Experimental adsorption and reaction enthalpies can be significantly more accurate than DFT data. Adsorption enthalpies can be derived from temperature-programmed desorption (TPD) spectra or measured using single-crystal adsorption calorimetry (SCAC). An excellent review on SCAC is provided by Campbell . Determining ∆ f H of the adsorbates anchored to the global thermochemical network from experimental adsorption enthalpies is straightforward. For associative adsorption, the adsorbate is directly referenced to the gas-phase precursor; for example, the adsorption enthalpy of CH 4 on Pt(111) was measured by Tait et al. via TPD: