International Energy Agency. World Energy Outlook 2024 (International Energy Agency, 2024).
Zeng, K. & Zhang, D. Recent progress in alkaline water electrolysis for hydrogen production and applications. Prog. Energy Combust. Sci. 36, 307–326 (2010).
Ullah, N. et al. In situ growth of M-MO (M = Ni, Co) in 3D graphene as a competent bifunctional electrocatalyst for OER and HER. Electrochim. Acta 298, 163–171 (2019).
Siwal, S. S., Yang, W. & Zhang, Q. Recent progress of precious-metal-free electrocatalysts for efficient water oxidation in acidic media. J. Energy Chem. 51, 113–133 (2020).
Xie, X. et al. Oxygen evolution reaction in alkaline environment: material challenges and solutions. Adv. Funct. Mater. 32, 2110036 (2022).
Sebbahi, S. et al. Assessment of the three most developed water electrolysis technologies: alkaline water electrolysis, proton exchange membrane and solid-oxide electrolysis. Mater. Today Proc. 66, 140–145 (2022).
Zhang, K. & Zou, R. Advanced transition metal-based OER electrocatalysts: current status, opportunities, and challenges. Small 17, e2100129 (2021).
Song, J. et al. A review on fundamentals for designing oxygen evolution electrocatalysts. Chem. Soc. Rev. 49, 2196–2214 (2020).
Naguib, M. et al. Two-dimensional nanocrystals produced by exfoliation of Ti3AlC2. Adv. Mater 23, 4248–4253 (2011).
Mohammadi, A. V., Rosen, J. & Gogotsi, Y. The world of two-dimensional carbides and nitrides (MXenes). Science 372, 1979 (2021).
Anne, B. R. et al. A review on MXene as promising support materials for oxygen evolution reaction catalysts. Adv. Funct. Mater. 33, 2306100 (2023).
Tsounis, C. et al. Advancing MXene electrocatalysts for energy conversion reactions: surface, stoichiometry, and stability. Angew. Chem. Int. Ed. 62, e202210828 (2023).
Tyndall, D. et al. Understanding the effect of MXene in a TMO/MXene hybrid catalyst for the oxygen evolution reaction. NPJ 2D Mater. Appl. 7, 15 (2023).
Browne, M. P., Tyndall, D. & Nicolosi, V. The potential of MXene materials as a component in the catalyst layer for the oxygen evolution reaction. Curr. Opin. Electrochem. 34, 101021 (2022).
Yu, M., Zhou, S., Wang, Z., Zhao, J. & Qiu, J. Boosting electrocatalytic oxygen evolution by synergistically coupling layered double hydroxide with MXene. Nano Energy 44, 181–190 (2018).
Benchakar, M. et al. MXene supported cobalt layered double hydroxide nanocrystals: facile synthesis route for a synergistic oxygen evolution reaction electrocatalyst. Adv. Mater. Interfaces 6, 1901328 (2019).
Ghidiu, M., Lukatskaya, M. R., Zhao, M. Q., Gogotsi, Y. & Barsoum, M. W. Conductive two-dimensional titanium carbide ‘clay’ with high volumetric capacitance. Nature 516, 78–81 (2014).
Alhabeb, M. et al. Guidelines for synthesis and processing of two-dimensional titanium carbide (Ti3C2Tx MXene). Chem. Mater 29, 7633–7644 (2017).
Chen, J. et al. Vertically-interlaced NiFeP/MXene electrocatalyst with tunable electronic structure for high-efficiency oxygen evolution reaction. Sci. Bull. 66, 1063–1072 (2021).
Schmiedecke, B. et al. Enhancing the oxygen evolution reaction activity of CuCo based hydroxides with V2CTx MXene. J. Mater. Chem. A Mater. (2024).
Vazhayil, A. et al. NiCo2O4/MXene hybrid as an efficient bifunctional electrocatalyst for oxygen evolution and reduction reaction. ChemCatChem 16, e202301250 (2024).
Li, Y. et al. A general Lewis acidic etching route for preparing MXenes with enhanced electrochemical performance in non-aqueous electrolyte. Nat. Mater. 19, 894–899 (2020).
Li, M. et al. Element replacement approach by reaction with Lewis acidic molten salts to synthesize nanolaminated MAX phases and MXenes. J. Am. Chem. Soc. 141, 4730–4737 (2019).
Wang, Y. et al. Simple one-step molten salt method for synthesizing highly efficient MXene-supported Pt nanoalloy electrocatalysts. Adv. Sci. 10, 2303693 (2023).
