External-field-driven molecular polarization manipulates reactant interface toward efficient hydrogen evolution

The reaction interface which governs the electrocatalytic behavior is notoriously hard to understand due to inadequate regulatory and detection methods. By using on-chip microdevices, we employ variable back-gate voltages to generate molecular polarization and thus fine-tune the concentration of hydronium ions (H3O+) in electrochemical double layers for efficient hydrogen evolution. Taking C-60/ MoS2 heterojunction as a prototype, electrical tests reveal that the back-gate promotes the charge transfer from C-60 to MoS2, leading to the polarization of C-60. In situ photoluminescence spectra verify that the polarized C-60 can attract H3O+ to accumulate in the vicinity of MoS2 in the external electric field. Profiting from the back-gated H3O+ enrichment, the hydrogen evolution current is increased by five times at -0.45 V-RHE when a 1.5-V back-gate voltage is applied. The insight into the reaction interface from manipulation to detection can facilitate diverse catalytic reactions.

Automated summary

By using on-chip microdevices, the concentration of hydronium ions in electrochemical double layers can be fine-tuned for efficient hydrogen evolution. The electrical tests reveal that the back-gate voltage promotes charge transfer and polarization, attracting hydronium ions to accumulate near the reaction interface. The hydrogen evolution current is significantly increased with the back-gated hydronium enrichment.