Tailoring the d-band center of N-doped carbon nanotube arrays with Co4N nanoparticles and single-atom Co for a superior hydrogen evolution reaction

Bo Cao,Minghao Hu,Yan Cheng,Xi Wang,Rui Gao,Xiaolei Sun,Peng Jing,Baocang Liu,Yaping Du,Jun Zhang,Bo Zhou

doi:10.1038/s41427-020-00264-x

Abstract

A 3D self-supported integrated electrode, consisting of heteroatomic nitrogen-doped carbon nanotube arrays on carbon cloth with confined ultrafine Co4N nanoparticles and a distribution of anchored single-atom Co, is fabricated via a cobalt-catalyzed growth strategy using dicyandiamide as the nitrogen and carbon source and a layered cobalt hydroxide-nitrate salt as the precursor. The abundance of exposed active sites, namely, the Co4N nanoparticles, single-atom Co, and heteroatomic N-doped carbon nanotubes, and multiple synergistic effects among these components provide suitable tailoring of the d-band center for facilitating vectorial electron transfer and efficient electrocatalysis. Benefiting from the merits of its structural features and electronic configuration, the prepared electrode exhibits robust performance toward the hydrogen evolution reaction with overpotentials of only 78 and 86 mV at 10 mA cm−2 in acidic and basic electrolytes, respectively. Density functional theory calculations and X-ray photoelectron spectroscopy valence band measurements reveal that the effective tailoring of the d-band center by Co4N nanoparticles plays a crucial role in optimizing the hydrogen adsorption free energy to a more thermoneutral value for efficient electrocatalysis.

Highlights

Impelled by the fast exhaustion of traditional fossil fuels and environmental stress, the request for clean renewable energy continues to increase every year[1]
The lamellar cobalt precursor composed of layered cobalt hydroxide-nitrate salts (Co-LHSs) modified with ligand molecules of TEOA on the surface, which possesses a similar structure to that of layered double hydroxides (LDHs), is newly developed in our lab and plays a very important role in achieving high-quality Co4N@CoSA/N-carbon nanotubes (CNTs)/carbon cloth (CC) due to the well-controlled transformation of Co-LHSs into ultrafine Co nanoparticles embedded in N-CNTs and highly distributed single-atom Co anchored on N-CNTs
Dicyandiamide can be catalyzed to grow well-defined N-CNTs in situ with heteroatomic N atom doping to form N-CNT arrays on CC. This treatment induces the in situ transformation of Co-LHSs into ultrafine Co nanoparticles embedded in N-CNTs and highly dispersive Co single atoms anchored on N-CNTs (Co@CoSA/N-CNT/CC)

Summary

Introduction

Impelled by the fast exhaustion of traditional fossil fuels and environmental stress, the request for clean renewable energy continues to increase every year[1]. Electrochemical water splitting is identified as one of the Currently, the development of superior electrocatalysts with earth-abundant elements for the HER has become a research priority Among these studies, due to admirable electronic conductivity, vigorous stability, and environmental friendliness[4], many works are centralized on. Page 2 of 14 1 carbon-based materials with various nanostructures, such as carbon nanotubes (CNTs)[5], carbon nanosheets[6], hollow carbons[7], and g-C3N4-based materials[8]. Heteroatoms such as N, P, B, and S are doped into carbonbased materials to optimize their electrocatalytic performances[9].

Methods

Results

Conclusion