Monitoring Bipolar Electrochemistry and Hydrogen Evolution Reaction of a Single Gold Microparticle under Sub-Micropipette Confinement

Abstract

Herein, an approach to track the process of autorepeating bipolar reactions and hydrogen evolution reaction (HER) on a micro gold bipolar electrode (BPE) is established. Once blocking the channel of the sub-micropipette tip, the formed gold microparticle is polarized into the wireless BPE, which induces the dissolution of the gold at the anode and the HER at the cathode. The current response shows a periodic behavior with three regions: the bubble generation region (I), the bubble rupture/generation region (II), and the channel opening region (III). After a stable low baseline current of region I, a series of positive spike signals caused by single H2 nanobubbles rupture/generation are recorded standing for the beginning of region II. Meanwhile, the dissolution of the gold blocking at the orifice will create a new channel, increasing the baseline current for region III, where the synthesis of gold occurs again, resulting in another periodic response. Finite element simulations are applied to unveil the mechanism thermodynamically. In addition, the integral charge of the H2 nanobubbles in region II corresponds to the consumption of the anode gold. It simultaneously monitors autorepeating bipolar reactions of a single gold microparticle and HER of a single H2 nanobubble electrochemically, which reveals an insightful physicochemical mechanism in nanoscale confinement and makes the glass nanopore an ideal candidate to further reveal the heterogeneity of catalytic capability at the single particle level.

Multiphase Chemistry under Nanoconfinement: An Electrochemical Perspective

“…This nanobubble-amplified transient ion current strategy is further expanded to monitor heterogeneous electron transfer in single living cells . Additionally, the focused electrical potential at the nanopipette tip can drive bipolar electrochemistry on a single nanoparticle. − Three-phase interface (metal–liquid–gas) is formed when HER is catalyzed by MoS 2 quantum dots as shown in Figure b . This geometrically well-defined single nanoparticle electrode shows the potential in operando , a particle-by-particle investigation of the structure–activity relationship of single nanocatalysts.…”

Catalytic ability characterization of in situ synthesized Pt NP coated SBA-15 within a sub-micropipette

“…For example, our team has reported resistive pulse signals of O 2 nanobubble generated from H 2 O 2 decomposition catalysed by a single MnO 2 microparticle and illustrated the catalytic abilities of similar-sized spherical and cubic MnO 2 particles. 6 Moreover, nanoreactors have gained attention in applications such as the in situ synthesis of precious metals 8,9 and porous materials [10][11][12] owing to the nanoconfinement of nanopipettes. Especially, in the in situ synthesis of porous materials with a controllable pore size in a nanopipette reactor, it not only achieves the purpose of adjusting the orifice, but also provides a substrate to support porous materials and solve the obstacle of immobilizing porous materials into a membrane.…”