Researchs Reveal the Origin of High H Evolution Activity of Single Platinum Catalysts on Nitrogen-Doped Graphene
Update: 2017-03-02 14:58:08      Author: yangjuan@csrc.ac.cn

Hydrogen is generally thought to be one of the most promising energy sources of the 21st century, and platinum-based catalysts are widely considered to be the most effective electrocatalysts for the hydrogen evolution reaction (HER). Unfortunately, Pt is expensive and scarce, limiting the commercial potential for such catalysts. In order to overcome the challenges associated with the Pt HER catalysts and to drive the cost of H2 production down from water electrolysis, it is very important to dramatically decrease the Pt loading and increase the Pt utilization efficiency. Currently, the typically supported Pt nanoparticles (NPs) catalyst limit the majority of the Pt atoms to the particle core, deeming them ineffective as only surface atoms are involved in the electrochemical reaction. Thus, further reducing the size of the Pt NPs to clusters or even single atoms to decrease the noble metal usage and increase their catalytic activity is highly desirable. However, in practical applications, controlled and large-scale synthesis of stable single atoms and clusters remains a considerable challenge due to the natural tendency for these active metal atoms to diffuse and agglomerate.

 

A group of researchers at CSRC, led by Dr. Li-Min Liu, has worked together with Prof. Xueliang Sun’ group at University of Western Ontario and Prof. Gianluigi A. Botton at McMaster University to explore an effective means to synthesize the stable single-atom catalyst on a large scale. Utilizing a combined aberration corrected scanning transmission electron microscopy (STEM) and density functional theory (DFT) calculations, the atomic layer deposition (ALD) technique has been proven to successfully fabricated single Pt atoms supported by nitrogen-doped graphene nanosheets (NGNs) for the HER. From DFT analysis, the stabilization mechanism of single Pt atom on N-doped graphene was uncovered. They have discovered that the remarkable performance of the single Pt atoms on the NGNs arise from their small size and the unique electronic structure originating from the partially unoccupied density of states of the platinum atoms’ 5d orbitals. This study paved the way for the investigation of the electrocatalytic activity properties and the electronic structure of other single atom catalysts.

 

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Fig. 1. (a)-(d) The hybrid orbitals between the Pt and H atoms for the 2 H and 4 H atoms adsorption on the Pt single atom. (e)-(f) The normalized XANES spectra at the Pt L3- and L2- edge of the ALDPt/NGNs, Pt/C catalysts, and Pt foil, respectively.

 

For more information, please see the paper “Platinum single-atom and cluster catalysis of the hydrogen evolution reaction”, Niancai Cheng#, Samantha Stambula#, Da Wang# , Mohammad Norouzi Banis, Jian Liu, Adam Riese, Biwei Xiao, Ruying Li, Tsun-Kong Sham, Li-Min Liu*, Gianluigi A. Botton*, and Xueliang Sun*, Nature Commutations, 7, 13638 (2016). (#equal contribution to this work)


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