Decoupling Product Selectivity in Electrocatalytic CO2 Reduction by Steering the Interfacial Water Structure
Yang, Yu Wang, Jun Shi, Yaohui Han, Xue Wang, Yuhang Mohanty, Biswaranjan Liang, Yongxiang Xue, Mianqi Zeng, Jie Liu, Tongliang
Yang, Yu
Wang, Jun
Shi, Yaohui
Han, Xue
Wang, Yuhang
Mohanty, Biswaranjan
Liang, Yongxiang
Xue, Mianqi
Zeng, Jie
Liu, Tongliang
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Machine Learning
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Journal article
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English
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Abstract
Achieving precise control over reaction pathways in the electrochemical CO<sub>2</sub> reduction reaction (CO<sub>2</sub>RR) is a central challenge. Silver, for instance, is widely recognized for its high selectivity toward carbon monoxide (CO). Here, we demonstrate a strategy to steer the selectivity of Ag away from CO and toward formic acid (HCOOH) by engineering the nanoscale structure of water at the electrode-electrolyte interface. Using a polymeric cation, poly(diallyldimethylammonium chloride) (PDDA), in an alkali-metal-cation-free, strongly acidic electrolyte, we create a hydrophobic interfacial environment that promotes weakly hydrogen-bonded, "free-like" water (<i>f</i>-H<sub>2</sub>O). Using operando spectroscopy and isotope labeling, we establish a direct, quantitative correlation between the abundance of <i>f</i>-H<sub>2</sub>O and HCOOH selectivity. Electrochemical analyses and theoretical simulations using density functional theory and ab initio molecular dynamics suggest that the <i>f</i>-H<sub>2</sub>O-rich environment opens a distinct mechanistic channel for HCOOH formation via a direct, energetically favorable *H + CO<sub>2</sub> hydrogenation reaction, a pathway disfavored in conventional alkali-metal-cation-based electrolytes where strongly hydrogen-bonded water (<i>h</i>-H<sub>2</sub>O) facilitates the *COOH pathway to CO. These findings highlight that the tuning of interfacial water structure is powerful in overriding the intrinsic selectivity of a catalyst and rationally directing CO<sub>2</sub>RR pathways.
Citation
Y. Yang, J. Wang, Y. Shi, X. Han, Y. Wang, B. Mohanty , et al., "Decoupling Product Selectivity in Electrocatalytic CO2 Reduction by Steering the Interfacial Water Structure," Journal of the American Chemical Society, vol. 148, no. 10, pp. 11284-11295, 2026, https://doi.org/10.1021/jacs.6c00420.
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Journal of the American Chemical Society
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Keywords
34 Chemical Sciences, 3403 Macromolecular and Materials Chemistry, 3406 Physical Chemistry, 7 Affordable and Clean Energy
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American Chemical Society