Interfacial engineering of cobalt sulfide/graphene hybrids for highly efficient ammonia electrosynthesis

Pengzuo Chen; Nan Zhang; Sibo Wang; Tianpei Zhou; Yun Tong; Chengcheng Ao; Wensheng Yan; Lidong Zhang; Wangsheng Chu; Changzheng Wu; Yi Xie

doi:10.1073/pnas.1817881116

Interfacial engineering of cobalt sulfide/graphene hybrids for highly efficient ammonia electrosynthesis

Proc Natl Acad Sci U S A. 2019 Apr 2;116(14):6635-6640. doi: 10.1073/pnas.1817881116. Epub 2019 Mar 14.

Authors

Pengzuo Chen^{1

2

3}, Nan Zhang⁴, Sibo Wang^{1

2

3}, Tianpei Zhou^{1

2

3}, Yun Tong^{1

2

3}, Chengcheng Ao⁴, Wensheng Yan⁴, Lidong Zhang⁴, Wangsheng Chu⁴, Changzheng Wu^{5

2

3}, Yi Xie^{1

2

3}

Affiliations

¹ Hefei National Laboratory for Physical Science at the Microscale, University of Science and Technology of China, Hefei, 230026 Anhui, People's Republic of China.
² Collaborative Innovation Center of Chemistry for Energy Materials, University of Science and Technology of China, Hefei, 230026 Anhui, People's Republic of China.
³ Chinese Academy of Sciences Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China, Hefei, 230026 Anhui, People's Republic of China.
⁴ National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029 Anhui, People's Republic of China.
⁵ Hefei National Laboratory for Physical Science at the Microscale, University of Science and Technology of China, Hefei, 230026 Anhui, People's Republic of China; czwu@ustc.edu.cn.

Abstract

Electrocatalytic N₂ reduction reaction (NRR) into ammonia (NH₃), especially if driven by renewable energy, represents a potentially clean and sustainable strategy for replacing traditional Haber-Bosch process and dealing with climate change effect. However, electrocatalytic NRR process under ambient conditions often suffers from low Faradaic efficiency and high overpotential. Developing newly regulative methods for highly efficient NRR electrocatalysts is of great significance for NH₃ synthesis. Here, we propose an interfacial engineering strategy for designing a class of strongly coupled hybrid materials as highly active electrocatalysts for catalytic N₂ fixation. X-ray absorption near-edge spectroscopy (XANES) spectra confirm the successful construction of strong bridging bonds (Co-N/S-C) at the interface between CoS _x nanoparticles and NS-G (nitrogen- and sulfur-doped reduced graphene). These bridging bonds can accelerate the reaction kinetics by acting as an electron transport channel, enabling electrocatalytic NRR at a low overpotential. As expected, CoS₂/NS-G hybrids show superior NRR activity with a high NH₃ Faradaic efficiency of 25.9% at -0.05 V versus reversible hydrogen electrode (RHE). Moreover, this strategy is general and can be extended to a series of other strongly coupled metal sulfide hybrids. This work provides an approach to design advanced materials for ammonia production.

Keywords: NH3 electrosynthesis; bridging bonds; cobalt sulfides; general strategy; interfacial engineering.

Publication types

Research Support, Non-U.S. Gov't