Interfacial Electronic Interaction in Amorphous–Crystalline CeO_x-Sn Heterostructures for Optimizing CO₂ to Formate Conversion

Formate, a crucial chemical raw material, holds significant promise for industrial applications in the context of CO₂ electroreduction reaction (CO₂RR). Despite its potential, challenges, such as poor selectivity and low formation rate at high current densities persist, primarily due to the competing hydrogen evolution reaction (HER) and high energy barriers associated with *OCHO intermediate generation. Herein, one-step chemical co-reduction strategy is employed to construct an amorphous–crystalline CeO_x-Sn heterostructure, demonstrating remarkable catalytic performance in converting CO₂ to formate. The optimized CeO_x-Sn heterostructures reach a current density of 265.1 mA cm⁻² and a formate Faraday efficiency of 95% at −1.07 V versus RHE. Especially, CeO_x-Sn achieves a formate current density of 444.4 mA cm⁻² and a formate production rate of 9211.8 µmol h⁻¹cm⁻² at −1.67 V versus RHE, surpassing most previously reported materials. Experimental results, coupled with （density functional theory）DFT calculations confirm that robust interface interaction between CeO_x and Sn active center induces electron transfer from crystalline Sn site to amorphous CeO_x, some Ce⁴⁺of CeO_x get electrons and convert to unsaturated Ce³⁺, optimizing the electronic structure of active Sn. This amorphous–crystalline heterostructure promotes electron transfer during CO₂RR, reducing the energy barrier formed by *OCHO intermediates, and thus achieving efficient reduction of CO₂ to formate.