Synergistic CO₂-Philic/H₂O-Phobic Interface Engineering in PEDOT/NHCS/Au Composite for High-Efficiency CO₂ Electroreduction With Suppressed Hydrogen Evolution Reaction

Abstract

The electrocatalytic CO₂ reduction reaction (CO₂RR) offers a viable solution for the conversion and storage of renewable energy. Utilizing electronic metal-support interactions (EMSI) to adjust the electronic properties of metal catalysts has demonstrated effectiveness in enabling highly selective CO₂ electroreduction. Here, a cleverly designed ternary composite is presented, which is synthesized by using nitrogen-doped hollow carbon spheres (NHCS) as the substrate and coating them with poly(3,4-ethylenedioxythiophene) (PEDOT) to form a PEDOT/NHCS support for anchoring Au nanoparticles. This innovative design enables the catalyst to reach a stunning 98.21% at −0.8 V versus RHE, achieving an extraordinarily high Faradaic efficiency for CO (FE_CO) over a broad potential window (−0.6 to −1.5 V vs. RHE). The result is mainly due to the Au–S bond between the S in the PEDOT thiophene ring and the metal Au, which induces electron transfer, causing the d-band center of the Au atoms to shift negatively. The hydrophobic surface of PEDOT and the hollow structure of NHCS synergistically construct an interface of “CO₂-philic and H₂O-phobic.” This interface, in coordination with the Au NPs, enhances CO₂ adsorption, stabilizes the *COOH intermediate, accelerates the desorption of *CO, and simultaneously weakens the competitive adsorption of *H, effectively suppressing the HER.

Keywords

Au-based catalysts / electrocatalytic CO₂ reductions / hydrogen evolution reaction / NHCS / PEDOT

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