Covalent 0D–2D Heterostructuring of Co₉S₈–MoS₂ for Enhanced Hydrogen Evolution in All pH Electrolytes

Abstract

Ultrasmall Co 9 S 8 nanoparticles are introduced on the basal plane of MoS 2 to fabricate a covalent 0D-2D heterostructure that enhances the hydrogen evolution reaction (HER) activity of electrochemical water splitting. In the heterostructure, separate phases of Co 9 S 8 and MoS 2 are formed, but they are connected by CoS -Mo type covalent bonds. The charge redistribution from Co to Mo occurring at the interface enhances the electron-doped characteristics of MoS 2 to generate electron-rich Mo atoms. Besides, reductive annealing during the synthesis forms S defects that activates adjacent Mo atoms for further enhanced HER activity as elucidated by the density functional theory (DFT) calculation. Eventually, the covalent Co 9 S 8-MoS 2 heterostructure shows amplified HER activity as well as stability in all pH electrolytes. The synergistic effect is pronounced when the heterostructure is coupled with a porous Ni foam (NF) support to form Co 9 S 8-MoS 2 /NF that displays superior performance to those of the state-ofthe-art non-noble metal electrocatalysts, and even outperforms a commercial Pt/C catalyst in a practically meaningful, high current density region in alkaline (>170 mA cm −2) and neutral (>60 mA cm −2) media. The high HER performance and stability of Co 9 S 8-MoS 2 heterostructure make it a promising pH universal alternative to expensive Pt-based electrocatalysts for practical water electrolyzers.

Electrocatalytic Hydrogen Evolution Reaction Related to Nanochannel Materials

“…From a supporting materials point of view, the HER performance of the electrode can be affected not only by their structure, but also by other properties. [49] If the supporting materials themselves have catalytic activity, some confined catalysts materials may form a synergistic effect with them and further promote the activity. For instance, transition metals (Fe, Co, and FeCo alloy)-encapsulated N-CNTs have been prepared (Figure 4a).…”

Interfacial electronic structure engineering on molybdenum sulfide for robust dual-pH hydrogen evolution

“…Researchers recently have designed a wide range of low-cost catalysts, including transition-metal chalcogenides (TMDCs) 15 , 16 , metal nitrides 17 , 18 , metal carbides 19 , 20 , and metal phosphides 21 , 22 . Among these candidates, MoS 2 , a typical layered 2D TMDCs formed by Van der Waals interaction and stacking of S–Mo–S layers, attracts extensive interests with its adjustable bandgap, unique band structure, high energy-conversion efficiency, and earth abundance 23 – 25 . However, the electrocatalytic activity of MoS 2 is closely associated with its surface electric structure 26 – 36 , many researchers have focused on adjusting the electronic structure of the MoS 2 surface to promote electrocatalytic activity, such as surface engineering 26 , doping 27 , single-atom anchoring 28 , phase structure 29 – 33 , interface active site 34 , 35 , and defect 36 .…”

Interface Engineering of Needle‐Like P‐Doped MoS2/CoP Arrays as Highly Active and Durable Bifunctional Electrocatalyst for Overall Water Splitting

“…[38] The lower R ct of P-MoS 2 @CoP/CC is attributed to the formation of the heterostructure with metallic composite, leading to improved charge transfer at the P-MoS 2 @CoP interface, which eventually accelerates OER reaction (Figure 5d). [39] These results demonstrate that, to some extent, the interfacial interactions of P-MoS 2 @CoP/CC between P-MoS 2 and CoP can accelerate the electron transfer and improve the OER catalytic performance. However, the OER stability of the P-MoS 2 @CoP/CC catalyst over a long period showed a slight decrease in catalytic activity at a constant current density of 100 mA cm À 2 for 80 h (Figure S18), which could be due to the partial oxidation of Mo and Co species under robust oxidative environment.…”