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Issue 8, 2019
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Three-dimensionally patterned Ag–Pt alloy catalyst on planar Si photocathodes for photoelectrochemical H2 evolution

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Abstract

Platinum is still the most active element for the hydrogen evolution reaction (HER); however, it suffers from its scarcity and high cost. Thus, significant efforts have been dedicated to maximize the catalytic activity with less loading. When Pt is utilized at a semiconductor surface, more factors have to be considered. Placing a catalyst directly in contact with a semiconductor supports the extraction of photogenerated minority carriers as well as boosts the catalytic reactions. In addition, a catalyst should be designed with prudence not to interfere in the light path with respect to absorption at the underlying substrate. Herein, we report the development of planar Si-based photocathodes, covered with a native oxide, for the HER, which also satisfy the prerequisites for the use of a three-dimensionally patterned, flower-like Ag–Pt catalyst. The catalyst consisted of nanoparticles of homogeneously alloyed Ag and Pt, fabricated by a galvanic exchange of Pt with Ag. Importantly, these two elements were proven to have their own functionalities. Ag not only contributed to transporting e and Had to the Pt for subsequent processes of the HER but also effectively extracted minority carriers by diluting the high work function of Pt, leading to a better Schottky barrier at the catalyst–insulator–semiconductor junction. Furthermore, computational simulation revealed that the proposed catalyst pattern alleviated optical light loss with the increasing catalyst loading compared to the two-dimensional case. Owing to these effects, we could achieve 0.36 V (vs. reversible hydrogen electrode) as an open circuit potential and the near maximum current density of planar p-type Si. The findings in this work suggests deeper insights that could support the design of catalysts for solar-fuel systems.

Graphical abstract: Three-dimensionally patterned Ag–Pt alloy catalyst on planar Si photocathodes for photoelectrochemical H2 evolution

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Publication details

The article was received on 28 Nov 2018, accepted on 23 Jan 2019 and first published on 23 Jan 2019


Article type: Paper
DOI: 10.1039/C8CP07304J
Citation: Phys. Chem. Chem. Phys., 2019,21, 4184-4192

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    Three-dimensionally patterned Ag–Pt alloy catalyst on planar Si photocathodes for photoelectrochemical H2 evolution

    S. Y. Lim, K. Ha, H. Ha, S. Y. Lee, M. S. Jang, M. Choi and T. D. Chung, Phys. Chem. Chem. Phys., 2019, 21, 4184
    DOI: 10.1039/C8CP07304J

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