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

Hydrogen evolution reaction (HER) catalyzed by molybdenum sulfide quantum dots (MoS QDs) has attracted extensive attention in the energy field. Monitoring HER catalyzed by MoS QDs based on a glass nanopore with an electrochemically confined effect was proposed for the first time. MoS 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 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 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 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.