Interface‐Engineered 2D Heterojunction with Photoelectric Dual Gain: Mxene@MOF‐Enhanced SPR Spectroscopy for Direct Sensing of Exosomes

Abstract MXene is widely used in the construction of optoelectronic interfaces due to its excellent properties. However, the hydrophilicity and metastable surface of MXene lead to its oxidation behavior, resulting in the degradation of its various properties, which seriously limits its practical application. In this work, a 2D metal‐organic framework (2D MOF) with matching 2D morphology, excellent stability performance, and outstanding optoelectronic performance is grown in situ on the MXene surface through heterojunction engineering to suppress the direct contact between reactive molecules and the inner layer material without affecting the original advantages of MXene. The photoelectric dual gain MXene@MOF heterojunction is confirmed. As a photoelectric material, its properties are highly suitable for the demand of interface sensitization layer materials of surface plasmon resonance (SPR). Therefore, using SPR as a platform for the application of this interface material, the performance of MXene@MOF and its potential mechanism to enhance SPR are analyzed in depth using experiments combined with simulation calculations (FDTD/DFT). Finally, the MXene@MOF/peptides‐SPR sensor is constructed for rapid and sensitive detection of the cancer marker exosomes to explore its potential in practical applications. This work offers a forward‐looking strategy for the design of interface materials with excellent photoelectric performance.