Luo, R. et al. Facile synthesis of cobalt modified 2D titanium carbide with enhanced hydrogen evolution performance in alkaline media. Int. J. Hydrog. Energy 46, 32536–32545 (2021).
Jiang, J. et al. Strategic design and fabrication of MXenes-Ti3CNCl2@CoS2 core-shell nanostructure for high-efficiency hydrogen evolution. Nano Res. 15, 5977–5986 (2022).
Zhang, Z. et al. Synergistically coupling CoS/FeS2 heterojunction nanosheets on a MXene via a dual molten salt etching strategy for efficient oxygen evolution reaction. J. Mater. Chem. A Mater. 12, 14517–14530 (2024).
Kruger, D. D. et al. Influence of surface terminal groups on the efficiency of two-electron oxygen reduction reaction catalyzed by iron single atoms on Ti3C2Tx (T = Cl, Br, NH) MXene. J. Mater. Chem. A Mater. 12, 25291–25303 (2024).
Cui, Z. et al. Molten salts etching strategy construct alloy/MXene heterostructures for efficient ammonia synthesis and energy supply via Zn-nitrite battery. Appl. Catal. B 348, 123862 (2024).
Wang, Y. et al. Controlled etching to immobilize highly dispersed Fe in MXene for electrochemical ammonia production. Carbon Neutraliz. 1, 117–125 (2022).
Zhao, Q. et al. Selective etching quaternary MAX phase toward single atom copper immobilized MXene (Ti3C2Clx) for efficient CO2 electroreduction to methanol. ACS Nano 15, 4927–4936 (2021).
Kruger, D. D., García, H. & Primo, A. Molten salt derived mxenes: synthesis and applications. Adv. Sci. 11, 2307106 (2024).
Zhang, Z., Ji, Y., Jiang, Q. & Xia, C. Molten-salt synthesized MXene for catalytic applications: a review. Chem. Phys. Rev. 5, 031311 (2024).
Wang, F. et al. Advances in molten-salt-assisted synthesis of 2D MXenes and their applications in electrochemical energy storage and conversion. Chem. Eng. J. 470, 144185 (2023).
Wu, Z. et al. One-step in-situ synthesis of Sn-nanoconfined Ti3C2Tx MXene composites for Li-ion battery anode. Electrochim. Acta 407, 139916 (2022).
Chen, X. et al. Enhanced sodium storage in MXene transition metal chalcogenides anode through dual molten salt etching. Electrochim. Acta 509, 145334 (2025).
Song, H. et al. Anchoring single atom cobalt on two-dimensional MXene for activation of peroxymonosulfate. Appl. Catal. B 286, 119898 (2021).
Bai, Y. et al. MXene-copper/cobalt hybrids via Lewis acidic molten salts etching for high performance symmetric supercapacitors. Angew. Chem. Int. Ed. 60, 25318–25322 (2021).
Wierzba, B., Nowak, W. J. & Serafin, D. The interface reaction between titanium and iron-nickel alloys. High. Temp. Mater. Process. 37, 683–691 (2018).
Cacciamani, G. et al. Critical evaluation of the Fe-Ni, Fe-Ti and Fe-Ni-Ti alloy systems. Intermetallics 14, 1312–1325 (2006).
Raimundo, R. A. et al. NiFe alloy nanoparticles tuning the structure, magnetism, and application for oxygen evolution reaction catalysis. Magnetochemistry 9, 201 (2023).
Kim, S. M. et al. Cooperativity and dynamics increase the performance of NiFe dry reforming catalysts. J. Am. Chem. Soc. 139, 1937–1949 (2017).
Sahoo, A., Medicherla, V. R. R., Vijay, K. & Banik, S. Resonant photoemission studies on Fe-Ni alloys. J. Alloys Compd. 994, 174544 (2024).
Seto, Y. & Ohtsuka, M. ReciPro: free and open-source multipurpose crystallographic software integrating a crystal model database and viewer, diffraction and microscopy simulators, and diffraction data analysis tools. J. Appl. Crystallogr. 55, 397–410 (2022).
Biesinger, M. C., Payne, B. P., Lau, L. W. M., Gerson, A. & Smart, R. S. C. X-ray photoelectron spectroscopic chemical state Quantification of mixed nickel metal, oxide and hydroxide systems. Surf. Interface Anal. 41, 324–332 (2009).
