Amorphous materials disrupt the intrinsic linear scalar dependence seen in their crystalline counterparts, typically exhibiting enhanced catalytic characteristics. Nevertheless, substantial obstacles remain in terms of boosting their stability, enhancing their conductivity, and elucidating distinct catalytic mechanisms. Herein, a core–shell catalyst, comprising a crystalline SnO2core and an amorphous SnOxshell supported on MXene (denoted as SnO2@SnOx/MXene), was prepared utilizing hydrothermal and solution reduction methods. The SnO2@SnOx/MXene catalyst excels in the electrocatalytic conversion of CO2to formate, yielding a Faradaic efficiency (FE) as high as 93% for formate production at −1.17 V vs RHE and demonstrating exceptional durability. Both density functional theory (DFT) calculations and experimental results indicate that the SnOxshell bolsters formate formation by fine-tuning the adsorption energy of the *OCHO intermediate. In SnO2@SnOx/MXene, MXene plays a vital role in enhancing the conductivity and stability of the amorphous shell and especially amplifying Raman signals of catalyst components. The ex/in situ surface-enhanced Raman scattering (SERS) application further confirms the formation of amorphous SnOxand further enables the direct detection of the formation of the intermediate species. This work provides the basis for the application of amorphous materials in practical electrocatalytic reduction of CO2reduction.