Cluster catalysts are rapidly growing into an important sub-field in heterogeneous catalysis, owing to their distinct geometric structure, neighboring metal sites, and unique electronic structure. Although the thermodynamics and kinetics of the formation of nanoparticles have been largely investigated, the precise synthesis of clusters in wet chemical methods still faces great challenges. In the study, a quenching strategy of asymmetric temperature in solution for the rapid generation of vacancy-defect rich clusters is reported. The quenching process can be used to synthesize multitudinous metal compound clusters, including metal oxides, fluorides, oxygen-sulfur compounds, and tungstate. For oxygen evolution reaction (OER), IrO₂ clusters with abundant oxygen vacancies were obtained and uniformly dispersed in the solution. Compared to commercial IrO₂, the prepared IrO₂ cluster can be directly loaded on carbon paper and used as binder-free electrodes, which exhibit higher OER activity and long-term operational stability in alkaline electrolytes. The quenching strategy provides a simple and efficient method for the synthesis of clusters, which has tremendous potential for industrial-scale preparation and application, especially can be further applied to flow electrochemical generators.

Being a typical state of the art heterogeneous catalyst, supported noble metal catalyst often demonstrates enhanced catalytic properties. However, a facile synthetic method for realizing large-scale and low-cost supported noble metal catalyst is strictly indispensable. To this end, by making use of the strong metal–support interaction (SMSI) and mechanochemical reaction, we introduce an efficient synthetic route to obtain ultrafine Pt and Ir nanoclusters immobilized on diverse substrates by wet chemical milling. We further demonstrate the scaling-up effect of our approach by large-scale ball-milling production of Pt nanoclusters immobilized on TiO₂ substrate. The synthesized Pt/Ir@Co₃O₄ catalysts exhibit superior oxygen evolution reaction (OER) performance with only 230 and 290 mV overpotential to achieve current density of 10 and 100 mA·cm⁻², beating the catalytic performance of Co₃O₄ supported Pt or Ir clusters and commercial Ir/C. It is envisioned that the present work strategically directs facile ways for fabricating supported noble metal heterogeneous catalysts.