The Generation V TEM optical bulk liquid-electrochemistry sample holder integrates a sealed microfluidic liquid cell with true bulk reference and counter electrodes positioned off-chip, and a fiber optic feedthrough, enabling accurate photo-electrochemical control within the TEM. Real reference electrodes (e.g., Ag/AgCl) provide stable potentials, while bulk counter electrodes (e.g., Pt) support consistent current flow, eliminating the instability and drift common in on-chip systems.

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During operation, electrolyte flows through the liquid cell while electrochemical cycling is performed on the working electrode under direct electron beam observation and light illumination. This architecture decouples photo-electrochemical performance from geometric and material limitations of on-chip microfabricated electrodes, delivering reproducible current–voltage responses with well-defined redox peaks—closely matching bulk electroanalytical behavior while simultaneously enabling high-resolution imaging in liquid.