Interfacial Synergy of Cation Enrichment and Hydrophobicity in Bi<sub>2</sub>S<sub>3</sub> Nanoflowers for Efficient Acidic CO<sub>2</sub> Electroreduction.

Wang, Weizhou; Zhao, Xuhua; Dong, Tian; Geng, Yanling; Wu, Zexing; Lai, Jianping; Li, Bin; Li, Hongdong et al. · Nano Lett · 2025

basic_science · Level V

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Abstract

The implementation of acidic CO<sub>2</sub> electroreduction (CO<sub>2</sub>RR) is hindered by catalyst corrosion and the parasitic hydrogen evolution reaction (HER). We construct a hydrophobic hexadecyltrimethoxysilane (HDTMS)-modified Bi<sub>2</sub>S<sub>3</sub> nanoflower catalyst (Bi<sub>2</sub>S<sub>3</sub>-C<sub>16</sub>) synergistically integrating cationic enrichment and interfacial hydrophobicity to achieve stable CO<sub>2</sub>-to-HCOOH conversion at pH = 2. COMSOL simulations reveal that the high-curvature architecture amplifies local electric fields, driving K<sup>+</sup> accumulation to stabilize *OCHO intermediates via dipole interactions. The density functional theory also confirms this, showing a reduced *CO<sub>2</sub>→*OCHO energy barrier. In situ ATR-FTIR captures *OCHO vibrational modes (1575 cm<sup>-1</sup>) and HCOOH signatures (1695 cm<sup>-1</sup>). HDTMS reduces proton accessibility (rotating disc electrode analysis), suppressing HER. Consequently, Bi<sub>2</sub>S<sub>3</sub>-C<sub>16</sub> achieves 89.6% HCOOH Faradaic efficiency at -400 mA cm<sup>-2</sup> with 44.46% cathodic energy efficiency, operating stably for 48 h. This provides a paradigm for interfacial microenvironment control in harsh electrocatalytic systems.