Dynamic gas bubble template electrodeposition mechanisms and amperometric glucose sensing performance of three kinds of three-dimensional honeycomb-like porous nano-golds

Abstract

One-pot electrodeposition of three kinds of three-dimensional honeycomb-like porous nano-golds (3DHPNGs) is potentiostatically conducted on Au electrodes in the aqueous baths containing HAuCl4 and a sufficient-quantity strong acid (3DNPNG1), or chemically synthesized fulminating gold precipitate and sufficient NH4+/acid (3DNPNG2), or HAuCl4 and sufficient NH4+ (3DNPNG3). The dynamic precipitation and the fast electroreduction of fulminating gold in the aqueous baths containing HAuCl4 and sufficient NH4+ are explored. We suggest new extrusion-shaping mechanisms that a sufficiently violent electrogenerated-gas bubbling can mechanically squeeze the “soft” electroreducible fulminating gold precipitates (dynamically electrogenerated and chemically synthesized) and even the “hard” Au deposits (directly from the electroreduction of soluble Au compounds) to form an ordered and stabilized dynamic gas bubble template for the final formation of 3DHPNGs. The suggested mechanisms including the more general discussion made on the topic provide new insights into metal electrodeposition by dynamic hydrogen bubble template. A comparison study under similar conditions reveals that the 3DNPNG3/Au electrode gives the largest real surface area and the highest electrocatalytic activity for alkaline/neutral oxidation and amperometric sensing of glucose with superior performance, giving a sensitivity of 960 μA cm−2 mM−1 and a limit of detection (LOD) of 0.044 μM in 1 M aqueous NaOH as well as a sensitivity of 316 μA cm−2 mM-1 and a LOD of 0.20 μM in 0.1 M phosphate buffer (pH = 7.4).