The catalytic hydrogen evolution reaction (HER) using Pt-doped graphene is highly efficient due to its exothermic nature (ΔH<0), which drives the reaction thermodynamically . In an exothermic HER, energy is released as protons (H + ) are reduced and combine to form molecular hydrogen (H2), making the process spontaneous under standard conditions. The negative enthalpy change indicates that Pt-doped graphene provides a favorable surface for adsorbing hydrogen intermediates, lowering the energy barrier for the reaction . This efficient energy transfer enables the formation of stable hydrogen bonds on the catalyst surface, which facilitates the reduction of protons and promotes the recombination of adsorbed hydrogen (Hads) into molecular hydrogen.