Integrated Sn/CNT@N[sbnd]C hierarchical porous gas diffusion electrode by phase inversion for electrocatalytic reduction of CO2

Abstract

A 3D integrated hierarchical porous N-doped Sn/CNT@NC gas diffusion electrode is proposed via phase inversion to synergistically improve electron-proton-gas transfer and efficiency of CO2 reduction reaction (CO2RR). Hierarchical porous structure is tuned by the carbon nanotube additive during phase inversion, which integrates microporous layer and diffusion layer to decrease mass transfer resistance comparing with the 2D layer structure of commercial carbon paper. XPS results show that Sn/CNT@NC 800 contains pyridinic nitrogen and pyrrolic nitrogen with catalytic activity. EIS and LSV curves show that Sn/CNT@NC 800 is beneficial to reduce mass transfer resistance and increase current density after twice hydrophobic treatments. As a result, Sn/CNT@NC 800 shows higher CO2RR electrocatalytic activity. The reaction rate and Faraday efficiency of CO at 12 mA cm−2 increase by 40.2% and 40.6%, respectively compared with Sn/carbon paper. The reaction rate and Faraday efficiency of formate are also slightly higher than those of Sn/carbon paper.