In situ oxidative etching-enabled synthesis of hollow Cu2O nanocrystals for efficient CO2RR into C2+ products

Abstract

Multicarbon (C₂₊) products are one of the most attractive carbon-based chemicals that can be manufactured through the CO₂ electroreduction reaction (CO₂RR), but they face challenges of low current density and poor selectivity due to unsatisfactory catalysts. Herein, we report the fabrication of hollow Cu₂O nanocrystals with defect-rich sites and abundant stepped facets and the investigation of their applications as electrocatalysts in the CO₂RR. In particular, the reduction of self-made Cu precursor, Cu₂(OAc)₄(py)₂, at an elevated temperature, leads to the formation of polyhedral Cu nanoparticles in advance, followed by bubbling gaseous oxygen to proceed with in situ oxidative etching. Ascribed to structural advantages, a remarkable faradaic efficiency of 75.9% and partial current density of 0.54 A cm⁻² are actualized for C₂₊ products. Impressively, hollow Cu₂O catalysts can generate n-propanol with faradaic efficiencies of up to 8.21% due to the boosted C–C coupling step for C₃₊ production. Density functional theory (DFT) calculations reveal that the high CO coverage and the high index planes of Cu₂O can enhance the C–C coupling reaction. The current work offers an effective crystal engineering route to the rational design of CO₂RR electrocatalysts with boosted electrochemical activity and selectivity of C₂₊ products.