In situ infrared electrochemical ATR can obtain the orientation, arrangement, coverage and other state information of adsorbed species on the electrode surface, which is an effective means to study the electrode process at the molecular level. The attenuated total reflection mode of the surface enhancement spectrum has the advantages of simple surface selection law, strong surface signal, easy mass transfer and small interference by bulk solution. It is especially suitable for real-time detection of dynamic electrode surface processes. The in-situ reaction system introduces three electrodes and a gas interface, which can pass CO2, N2 and other reaction gases into the solution under the condition of external bias, and realize the photocatalytic in-situ infrared spectroscopy characterization. On this basis, surface plasmon resonance wave is introduced to achieve surface enhancement effect by evaporating (or sputtering, etc.) gold layer on the surface of monocrystalline silicon to enhance the signal characterized in situ.