Typically, calculated amounts of zinc nitrate hexahydrate (10mM) was dissolved into 10 ml distilled water and a white precipitate of zinc hydroxide [Zn(OH)2] is formed upon addition of 2 ml (2M) sodium hydroxide solution. Then, excess amount of sodium hydroxide solution was added to dissolve the white precipitate to form sodium zincate (Na2ZnO2). Then, 1ml sodium zincate (10 mM) solution was diluted to 5ml.This solution was the added to as prepared 0.2 mM Au colloid under stirring condition for 3-4 mins. Finally, this solution was kept at 90oC-95oC for 30 mins under stirring condition to prepare Au/ZnO core-shell nanocomposites. To prepare higher shell thickness of Au/ZnO, 1.6, 2.1 and 2.8 ml sodium zincate (10 mM) solution can be used.