Water–Gas Shift Reaction Produces Formate at Extreme Pressures and Temperatures in Deep Earth Fluids

The water-gas shift reaction is one of the most important reactions in industrial hydrogen production and plays a key role Fischer-Tropsch-type synthesis, which widely believed to generate hydrocarbons deep carbon cycle but little known at extreme pressure-temperature conditions found Earth's upper mantle. Here, we performed extensive ab initio molecular dynamics simulations free energy calculations study reaction. We direct formation formic acid from CO supercritical water 10-13 GPa 1400 K without any catalyst. Contrary common assumption that or formate an intermediate product, HCOOH thermodynamically more stable than products above 3 1000-1400 K. Our suggests may not happen mantle, be carrier reducing environments, participating many geochemical processes Earth.