Ligand dominating the catalytic performance of cucurbit[6]uril modified gold nanoparticles for electrocatalytic CO2 reduction

Abstract

Electrocatalytic conversion of CO2 into high-value products provides a promising means to solve the problem of the greenhouse effect and energy storage but is limited by its sluggish kinetics and poor selectivity. In this work, we report cucurbit[6]uril (CB[6]) modified gold nanoparticles (Au-CB[6] NPs) with different sizes (40 nm, 60 nm, and 80 nm) using a facile in situ method and investigate their electrocatalytic performance for CO2 reduction reaction (CO2RR). The 60 nm Au-CB[6] NPs exhibits exceptional selectivity for CO with the highest Faraday efficiency (FECO) reaching 97.6% at − 0.6 V vs. reversible hydrogen electrode (RHE) and excellent stability with FECO over 95% for 10 h. The partial current density of CO formed by 60 nm Au-CB[6] NPs is 8.1 mA/cm2, which is 18-fold that of 60 nm gold nanoparticles (Au NPs). Additionally, when the size increases from 40 nm to 80 nm, the CO selectivity of Au-CB[6] NPs remains around 97%, but that of Au NPs decreases from 81% to 61%. The ligand dominated catalytic performance of Au-CB[6] NPs can be attributed to the excess CB[6] coating on catalyst’s surface, which creates a CO2 enriched and hydrophobic environment. The CB[6] modification on Au NPs not only improves the catalytic activity, but it also suppresses the size effect for selectivity in electrocatalytic CO2RR, which proposes a universal strategy for other nanostructures to simplify preparation and separation process and still maintain decent catalytic performance.