Stabilization of Cu Nanoclusters on Hydroxylated SiO ₂ : Static and Dynamic Contributions from Metal–Support Interactions

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 SiO 2 (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.