The creation of high-performing, robust bifunctional electrocatalysts for both cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER) in water-splitting is crucial for producing emerging hydrogen economy. Here we report a high entropy alloy (HEA) – FeCoNiCuPd – thin film catalyst, which demonstrated excellent alkaline HER and OER performance with ultralow overpotentials as low as 29 mV for HER and 194 mV for OER at a current density of 10 mA cm− 2. The outstanding catalytic activity for HER was found to originate from the multiple active sites present on the FeCoNiCuPd surface, while for OER it came from the highly functional (FeCoNi)-oxyhydroxide species formed on the film surface. Moreover, the two-electrode electrolyzer made of the FeCoNiCuPd film electrodes required a low cell voltage of 1.52 V to achieve 10 mA cm−2 in 1.0 M KOH, greatly outperforming commercially available Pt/C||RuO2 electrodes, while maintaining a notable durability. This work demonstrated the remarkable potential of a HEA thin film in catalyzing water-splitting process. 

Efficient FeCoNiCuPd thin-film electrocatalyst for alkaline oxygen and hydrogen evolution reactions

High entropy alloy/C nanoparticles derived from polymetallic MOF as promising electrocatalysts for alkaline oxygen evolution reaction

High entropy alloys are considered one of the major breakthroughs in alloying concepts. Their unique design concept and mixed entropy effects make the materials potentially valuable in many applications in various fields. This Research Update summarizes recent research progress on high entropy alloy catalysts in electrolytic water splitting. The definition and properties of high entropy alloys are described and the common preparation methods and organizational characteristics of high entropy alloys are discussed. The catalytic effects of high entropy alloys in water electrolysis are evaluated, and finally, the future development trend and application prospects of high entropy alloys are outlined.

Preparation of high entropy alloys and application to catalytical water electrolysis

Although Pt and other noble metals are the state‐of‐the‐art catalysts for various energy conversion applications, their low reserve, high cost, and instability limit their large‐scale utilization. Herein, we report a hybrid catalysts design featuring noble metal clusters (e.g., Pt) uniformly dispersed and stabilized on high‐entropy alloy nanoparticles (HEA, e.g., FeCoNiCu), denoted as HEA@Pt, which is prepared via ultra‐fast shock synthesis (∼300 ms) for HEA alloying combined with Pt galvanic replacement for surface anchoring. In our design, the HEA core critically ensures high dispersity, stability, and tunability of the surface Pt clusters through high entropy stabilization and core‐shell interactions. As an example in the hydrogen evolution reaction, HEA@Pt achieved a significant mass activity of 235 A/gPt, which is 9.4, 3.6, and 1.9‐times higher compared to that of homogeneous FeCoNiCuPt (HEA‐Pt), Pt, and commercial Pt/C, respectively. We also demonstrated noble Ir stabilized on FeCoNiCrMn nanoparticles (HEA‐5@Ir), achieving excellent anodic oxygen evolution performance and highly efficient overall water splitting when combined with the cathodic HEA@Pt. Therefore, our work developed a general catalysts design strategies by using high entropy nanoparticles for effective dispersion, stabilization, and modulation of surface active sites, achieving a harmonious combination of high activity, stability, and low cost.

High‐entropy alloy stabilized and activated Pt clusters for highly efficient electrocatalysis

Advanced materials for electrocatalytic water splitting applications have been sought-after considering both environmental and economic requirements. However, the traditional materials design concept limits the exploration of high-performance catalysts. The born of a materials design concept based on multiple elements, high-entropy materials, provides a promising path to break the shackles of compositional design in materials science. A number of high-entropy materials were reported to show remarkable properties for electrocatalytic water splitting applications. High-entropy materials were widely confirmed to be one kind of the best electrocatalysts for water splitting applications. Due to the synergy of multiple metal components, they show excellent catalytic activity. Several nontraditional methods were developed and reported to prepare high-performance high-entropy materials. This review article presents the recent progress on high-entropy materials for electrocatalytic water splitting applications. Moreover, it presents the research interests and future prospects in this field.

Wen-Han Zhu

Papers

Recent progress on high-entropy materials for electrocatalytic water splitting applications