A process for producing atomic quantum clusters (AQCs) comprising the following steps: a) providing a mixture comprising: - a starting atomic quantum cluster in a picomolar to micromolar concentration, - a metal salt, - a polar solvent, - a hole scavenger having a standard electrode potential lower than the higher occupied molecular orbital (HOMO) of the starting atomic quantum cluster, wherein said starting atomic quantum cluster is formed by transition metals selected from: platinum (Pt), gold (Au), rhodium (Rh), iridium (Ir), palladium (Pd), ruthenium (Ru), osmium (Os), silver (Ag), copper (Cu), iron (Fe), cobalt (Co), nickel (Ni), titanium (Ti), vanadium, chrome (Cr) or their bi and multimetal combinations; wherein said metal salt and said hole scavenger are soluble in said polar solvent and do not react with each other; wherein the number of equivalents of said hole scavenger is higher than the number of equivalents of the metal salt in the mixture; b) applying a promoter to the mixture of step a), wherein the promoter is a light radiation having energy equal or larger than the HOMO-LUMO gap of the starting atomic quantum cluster of the mixture of step a); and c) adding an oxidant having a standard electrode potential over the standard electrode potential of the metal of the metal salt; wherein the oxidant can be either added in the mixture of step (a), and/or added to said mixture during and/or after applying said promoter in step (b). a) providing a mixture comprising: - a starting atomic quantum cluster in a picomolar to micromolar concentration, - a metal salt, - a polar solvent, - a hole scavenger having a standard electrode potential lower than the higher occupied molecular orbital (HOMO) of the starting atomic quantum cluster, wherein said starting atomic quantum cluster is formed by transition metals selected from: platinum (Pt), gold (Au), rhodium (Rh), iridium (Ir), palladium (Pd), ruthenium (Ru), osmium (Os), silver (Ag), copper (Cu), iron (Fe), cobalt (Co), nickel (Ni), titanium (Ti), vanadium, chrome (Cr) or their bi and multimetal combinations; wherein said metal salt and said hole scavenger are soluble in said polar solvent and do not react with each other; wherein the number of equivalents of said hole scavenger is higher than the number of equivalents of the metal salt in the mixture; - a starting atomic quantum cluster in a picomolar to micromolar concentration, - a metal salt, - a polar solvent, - a hole scavenger having a standard electrode potential lower than the higher occupied molecular orbital (HOMO) of the starting atomic quantum cluster, wherein said starting atomic quantum cluster is formed by transition metals selected from: platinum (Pt), gold (Au), rhodium (Rh), iridium (Ir), palladium (Pd), ruthenium (Ru), osmium (Os), silver (Ag), copper (Cu), iron (Fe), cobalt (Co), nickel (Ni), titanium (Ti), vanadium, chrome (Cr) or their bi and multimetal combinations; wherein said metal salt and said hole scavenger are soluble in said polar solvent and do not react with each other; wherein the number of equivalents of said hole scavenger is higher than the number of equivalents of the metal salt in the mixture; b) applying a promoter to the mixture of step a), wherein the promoter is a light radiation having energy equal or larger than the HOMO-LUMO gap of the starting atomic quantum cluster of the mixture of step a); and c) adding an oxidant having a standard electrode potential over the standard electrode potential of the metal of the metal salt; wherein the oxidant can be either added in the mixture of step (a), and/or added to said mixture during and/or after applying said promoter in step (b).