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. 2025 Aug 25;16(1):7915.
doi: 10.1038/s41467-025-63317-1.

Maximized atom utilization in a high-entropy metallene via single atom alloying for boosted nitrate electroreduction to ammonia

Yuanbo Zhou #  1   2 , Lifang Zhang #  3 , Mengfan Wang  4 , Xiaowei Shen  3 , Zebin Zhu  1 , Tao Qian  3 , Chenglin Yan  5   6 , Jianmei Lu  7
Affiliations

Maximized atom utilization in a high-entropy metallene via single atom alloying for boosted nitrate electroreduction to ammonia

Yuanbo Zhou et al. Nat Commun. .

Abstract

High-entropy alloys, with their unique structural characteristics and intrinsic properties, have evolved to be one of the most popular catalysts for energy-related applications. However, the geometry of the traditional nanoparticle morphology confines the majority of active atoms to the particle core, deeming them ineffective. In this study, we present a class of two-dimensional high-entropy alloys, namely, high-entropy metallenes, constructed by alloying various single-atom metals in atomically thin layers and reveal their great feasibility for electrocatalytic nitrate reduction to ammonia. Through multimetal interactions, various active centres are formed and sufficiently exposed over the metallene. Each element performs its own duties and jointly lowers the energy barrier of the rate-determining step. As expected, the proof-of-concept PdCuNiCoZn high-entropy metallene delivers satisfactory catalytic performance across wide pH ranges. In particular, in a strongly alkaline electrolyte, a maximum ammonia yield rate of 447 mg h-1 mg-1 and a high Faradaic efficiency of 99.0% are achieved.

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Conflict of interest statement

Competing interests: The authors declare no competing interests.

Figures

Fig. 1
Fig. 1. Physical characterization of the PdCuNiCoZn high-entropy metallene.
a Scanning electron microscopy (SEM), b scanning transmission electron microscopy (STEM), and c high-resolution transmission electron microscopy (HRTEM) images of the PdCuNiCoZn high-entropy metallene. d X-ray diffraction (XRD) patterns of different samples. The abbreviation “arb. units” refers to “arbitrary units”. e, f aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC-HAADF-STEM) images of the PdCuNiCoZn high-entropy metallene. The inset in (f) shows the fast Fourier transformation (FFT) pattern of the PdCuNiCoZn high-entropy metallene.
Fig. 2
Fig. 2. XAS characterization of the PdCuNiCoZn high-entropy metallene.
a–e X-ray absorption near edge structure (XANES) spectra of the K-edges of Pd, Cu, Ni, Co, and Zn in the PdCuNiCoZn high-entropy metallene. f–j FT k3-weighted extended X-ray absorption fine structure (EXAFS) spectra of Pd, Cu, Ni, Co, and Zn in the PdCuNiCoZn high-entropy metallene. k–o Wavelet transform (WT) EXAFS data of Pd, Cu, Ni, Co, and Zn in the PdCuNiCoZn high-entropy metallene. The abbreviation “arb. units” refers to “arbitrary units”.
Fig. 3
Fig. 3. Electrochemical NO3RR performance of the PdCuNiCoZn high-entropy metallene.
a Linear sweep voltammetry (LSV) curves of PdCuNiCoZn high-entropy metallenes in 0.5 M K2SO4 with different concentrations of NO3-. b, c Comparison of mass-normalized NH3 yield rates and corresponding Faradaic efficiencies under different applied potentials in Ar-saturated 0.1 M KNO3 + 0.5 M K2SO4 (pH = 7 ± 0.3) at room temperature of 25 °C with Ar flow rate of 10 sccm. d NH3 Faradaic efficiencies and mass-normalized yield rates at −0.6 V versus RHE of PdCuNiCoZn high-entropy metallenes in 0.5 M K2SO4 with different KNO3 concentrations. e LSV curves of PdCuNiCoZn high-entropy metallene in 0.1 M KNO3 + 1.0 M KOH. f NH3 Faradaic efficiencies and mass-normalized yield rates of PdCuNiCoZn in Ar-saturated 0.1 M KNO3 + 1.0 M KOH (pH = 14 ± 0.2) at room temperature of 25 °C with Ar flow rate of 10 sccm. The error bars correspond to the standard deviations of measurements of three separately prepared samples under the same conditions. g 1H-nuclear magnetic resonance (1H-NMR) spectra of the electrolytes produced from the NO3RR using 14NO3- and 15NO3- as the isotopic NO3- source. h Consecutive recycling test over PdCuNiCoZn high-entropy metallene in 0.1 M KNO3 + 0.5 M K2SO4 at −0.9 V versus RHE. The electrolytic cell resistance was 4.3 ± 0.2 Ω, and all the potentials were not iR-corrected.
Fig. 4
Fig. 4. Analysis of the NO3RR pathway over the PdCuNiCoZn high-entropy metallene.
a In situ Raman spectra of PdCuNiCoZn high-entropy metallenes as a function of time. The abbreviation “arb. units” refers to “arbitrary units”. b In situ attenuated total reflectance surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) spectra of PdCuNiCoZn high-entropy metallenes at different potentials during the NO3RR. c Online differential electrochemical mass spectrometry (DEMS) spectra of PdCuNiCoZn high-entropy metallenes during the NO3RR. The abbreviation “m/z” refers to “mass-to-charge ratio”. The (d) Gibbs free energy diagrams for the NO3RR at different active centres of PdCuNiCoZn high-entropy metallenes. e Gibbs free energy diagrams for the NO3RR on PdCuNiCoZn, PdCu, and Pd. The abbreviation “RDS” refers to “rate-determining step”.
Fig. 5
Fig. 5. Mechanistic investigation of the NO3RR over the PdCuNiCoZn high-entropy metallene.
a Projected density of states (PDOSs) of all the elements in the PdCuNiCoZn high-entropy metallene. The abbreviation “EF” refers to “Fermi level”. b PDOSs for NO3- adsorption on PdCuNiCoZn. c, d PDOSs and d-band centres of PdCuNiCoZn, PdCu, and Pd.
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