Pulse electrodeposited NiMoZn alloy hydrophobicized with PTFE for high performance alkaline water electrolysis
Green hydrogen production by alkaline water electrolysis is an important technology in the decarbonization of the current industry. However, its large-scale application is limited by mediocre performance of conventional Raney Ni electrocatalysts. Herein, high-performance NiMoZn alloy catalysts of the Raney Ni type are developed by pulse electrodeposition for the hydrogen evolution reaction (HER). The optimized catalyst, NMZ-CA, exhibits an overpotential of 37 mV at 10 mA⋅cm −2 and a Tafel slope of 27 mV⋅dec −1 in 1 mol·L –1 KOH. Tafel slope measurements, X-ray photoelectron spectroscopy, and H 2 temperature-programmed desorption experiments show that the incorporation of Mo and Zn in Ni weakens the binding of HER intermediate (H ads ) on strongly adsorbing sites, leading to improved electrochemical kinetics. Electron microscopy and X-ray diffraction study reveals that a phase-pure Mo-doped Ni 2 Zn 11 intermetallic precatalyst formed via pulse electrodeposition and subsequent heat treatment is key to the structure integrity and performance of the catalyst after activation by alkaline leaching. Modification of NMZ-CA with PTFE enhances its HER performance by facilitating gas removal and improving structure integrity. A practical alkaline water electrolyzer built on the modified NMZ/PTFE-CA electrode delivers 2.0 A⋅cm −2 at 1.92 V cell voltage and operates for 250 h without decay. This work provides insights into the synergy between Ni, Mo, and Zn in Raney Ni-type catalysts, and demonstrates the hydrophobic modification as an effective strategy for electrode development in high-performance alkaline water electrolysis.
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