In conclusion, by applying finite-field DFTMD simulations, the effect of water adsorption energy E ads on surface acidity and Helmholtz capacitance have been studied by selecting BiVO 4 as an example of metal oxide electrodes with weakly chemisorbed water. Based on a oxide series composed of BiVO 4 , TiO 2 and SnO 2 , we investigate the effect of E ads on the coordination number, the length of H-bond, the orientation of chemisorbed water.