Highly efficient electrocatalytic hydrogen evolution promoted by O-Mo-C interfaces of ultrafine β-Mo2C nanostructures

Hui Yang; Xing Chen; Guoxiang Hu; Wan-Ting Chen; Siobhan J Bradley; Weijie Zhang; Gaurav Verma; Thomas Nann; De-En Jiang; Paul E Kruger; Xiangke Wang; He Tian; Geoffrey I N Waterhouse; Shane G Telfer; Shengqian Ma

doi:10.1039/d0sc00427h

Highly efficient electrocatalytic hydrogen evolution promoted by O-Mo-C interfaces of ultrafine β-Mo₂C nanostructures

Chem Sci. 2020 Mar 12;11(13):3523-3530. doi: 10.1039/d0sc00427h.

Authors

Hui Yang^{1

2}, Xing Chen³, Guoxiang Hu⁴, Wan-Ting Chen⁵, Siobhan J Bradley⁶, Weijie Zhang², Gaurav Verma², Thomas Nann⁶, De-En Jiang⁷, Paul E Kruger⁸, Xiangke Wang¹, He Tian³, Geoffrey I N Waterhouse⁵, Shane G Telfer⁹, Shengqian Ma²

Affiliations

¹ College of Environmental Science and Engineering, North China Electric Power University Beijing 102206 P. R. China xkwang@ncepu.edu.cn.
² Department of Chemistry, University of South Florida 4202 E. Fowler Avenue Tampa Florida 33620 USA sqma@usf.edu.
³ Center of Electron Microscopy, Zhejiang University Hangzhou 310027 P. R. China hetian@zju.edu.cn.
⁴ Center for Nanophase Materials Sciences, Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA.
⁵ MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical Sciences, The University of Auckland Auckland 1142 New Zealand.
⁶ MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington Wellington 6140 New Zealand.
⁷ Department of Chemistry, University of California Riverside California 92521 USA.
⁸ MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Physical and Chemical Sciences, University of Canterbury Christchurch 8140 New Zealand.
⁹ MacDiarmid Institute for Advanced Materials and Nanotechnology, Institute of Fundamental Sciences, Massey University Palmerston North 4442 New Zealand.

Abstract

Optimizing interfacial contacts and thus electron transfer phenomena in heterogeneous electrocatalysts is an effective approach for enhancing electrocatalytic performance. Herein, we successfully synthesized ultrafine β-Mo₂C nanoparticles confined within hollow capsules of nitrogen-doped porous carbon (β-Mo₂C@NPCC) and found that the surface layer of molybdenum atoms was further oxidized to a single Mo-O surface layer, thus producing intimate O-Mo-C interfaces. An arsenal of complementary technologies, including XPS, atomic-resolution HAADF-STEM, and XAS analysis clearly reveals the existence of O-Mo-C interfaces for these surface-engineered ultrafine nanostructures. The β-Mo₂C@NPCC electrocatalyst exhibited excellent electrocatalytic activity for the hydrogen evolution reaction (HER) in water. Theoretical studies indicate that the highly accessible ultrathin O-Mo-C interfaces serving as the active sites are crucial to the HER performance and underpinned the outstanding electrocatalytic performance of β-Mo₂C@NPCC. This proof-of-concept study opens a new avenue for the fabrication of highly efficient catalysts for HER and other applications, whilst further demonstrating the importance of exposed interfaces and interfacial contacts in efficient electrocatalysis.