Spiky Nickel Electrodes for Electrochemical Oxygen Evolution Catalysis by Femtosecond Laser Structuring

Figure 3

Cyclic voltammograms (CV) of as prepared laser-structured and tempered Ni plates (a) with a scan speed of = 20 mV s⁻¹. All electrochemical measurements were performed in 25 wt.-% KOH solution at room temperature. The sum of the absolute anodic and cathodic current densities versus the scan speed (b). The slope of the resulting fit curves corresponds to the double layer capacitances of tempered and laser-structured Ni electrodes. The corresponding CV cascades can be found in the supplementary information. CVs were carried out at nonfaradaic regions in a potential window of ΔE = 0.1 V around the open circuit potential. Linear sweep voltammograms as prepared (c) and activated (d) recorded with a scan speed of = 10 mV s⁻¹. Inset: magnifications of the area at J = 10 mA cm⁻² with markings highlighting the corresponding overpotentials at J = 10 mA cm⁻². Magnified linear sweep voltammograms in the potential region of the Ni(OH)₂ to NiOOH oxidation (e). Chronopotentiometric curves for long-term stability of the water electrolysis electrodes at a current density of  mA cm⁻² (f).

(a)

(b)

(c)

(d)

(e)

(f)