Shuo Wang,Yong Yan,Yongping Du,Yuguo Zhao,Tongxian Li,Dong Wang,Peter Schaaf,Xiayan Wang
Recently, Ni-based chalcogenides havedemonstrated remarkable activity and selectivity for alcohol electrooxidation, but the mechanisms remain debated. This study synthesizes Ni-based electrodeswith different chalcogen anion coordination on nickel nanorod arrays (NiO x /Ni,NiS x /Ni, and NiSe x /Ni NRAs). NiSe x /Ni NRAsshowcases superior performance (Faradaic efficiency 92.9%) in glycerolelectrooxidation reaction (GOR). In situ spectroscopy reveals that NiSecoordination inhibits deep oxidative reconstruction of the Ni-based interface, preventingNiOOH phase formation during GOR, enhancing activity and stability of NiSe x /NiNRAs. Conversely, NiS and NiO coordination lead to deep reconstruction with NiOOHphase formation, limiting GOR performance. Differently, during competingreaction of GOR, the oxygen evolution reaction (OER) leads to deepreconstruction of NiSex interface due to the instability of Ni-Sebonds, inducing performance degradation and dissolution of Se components. Furthermechanism investigation elucidates that the rate-determining step (RDS) ofGOR at the NiSe x interface involves oxidation of *C 2 H 3 O 3 intermediatesthrough H 2 O adsorption, favoring stable formate production.Contrarily, the RDS at the NiS x , NiO x , and NiOOHinterfaces predominantly focus on the decarboxylation of multi-carbon intermediates, raisingenergy barriers and over-oxidizing formate to CO 2 . These results providenew insights for designing Ni-based non-oxide catalysts forefficient and stable electrocatalytic oxidation.
Electrochemical water splitting for hydrogen production is currently constrained by the sluggish kinetics of the anodic oxygen evolution reaction (OER). NiFe-based catalysts have emerged as promising alternatives to precious metal OER catalysts due to their low cost and relatively high electrocatalytic activity. However, NiFe-based catalysts prepared by conventional synthesis methods suffer from a low density of exposed active sites and ambiguous structures. Herein, we report a straightforward solution-thermal strategy for constructing two-dimensional sub-1 nm nanosheets (SNSs) through the self-assembly of an iron-substituted polyoxometalate (FeMo 6 ) cluster with Ni 3 S 2 . The Ni 3 S 2 –FeMo 6 SNSs exhibit excellent electrocatalytic performance in 1 M KOH, achieving an overpotential of only 342 mV at a current density of 100 mA cm −2 and maintaining stability for 100 h at 10 mA cm −2 . The synergistic effect between Fe and Ni 3 S 2 effectively modulates the electronic structure of the catalyst, accelerating the formation of the active NiOOH phase. Furthermore, Fe incorporation actively enhances hydroxyl groups adsorption on the catalyst surface and facilitates lattice oxygen participation in the reaction. This work clarifies the role of Fe in NiFe-based electrocatalysts, providing new perspectives for developing facile-to-synthesize and high-performance electrocatalysts.
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