An Operando Investigation of (Ni–Fe–Co–Ce)O_x System as Highly Efficient Electrocatalyst for Oxygen Evolution Reaction

Abstract

Abstract. The oxygen evolution reaction (OER) is a critical component of industrial processes such as electrowinning of metals and the chlor-alkali process. It also plays a central role in the developing renewable energy field of solar-fuels generation by providing both the protons and electrons needed to generate fuels such as H 2 or reduced hydrocarbons from CO 2 . To improve these processes, it is necessary to expand the fundamental understanding of catalytically active species at low overpotential, which will further the development of electrocatalysts with high activity and durability. In this context, performing experimental investigations of the electrocatalysts under realistic working regimes, i.e. under operando conditions, is of crucial importance. Here, we study a highly active quinary transition metal oxide-based OER electrocatalyst by means of operando ambient pressure X-ray photoelectron spectroscopy and X-ray absorption spectroscopy performed at the solid/liquid interface. We observe that the catalyst undergoes a clear chemical-structural evolution as a function of the applied potential with Ni, Fe and Co oxyhydroxides comprising the active catalytic species. While CeO 2 is redox inactive under catalytic conditions, its influence on the redox processes of the transition metals boosts the catalytic activity at low overpotentials, introducing an important design principle for the optimization of electrocatalysts and tailoring of high performance materials.

Elucidating the alkaline oxygen evolution reaction mechanism on platinum

“…Thus motivating the need for these types of operando experiments and the development of new thermodynamic, kinetic, and computational models for electried interfaces under realistic operating conditions. 53 Expanding this experimental strategy for the study of different materials and catalytic reactions under operando conditions, 31,32,54 will open a path for new discoveries that will deepen our knowledge towards the accelerated development of novel tailored materials.…”

Application of In Situ Techniques for the Characterization of NiFe‐Based Oxygen Evolution Reaction (OER) Electrocatalysts

“…XPS is au seful tool to obtain the surface elemental composition as well as the chemical oxidation and electronic states of materials. [76][77][78] However,many in situ applications by the standard XPS are limited due to the requirement of ultrahigh vacuum (UHV) conditions.A PXPS based on using synchrotron radiation can overcome the limitation of UHV conditions. [79,80] Therefore,i ti sf easible to use APXPS to in situ probe the surface chemistry of electrocatalysts and monitor their electrochemical reactions.Aschematic diagram of the APXPS instrument is shown in Figure 9a.…”

Combined soft and hard X-ray ambient pressure photoelectron spectroscopy studies of semiconductor/electrolyte interfaces

“…By combining these two techniques, the semiconductor/aqueous electrolyte interface can be studied as it is built-up in a step-wise fashion from its initial stages of formation to an interface closely resembling that found in a functioning water splitting device. The application of AP-photoelectron spectroscopy, AP-PES, (we will use AP-PES to designate generic photoelectron spectroscopy (i.e., with soft and/or hard X-rays) under ambient conditions) for studying solid/liquid interfaces is a relatively recent development [4,5,6,7,8]. Its implementation requires novel technical solutions to minimize the elastic and inelastic scattering of electrons by the liquid phase and the relatively high pressure of gas (the vapor pressure of water at 20 °C is 17.5 Torr).…”