Efficient and Robust Hydrogen Evolution: Phosphorus Nitride Imide Nanotubes as Supports for Anchoring Single Ruthenium Sites

Jian Yang; Bingxu Chen; Xiaokang Liu; Wei Liu; Zhijun Li; Juncai Dong; Wenxing Chen; Wensheng Yan; Tao Yao; Xuezhi Duan; Yuen Wu; Yadong Li

doi:10.1002/anie.201804854

Efficient and Robust Hydrogen Evolution: Phosphorus Nitride Imide Nanotubes as Supports for Anchoring Single Ruthenium Sites

Angew Chem Int Ed Engl. 2018 Jul 20;57(30):9495-9500. doi: 10.1002/anie.201804854. Epub 2018 Jul 2.

Authors

Jian Yang^{1

2}, Bingxu Chen³, Xiaokang Liu⁴, Wei Liu⁴, Zhijun Li^{1

2}, Juncai Dong^{2

5

6}, Wenxing Chen^{2

5

6}, Wensheng Yan⁴, Tao Yao⁴, Xuezhi Duan³, Yuen Wu^{1

2}, Yadong Li^{1

2}

Affiliations

¹ Department of Chemistry, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), University of Science and Technology of China, Hefei, 230026, China.
² Department of Chemistry, Tsinghua University, Beijing, 100084, P.R. China.
³ State Key Laboratory of Chemical Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China.
⁴ National Synchrotron Radiation Laboratory (NSRL), University of Science and Technology of China, Hefei, Anhui, 230029, China.
⁵ Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green Application, School of Materials Science and Engineering, Beijing Institute of Technology, Beijing, 100081, China.
⁶ Institute of High Energy Physics, Beijing, 100029, China.

PMID: 29897158
DOI: 10.1002/anie.201804854

Abstract

Amorphous phosphorus nitride imide nanotubes (HPN) are reported as a novel substrate to stabilize materials containing single-metal sites. Abundant dangling unsaturated P vacancies play a role in stabilization. Ruthenium single atoms (SAs) are successfully anchored by strong coordination interactions between the d orbitals of Ru and the lone pair electrons of N located in the HPN matrix. The atomic dispersion of Ru atoms can be distinguished by X-ray absorption fine structure measurements and spherical aberration correction electron microscopy. Importantly, Ru SAs@PN is an excellent electrocatalyst for the hydrogen evolution reaction (HER) in 0.5 m H₂ SO₄ , delivering a low overpotential of 24 mV at 10 mA cm^-2 and a Tafel slope of 38 mV dec^-1 . The catalyst exhibits robust stability in a constant current test at a large current density of 162 mA cm^-2 for more than 24 hours, and is operative for 5000 cycles in a cyclic voltammetry test. Additionally, Ru SAs@PN presents a turnover frequency (TOF) of 1.67 H₂ s^-1 at 25 mV, and 4.29 H₂ s^-1 at 50 mV, in 0.5 m H₂ SO₄ solution, outperforming most of the reported hydrogen evolution catalysts. Density functional theory (DFT) calculations further demonstrate that the Gibbs free energy of adsorbed H* over the Ru SAs on PN is much closer to zero compared with the Ru/C and Ru SAs supported on carbon and C₃ N₄ , thus considerably facilitating the overall HER performance.

Keywords: carbon-free supports; hydrogen evolution reaction (HER); phosphorus nitride; ruthenium; single atoms.