Unveiling the Accelerated Water Electrolysis Kinetics of Heterostructural Iron‐Cobalt‐Nickel Sulfides by Probing into Crystalline/Amorphous Interfaces in Stepwise Catalytic Reactions

Abstract

Amorphization and crystalline grain boundary engineering are adopted separately in improving the catalytic kinetics for water electrolysis. Yet, the synergistic effect and advance in the cooperated form of crystalline/amorphous interfaces (CAI) have rarely been elucidated insightfully. Herein, a trimetallic FeCo(NiS 2 ) 4 catalyst with numerous CAI (FeCo(NiS 2 ) 4 -C/A) is presented, which shows highly efficient catalytic activity toward both hydrogen and oxygen evolution reactions (HER and OER). Density functional theory (DFT) studies reveal that CAI plays a significant role in accelerating water electrolysis kinetics, in which Co atoms on the CAI of FeCo(NiS 2 ) 4 -C/A catalyst exhibit the optimal binding energy of 0.002 eV for H atoms in HER while it also has the lowest reaction barrier of 1.40 eV for the key step of OER. H 2 O molecules are inclined to be absorbed on the interfacial Ni atoms based on DFT calculations. As a result, the heterostructural CAI-containing catalyst shows a low overpotential of 82 and 230 mV for HER and OER, respectively. As a bifunctional catalyst, it delivers a current density of 10 mA cm −2 at a low cell voltage of 1.51 V, which enables it a noble candidate as metal-based catalysts for water splitting. This work explores the role of CAI in accelerating the HER and OER kinetics for water electrolysis, which sheds light on the development of efficient, stable, and economical water electrolysis systems by facile interface-engineering implantations.

A General Strategy for Synthesis of Binary Transition Metal Phosphides Hollow Sandwich Heterostructures

“…However, the lattice information of FeCoP x is not found in the HR-TEM and SAED, which could be ascribed to the low content and weakened crystallinity. [22] From the elemental mappings in Figure 5e, the Co, Ni, and P elements are intensively distributed in the prominent hexagonal profile of sample, while the signal of Fe element is detected only in the framework due to its local distribution in hexagonal boundary, which is clearly embodied in the overlay image. Although interfered with the micro-grid copper mesh, the profile of carbon layer can be clearly seen in Figure S15 (Supporting Information).…”

Recent Progress of Non‐Noble Metallic Heterostructures for the Electrocatalytic Hydrogen Evolution

“…Luo et al constructed FeCo(NiS 2 ) 4 ‐C/A with rich crystalline/amorphous interfaces through the cation exchange method. [ 159 ] The introduction of iron ions not only adjusts the heterogeneity of the interface but also transforms the nanostructures into porous and hollow nanotubes, which is conducive to charge transfer and ion exchange during water dissociation. Lee et al deposited ultrathin amorphous CoNiPO x nanoslice arrays on crystalline V 3% –Co 4 N nanowires by taking advantage of the worse rigidity of the amorphous structure.…”

Electrolyzing spent cupronickel to fabricate superhydrophilic electrocatalysts for enhanced water splitting

“…However, the performance and stability of Ni-based materials also need further enhancement, especially under high current density. 18–20 For this reason, some research work has proposed many facile methods, such as adjusting the elemental ratio or modification with other transition metals such as manganese, to enhance the catalytic activity of Ni-based electrocatalysts. 21–25 In addition, since surface superhydrophilicity is of vital significance for improving the electrolyte wetting of materials and reaction activity, fabricating superhydrophilic materials is seen as an extremely effective approach to promote catalytic activity.…”