Ultrathin Alumina Mask-Assisted Nanopore Patterning on Monolayer MoS₂ for Highly Catalytic Efficiency in Hydrogen Evolution Reaction

Abstract

Nanostructured molybdenum disulfide (MoS) has been considered as one of the most promising catalysts in the hydrogen evolution reaction (HER), for its approximately intermediate hydrogen binding free energy to noble metals and much lower cost. The catalytically active sites of MoS are along the edges, whereas thermodynamically MoS favors the presence of a two-dimensional (2-D) basal plane and the catalytically active atoms only constitute a small portion of the material. The lack of catalytically active sites and low catalytic efficiency impede its massive application. To address the issue, we have activated the basal plane of monolayer 2H MoS through an ultrathin alumina mask (UTAM)-assisted nanopore arrays patterning, creating a high edge density. The introduced catalytically active sites are identified by Cu electrochemical deposition, and the hydrogen generation properties are assessed in detail. We demonstrate a remarkably improved HER performance as well as the identical catalysis of the artificial edges and the pristine metallic edges of monolayer MoS. Such a porous monolayer nanostructure can achieve a much higher edge atom ratio than the pristine monolayer MoS flakes, which can lead to a much improved catalytic efficiency. This controllable edge engineering can also be extended to the basal plane modifications of other 2-D materials, for improving their edge-related properties.

Discontinuity‐Enhanced Thin Film Electrocatalytic Oxygen Evolution

“…Recent designs of single atom catalysts may further support this idea . In fact, strong edge effects on improving hydrogen evolution reaction (the other half reaction in water splitting) have been well recognized . However, this concept of edge exposure in thin film has received much less attentions possibly due to the investigation complexity and coverage uncertainty of discontinuous deposition.…”

Ion Beam Defect Engineering on ReS2/Si Photocathode with Significantly Enhanced Hydrogen Evolution Reaction

“…Extensive studies have suggested that the catalysis of 2D TMDs originates mainly from the unsaturated atoms at edge sites of the sulfide compounds . Recently, enormous efforts have been dedicated to a variety of nanostructured TMDs to expose more active edge sites for enhancing HER performances …”

Nanoporous Silicon-Assisted Patterning of Monolayer MoS2 with Thermally Controlled Porosity: A Scalable Method for Diverse Applications

“…The nanomesh created by the BCP lithography can be a potential nanoporous membrane material that is generated by the simple and fast nanopatterning technique, despite the current state-of-the-art patterning capability restricted to a few micron scale due to the non-uniform BCP phase separation across the cm-size substrates 10 or limited by the micron scale substrate. 9 While the optimization of the BCP lithography technique will enable the fabrication of uniform nanomeshes of TMD monolayers, alternative lithographic methods utilizing nonpolymeric mask materials have also been explored, including nanoporous anodized aluminum oxide (AAO) which has been applied to graphene 11 and MoS 2 12 patterning. Such an approach offers advantages with regard to its highly controllable pore sizes, ordered structures, and physical and chemical durability during the etch process.…”