Structurally Modified MXenes-Based Catalysts for Application in Hydrogen Evolution Reaction: A Review

Abstract

Green hydrogen production via electrocatalytic water splitting paves the way for renewable, clean, and sustainable hydrogen (H2) generation. H2 gas is produced from the cathodic hydrogen evolution reaction (HER), where the reaction is catalyzed primarily from Pt-based catalysts under both acidic and alkaline environments. Lowering the loading of Pt and the search for alternative active catalysts for HER is still an ongoing challenge. Two-dimensional MXenes are effective supports to stabilize and homogenously distribute HER-active electrocatalysts to boost the HER performance. Factors involved in the effectiveness of MXenes for their role in HER include transition metal types and termination groups. Recently, tailoring the conditions during the synthesis of MXenes has made it possible to tune the morphology of MXenes from multilayers to few layers (delaminated), formation of porous MXenes, and those with unique crumpled and rolled structures. Changing the morphology of MXenes alters the surface area, exposed active sites and accessibility of electrolyte materials/ions to these active sites. This review provides insight into the effects of varying morphology of MXenes towards the electrocatalytic HER activity of the MXene itself and MXene composites/hybrids with HER-active catalysts. Synthesis methods to obtain the different MXene morphologies are also summarized.

Recent Progress on Nickel- and Iron-Based Metallic Organic Frameworks for Oxygen Evolution Reaction: A Review

“…Gaining a full comprehension of the operational principles behind OER is crucial to enhance the efficacy of these technological advancements. The following section provides an in-depth description of the OER process. , …”

“…The following section provides an in-depth description of the OER process. 56,57 Water Molecule Adsorption. The process of OER begins with the adsorption of water molecules (H 2 O) onto the electrode's surface.…”

Recent Advanced Developments and Prospects of Surface Functionalized MXenes-Based Hybrid Composites toward Electrochemical Water Splitting Applications

“…Furthermore, the carefully designed i-MAX, non-MAX, and o-MAX hybrid MAX phase preparations have sparked the opportunity for new types of MXenes to be produced, thus extending the list of MXenes. 31 Depending on the application, MXenes can be tailored and functionalized easily. Studies show that MXene materials have high flexibility and utilization in printed and electronic materials, making them suitable for applications in medical care, biomedicine, electronic devices, and energy storage.…”

MXenes and Clay Minerals in the Framework of the 2D Organic–Inorganic Hybrid Nanomaterials

“…The delamination of kaolinite into very thin particles of nanometer thickness allows these nanosheets to roll up on themselves, giving rise to solids of nanotubular morphology, similar to natural halloysite . Delaminated MXenes of nanometer thickness appear as wrinkled and coiled nanosheets that could generate coiled nanotubular materials similar to kaolinite . The presence of hollow cavities (nanosized lumen) in halloysite nanotubes facilitates the access of organic compounds to the interior of that aluminosilicate acting as a reservoir (nanocontainer) for the loaded of components as above indicated. ,,, In case of rolled-up MXenes it would be expected to observe an alike behavior that halloysite and perhaps nanotubular carbides can be efficient in a comparable manner to the uptake of organic compounds as observed in equivalent delaminated kaolinite as well as in halloysite.…”