Question

what are the possible bonding between Gold colloids and Oxygen? why?

Answer 1

• Gold colloid is sol of gold nanoparticles in a fluid.Smaller gold nanoparticles consisting of less than 30 gold atoms are characterised by  positively and negatively charged active sites on the surface.Larger gold nanoparticles are characterised by core shell structure i.e. a positively charged core with negatively charged shell.
• The activation occurs when oxygen is bonded to colloidal sol.The activation occurs because of transfer of electron density from  gold nanoparticle to pie antibonding orbital of oxygen. The pie antibonding orbitals of oxygen overlap well with the d orbitals of gold.The oxidation activation occurs on negatively charged atoms.With large nanoparticles large number of oxygen atoms can be activated due to partial negative charge on entire surface.