Structure and dynamics of electric double layer (EDL), the sub-nanometer region at the electrode/electrolyte interface, are essential to the function and performance of many energy conversion and storage devices, ranging from electrolyzers, photoelectrochemical cells, fuel cells to batteries. In situ probe of the EDL structure and dynamics at the molecular level requires advanced molecular spectroscopic tools with interfacial sensitivity and/or selectivity. In this talk, I will discuss three recent studies in developing and applying vibrational sum frequency generation (VSFG) spectroscopy and surface enhanced Raman spectroscopy (SERS) as powerful in situ interface specific/sensitive vibrational spectroscopic tools. 1) Using combined VSFG and DFT calculation, we determine the binding structure of a molecular CO2 reduction catalyst on metal electrodes and interfacial electric field profile in the EDL, revealing surprisingly large electrode induction effects on molecular catalyst. 2) Using combined SERS and MD simulation, we obtain an atomistic view of the structure of solvent and ion molecules at the EDL, revealing an unconventional interfacial water structure change at high negative electrode polarizations in water-in-salt electrolytes. 3) Using time-resolved VSFG, we directly measure hot electron transfer induced vibrational dynamics of adsorbates on metal electrodes, suggesting the possibility of plasmon (or light)-enhanced electrochemistry.