Using theoretical and computational chemistry methods, we have studied the oxygen reduction and proton transfer in molten carbonate salts related to solid oxide fuel cells, and adsorption of nerve agents of sarin on surfaces of CaO, graphene and graphane. The mechanism of oxygen reduction through CO52- and CO42- is confirmed for the first time by DFT. It was found the proton has very good mobility in molten carbonate salts with activation energy of 8.0 kcalmol, which agrees with the value measured by experiment. For sarin on the selected surfaces, its polarized phosphate region as Lewis-base acts as the binding agent. The binding energy ranges from 2.4-13.2 kcalmol at the level of CI, showing relative weak interactions with the surfaces.