Gd Sparks Lattice Oxygen Boost in Water Electrolysis

Producing clean hydrogen energy usually involves the oxygen evolution reaction (OER), which has the unfortunate drawback of being sluggish and inefficient. Catalysts can fast-track this process, but it is no easy task finding the ideal candidate for the job. However, researchers at Tohoku University found that incorporating gadolinium (Gd) into iron (Fe)-doped nickel oxide (NiO) markedly enhances OER activity. In addition, this catalyst is naturally abundant, relatively inexpensive, nontoxic, and stable.

Density functional theory (DFT) calculations were used to provide an in-depth analysis of the reaction mechanisms. They found that Gd-doping improves performance by opening up oxygen vacancies that facilitate the lattice oxygen oxidation mechanism.

Theoretical calculations of Gd-NiFe oxide. a) pH dependence of the OER activities of NiFe oxide. Calculated b) 1D and c) 2D surface Pourbaix diagrams for the NiO (100) surface as a function of potential (pH = 14; T = 298.15 K) (The surface structure contains 9 metal atoms, and 1/9 to 1 ML represent the adsorption of 1 to 9 HO* or O* species on the surface, respectively.). d) Optimized structures for Gd-NiFe and NiFe oxides. e) Projected density of states of Gd-NiFe and NiFe oxides (EF: Fermi level; ɛO-2p: O 2p band center). f) Schematic band diagrams (UHB: upper Hubbard band; LHB: lower Hubbard band) of Gd-NiFe and NiFe oxides. g) Schematic diagram of the oxygen vacancy formation process. (The black circles indicate the oxygen vacancy positions.) h) Oxygen vacancy formation energy of Gd-NiFe and NiFe. i) Bader charge of Gd-NiFe and NiFe. ©Yong Wang et al.

Gd-doping reduces the theoretical overpotentials for the Fe and Ni sites, which improves performance. The overpotential was 40mV lower than Fe-doped NiO (without Gd). It also demonstrates favourable kinematics (Tafel slope: 43.1 mV dec^-1). In addition, Gd and Fe co-doped NiO exhibits remarkable long-term stability exceeding 150 hours and robust performance in an anion exchange membrane water electrolysis system, operating continuously for over 120 hours.

"This research plays a crucial role in advancing green energy solutions by improving water electrolysis, a key technology for producing green hydrogen from renewable sources like wind and solar power," says Hao Li, associate professor at Tohoku University's Advanced Institute for Materials Research (WPI-AIMR).

Green hydrogen is essential for clean energy systems, with applications in fuel cell vehicles, industrial processes, and other energy-intensive sectors. By enhancing electrolysis efficiency, this study supports large-scale hydrogen production - thus reducing our reliance on fossil fuels and lowering greenhouse gas emissions.

Morphological and structural characterization of Gd, Fe-NiO. a) XRD patterns of Gd, Fe-NiO, and Fe-NiO. bc) Brightfield TEM and HRTEM images of Gd, Fe-NiO. d) EDS maps of Gd, Fe-NiO. e) Ni 2p f), Fe 2p, and g) O 1s h) XPS spectra of Gd, Fe-NiO and Fe-NiO. ©Yong Wang et al.

"We plan to scale up the synthesis process to ensure consistent production for industrial applications, and conduct extended stability tests under realistic conditions," says Li.

Key experimental data and computational structures from this study are available in the Digital Catalysis Platform (DigCat), the largest catalysis database developed by the Hao Li Lab.

The findings were published in Advanced Functional Materials on February 26, 2025. The article processing charge (APC) was supported by the Tohoku University Support Program.

Electrocatalysis OER of Gd, Fe-NiO in 1 m KOH. a) iR-corrected LSV curves of Gd, Fe-NiO, Fe-NiO, NiO, and commercial IrO2 catalysts in 1 m KOH. b) Overpotentials required for j = 10 mA cm-2 of different catalysts. c) Tafel plots of different catalysts. d) 𝜂10 comparisons of Gd, Fe-NiO, and state-of-the-art transition metal oxide OER catalysts in an alkaline electrolyte (data source: the DigCat database: https://www.digcat.org/). e) iRcorrected LSV curves of Gd, Fe-NiO, Fe-NiO, NiO normalized against BET. f) 𝜂0.1 values of Gd, Fe-NiO, Fe-NiO, NiO normalized against their BET values. g) Chronopotentiometry curves of Gd, Fe-NiO at a current density of 10 mA cm^-2. ©Di Zhang et al.

Publication Details:

Title: Gd-Induced Oxygen Vacancy Creation Activates Lattice Oxygen Oxidation for Water Electrolysis
Authors: Yong Wang, Yadong Liu, Sijia Liu, Yunpu Qin, Jianfang Liu, Xue Jia, Qiuling Jiang, Xuan Wang, Yongzhi Zhao, Luan Liu, Hongru Liu, Hong Zhao, Yirui Jiang, Dong Liang, Haoyang Wu, Baorui Jia, Xuanhui Qu, Hao Li, and Mingli Qin
Journal: Advanced Functional Materials
DOI: 10.1002/adfm.202500118

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