Al12Co4: a pioneering heterometallic aluminum oxo cluster with surface-exposed Co sites for the oxygen evolution reaction

We report an unprecedented heterometallic aluminum oxo cluster (AlOC) containing four surface-exposed Co II sites, designated as Al12Co4, protected by four t -butylcalix[4]arene (TBC[4]) molecules. The Al 12 Co 4 nanocluster represents a significant advancement on multiple innovative fronts. First, it stands as an pioneering example of an Al III -based metallocalixarene nanocluster. It is also the first instance of heterometallic AlOCs shielded by macrocyclic ligands. Notably, this cluster also holds the distinction of being the highest nuclearity Al–Co bimetallic nanocluster known to date. Additionally, by depositing Al12Co4 on carbon nanotubes (CNTs) as a supported catalyst, we investigated its electrocatalytic performance for the oxygen evolution reaction in alkaline media. To reach a 10 mA cm −2 current density in alkaline solution, the Al12Co4@CNT electrode needs overpotential as low as 320 mV.