Monolayer assembly of gold nanodots on polyelectrolyte support: A multifunctional electrocatalyst for reduction of oxygen and oxidation of sulfite and nitrite

The present work demonstrates a monolayer self-assembly of methionine-capped gold nanodots (AuNDs) on the glassy carbon electrode (GCE) and its application in various electrocatalytic reactions. Positively charged poly(acrylamide-co-diallyldimethylammonium chloride) (PADA)-modified GCE was used as electrode substrate and monolayer assembly of negatively charged AuNDs was performed over PADA-modified GCE by simple dipping method. The successful modification of AuNDs on GCE was confirmed by characteristic cyclic voltammetry behavior of gold oxidation and reduction. Further to optimize the dipping time duration of AuNDs self-assembly, dipping time-dependent electrocatalysis was performed. Interestingly, the prepared AuNDs self-assembled electrodes exhibit very good electrocatalytic activity in the reduction of oxygen with excellent methanol tolerance and simultaneous electrooxidation of pollutants and food additives, nitrite, and sulfite ions.