Abstract
Polyoxometalates (POMs) are promising catalysts for the electrochemical hydrogen production from water owing to their high intrinsic catalytic activity and chemical tunability. However, poor electrical conductivity and easy detachment of the POMs from the electrode cause significant challenges under operating condition. Herein, a simple one‐step hydrothermal method is reported to synthesize a series of Dexter–Silverton POM/Ni foam composites (denoted as NiM‐POM/Ni; M=Co, Zn, Mn), in which the stable linkage between the POM catalysts and the Ni foam electrodes lead to high activity for the hydrogen evolution reaction (HER). Among them, the highest HER performance can be observed in the NiCo‐POM/Ni, featuring an overpotential of 64 mV (at 10 mA cm−2, vs. reversible hydrogen electrode), and a Tafel slope of 75 mV dec−1 in 1.0 m aqueous KOH. Moreover, the NiCo‐POM/Ni catalyst showed a high faradaic efficiency ≈97 % for HER. Post‐catalytic of NiCo‐POM/Ni analyses showed virtually no mechanical or chemical degradation. The findings propose a facile and inexpensive method to design stable and effective POM‐based catalysts for HER in alkaline water electrolysis.
Highlights
Hydrogen is an attractive sustainable energy carrier to address the challenges related with fossil fuel.[1,2] One of the most promising routes to generate hydrogen is electrochemical water splitting
A series of NiM-POM clusters were successfully fabricated on the porous Ni foam by hydrothermal methods
The NiCo-POM/Ni exhibited the best performance with low overpotential of 64 mV together with Tafel slope of 75 mV decÀ1 at 10 mA cmÀ2
Summary
Development of electrocatalysts to overcome the high energy barriers and slow kinetics of HER reaction in alkaline solution. Zhang et al presented the P8W48/rGO nanomaterial as an efficient electrocatalyst for the HER in acidic aqueous solution.[27] Ma et al synthesized two POM-encapsulated twenty-nuclear silver-tetrazole nanocage frameworks, which exhibited high activity for HER in 0.5 m H2SO4 aqueous solution.[28] In contrast, few studies can be found on POM-based electrocatalysts for HER in alkaline media. Under such circumstances, development of highly active and stable electrocatalysts for HER at high pH by technologically viable and scalable synthetic routes remains highly challenging. Mechanistic studies indicate that the stable electrical “wiring” between electrocatalyst and electrode, together with a high number of accessible reaction sites lead to excellent HER performance comparable with commercial Pt/C catalysts under alkaline condition.[29,30,31]
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