Facile Synthesis of FeCoNiCuIr High Entropy Alloy Nanoparticles for Efficient Oxygen Evolution Electrocatalysis

Abstract

The lack of an efficient and stable electrocatalyst for oxygen evolution reaction (OER) greatly hinders the development of various electrochemical energy conversion and storage techniques. In this study, we report a facile synthesis of FeCoNiCuIr high-entropy alloy nanoparticles (HEA NPs) by a one-step heat-up method. The involvement of glucose made the NPs grow uniformly and increased the valence of Ir. The resulting FeCoNiCuIr NPs exhibit excellent OER performance in alkaline solution, with a low overpotential of 360 mV to achieve a current density of 10 mA cm−2 at a Tafel slope of as low as 70.1 mV dec‒1. In addition, high stability has also been observed, which remained at 94.2% of the current density after 10 h constant electrolysis, with a constant current of 10 mA cm‒2. The high electrocatalytic activity and stability are ascribed to the cocktail effect and synergistic effect between the constituent elements. Our work holds the potential to be extended to the design and synthesis of high-performance electrocatalysts.

Water Splitting as an Alternative for Electrochemical Hydrogen and Oxygen Generation: Current Status, Trends, and Challenges

“…It is well known that multimetallic alloys can facilitate the adsorption and desorption of reactants during the OER. Cai et al proposed the design of high-entropy alloys regarding the unusual physicochemical and mechanical properties of this type of compound [89]. The material was readily prepared by mixing the Fe, Cu, Ni, Ir, and Mo precursors in a solution containing glucose and oleylamine.…”

Understanding the Structural Evolution of IrFeCoNiCu High-Entropy Alloy Nanoparticles under the Acidic Oxygen Evolution Reaction

“…After 12 h, the overpotential increase measured from the chronopotentiometry test for IrFeCoNiCu-HEA is less than 60 mV, while for pure Ir is up to 120 mV. In addition, a study conducted by Cai et al showed that the same elemental combination also exhibits improved OER activity in an alkaline environment …”

“…High-entropy alloy (HEA) nanoparticles are promising nanomaterials that provide tremendous opportunities for various fields, including catalysis. − The considerable configurational entropy generated by incorporating five or more elements into a single particle, in principle, can dominate the particle’s thermodynamic behavior, stabilize the alloyed structure, and even mitigate structural degradation under unrelenting conditions . In addition, HEA manifests a mixing effect, resulting in synergistic responses from the mutual electronic interactions between its constituent elements. − The availability of multielement active sites on the HEA nanoparticle surface also makes HEA suitable for catalytic reactions, including the OER. − However, the use of HEA as a catalyst in acidic OER environments is relatively underexplored, − as most studies have focused on alkaline electrolytes. , …”

“…19−22 However, the use of HEA as a catalyst in acidic OER environments is relatively underexplored, 23−26 as most studies have focused on alkaline electrolytes. 27,28 Our work focuses on developing Ir-based HEA nanoparticles as efficient catalysts for the acidic OER. Using microwaveassisted shock synthesis, we successfully synthesized IrFeCo-NiCu-HEA, which outperforms monometallic Ir and other Irbased bimetallic alloys such as IrFe, IrCo, and IrNi.…”

“…In addition, a study conducted by Cai et al showed that the same elemental combination also exhibits improved OER activity in an alkaline environment. 27 It should be noted that during the synthesis process we observed the existence of carbon layers encapsulating the HEA nanoparticles with a thickness of about 5 nm (Figure S9a,b). The encapsulating layers have been reported to be formed by typical processes that involve heat treatment of nanoparticles on different types of carbon substrates.…”