Stabilization of Cu Nanoclusters on Hydroxylated SiO₂: Static and Dynamic Contributions from Metal-Support...

Oxide-supported nanosized copper clusters exhibit high catalytic activity but often suffer from limited thermal stability governed by the metal-support interaction (MSI). Here, we systematically investigate how surface hydroxylation modulates the interfacial stability of Cu clusters supported on crystalline SiO₂(001). Four model surfaces with hydroxyl coverages of 0, 3.2, 4.8, and 9.6 OH nm^-2 were constructed to isolate hydroxyl effects. Density functional theory (DFT) calculations combined with ab initio molecular dynamics (AIMD) simulations were employed to examine adsorption energetics, interfacial bonding, and high-temperature diffusion behavior. DFT results show that surface hydroxylation markedly strengthens the MSI by enhancing adsorption energies, orbital hybridization, and charge transfer, with a clear size dependence of the adsorption strength. AIMD simulations further reveal that hydroxylation leads to shorter and more localized Cu-O coordination, thereby suppressing the in-plane diffusion and migration of Cu clusters. This migration inhibition saturates with increasing hydroxyl coverage, with 4.8 OH nm^-2 identified as a near-optimal regime. At high temperatures, reverse hydrogen spillover induces interfacial reconstruction and forms strong Cu-O anchoring sites. These results establish surface hydroxylation as a tunable interfacial parameter for controlling metal-oxide interactions and suppressing thermally driven cluster migration.