Ni-Fe (Oxy)hydroxide Modified Graphene Additive Manufactured (3D-Printed) Electrochemical Platforms as an Efficient Electrocatalyst for the Oxygen Evolution Reaction

We demonstrate that polylactic acid (PLA)/graphene additive manufactured (3D-printed) electrodes (Gr/AMEs) electrodeposited with Ni-Fe (oxy)hydroxide can efficiently catalyse the oxygen evolution reaction (OER). X-ray photoelectron spectroscopy (XPS) depth profiling combined with Atomic Force Microscopy (AFM) and Tip Enhanced Raman Spectroscopy (TERS) deduced the composition and depth of the Ni-Fe (oxy)hydroxide layer. The composition of the resulting electrocatalytic surfaces are tailored through altering the concentrations of nickel and iron within the electrodeposited solutions, which give rise to optimised AMEs OER performance (within 0.1 M KOH). The optimal OER performance was observed from a Ni-Fe (oxy)hydroxide with a 10 % content of Fe, which displayed an OER onset potential and overpotential of+1.47 V (vs. RHE) and 519 mV, respectively. These values arecomparable to that of polycrystalline Iridium (+ 1.43 V (vs. RHE) and ca. 413 mV), as well as being significantly less electropositive than a bare/unmodified AME. This work is essential for those designing, fabricating and modulating additive manufactured electrodes.