In situ modification of delafossite-type PdCoO2 bulk single crystal for reversible hydrogen sorption and fast hydrogen evolution
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The observation of extraordinarily high conductivity in delafossite-type PdCoO2 is of great current interest, and there is some evidence that electrons behave like a fluid when flowing in bulk crystals of PdCoO2. Thus, this material is an ideal platform for the study of the electron transfer processes in heterogeneous reactions. Here, we report the use of bulk single crystal PdCoO2 as a promising electrocatalyst for hydrogen evolution reactions (HERs). An overpotential of only 31 mV results in a current density of 10 mA cm-2, accompanied by excellent long-term stability. We have precisely determined that the crystal surface structure is modified after electrochemical activation with the formation of strained Pd nanoclusters in the surface layer. These nanoclusters exhibit excellent hydrogen sorption/desorption reversibility, creating more active sites for hydrogen access. The bulk PdCoO2 single crystal with ultra-high conductivity, which acts as a natural substrate for the Pd nanoclusters, provides a high-speed channel for electron transfer.
Li , G , Khim , S , Chang , C S , Fu , C , Nandi , N , Li , F , Yang , Q , Blake , G R , Parkin , S , Auffermann , G , Sun , Y , Muller , D A , Mackenzie , A P & Felser , C 2019 , ' In situ modification of delafossite-type PdCoO 2 bulk single crystal for reversible hydrogen sorption and fast hydrogen evolution ' , ACS Energy Letters , vol. 4 , no. 9 , pp. 2185-2191 . https://doi.org/10.1021/acsenergylett.9b01527
ACS Energy Letters
Copyright © 2019 American Chemical Society. This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.
DescriptionThis work was financially supported by the European Research Council (ERC Advanced Grant No. 291472 'Idea Heusler') and ERC Advanced Grant (No. 742068). TOPMAT’. Electron Microscopy (C.C., D.M.) supported by the U.S. Department of Energy, Basic Energy Sciences grant No. DE-SC0019445, with facility support from the National Science Foundation NSF Grant No. DMR-1719875.
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