Polyoxometalate precursors for precisely controlled synthesis of bimetallic sulfide heterostructure through nucleation-doping competition

Abstract

Molybdenum disulfide (MoS₂)-based bimetallic sulfides have drawn increasing research attention because of their unique structures and properties. Herein, a one-pot hydrothermal synthesis method is 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. An ideal model of M–Mo–S/CC was used to study the growth process through the nucleation-doping competition mechanism. It is proved for the first time that M–Mo–S/CC possess certain compositions of bimetallic sulfides rather than metal doped MoS₂ structures because the nucleation reaction is predominant in the nucleation-doping competition. Moreover, the nucleation rates of different metals can be compared to study the 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 spherical heterostructures with CoS₂ or NiS mainly inside and interconnected MoS₂ nanosheets outside, while Fe–Mo–S exhibits uniform nanosheet morphology without stacking. As electrodes for alkaline water electrolysis, M–Mo–S/CC with different compositions and morphologies exhibit a variety of activities. Particularly, among the M–Mo–S/CC samples, Co–Mo–S/CC achieves the best performance for hydrogen evolution reaction, oxygen evolution reaction and overall water splitting. This study presents a facile strategy of using POMs as bimetallic precursors for studying the growth mechanism as well as the water electrolysis performances of MoS₂-based bimetallic sulfides.