Electrospinning Machine | In Situ Formed Carbon-Encapsulated RuNi Alloy and Ni Heterointerface as an Efficient HER Electrocatalyst for Alkaline Water Splitting

Under the urgent situation of global energy transition, seeking sustainable and efficient clean energy production technologies has become imperative. Hydrogen energy, as a clean energy source, is of great significance for achieving carbon neutrality and promoting low-carbon transition. Electrocatalytic water splitting, as a highly promising green hydrogen production pathway, can efficiently convert electrical energy into hydrogen energy for storage. This process mainly includes the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). As a key step in electrocatalytic water splitting, HER is closely related to the overall efficiency of electrocatalytic hydrogen production. Developing advanced HER electrocatalysts is crucial for improving overall water splitting efficiency.

Recently, the team of Professor Guancheng Xu and Professor Li Zhang from Xinjiang University successfully prepared carbon-encapsulated RuNi/Ni heterojunction nanoparticles (RuNi/Ni@C-CNF) on coal-based carbon nanofibers through a strategy combining electrospinning, impregnation, and in-situ pyrolysis. They achieved high dispersion of metal nanoparticles while realizing graphitization of the outer carbon layer of the particles. Furthermore, the encapsulating carbon effectively restricted the aggregation of metal particles and protected the metal active sites from (electro)chemical corrosion by the alkaline electrolyte. This work provides new insights for the design of carbon-encapsulated heterojunction alkaline catalysts. The related research was published in the journal Small with the title "In Situ Formed Carbon-Encapsulated RuNi Alloy and Ni Heterointerface as an Efficient HER Electrocatalyst for Alkaline Water Splitting".

Figure 1: Preparation process and microstructure characterization of the RuNi/Ni@C-CNF catalyst.

Figure 2: Bond valence and coordination structure of the RuNi/Ni@C-CNF catalyst.

In this study, RuNi/Ni heterojunction nanoparticles were constructed on coal-based carbon nanofibers via a strategy involving electrospinning, impregnation, and in-situ pyrolysis. Transmission electron microscopy (TEM) images showed that the outer layer of the nanoparticles was encapsulated by an in-situ formed, relatively thin graphitic carbon layer. The metal nanoparticles can promote the migration and rearrangement of carbon atoms, which is beneficial for the formation of graphitic structures. Additionally, the in-situ formed carbon layer played a key morphological stabilization role through a spatial confinement effect, effectively suppressing particle aggregation caused by Ostwald ripening, thereby ensuring high dispersion of active sites and catalytic stability.

Figure 3: Alkaline hydrogen evolution performance of the RuNi/Ni@C-CNF catalyst.

Figure 4: Overall water splitting performance and AEM device testing of the RuNi/Ni@C-CNF catalyst.

Figure 5: HER mechanism analysis of the RuNi/Ni@C-CNF catalyst.

RuNi/Ni@C-CNF exhibited excellent HER activity in 1 M KOH electrolyte. It showed an overpotential of 9 mV at a current density of 10 mA cm⁻² and demonstrated good stability within 300 hours. Meanwhile, using RuNi/Ni@C-CNF as both the cathode and anode in an assembled electrolyzer, the system required only a cell voltage of 1.49 V to achieve a current density of 10 mA cm⁻². The introduction of RuNi not only promoted the water dissociation process at Ni sites but also acted as an adsorption site for H, thereby optimizing H adsorption. Furthermore, the coated carbon layer effectively confined the aggregation of metal particles and protected the metal active sites from (electro)chemical corrosion by the alkaline electrolyte. This work provides a new idea for designing carbon-encapsulated heterostructured HER catalysts. This helps advance the practical application process of efficient hydrogen production technology through water electrolysis.

Paper link::https://doi.org/10.1002/smll.202506911