Liquid‐Phase Exfoliated Indium–Selenide Flakes and Their Application in Hydrogen Evolution Reaction

Abstract

Single- and few-layered InSe flakes are produced by the liquid-phase exfoliation of β-InSe single crystals in 2-propanol, obtaining stable dispersions with a concentration as high as 0.11 g L . Ultracentrifugation is used to tune the morphology, i.e., the lateral size and thickness of the as-produced InSe flakes. It is demonstrated that the obtained InSe flakes have maximum lateral sizes ranging from 30 nm to a few micrometers, and thicknesses ranging from 1 to 20 nm, with a maximum population centered at ≈5 nm, corresponding to 4 Se-In-In-Se quaternary layers. It is also shown that no formation of further InSe-based compounds (such as In Se ) or oxides occurs during the exfoliation process. The potential of these exfoliated-InSe few-layer flakes as a catalyst for the hydrogen evolution reaction (HER) is tested in hybrid single-walled carbon nanotubes/InSe heterostructures. The dependence of the InSe flakes' morphologies, i.e., surface area and thickness, on the HER performances is highlighted, achieving the best efficiencies with small flakes offering predominant edge effects. The theoretical model unveils the origin of the catalytic efficiency of InSe flakes, and correlates the catalytic activity to the Se vacancies at the edge of the flakes.

Solution‐Processed GaSe Nanoflake‐Based Films for Photoelectrochemical Water Splitting and Photoelectrochemical‐Type Photodetectors

“…The concentration of the GaSe flakes dispersion was estimated by the Beer–Lambert law: Ext(λ) = ε(λ) cL , in which Ext(λ) is the spectral extinction, ε(λ) is the extinction coefficient, c is the material concentration, and L is the optical path length . More in detail, optical extinction measurements of controlled dilutions/concentrations of the as‐produced GaSe flakes dispersion allow the extinction coefficient (ε(λ)) to be estimated from the slope of Ext(λ) versus c plot, being the slope = ε(λ) L . The concentration value of the as‐produced dispersion (0.20 ± 0.02 g L −1 ) was measured by weighting the solid material content in a known volume of the dispersion.…”

Transition Metal Selenides for Electrocatalytic Hydrogen Evolution Reaction

“…Obviously, the electrocatalytic performance declined with the decrease of the surface adsorbed sulfur atoms . Actually, some non‐transition single metal selenides were also developed in this field, e. g., GaSe, InSe . However, these catalysts possess relatively lower activity compared to Co, Mo, Ni‐based materials.…”

“…[32c] Actually, some non-transition single metal selenides were also developed in this field, e. g., GaSe, [115] InSe. [13] However, these catalysts possess relatively lower activity compared to Co, Mo, Ni-based materials.…”

Octapod-Shaped CdSe Nanocrystals Hosting Pt with High Mass Activity for the Hydrogen Evolution Reaction

“…2H + + 2e - H2 in acidic media 2H2O + 2e - H2 + 2OHin alkaline media 5,6 However, the high cost and the scarcity of these materials (e.g., for Pt, > US$ 40 g -1 and < 0.005 ppm, respectively) 7, 8 hamper the market entry of the electrochemical water splitting technologies, 9,10 which are still far from conveniently replacing the diminishing fossil fuels. 11,12 To overcome these hurdles, catalysts based on non-precious materials have been extensively reported. [13][14][15] However, they typically suffer from remarkable overpotentials (in the order of hundreds mV) or poor stability (hour-/day-time scale) in acidic media, 16,17 impeding their application in inexpensive efficient acidic solid polymer electrolytes.…”