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Abstract The hydrogen bonding network at the electrochemical interface plays a critical role in determining alkaline hydrogen oxidation reaction (HOR) kinetics. However, strategies for regulating this network are limited, and there is a lack of systematic understanding regarding the regulatory mechanisms. In this study, 16 small organic molecules with varying functional groups were employed to systematically adjust the contact angle between the Pt/C surface and water. Density functional theory (DFT) calculations revealed that the electrostatic potential range (ESPrange) of these molecules can be used as a descriptor to correlate their properties with the hydrophilicity of the modified Pt/C surfaces. The ESPrange also demonstrated a volcanic relationship with HOR exchange current densities (i0,HOR) on the modified Pt/C surfaces. Ab initio molecular dynamics simulations (AIMD) further highlighted that the molecule modifications can increase the potential of zero charge (PZC) of Pt surface and regulate its double-layer capacitance (Cdl). These combined effects influence the crowding of K+ cations in double-layer, thereby impacting the connectivity of the interfacial hydrogen bonding network and the HOR kinetics. The experimental results suggest the i0,HOR of Pt/C can be doubled by appropriately increasing the hydrophilicity and decreasing the Cdl of the Pt surface. The methodology presented in this study is also applicable to investigating hydrophilicity and connectivity of the interfacial hydrogen bonding network regulation on other electrode surfaces.
Xiao et al. (Tue,) studied this question.