Thermochemical hydrogen production materials screening. One example where all three down-selection criteria are important is the identification of metal oxides for thermochemical hydrogen (TCH) production, i.e., water-splitting via a direct two-step thermal redox cycle. Criterion #1 is that ∆H V ∈ [2.5, 4.0] eV, ), many materials possess an excellent stability range for TCH, but this is inextricably correlated with vacancy formation energies that are too high, which eliminates a large swath of candidates. Only O( 2 ) candidates survive these downselection criteria, as examined in more detail in Supplementary Section 7.