3 years ago

An Oxygen-Insensitive Hydrogen Evolution Catalyst Coated by a Molybdenum-Based Layer for Overall Water Splitting

An Oxygen-Insensitive Hydrogen Evolution Catalyst Coated by a Molybdenum-Based Layer for Overall Water Splitting
Samy Ould-Chikh, Nini Wei, Kazunari Domen, Kazuhiro Takanabe, Alain Clo, Tsu-Chien Weng, Angel T. Garcia-Esparza, Dalaver H. Anjum, Dennis Nordlund, Xuyuan Peng, Dimosthenis Sokaras, Tatsuya Shinagawa, Jun Kubota, Muhammad Qureshi
For overall water-splitting systems, it is essential to establish O2-insensitive cathodes that allow cogeneration of H2 and O2. An acid-tolerant electrocatalyst is described, which employs a Mo-coating on a metal surface to achieve selective H2 evolution in the presence of O2. In operando X-ray absorption spectroscopy identified reduced Pt covered with an amorphous molybdenum oxyhydroxide hydrate with a local structural order composed of polyanionic trimeric units of molybdenum(IV). The Mo layer likely hinders O2 gas permeation, impeding contact with active Pt. Photocatalytic overall water splitting proceeded using MoOx/Pt/SrTiO3 with inhibited water formation from H2 and O2, which is the prevailing back reaction on the bare Pt/SrTiO3 photocatalyst. The Mo coating was stable in acidic media for multiple hours of overall water splitting by membraneless electrolysis and photocatalysis. Oxygen-tolerant hydrogen evolution: Molybdenum species inhibit water-forming reactions on platinum and other metal catalysts. Hydrogen was selectively produced by electro- and photocatalytic water splitting in the presence of competing oxygen. In operando characterization revealed an amorphous oxyhydroxide hydrated structure of polyanionic trimeric molybdenum(IV) protecting metallic platinum.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/anie.201701861

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