Simulation and calculation studies of gas hydrate formation process and in situ Raman studies. (a) Comparison of CO2-H2O adsorptive structure on graph (001). (b) Adsorption enthalpy change of water and CO2 on slit pore model with different pore size: (1) for CO2; (2) for water; and (3) is the difference of enthalpy between water adsorption and CO2 adsorption in slit pore with different pore size. (c) Relationship between pressure, pore size, and temperature when the Gibbs energy of the process is less than zero. (d) In situ Raman spectra after (I) loading CO2 on CMK-3 (Rw = 1) immediately and (II) loading CO2 on CMK-3 (Rw=1) for 8 h. (e) In situ Raman spectra after loading CO2 on (I) AC-carbon (Rw = 3.1) for 8 h and (II) AC-carbon (Rw = 1.58) for 8 h.