Br-Doped Nickel-CobaltPhosphide Nanoarrays on Engineered Porous NF forHigh-Efficiency Water Oxidation

Abstract

Therational design of cost-effective electrocatalysts for the oxygen evolutionreaction (OER) is pivotal for advancinggreen hydrogen production. This study presents a substrate-engineered Br-dopednickel-cobalt phosphide (NiCoP) electrocatalyst fabricated through a stepwisesynthesis protocol. A porous and roughened nickel foam (NF)is initially constructed to provide a 3D conductive scaffold, followed by the hydrothermalgrowth of vertically aligned NiCo-layered double hydroxide (LDH) nanosheets.Subsequent controlled pyrolysis in the presence of a bromine source yieldsBr-doped NiCoP nanoarrays securely anchoredon the NF/Nisubstrate. Comprehensive structuralcharacterization confirms the successful Br incorporation, which induceslattice distortion and optimizes the electronic configuration of NiCoP, whilethe interconnected porous architecture enhances electrolyte infiltration andgas release. Electrochemical evaluations reveal exceptional OER performance,achieving an ultralow overpotential of 220 mVat 10 mA·cm^-2 and a Tafel slope of 61.2 mV·dec^-1 in 1 M KOH, surpassing most reported NiCo-basedphosphides. In-situ Raman spectroscopy and post-OER characterizationuncover dynamic surface reconstruction into Br-enriched (oxy)hydroxide activespecies, elucidating the dual role of Br as both an electronic modulator and astabilizer for reactive intermediates. This work demonstrates asubstrate-guided heteroatom doping strategy to engineer high-performancebimetallic phosphide electrocatalysts, offering insights into interfaceengineering for sustainable energy technologies.

Keywords

Oxygen evolution reaction / Br-doped nickel-cobalt phosphide / In-situ surface reconstruction / Heteroatom modulation / Electrocatalytic mechanism

Supplementary Materials

The following supporting information can be found at: https://www.sciepublish.com/article/pii/963, Figure S1: The physical characterization of NF/Ni. (a) XRD patterns, XPS of NF/Ni (b) survey spectrum and high resolution XPS of (c) Ni 2p and (d) O 1s. Figure S2: SEM images of pristine (a) NF and NF-Ni deposited for (b) 100 s, (c) 200 s, (d) 300 s, (e) 400 s and (f) 500 s. Figure S3: Polarization curves for OER of NF and NF-Ni with different deposition time (100 s, 200 s, 300 s, 400 s and 500 s). Figure S4: The SEM images of NF/NiCo LDH in (a) low magnification and (b) high magnification. Figure S5: The survey XPS spectrum for NF/Ni@Br-NiCoP. Figure S6: The wettability measurements for (a) NF and (b) NF/Ni@Br-NiCoP. Figure S7: The CV and LSV curves of (a,b) NF/Ni@NiCoP NNS and (c,d) NF/Ni@Br-NiCoP. Figure S8: The CV curves in non-faradic region for (a) NF, (b) NF/Ni, (c) NF/Ni@NiCoP and (d) NF/Ni@Br-NiCoP. Figure S9: The ECSA normalized LSV curves. Figure S10: The (a) CV curves and (b) LSV curves for NF/Ni@Br-NiCoP after different CV cycles. Figure S11: The SEM-EDS characterization for NF/Ni@Br-NiCoP post OER test. Figure S12: The XPS characterization for NF/Ni@Br-NiCoP at initial state and post OER test. High resolution XPS spectra for (a) Co 2p, (b) Ni 2p, (c) P 2p and (d) Br 3d. Figure S13: The dynamics reconstruction characterization of NF/Ni@Br-NiCoP under OER process. (a–e) TEM and (HR)TEM and (f) EDS spectra. Figure S14: The LSV curves for NF/Ni@NiCoP and NF/Ni@Br-NiCoP in KOH and TMAOH. Table S1: The concentration of Co, Ni P and Br in the NF/Ni@Br-NiCoP. Table S2: The OER overpotential of catalysts reported recently. Table S3: Comparison of OER stability performance of Br-NiCoP with recently reported catalysts.

Acknowledgments

The authors acknowledge the Researcher Center for Analysis and Measurement, Kunming University of Science and Technology, for providing the necessary materials characterization facilities. We are also grateful to Dr. Enze Zhu for their insightful discussions regarding the electrocatalytic mechanism and their helpful suggestions during the manuscript revision process.

Author Contributions

X.W. and Y.Z.: investigation, conceptualization, data curation, formal analysis, writing—original draft, resources, funding acquisition, validation, and supervision. S.Y. and J.W.: investigation, conceptualization, data curation, validation and review & editing. N.L.: data curation and formal analysis. R.X. and L.Y.: conceptualization and data curation.

Ethics Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The statement is required for all original articles which informs readers about the accessibility of research data linked to a paper and outlines the terms under which the data can be obtained.

Funding

The authors appreciate the financial support from National Natural Science Foundation of China (No. 52574436), The Industrial Innovation Talent Special Project of Yunnan Province’s Xingdian Talent Support Plan (No. yfgrc202417). and the Yunnan Fundamental Research Projects (Grant no. 202301AT070399).

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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