Expanding the Potential of Identical Location Scanning Transmission Electron Microscopy for Gas Evolving Reactions: Stability of Rhenium Molybdenum Disulfide Nanocatalysts for Hydrogen Evolution Reaction

Abstract

Identical location (scanning) transmission electron microscopy provides valuable insights into the mechanisms of the activity and degradation of nanocatalysts during electrochemical reactions. However, the technique suffers from limitations that hinder its widespread use for nanocatalysts of gas evolving reactions, e.g., the hydrogen evolution reaction (HER). The main issue is the production of bubbles that cause the loss of electric contact in identical location measurements, which is critical for the correct cycling of the nanocatalysts and interpretation of the electron microscopy results. Herein, we systematically evaluate different set-ups, materials, and tools to allow the facile and reliable study of the stability of HER nanocatalysts. The optimized conditions are applied for the study of layered rhenium molybdenum disulfide (Re0.2Mo0.8S2) nanocatalysts, a relevant alternative to Pt catalysts for the HER. With our approach, we demonstrate that although the morphology of the Re0.2Mo0.8S2 catalyst is maintained during HER, chemical composition changes could be correlated to the electrochemical reaction. This study expands the potential of the IL­(S)­TEM technique for the construction of structure–property relationships of nanocatalysts of gas evolving reactions.

Deciphering the role of Fe impurities in the electrolyte boosting the OER activity of LaNiO3

“…In identical location IL-STEM, the same region of the sample can be studied before and aer an electrocatalytic reaction, and has been used for determining degradation mechanisms 33,34 and the nature of active species 35 of nanocatalysts. For the IL experiments, a 10 mL drop of a 0.3 mg mL −1 dispersion of LaNiO 3 on deionized water was drop-cast on a hole carboncoated Au TEM nder grid (Plano).…”

Allotrope-dependent activity-stability relationships of molybdenum sulfide hydrogen evolution electrocatalysts

“…Among these, molybdenum disulfide (MoS 2 ) presents HER performances closely matching those of Pt and has already been implemented in PEMWE cathodes 7 – 9 . While a plethora of works reported detailed insights on the influence of crystalline phase (i.e., 1 T, 2H and 3 R, presenting different Mo-S atomic arrangements and stacking across a long-range periodical structure) 10 – 12 , degree of crystallinity/disorder 13 – 15 and edge-to-basal plane ratio 16 – 19 in the HER electrocatalytic activity, the intrinsic stability of MoS 2 under HER operating conditions is rarely (if ever) assessed besides indirect electrochemical metrics or identical location transmission electron microscopy 20 .…”