Polyoxometalate Precursors for Precisely Controlling Synthesis of Bimetallic Sulfide Heterostructure through Nucleation-Doping Competition

Ya-Qian Lan, Yu-Jia Tang, A-Man Zhang, Hong-Jing Zhu, Long-Zhang Dong, Xiao-Li Wang, Min Han, Shun-Li Li, Xiangxing Xu

Index: 10.1039/C8NR00925B

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Abstract

Molybdenum disulfide (MoS2)-based bimetallic sulfides have drawn the increasing research attention because of the unique structures and properties. Herein, a one-pot hydrothermal synthesis method was proposed to grow a series of bimetallic sulfides on carbon cloth (M-Mo-S/CC, M = Co, Ni, Fe) using Anderson-type polyoxometalates (POMs) as bimetallic sources for the first time. The ideal model of M-Mo-S/CC was used to study the growth process through the nucleation-doping competition mechanism. It is firstly proved that M-Mo-S/CC possess certain compositions of bimetallic sulfides rather than metal doping into MoS2 structures because the nucleation reaction plays a main role in the nucleation-doping competition. Moreover, the nucleation rates of different metals can be compared to study different morphologies of M-Mo-S/CC because Anderson-type POMs have fixed bimetal proportions and precise structures. Co-Mo-S and Ni-Mo-S show the spherical structures with CoS2 or NiS inside and interconnected MoS2 nanosheets outside, while Fe-Mo-S exhibits the uniform nanosheets morphology without stacking. As the electrodes for alkaline water electrolysis, M-Mo-S/CC with different compositions and morphologies exhibit distinguishing activities. Particularly, Co-Mo-S/CC achieves the best performance for hydrogen evolution reaction, oxygen evolution reaction and overall water splitting among all M-Mo-S/CC samples. This work presents a facile strategy using POMs as bimetallic precursors to study growth mechanism as well as water electrolysis performance of MoS2-based bimetallic sulfides.