Ni-decorated porous dendritic Cu film on Cu foam for enhanced hydrazine oxidation catalysis

Abstract

Two major challenges limit the widespread use of direct hydrazine fuel cells (DHFCs): slow hydrazine oxidation reaction (HzOR) kinetics and the reliance on expensive noble-metal catalysts. To overcome these limitations, a Ni-Cu film/Cu foam (CF) electrode was developed through a two-stage electrochemical deposition approach. This process involved initially depositing a three-dimensional (3D) porous dendritic Cu film onto a CF substrate (denoted as Cu film/CF), followed by the controlled electrodeposition of Ni nanoparticles onto the prepared Cu film. The well-designed Ni-Cu film/CF electrode demonstrated noticeable superiority in terms of catalytic activity over single-metal electrodes and commercial Pt/C catalyst, displaying a current density (j) of 295.1 mA cm⁻² at −0.65 V and an onset potential (E_on) of −1.1 V. Electrochemical kinetic parameters were determined, revealing that the Ni-Cu film/CF electrode exhibited a reduced activation energy (E_a), diminished charge-transfer resistance (R_ct), and an increased electrochemically active surface area (ECSA) compared to its monometallic electrodes. The electrocatalytic performance enhancement stems from the unique 3D porous dendritic shape of the Ni-Cu film/CF electrode in conjunction with synergistic Ni-Cu effect, which promotes electron transport, facilitates accessibility to catalytic sites, and optimizes HzOR kinetics.