Stainless steel supported NiCo2O4 active layer for oxygen evolution reaction

• Published in: Electrochimica acta 2023-06, Vol.453, p.142295, Article 142295
• Main Authors: Perroni, P.B., Ferraz, T.V.B., Rousseau, J., Canaff, C., Varela, H., Napporn, T.W.
• Format: Article
• Language: English
• Subjects: Catalysis; Chemical Sciences; Electrodeposition; Material chemistry; Ni cobaltite; Oxygen evolution reaction, Alkaline medium; Stainless steel; Water splitting
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2023.142295

•Electrodeposition of precursor layer of NiCo2O4 on stainless steel substrate.•Nanoflowers-like morphology.•High performance of calcined layer of NiCo2O4 for splitting water.•24 h operation with negligible difference in potential. The energy demand from a clean, renewable and cheap source has been increasingly urgent. In this work, a simple two steps preparation method was used to obtain NiCo2O4. NiCo2O4 layer was electrodeposited and calcined on two different stainless-steel alloys AISI 304 and AISI 316 L. The samples were characterized with XRD and XPS, which confirmed the material to be NiCo2O4. In both substrates the results suggest that the catalysts obtained, have good activity for OER, with an overpotential at 10 mA cm−2 of 360 and 340 mV for SS304 and SS316L respectively. However, the OER curve of the layer on SS316L achieves higher current density of 41.7 mA cm−2 while that on SS304 is 29.7 mA cm−2 at 1.7 V vs. RHE. The Tafel slope value shows better kinetics for the layer on SS304. From the EIS studies and the Nyquist plot the RCT for SS304 is 15.07 Ω and for SS316L is 36.74 Ω. This can be explained by the higher conductivity of SS304 which promotes the fast growth of nanoflowers with bigger nanopetals during the electrodeposition. The high material density in the surface causes crinkles, as can be seen in SEM analysis. This default in catalysts' morphology leads to a discontinuity in electrons transfer through the layer and then a decrease in kinetics. Another hypothesis is the presence of Mo in SS316L, which has a synergistic effect with the other metals. In this latter case the stainless-steel composition would have a direct influence on the reaction kinetics. [Display omitted]