Guillot, J. et al. Quantification of a Ti(CxN1-x) based multilayer by Auger electron spectroscopy. Appl. Surf. Sci. 256, 773–778 (2009).
Biesinger, M. C. et al. Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Cr, Mn, Fe, Co and Ni. Appl. Surf. Sci. 257, 2717–2730 (2011).
Halim, J. et al. X-ray photoelectron spectroscopy of select multi-layered transition metal carbides (MXenes). Appl. Surf. Sci. 362, 406–417 (2016).
Naslund, L. Å., Persson, P. O. Å. & Rosen, J. X-ray photoelectron spectroscopy of Ti3AlC2, Ti3C2Tz, and TiC provides evidence for the electrostatic interaction between laminated layers in max-phase materials. J. Phys. Chem. C 124 27732–27742 (2020).
Frenkel, A. I. Applications of extended X-ray absorption fine-structure spectroscopy to studies of bimetallic nanoparticle catalysts. Chem. Soc. Rev. 41, 8163–8178 (2012).
Mirehbar, S. et al. Evidence of cathodic peroxydisulfate activation via electrochemical reduction at Fe(II) sites of magnetite-decorated porous carbon: application to dye degradation in water. J. Electroanal. Chem. 902, 115807 (2021).
Roberts, J. J. P., Westgard, J. A., Cooper, L. M. & Murray, R. W. Solution voltammetry of 4 nm magnetite iron oxide nanoparticles. J. Am. Chem. Soc. 136, 10783–10789 (2014).
Dionigi, F. et al. In-situ structure and catalytic mechanism of NiFe and CoFe layered double hydroxides during oxygen evolution. Nat. Commun. 11, 2522 (2020).
Xiang, W. et al. Unveiling surface species formed on Ni-Fe spinel oxides during the oxygen evolution reaction at the atomic scale. Adv. Sci. 12, 2501967 (2025).
Rao, R. R. et al. Unraveling the role of particle size and nanostructuring on the oxygen evolution activity of Fe-doped NiO. ACS Catal. 14, 11389–11399 (2024).
Flores, G. et al. Understanding the impact of M-OH activation on oxygen evolution in Hofmann-type 2D coordination polymers: insights from experiments and theory. Int. J. Hydrog. Energy 157, 150385 (2025).
Klaus, S., Louie, M. W., Trotochaud, L. & Bell, A. T. Role of catalyst preparation on the electrocatalytic activity of Ni1-xFexOOH for the oxygen evolution reaction. J. Phys. Chem. C 119, 18303–18316 (2015).
Doyle, R. L. & Lyons, M. E. G. An electrochemical impedance study of the oxygen evolution reaction at hydrous iron oxide in base. Phys. Chem. Chem. Phys. 15, 5224–5237 (2013).
Zheng, W. iR compensation for electrocatalysis studies: considerations and recommendations. ACS Energy Lett. 8, 1952–1958 (2023).
Tahir, M. et al. Electrocatalytic oxygen evolution reaction for energy conversion and storage: a comprehensive review. Nano Energy 37, 136–157 (2017).
Trze¨sniewski, B. J. et al. In situ observation of active oxygen species in Fe-containing Ni-based oxygen evolution catalysts: the effect of pH on electrochemical activity. J. Am. Chem. Soc. 137, 15112–15121 (2015).
Trotochaud, L., Young, S. L., Ranney, J. K. & Boettcher, S. W. Nickel-iron oxyhydroxide oxygen-evolution electrocatalysts: the role of intentional and incidental iron incorporation. J. Am. Chem. Soc. 136, 6744-6753 (2014).
Schönleber, M., Klotz, D. & Ivers-Tiffée, E. A method for improving the robustness of linear Kramers-Kronig validity tests. Electrochim. Acta 131, 20–27 (2014).
Murbach, M. D., Gerwe, B., Dawson-Elli, N. & Tsui, L. impedance.py: a Python package for electrochemical impedance analysis. J. Open Source Softw. 5, 2349 (2020).
Bisquert, J. & Balaguera, E. H. Brief guide to transformation of constant phase element impedance to equivalent capacitor or inductor. J. Phys. Chem. Lett. 16, 5779–5783 (2025).
Brug, G. J., van den Eeden, A. L. G., Sluyters-Rehbach, M. & Sluyters, J. H. The analysis of electrode impedances complicated by the presence of a constant phase element. J. Electroanal. Chem. Interfacial Electrochem. 176, 275–295 (1984).
