Bimetal Modulation Stabilizing a Metallic Heterostructure for Efficient Overall Water Splitting at Large Current Density

Abstract

Large current‐driven alkaline water splitting for large‐scale hydrogen production generally suffers from the sluggish charge transfer kinetics. Commercial noble‐metal catalysts are unstable in large‐current operation, while most non‐noble metal catalysts can only achieve high activity at low current densities <200 mA cm−2, far lower than industrially‐required current densities (>500 mA cm−2). Herein, a sulfide‐based metallic heterostructure is designed to meet the industrial demand by regulating the electronic structure of phase transition coupling with interfacial defects from Mo and Ni incorporation. The modulation of metallic Mo2S3 and in situ epitaxial growth of bifunctional Ni‐based catalyst to construct metallic heterostructure can facilitate the charge transfer for fast Volmer H and Heyrovsky H2 generation. The Mo2S3@NiMo3S4 electrolyzer requires an ultralow voltage of 1.672 V at a large current density of 1000 mA cm−2, with ≈100% retention over 100 h, outperforming the commercial RuO2||Pt/C, owing to the synergistic effect of the phase and interface electronic modulation. This work sheds light on the design of metallic heterostructure with an optimized interfacial electronic structure and abundant active sites for industrial water splitting.

Recent Development of Self‐Supported Alkaline Hydrogen Evolution Reaction Electrocatalysts for Industrial Electrolyzer

“…A metallic Mo 2 S 3 @NiMo 3 S 4 heterostructure was proposed in Huang's study [ 7 ] to satisfy the industrial demands for HER due to its superior electrical conductivity, sufficient reactive active sites, and excellent structural stability in alkaline medium at large current density. To construct the metallic Mo 2 S 3 @NiMo 3 S 4 heterostructure, the semiconductor MoS 2 was first converted to metallic Mo 2 S 3 by introducing excessive Mo with the appearance of MoMo bonds.…”

“…Reproduced with permission. [ 7 ] Copyright 2022, Wiley‐VCH GmbH. b) Synthesis and characterization of the Ta–TaS 2 MC: the OSPS synthesis process of Ta–TaS 2 MC and corresponding SEM images and HER polarization curves.…”

“…[ 6 ] Raney nickel and the alloys are the common electrocatalysts for the industrial alkaline HER due to their acceptable activity, low cost, large surface area, and good stability. However, although Raney nickel operates well at a high current density of 500–1000 mA cm −2 , it needs large overpotentials of ≈300–500 mV at 500 mA cm −2 and requires a cell voltage of 2.4 V for overall water splitting, which considerably exceeds the thermodynamic voltage of 1.23 V. [ 7 ] Thus, innovative strategies to develop high‐efficiency, low‐cost, and durable electrocatalysts are crucial for reducing capital expenditure and electricity consumption for the industrial alkaline HER. Recently, plenty of nonprecious metal‐based electrocatalysts have been developed for alkaline HER, which show excellent HER performance at small current densities, but mostly experience severe degradation at large current densities (>1000 mA cm −2 ).…”

“…a) Design and characterizations for Mo 2 S 3 @NiMo 3 S 4 heterostructure: Schematic illustration of the epitaxial construction of Mo 2 S 3 @NiMo 3 S 4 , energy band diagrams of Mo 2 S 3 and NiMo 3 S 4 , TEM image, and HER polarization curves of Mo 2 S 3 @NiMo 3 S 4 heterostructure. Reproduced with permission [7]. Copyright 2022, Wiley-VCH GmbH.…”

The Synergistic Activation of Ce‐Doping and CoP/Ni3P Hybrid Interaction for Efficient Water Splitting at Large‐Current‐Density

“…For the improvements of intermediate ad-/desorption, electronic structure engineering is imperatively introduced into activating the electronic states of the catalyst to reduce energy barriers and strengthen structural stability. [15] For example, the regulation of electronic interface states of Ni 3 N@2M-MoS 2 heterostructure, [16] the d-band center displacements of the Ru-Mo 2 N hybrid structure, [17] CePO 4 /MoP hybrid structure, [18] and Fe-doping in Ni 5 P 4 /NiFeOH [19] have effectively optimized intermediate ad-/desorption to reduce HER overpotential. Particularly, owing to the empty or half-filled 4f electron properties and oxygen affinity, [20] rare earth elements such as Ce and corresponding CeO 2 as activators to modify the electronic structure of electrocatalysts showed excellent prospects.…”