What are the gas storage methods (mechanics, materials, chemistry)?

At present, there is a lot of research on hydrogen storage materials, because hydrogen is recognized as one of the most promising new energy sources, but it is limited because it is difficult to store in large quantities (high-pressure gas storage tanks are dangerous and hydrogen is extremely difficult to liquefy). Searching for "hydrogen storage materials" can find a lot of information. The most primitive hydrogen storage material may be palladium, which can atomize hydrogen atoms and diffuse hydrogen atoms into palladium, so palladium can catalyze many reactions involving hydrogen, which is a very strange combination. There seems to be an "oxygen storage material". I have been paying attention to porous materials for gas storage for six years. The porous materials here include zeolite molecular sieve, activated carbon, metal-organic framework Mof, zeolite imidazole framework ZIF, carbon nanotubes and so on. It can only be said that the adsorption of stored gas is still in the experimental stage, and there are few large-scale applications, especially hydrogen storage. Most materials can only meet the commercial hydrogen storage standard of DOE at 77K (I remember it was 6 wt. %), it's terrible at room temperature, so America gave up after O 'Hea took office. Later, natural gas was stored, and the effect was better than hydrogen. Individual materials can meet the requirements of DOE 180 L/L at 35 bar, but they are also individual materials, which are in the laboratory stage and the cost is extremely high. Moreover, it is adsorbed by powder, not bonded into particles, and has not been tested for stability. Then carbon dioxide capture. Now it seems that this is the easiest to achieve, and there are many good performances. Because of the characteristics of carbon dioxide molecules, a large number of functional materials have been modified and absorbed, which is the first system that should be industrialized among the above three gases. At low temperature, gas will liquefy. For example, below 100 degrees, water vapor will become water. Of course, this is relatively high. The low temperature is liquid nitrogen, and liquid helium will liquefy only when it is close to absolute zero -273 degrees. If you want to liquefy at high temperature, you need to increase the pressure. For example, strong reducing substances in gas tanks can replace hydrogen ions in water and become hydrogen (in large quantities), such as potassium and sodium, but potassium and sodium will be oxidized in the air, so they need to be sealed and preserved. Some acids react with alkaline substances, such as hydrochloric acid and soda (or baking soda), which can give off gas and react quickly.