Copper oxide subnanoparticles of three specific sizes were synthesized within tree-like structures called dendrimers.
X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR) were used to analyze the synthesized SNPs' structures, and the results were supported by density functional theory (DFT) calculations. The XPS analysis and DFT calculations revealed increasing ionicity of the copper–oxygen (Cu–O) bonds as SNP size decreased. This bond polarization was greater than that seen in bulk Cu–O bonds and the greater polarization was the cause of the enhanced catalytic activity of the CunOx SNPs. Tanab