Concerning the energetic properties shown in Figure , a monotonously increasing sizedependence can be seen for the adsorption energy, Pt8 being the most stable structure. Interestingly, the Eads are significantly bigger than the ones reported for common oxide supports, even for the smallest sizes. Another indication of the beneficial effects that this particular support can have in the sintering resistance of Pt. On the contrary, Ge alloying has a detrimental effect on their stability. Indeed, Ge-rich clusters exhibit significantly lower adsorption energies and therefore might be prompted to undergo sintering. However, we stress that all catalytic properties must be addressed simultaneously. Even though monometallic Pt clusters may be more stable than PtGe nanoalloys, the catalytic activity may increase with Ge concentration. So a balance between the two may be necessary, being intermediate concentrations the best candidates. To shed more light on the electronic structure, we have computed the projected density of states (PDOS) of all GM, displayed in Figure . After deposition, the Pt d atomic orbitals (AOs) get very smeared below the fermi energy (EF) and display a strong hybridization with P AOs. But more surprisingly, the interaction between the phosphorene and the cluster leads to new states with Pt d and P character near the EF. As a result, the band gap is reduced. This effect is found to be size-dependent, becoming stronger with increasing size, until the band gap closes in Pt8. Namely, the addition of Pt increases the carrier concentration and hence the conductivity. On the contrary, the band gap reopens again at high Ge concentration.