Polarization-Switchable Electrochemistry of 2D Layered Bi<sub>2</sub>O<sub>2</sub>Se Bifunctional Microreactors by Ferroelectric Modulation.

Chiang, Chun-Hao; Yu, Chun-Hung; Lu, Yang-Sheng; Yang, Yueh-Chiang; Lin, Yin-Cheng; Chen, Hsin-An; Ho, Sheng-Zhu; Chen, Yi-Chun et al. · Nano Lett · 2024

basic_science · Level V

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Abstract

Ferroelectric catalysts are known for altering surface catalytic activities by changing the direction of their electric polarizations. This study demonstrates polarization-switchable electrochemistry using layered bismuth oxyselenide (L-Bi<sub>2</sub>O<sub>2</sub>Se) bifunctional microreactors through ferroelectric modulation. A selective-area ionic liquid gating is developed with precise control over the spatial distribution of the dipole orientation of L-Bi<sub>2</sub>O<sub>2</sub>Se. On-chip microreactors with upward polarization favor the oxygen evolution reaction, whereas those with downward polarization prefer the hydrogen evolution reaction. The microscopic origin behind polarization-switchable electrochemistry primarily stems from enhanced surface adsorption and reduced energy barriers for reactions, as examined by nanoscale scanning electrochemical cell microscopy. Integrating a pair of L-Bi<sub>2</sub>O<sub>2</sub>Se microreactors consisting of upward or downward polarizations demonstrates overall water splitting in a full-cell configuration based on a bifunctional catalyst. The ability to modulate surface polarizations on a single catalyst via ferroelectric polarization switching offers a pathway for designing catalysts for water splitting.