Anchoring stable FeS2 nanoparticles on MXene nanosheets via interface engineering for efficient water splitting

Abstract

Exploring highly efficient, economical and environment friendly electrocatalysts for the hydrogen and oxygen evolution reactions (HER and OER) is necessary but challenging for economical water splitting. Herein, FeS₂ nanoparticles were anchored on the surface of MXene through a simple adsorption-growth route (FeS₂@MXene). By virtue of the large active surface area of FeS₂ and its robust interfacial interaction with conductive and hydrophilic MXene nanosheets, the obtained FeS₂@MXene composite can accelerate the transfer of mass/charge and facilitate contact between water molecules and reactive sites of FeS₂. Specifically, MXene as a support material can not only alter the electrophilicity of the active centers of FeS₂ through modulating the electron density but also prevent the aggregation of FeS₂, thereby promoting activity and stability. The optimized FeS₂@MXene delivers a 10 mA cm⁻² current density at overpotentials of 87 and 240 mV in alkaline solution for the HER and OER, respectively, which is comparable with reported transition metal sulfide (TMS) based catalysts. More importantly, in situ Raman spectroscopy reveals that the FeOOH generated during the OER process as a actual active species enhances the intrinsic activity of the catalyst. This work paves a new way for the interface engineering of TMS-based electrocatalysts towards water splitting.