Controllable Disorder Engineering in Oxygen-Incorporated MoS₂ Ultrathin Nanosheets for Efficient Hydrogen Evolution

Abstract

Molybdenum disulfide (MoS2) has emerged as a promising electrocatalyst for catalyzing protons to hydrogen via the so-called hydrogen evolution reaction (HER). In order to enhance the HER activity, tremendous effort has been made to engineer MoS2 catalysts with either more active sites or higher conductivity. However, at present, synergistically structural and electronic modulations for HER still remain challenging. In this work, we demonstrate the successfully synergistic regulations of both structural and electronic benefits by controllable disorder engineering and simultaneous oxygen incorporation in MoS2 catalysts, leading to the dramatically enhanced HER activity. The disordered structure can offer abundant unsaturated sulfur atoms as active sites for HER, while the oxygen incorporation can effectively regulate the electronic structure and further improve the intrinsic conductivity. By means of controllable disorder engineering and oxygen incorporation, an optimized catalyst with a moderate degree of disorder was developed, exhibiting superior activity for electrocatalytic hydrogen evolution. In general, the optimized catalyst exhibits onset overpotential as low as 120 mV, accompanied by extremely large cathodic current density and excellent stability. This work will pave a new pathway for improving the electrocatalytic activity by synergistically structural and electronic modulations.

Enhancing Oxygen Evolution Reaction at High Current Densities on Amorphous‐Like Ni–Fe–S Ultrathin Nanosheets via Oxygen Incorporation and Electrochemical Tuning

“…The peak position at 529.9 eV in O‐NFS is corresponding to the binding energy of oxygen atom and metal,17 suggesting the existence of metal‐oxygen bonds. Similar phenomenon was observed in oxygen‐incorporated MoS 2 nanomaterials 18. In addition, the oxygen amount in the form of metal‐oxygen bonds is estimated to 3.3% in O‐NFS based on the XPS analysis.…”

“…From Nyquist plots of O‐NFS and NFS in Figure 3b, the O‐NFS catalyst shows a smaller charge transfer resistance than that of NFS, revealing the improved conductivity of O‐NFS due to the oxygen incorporation. The conductivity improvement implies that the electronic structure of O‐NFS has changed after the oxygen incorporation 18. In addition, the higher valence state of Fe in O‐NFS may make it harder to oxidize surrounding Ni, leading to the faster OER kinetics and enhanced OER activity 13, 19.…”

Solvent-Assisted Oxygen Incorporation of Vertically Aligned MoS2 Ultrathin Nanosheets Decorated on Reduced Graphene Oxide for Improved Electrocatalytic Hydrogen Evolution

“…18,43 The enlargement of the interlayer distance of O-MoS 2 sheets is further confirmed by the XRD pattern (002 diffraction peak shifts to 9.1°, Figure 2a) when compared to bulk MoS 2 (2H-MoS 2 , JCPDS 37-1492) with the 002 diffraction peak located at 14.2°. 6,14,35,44 The broad peak at approximating to 23.9°suggests the formation of stacked rGO nanosheets and the successful reduction from GO to rGO after …”

“…Double-layer capacitance (C dl ) and turnover frequency (TOF) were calculated according to the methods reported previously. 6,10 All the potentials were calibrated to RHE according to the previous literature. 17 The potential transfer from SCE to RHE was obtained according to the following equation: E(RHE) = E(SCE) + 0.267 V ( Figure S1).…”

“…Thereinto, oxygen incorporation is considered as an effective route to facilitating the HER performance by engineering the surface disorder of MoS 2 with additional active sites. 4,6,14,40 However, the exact origin of the incorporated oxygen from chemical precursors 6,40 or oxygencontaining groups (e.g., graphene oxide/GO) 14 and the associated incorporation process are still controversial and inconclusive.…”