Tyndall, D. et al. Demonstrating the source of inherent instability in NiFe LDH-based OER electrocatalysts. J. Mater. Chem. A Mater. 11, 4067–4077 (2023).
Hu, C. et al. Surface-enhanced Raman spectroscopic evidence of key intermediate species and role of NiFe dual-catalytic center in water oxidation. Angew. Chem. Int. Ed. 60, 19774–19778 (2021).
Hedenstedt, K., Bäckström, J. & Ahlberg, E. In-situ Raman spectroscopy of α- and γ-FeOOH during cathodic load. J. Electrochem. Soc. 164, H621–H627 (2017).
Nakamoto, K. Infrared and Raman Spectra of Inorganic and Coordination Compounds: Part B: Applications in Coordination, Organometallic, and Bioinorganic Chemistry 161–183 (John Wiley and Sons, 2008).
Shi, Z. et al. Oxidation of Fe-Ni alloys in air at 700°C, 800°C and 950°C. High. Temp. Mater. Process. 31, 89–96 (2012).
Zhu, K., Zhu, X. & Yang, W. Application of in situ techniques for the characterization of NiFe-based oxygen evolution reaction (OER) electrocatalysts. Angew. Chem. Int. Ed. 58, 1252–1265 (2019).
Avcl, ÖN., Sementa, L. & Fortunelli, A. Mechanisms of the oxygen evolution reaction on NiFe2O4 and CoFe2O4 inverse-spinel oxides. ACS Catal. 12, 9058–9073 (2022).
Ravel, B. & Newville, M. ATHENA, ARTEMIS, HEPHAESTUS: data analysis for X-ray absorption spectroscopy using IFEFFIT. J. Synchrotron Radiat. 12, 537–541 (2005).
Zabinsky, S. I., Rehr, J. J., Ankudinov, A., Albers, R. C. & Eller, M. J. Multiple-scattering calculations of x-ray-absorption spectra. Phys. Rev. B 52, 2995 (1994).
Kresse, G. & Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169 (1996).
Kresse, G. & Furthmüller, J. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comput. Mater. Sci. 6, 15–50 (1996).
Kresse, G. & Hafner, J. Ab initio molecular-dynamics simulation of the liquid-metal–amorphous-semiconductor transition in germanium. Phys. Rev. B 49, 14251 (1994).
Kresse, G. & Hafner, J. Ab initio molecular dynamics for liquid metals. Phys. Rev. B 47, 558 (1993).
Kresse, G. & Joubert, D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B 59, 1758 (1999).
Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865 (1996).
Dudarev, S. L., Botton, G. A., Savrasov, S. Y., Humphreys, C. J. & Sutton, A. P. Electron-energy-loss spectra and the structural stability of nickel oxide: an LSDA+U study. Phys. Rev. B 57, 1505 (1998).
Grimme, S., Antony, J., Ehrlich, S. & Krieg, H. A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu. J. Chem. Phys. 132 (2010).
Grimme, S., Ehrlich, S. & Goerigk, L. Effect of the damping function in dispersion corrected density functional theory. J. Comput. Chem. 32, 1456–1465 (2011).
Ong, S. P. et al. Python materials genomics (pymatgen): a robust, open-source python library for materials analysis. Comput. Mater. Sci. 68, 314–319 (2013).
Momma, K. & Izumi, F. VESTA3 for three-dimensional visualization of crystal, volumetric and morphology data. J. Appl. Crystallogr. 44, 1272–1276 (2011).
Cheng, R. et al. Understanding the lithium storage mechanism of Ti3C2Tx MXene. J. Phys. Chem. C 123, 1099–1109 (2018).
Kazemi, S. A. et al. Halogenation effect on physicochemical properties of Ti3C2 MXenes. J. Phys. Mater. 6, 035004 (2023).
Jain, A. et al. Commentary: The materials project: a materials genome approach to accelerating materials innovation. APL Mater. 1, 011002 (2013).
Zur, A. & McGill, T. C. Lattice match: an application to heteroepitaxy. J. Appl. Phys. 55, 378–386 (1984).
Kawashima, K. et al. Accurate potentials of Hg/HgO electrodes: practical parameters for reporting alkaline water electrolysis overpotentials. ACS Catal. 13, 1893–1898 (2023).
McCrory, C. C. L., Jung, S., Peters, J. C. & Jaramillo, T. F. Benchmarking heterogeneous electrocatalysts for the oxygen evolution reaction. J. Am. Chem. Soc. 135, 16977–16987 (2013).
