-standing μ-cones that evolved hydrogen from 0.50 M H_2SO_4(aq).

Additional Information

© The Royal Society of Chemistry 2019. Received 10th May 2019. Accepted 13th May 2019. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, as follows: electrochemical measurements for all devices, and fabrication of p-Si/Co–P devices was supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993; the development and fabrication of p-Si and n^+p-Si/Pt μ-cone arrays and reflection measurements were supported by the National Science Foundation (NSF) under NSF CA No. EEC-1041895. Additional support for this work was provided by the Lockheed Martin Corporation (Award 4103810021). Fabrication of Si μ-cones was performed in the Kavli Nanoscience Institute (KNI) at Caltech, and we thank the KNI staff for their assistance during fabrication.

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