Transition metal dichalcogenides as catalysts for the hydrogen evolution reaction: The emblematic case of “inert” ZrSe₂ as catalyst for electrolyzers

Abstract

The development of earth‐abundant electrocatalysts (ECs) operating at high current densities in water splitting electrolyzers is pivotal for the widespread use of the current green hydrogen production plants. Transition metal dichalcogenides (TMDs) have emerged as promising alternatives to the most efficient noble metal ECs, leading to a wealth of research. Some strategies based on material nanostructuring and hybridization, introduction of defects and chemical/physical modifications appeared as universal approaches to provide catalytic properties to TMDs, regardless of the specific material. In this work, we show that even a theoretically poorly catalytic (and poorly studied) TMD, namely zirconium diselenide (ZrSe2), can act as an efficient EC for the hydrogen evolution reaction (HER) when exfoliated in the form of two‐dimensional (2D) few‐layer flakes. We critically show the difficulties of explaining the catalytic mechanisms of the resulting ECs in the presence of complex structural and chemical modifications, which are nevertheless evaluated extensively. By doing so, we also highlight the easiness of transforming 2D TMDs into effective HER‐ECs. To strengthen our message in practical environments, we report ZrSe2‐based acidic (proton exchange membrane [PEM]) and alkaline water electrolyzers operating at 400 mA cm–2 at a voltage of 1.88 and 1.92 V, respectively, thus competing with commercial technologies.

Indium Selenide/Indium Tin Oxide Hybrid Films for Solution‐Processed Photoelectrochemical‐Type Photodetectors in Aqueous Media

“…The SEM-coupled with energy-dispersive X-ray spectroscopy (EDS) analysis (Figure 1b) evidenced an almost ideal elemental stoichiometry (In-to-Se atomic ratio ≈1.07, see Table S1, Supporting Information). Subsequently, β-InSe crystal was exfoliated through ultrasonication-assisted LPE in anhydrous IPA, [36,59,60] followed by sedimentation-based separation (SBS) [61,62] to remove unexfoliated crystals from the exfoliated material. The methods of synthesis, exfoliation, and characterization of InSe flakes are fully described in the Experimental Method section (Supporting Information).…”

Liquid-Phase Exfoliation of Bismuth Telluride Iodide (BiTeI): Structural and Optical Properties of Single-/Few-Layer Flakes

“…For further advancement of the production and processing of the material class of 2D BiTeX, we report here for the first time the ultrasonication-aided liquid-phase exfoliation (LPE) of contamination-free BiTeI crystals. Notably, the exfoliation of Rashba-type layered polar crystals in liquid media expands the portfolio of solution-processed 2D materials, providing a novel type of functional ink for large-scale, high-speed, and cost-effective device manufacturing. − …”

High-current density alkaline electrolyzers: The role of Nafion binder content in the catalyst coatings and techno-economic analysis

“…Actually, in both PEMELs ( Xu and Scott, 2010 ), ( Bühler et al, 2019 ) and AEMELs, ( Cho et al, 2018 ), ( Cho et al, 2017a ), ( Masel et al, 2016 ) the incorporation of ionomer binders in the catalysts coating extends the ion conduction from the bulk of the membrane to the surface of the catalysts (guaranteeing the ion transport from the wet electrode ( i.e ., anode) to dried one ( i.e ., cathode). Differently, AEL electrodes ( e.g ., conventional Raney-type Ni electrodes ( Gannon and Dunnill, 2019 )) operate in “wet conditions”, ( Najafi et al, 2022 ) meaning that the optimization of binder type and content may substantially differ from that of PEMELs and AEMELs. In general, the removal of gaseous hydrogen from the catalyst coating can be impeded when binder content exceeds a certain threshold, as a consequence of the decrease of the electrode porosity.…”