Monitoring Hydrogen Evolution Reaction Catalyzed by MoS 2 Quantum Dots on a Single Nanoparticle Electrode.

Hydrogen evolution reaction (HER) catalyzed by molybdenum sulfide quantum dots (MoS ₂ QDs) has attracted extensive attention in the energy field. Monitoring HER catalyzed by MoS ₂ QDs based on a glass nanopore with an electrochemically confined effect was proposed for the first time. MoS ₂ QDs inside the glass nanopore is driven toward the orifice of the nanopore and bonded with the Ag nanoparticles (Ag NPs) to form a single nanocomposite. When enough voltage is applied across the orifice, the single Ag NP acts as a single nanoparticle electrode to conduct the electrochemically bipolar reaction on its two extremities. In the process, HER is catalyzed by MoS ₂ QDs, and Ag NPs are oxidized at the same time. The appearance of blockages on the elevated ionic current is attributed to the generation of a H ₂ bubble. Furthermore, by analyzing the modulations in the ionic current oscillation, the frequency of hydrogen bubble generation that is related to the catalytic efficiency of MoS ₂ QDs could be estimated. The results reveal the capability of the glass nanopore for the real-time monitoring electrocatalytic behavior, which makes the glass nanopore an ideal candidate to further reveal the heterogeneity of catalytic capability at the single particle level.