Probing Temperature Effect on Enhanced Electrochemical CO2 Reduction of Hydrophobic Au25(SR)18 Nanoclusters

Abstract

The widely studied electrocatalytic CO₂ reduction reaction (eCO₂RR) has typically been operated at room temperature. However, practical electrolyzers might operate at elevated temperatures, but a major concern is low CO₂ solubility. One promising strategy is to construct a hydrophobic interface to enhance CO₂ diffusion. Regarding this, atomically precise gold nanoclusters (NCs) can be accurately decorated with hydrophobic ligands to create a local hydrophobic microenvironment to ensure rapid CO₂ transfer, yet the temperature effect on the reaction kinetics remains unknown. Here, we report, for the first time, the temperature-dependent eCO₂RR performance of hydrophobic Au₂₅(SR)₁₈ NCs by a close interplay between theory and experiment. Simulations revealed that the hydrophobic surface is very conducive to CO₂ activation, and the proton transfer process for *COOH and *CO formation can be significantly affected by temperature via modulating interface hydrogen bonding. Particularly, an elevated temperature at 330 K dramatically increases the catalytic activity while simultaneously suppressing the competitive hydrogen evolution reaction. We experimentally demonstrate that Au₂₅ exhibits high eCO₂RR performance at 330 K, achieving a high CO Faradaic efficiency of ∼93% and a CO partial current density about 2 times higher than that at room temperature. This work opens exciting opportunities in developing efficient electrocatalysts via synergistic implementation of surface hydrophobicity and temperature-mediated interface engineering.