Single-atom cobalt array bound to distorted 1T MoS2 with ensemble effect for hydrogen evolution catalysis

Kun Qi,Shaojun Guo,Ningbo Li,Mingchuan Luo,Lirong Zheng,Xiaofeng Fan,Weitao Zheng,Qinghua Zhang,Yue Gong,Wei Zhang,Shan Xu,Lin Gu,Haihua Huang,Shansheng Yu,Kai Wang,Xiaoqiang Cui,Jingyuan Ma,Fan Lv,Ping Liu

doi:10.1038/s41467-019-12997-7

Abstract

The grand challenge in the development of atomically dispersed metallic catalysts is their low metal-atom loading density, uncontrollable localization and ambiguous interactions with supports, posing difficulty in maximizing their catalytic performance. Here, we achieve an interface catalyst consisting of atomic cobalt array covalently bound to distorted 1T MoS2 nanosheets (SA Co-D 1T MoS2). The phase of MoS2 transforming from 2H to D-1T, induced by strain from lattice mismatch and formation of Co-S covalent bond between Co and MoS2 during the assembly, is found to be essential to form the highly active single-atom array catalyst. SA Co-D 1T MoS2 achieves Pt-like activity toward HER and high long-term stability. Active-site blocking experiment together with density functional theory (DFT) calculations reveal that the superior catalytic behaviour is associated with an ensemble effect via the synergy of Co adatom and S of the D-1T MoS2 support by tuning hydrogen binding mode at the interface.

Highlights

The grand challenge in the development of atomically dispersed metallic catalysts is their low metal-atom loading density, uncontrollable localization and ambiguous interactions with supports, posing difficulty in maximizing their catalytic performance
Highresolution Transmission electron microscopy (TEM) (HRTEM) image shows that MoS2 is intensely disordered after bonding with Co atoms (Supplementary Fig. 8i)
The atomically isolated Co species are dispersed on the distorted 1T (D-1T) MoS2 matrix, and the obvious interface between SA Co-D 1T MoS2 and the 2H MoS2 is confirmed by both the High-angle annular dark-field (HAADF)-scanning transmission electron microscopy (STEM) image (Fig. 1c) and simulated pattern (Fig. 1d, e)

Summary

Introduction

The grand challenge in the development of atomically dispersed metallic catalysts is their low metal-atom loading density, uncontrollable localization and ambiguous interactions with supports, posing difficulty in maximizing their catalytic performance. The phase of MoS2 transforming from 2H to D-1T, induced by strain from lattice mismatch and formation of Co-S covalent bond between Co and MoS2 during the assembly, is found to be essential to form the highly active single-atom array catalyst. The biggest issue is that previously reported atomically dispersed catalysts have been primarily in the form of atomic clusters, especially at high loading amounts, owing to the ambiguous interactions between the metal atoms and supports, posing a difficulty in maximizing the catalytic efficiency[11,12,13,14,15]. The ultrahigh activity is proved to be the ensemble effect through the synergy of single Co atom and S in distorted 1T phase of MoS2 that possesses the optimal hydrogen-binding energy

Methods

Results

Conclusion