High‐Resolution Electrochemical Mapping of the Hydrogen Evolution Reaction on Transition‐Metal Dichalcogenide Nanosheets

Abstract

High‐resolution scanning electrochemical cell microscopy (SECCM) is used to image and quantitatively analyze the hydrogen evolution reaction (HER) catalytically active sites of 1H‐MoS2 nanosheets, MoS2, and WS2 heteronanosheets. Using a 20 nm radius nanopipette and hopping mode scanning, the resolution of SECCM was beyond the optical microscopy limit and visualized a small triangular MoS2 nanosheet with a side length of ca. 130 nm. The electrochemical cell provides local cyclic voltammograms with a nanoscale spatial resolution for visualizing HER active sites as electrochemical images. The HER activity difference of edge, terrace, and heterojunction of MoS2 and WS2 were revealed. The SECCM imaging directly visualized the relationship of HER activity and number of MoS2 nanosheet layers and unveiled the heterogeneous aging state of MoS2 nanosheets. SECCM can be used for improving local HER activities by producing sulfur vacancies using electrochemical reaction at the selected region.

Characterizing photocatalysts for water splitting: from atoms to bulk and from slow to ultrafast processes

“…275 Takahashi et al quantitatively mapped the hydrogen evolution at 1H-MoS 2 nanosheets, MoS 2 , and WS 2 heteronanosheets with nanopipettes as small as 20 nm. 276 Maps of HER current, overpotentials, Tafel slopes, which were retrieved from recording cyclic voltammograms at each measurement point at a triangular 1H-MoS 2 sheet (see Fig. 18A(a-c) respectively) showing inhomogeneous catalytic activity between the edges and terraces as predicted by theory.…”

Rational Design and Controlled Synthesis of V‐Doped Ni3S2/NixPy Heterostructured Nanosheets for the Hydrogen Evolution Reaction

“…As a half‐reaction of overall water splitting, the hydrogen evolution reaction (HER) has been considered to be the most promising method to produce hydrogen with environmental and efficiency advantages [1–5] . Compared with acidic solution, H 2 O has higher dissociation energy under alkaline conditions and it is more difficult to generate H*, so it is meaningful to develop efficient catalysts for HER in alkaline solution [6,7] .…”

Advances and challenges for experiment and theory for multi-electron multi-proton transfer at electrified solid–liquid interfaces

“…Although we still need basic understanding about electrocatalytic reactions at single crystals, operando electrochemical techniques have already been applied to investigate these reactions not only for Pt nanoparticles and nanostructured MoS 2 , [509][510][511][512] but also for metal-free carbon catalysts. 513 Interestingly, most material systems with realistic structures and/or morphologies (Level 4 in Fig.…”