High-Entropy Alloy with Mo-Coordination as Efficient Electrocatalyst for Oxygen Evolution Reaction

Abstract

Electrochemical hydrolytic hydrogen production is the most promising method for renewable energy storage and conversion. However, the kinetic slow oxygen evolution reaction (OER) limits the development of water electrolysis at the anode. The state-of-the-art OER catalysts face a dilemma of high content of noble metals and low OER activities. Herein, a strategy for achieving efficient and stable high-entropy alloy (HEA) catalysts by Mo-coordination is reported. The earth-abundant FeCoNiMo HEA catalyst provides an overpotential as low as 250 mV at the current density of 10 mA cm −2 in alkaline medium, which is 89 mV lower than that of state-of-the-art IrO 2 . The turnover frequency of 0.051 s −1 at the overpotential of 300 mV of FeCoNiMo HEA is 3 times higher than that of commercial IrO 2 catalyst and even 11 times higher than that of the FeCoNi alloy without Mo-coordination. Importantly, the FeCoNiMo HEA exhibits high OER stability at a high current density of 100 mA cm −2 . Methanol molecular probe experiment and X-ray photoelectron spectroscopy analyses suggest that the electrons of Mo transfer to Fe, Co, and Ni in the FeCoNiMo HEA catalyst, which leads to a weakened OH* bonding and, as a result, enhanced OER performance of the FeCoNiMo HEA catalyst. Consistent with the methanol molecular probe analysis, the real-time OER kinetic simulation reveals that the coordination of Mo within FeCoNi can speed up the rate-determining OH* deprotonation step of OER. Our finding opens up a routine for designing efficient cost-effective electrocatalysts for OER, which could facilitate discoveries in OER catalysts.

Iron-doped novel Co-based metal–organic frameworks for preparation of bifunctional catalysts with an amorphous structure for OER/HER in alkaline solution

“…S9, † the absolute values of the zeta potentials of the Fe@Co-MOFs materials are higher than that of the original Co-MOF in both deionized water and alkaline solution, which also indicates that the post-treatment process improves the surface potential of the catalyst and facilitates the adsorption of hydroxide ions. 7,56 Based on a literature survey, the material Fe@Co-MOF-3 outperforms the previously reported MOF and MOF derivative OER catalysts in electrocatalytic reactions in alkaline media (Fig. 5e and Table S5 †).…”

“…S9,† the absolute values of the zeta potentials of the Fe@Co-MOFs materials are higher than that of the original Co-MOF in both deionized water and alkaline solution, which also indicates that the post-treatment process improves the surface potential of the catalyst and facilitates the adsorption of hydroxide ions. 7,56…”

“…55 Compared with FeSO 4 •7H 2 O, the binding energy of Fe@Co-MOF-3 is highly shifted to lower energy levels, which further indicates that the electronic structure of Fe in the material is greatly changed during the post-treatment process. 56,57 The transfer of the binding energy of metal elements is also strong evidence for the electron transfer and subsequent synergistic coupling effect between Fe and Co, which will be beneficial to the improvement of the OER performance of the material. 58 3.3.…”

Three novel coordination polymers as bifunctional materials for the photocatalytic degradation of dyes and the oxygen evolution reaction in alkaline solutions

“…S7, † in both deionized water and alkaline solution, the surface of the catalyst has a certain charge, which is beneficial for promoting the adsorption of hydroxide ions. 28 To further understand the electrocatalytic performance of the catalysts, the cyclic voltammetry curves and electrochemical impedance spectroscopy (EIS) of samples CPs 1-3 were analyzed. ESCA was calculated from the cyclic voltammetry curves obtained at different scan rates (Fig.…”

“…25,26 Currently, noble metal oxides IrO 2 , RuO 2 , and Pt-based materials have been considered benchmarks for electrocatalysts in commercial applications. 27,28 However, general problems such as high cost, scarcity, poor stability, and non-toxicity limit the widespread application of these commercial electrocatalysts in the field of electrocatalysis. Therefore, it is imperative to develop environmentally friendly, low-cost, and non-toxic electrocatalysts.…”