Methods of generating hydrogen in a subsurface formation

A method of generating hydrogen in a subsurface formation, the method comprising:

• injecting a liquid solution of oxidizable metal particles into a subsurface formation comprising subsurface water and a geologic trap, wherein:
• the subsurface water has a temperature of from 18° C. to 400° C. and a pressure of from 500 psi to 10,000 psi;
• the geologic trap comprises one or both of a structural trap or a stratigraphic trap;
• the geologic trap substantially prevents vertical migration of the subsurface water out of the subsurface formation;
• the oxidizable metal particles comprise iron nanoparticles, aluminum nanoparticles, or both, such that the oxidizable metal particles comprise a particle size of less than or equal to 100 nm;
• and
• the oxidizable metal particles react with the subsurface water to form hydrogen, metal oxides, metal hydroxides, or combinations thereof.