Kinetically controlled synthesis of nanoporous Au and its enhanced electrocatalytic activity for glucose-based biofuel cells.

Nanoporous gold (NPG) structures, which possess abundant high-index facets, kinks, and steps, have been demonstrated as effective catalysts for the glucose electrooxidation in biofuel cells. Herein, we designed surface-clean NPG structures with high-index facets by a trisodium citrate (Na3Cit) self-initiated reduction of chloroauric acid (HAuCl4) in a water-ice bath followed by a kinetically controlled self-assembly manner. This strategy breaks through the traditional trisodium citrate thermal-reducing chloroauric acid approach where solutions are required to heat to a certain temperature for the reaction to initiate. However, herein, the surface-clean NPG structures yielded highly enhanced catalytic activity in glucose electrooxidation with approximately 9 A cm-2 mg-1 current density, which is over 20 times higher than that of Au nanoparticles devised by Turkevich (Turkevich-Au NPs) under the same conditions. This remarkable electrocatalytic activity could be ascribed to the large electrochemically active surface area, clean surface, and high-index facets or highly active sites of the porous structure. The employment of the surface-clean NPG with high-index facets for glucose electrooxidation promises a substantial improvement in the current biofuel cell technology and indicates the potential of biofuel cells in practical applications.