Unlocking nanotubular bismuth oxyiodide toward carbon-neutral electrosynthesis

Abstract

The electrochemical CO₂ reduction reaction (CO₂RR) to formate is one of the attractive strategies for achieving carbon-neutral sustainability, but synthesizing highly active catalytic materials capable of selectively forming formate, especially under industrially relevant conditions, remains challenging. We herein report ultrathin one-dimensional nanotubular Bi₅O₇I with substantial amounts of nanopores and oxygen vacancies for the CO₂RR. A desirable selectivity of over 93% and high current density for formate are achieved in a potential window of 1000 mV in a flow cell. More importantly, a stable performance of 140 h with faradaic efficiency over 90% in a membrane electrode assembly system demonstrates great potential for industrial CO₂RR application. The abundant defects within the ultrathin nanotubular structure not only improve the CO₂ adsorption and charge transfer capabilities that facilitate the reaction kinetics, but also modulate the electronic structure and optimize the energy barrier toward formate as revealed by the theoretical calculations. Concurrently, the local high pH caused by the structural defects and hydrophobic surface could remarkably suppress the hydrogen evolution reaction and in turn, accelerate formate formation. These advances demonstrate an effective structure and defect engineering to unlock one-dimensional electrocatalysts to boost the CO₂RR toward target products.