The RDS varies depending on the support and cluster composition. For monometallic Pt10 over all supports except germanene, the RDS is found to be the fourth (H + + e -) transfer step (OH* hydrogenation). In Pt10/germanene the third (H + + e -) transfer step (O* protonation) yields a higher endothermic step due to a slightly weaker OH* adsorption strength. After alloying to equimolar compositions, the RDS flipped in some cases. In Pt5Ge5/2H-MoS2 and Pt5Ge5/SmSI, the RDS becomes the third (H + + e -) transfer step due to a stronger O* adsorption (Ge-O vs Pt-O) on the former and weaker OH* adsorption on the latter (Ge-OH vs Sm-OH). In turn, despite bonding to the support atoms, the RDS also shifts to the third and last reduction steps for Pt5Ge5 on silicene and germanene, where the cluster composition may alter the charge and hybridization of the support via the MSI. The values of the overpotentials are reported in Table . All catalysts show very high ηORR, due to the strong overbinding of the ORR intermediates. Pt5Ge5/germanene (ηORR = 1.09 V), Pt5Ge5/5-8-5-DV (ηORR = 1.16) and Pt10/2H-MoS2 (ηORR = 1.16 V) yield the lowest overpotentials, while Pt5Ge5/silicene (ηORR = 2.10 V) and Pt5Ge5/SmSI (ηORR = 2.19 V) are the ones with the greatest overpotentials. Regardless of the support, since the last two hydrogenation steps are always uphill, ORR will not occur spontaneously at 1.23 V (vs SHE) on these systems. None of the supports is able to reduce the oxophilicity and revert this trend.