Effect of Metal Layer Support Structures on the Catalytic Activity of NiFe(oxy)hydroxide (LDH) for the OER in Alkaline Media

Abstract

Photoelectrochemical (PEC) cells promise to combine the benefits of photovoltaics and electrolysis in one device. They consist of a photoabsorber functionalized with an electrocatalyst to harvest faradaic currents under reduced overpotentials. To protect the absorber from the harsh reaction conditions, a protective buffer layer (e. g. TiO2) is added between absorber and catalyst. In this work, we investigate the influence of the catalyst support systems Ti/TiOx and Ti/TiOx/M (M=Au, Ni, Fe) on the overall activity and stability of nickel and iron mixed layered double hydroxides for the alkaline oxygen evolution reaction (OER). The catalyst performance on the bare Ti/TiOx substrate is very poor, but the incorporation of a metallic interlayer leads to two orders of magnitude higher OER current densities. While a similar effect has been observed for M=gold supported systems, we show that the same effect can be achieved with M=nickel/iron, already contained in the catalyst. This proprietary metal interlayer promises a cheap OER performance increase for PEC cells protected with titania buffer layers. Detailed XPS show an improved transformation of the starting catalyst material into the highly active (oxy)hydroxide phase, when using metallic interlayers. From these experiments a pure conductivity enhancement was excluded as possible explanation, but instead an additional change in the local atomic and electronic structure at the metal‐support and metal‐catalyst interfaces is proposed.

Repurposing the current collector of a car battery module into a bifunctional electrode for overall electrochemical water splitting

“…8b) and may also contribute to the increased OER activity. Recent work by Strasser et al 75 demonstrated that the presence of a metal support layer such as Au, Ni or even Fe between Ti/TiO 2 and NiFe(oxy)hydroxide (LDH) materials can also significantly improve the OER activity. This is not simply due to an increase in conductivity but that the morphology and the related electronic structure between the catalyst and the substrate material as well as between the metal interlayer and the substrate play an important role for the finally observed improved activity.…”

Transition metal incorporation: electrochemical, structure, and chemical composition effects on nickel oxyhydroxide oxygen-evolution electrocatalysts

“…Typical NiO x H y films were electrodeposited on Ni foil (NF) substrates to avoid interference from substrate effects. 19,[30][31][32] Prior to deposition, substrates were cleaned in ethanol and 3 M HCl under sonication, rinsed with 18.2 MO cm deionized water, and dried. Films were cathodically deposited using a twoelectrode setup and a 20 mM nickel(II) nitrate aqueous solution (pH B 3).…”

Redefining the Stability of Water Oxidation Electrocatalysts: Insights from Materials Databases and Machine Learning

“…As noted previously, results for the TM selenide data set (Figure b) indicate that the surface area, via the double-layer capacitance, and the type of substrate significantly influence the outcome as precatalyst, suggesting a link to the reconstruction of precatalysts and enhancement of catalytic activity. Previous works have linked substrate effects to OER activity enhancement in transition metal oxyhydroxide catalysts. − More experimental and computational studies are necessary to explore the role of these extrinsic properties on the performance and transformation of TM X-ides. Furthermore, studies could explore how postreconstruction morphologies affect bubble removal, which is crucial for industrial water electrolysis, along with the reconstruction’s impact on mechanical stability, surface roughness, and corrosion over time. ,, Investigations at higher and fluctuating currents are also pertinent …”