The nature of interaction between Au and heteroatoms-doped carbon nanotubes: Size and electronic effects on CO2 electroreduction

[Display omitted] •The heteroatom-doped CNTs embedded with Au nanoparticles were fabricated.•The size and electronic effects induced by the Au/CNTs-S catalyst significantly boost the conversion of CO2.•The findings shed new light on understanding the catalytic mechanism of nano-metallic catalysts in CO2RR. Nanostructured metal electrocatalysts have recently been extensively researched for CO2 electroreduction reaction (CO2RR) to CO. Nevertheless, their exhibited low reaction activity can be attributed to the weak adsorption of CO2 (or relevant intermediates) on the catalyst surface. Herein, the potent nanometallic catalyst is selectively designed based on Au nanoparticles (NPs) as a module with heteroatom (O-, N-, and S-) doped carbon nanotubes (CNTs) as supports and used as a booster toward enhancing CO2RR. The structural characterization and electrochemical tests were conducted to study the relationship between the support effects (size and electronic effects) of CNTs and the catalytic performance of Au NPs. By comparison, the S-doped CNTs loading with Au NPs achieved a Faraday efficiency of 97% for CO at − 0.8 V vs RHE and a catalyst stability of 30 h at a current density of ∼ 18 mA cm−2. This work may guide a method to optimize nanometallic electrocatalysts for CO2RR in a relatively cost-effective manner.