Colloidal synthesis is an excellent tool for the study of cooperative effects in nanoalloys. In this work, bimetallic CuNi nanoparticles of defined size and composition are fully characterized and tested for the oxygen evolution reaction. Copper addition to nickel leads to modifications in the structural and electronic properties, showing a higher concentration of surface oxygen defects and formation of active Ni³⁺ sites under reaction conditions. The ratio O_V/O_L between oxygen vacancies and lattice oxygen shows a clear correlation with the overpotential, being an excellent descriptor of the electrocatalytic activity. This is attributed to modifications in the crystalline structure, leading to lattice strain and grain size effects. Bimetallic Cu₅₀Ni₅₀NP showed the lowest overpotential (318 mV vs RHE), low Tafel slope (63.9 mV dec⁻¹), and excellent stability. This work unravels the relative concentration between oxygen defects and lattice oxygen (O_V/O_L) as an excellent descriptor of the catalytic activity of bimetallic precatalysts.

Adding Cu to Ni/Al ₂ O ₃ is an excellent strategy to suppress methane formation and enhance carbon monoxide yield through formation of alloyed nanoparticles.

A facile and rational approach to synthesize bimetallic heterogeneous tandem catalysts is presented. Using core–shell structures, it is possible to create spatially controlled ensembles of different nanoparticles and investigate coupled chemocatalytic reactions. The CO₂ hydrogenation to methane and light olefins was tested, achieving a tandem process successfully.