Improving CO2 Electroreduction Activity by Creating an Oxygen Vacancy-Rich Surface with One-Dimensional In–SnO2 Hollow Nanofiber Architecture

Abstract

Highly active catalysts are in great demand for CO₂ electroreduction (CO₂ER) due to the kinetically sluggish nature of CO₂. Herein, a novel oxygen vacancy (Vo)-rich In–SnO₂ hollow nanofiber catalyst is developed to combine the advantages of tuning both morphological and electronic properties. In-doped SnO₂ grain-stacked hollow nanofiber morphology is fabricated through a simple electrospinning method, aiming to enlarge the surface area for hosting Vo, as well as facilitate long-range charge and mass transfer. In-doping synergistically enhances catalytic activity by suppressing SnO₂ grain size and increasing electron density on Sn. Superficial Vos on metal oxide are effectively generated and utilized through an in situ pre-electroreduction process successively with CO₂ER, which tailor surface electronic properties by stabilizing the reduction intermediate CO₂•– in an O-coordinated manner and provide interpretation for high activity of “oxide-derived” metals. The Vo-rich In–SnO₂ hollow nanofiber catalyst, assembled with an efficient three-phase interface established by an electrochemical hydrogen pump reactor, exhibits excellent overall performance with considerable HCOOH Faradaic efficiency of about 86.2% and partial current density of about 28.5 mA cm–² at −1.34 V versus reversible hydrogen electrode and is at the top-level as compared with other Sn-based catalysts reported recently.