Control of Ag nanofoam structure and its electrocatalytic performance in bromobenzene reductive debromination via variation of electrodeposition conditions
Abstrakt
Silver nanofoams were obtained on silver surface via electrodeposition from acidic aqueous electrolyte (AgNO3 + HBF4) under high current densities. The nanofoams consist of irregularly shaped Ag filaments (mean width 100-450 nm) arranged in walls surrounding void craters (mean diameter 7-40 μm).
Synthesis parameters (AgNO3 and HBF4 concentrations, deposition time, current density) were varied, and it was found that the higher the value of any synthesis parameter, the higher the observed mean crater diameter. An increase in the deposition time and current density also resulted in higher surface roughness.
The higher Ag(+) concentration led to higher mean filament width as well. The electrocatalytic performance of the nanofoams was studied via cyclic voltammetry by comparing potentials and currents of the peak corresponding to the bromobenzene reduction.
All nanofoams were notably more electrocatalytically active in the reaction than bulk silver (potentials were at least 200 mV less negative), but, unexpectedly, the significant changes in their structure resulted only in moderate adjustment of their activity (the peak potentials varied within 60 mV). These observations allowed us to choose the explanation of the superior nanofoams activity among several suppositions, namely, the presence of some kind of active sites on the facets of the nanofoam forming particles.