Electrodeposition of dendritic Pd nanoarchitectures on n-GaN(0001): nucleation and electrocatalysis for direct formic acid fuel cells

Dendritic Pd nanoarchitectures were electrochemically deposited on single- crystal n-GaN(0001) by cyclic voltammetry and employed as anode electrocatalyst for  direct formic acid fuel cells. The Pd deposition on n-GaN(0001) was found to  commence at 0.2 V vs. Ag/AgCl without underpotential deposition process and follow  the typical instantaneous nucleation in large overpotential region. High-resolution  transmission electron microscope images revealed that numerous small branches were  formed around the trunk of dendritic structures and grew along the directions.  The as-obtained dendritic Pd nanoarchitectures showed good catalytic performance for  formic acid and the oxidation peak potential appeared at 0.45 V vs. Ag/AgCl. The  maximum current density and mass activity were 19.7 mA cm(-1) and 904 mA mg(-1),  respectively, for the dendritic Pd nanocrystals obtained by cycling the potentials  from -0.25 to 1.0 V for 5 times. (C) 2014 Elsevier Ltd. All rights reserved.

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