Chaotropic nanoelectrocatalysis: chemically disrupting water intermolecular network at the point-of-catalysis to boost green hydrogen electrosynthesis

• Main Authors: Ng, Li Shiuan, Chah, Chloe Eu Li, Ngieng, Min Hui, Boong, Siew Kheng, Chong, Carice, Raja Mogan, Tharishinny, Lee, Jinn-Kye, Li, Haitao, Lee, Ken Chi-Lik, Lee, Hiang Kwee
• Other Authors: School of Chemistry, Chemical Engineering and Biotechnology
• Format: Article
• Language: English
• Published: 2024
• Subjects: Chemistry; Chaotropic; Electrocatalysis
• Online Access: https://hdl.handle.net/10356/174654
• Institution: Nanyang Technological University

Efficient green hydrogen production through electrocatalytic water splitting serves as a powerful catalyst for realizing a carbon-free hydrogen economy. However, current electrocatalytic designs face challenges such as poor hydrogen evolution reaction (HER) performance (Tafel slope, 100-140 mV dec-1 ) because water molecules are thermodynamically trapped within their extensive hydrogen bonding network. Herein, we drive efficient HER by manipulating the local water microenvironment near the electrocatalyst. This is achieved by functionalizing the nanoelectrocatalyst's surface with a monolayer of chaotropic molecules to chemically weaken water-water interactions directly at the point-of-catalysis. Notably, our chaotropic design demonstrates a superior Tafel slope (77 mV dec-1 ) and the lowest overpotential (0.3 V at 10 mA cm-2 ECSA ), surpassing its kosmotropic counterparts (which reinforces the water molecular network) and previously reported electrocatalytic designs by up to ≈2-fold and ≈3-fold, respectively. Comprehensive mechanistic investigations highlight the critical role of chaotropic surface chemistry in disrupting the water intermolecular network, thereby releasing free/weakly bound water molecules that strongly interact with the electrocatalyst to boost HER. Our study provides a unique molecular approach that can be readily integrated with emerging electrocatalytic materials to rapidly advance the electrosynthesis of green hydrogen, holding immense promise for sustainable chemical and energy applications.