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

Abstract

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 Al₁₂Co₄ 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.