Enhancing the d–Electrocatalytic Activity of MXene Through Defect Engineering

Abstract

Due to their versatile and tunable surface and bulk chemistry, MXenes have great potential as electrocatalysts for batteries and supercapacitors. When compared with other electrocatalytic processes, in electrocatalytic reactions, MXenes could improve ion diffusion and charge transfer by either providing functional groups binding to the surface metals to block the diffusion path or offering additional adsorption sites for metal cations or intermediate products on the material surface, so the electrocatalytic activity of MXenes should be sensitive to the surface configuration. Very recently, researchers revealed that introducing defects and strictly tuning the electronic property of the MXene surface could greatly improve its electrocatalytic efficiency; however, the exact mechanism by which defects could improve the electrocatalytic properties of MXenes was still unclear. In this study, authors classify surface defects in MXene, discuss the formation mechanism of each kind of defect, and demonstrate the application of atomic-level characterization tools to track the evolution of defects. Furthermore, based on the defect mechanics principles, we propose a rational design approach for MXene surface structures. Additionally, this paper discusses the development and application of defect structures in electrocatalytic efficiency improvement. Based on the analysis of the challenges existing in the MXene electrocatalysis, a future research direction is proposed. In this review, we establish a conceptual framework for MXene applications in electrocatalysis. This study advances the development of MXene materials in energy systems, provides the defect design strategies for researchers in further investigation on MXenes, and offers the emerging trends in this field.

Keywords

atomic-resolution characterization / defect engineering / electronic characteristics / MXenes electrocatalysts / surface configuration

References

[1] Y. Zhang, J. Liu, Y. Xu, C. Xie, S. Wang, and X. Yao, “Design and Regulation of Defective Electrocatalysts,” Chemical Society Reviews 53, no. 53 (2024): 10620–10659.

[2] H. Liu, R. Xiong, S. Ma, et al., “Recent Advances in Noble-Metal-Free Bifunctional Oxygen Electrode Catalysts,” Energy Advances 4, no. 4 (2025): 55–83.

[3] M. Jian and Y. Wang, “Construction of MXenes/COFs Heterojunctions for Photo/Electrocatalytic Applications: Opportunities and Challenges,” Chemical Engineering Journal 507, no. 507 (2025): 160631.

[4] L. He, H. Zhuang, Q. Fan, et al., “Advances and Challenges in Mxene-Based Electrocatalysts: Unlocking the Potential for Sustainable Energy Conversion,” Materials Horizons 11, no. 11 (2024): 4239–4255.

[5] Y. Jia, K. Jiang, H. Wang, and X. Yao, “The Role of Defect Sites In Nanomaterials for Electrocatalytic Energy Conversion,” Chem 5, no. 5 (2019): 1371–1397.

[6] M. Naguib, M. Kurtoglu, V. Presser, et al., “Two-Dimensional Nanocrystals Produced by Exfoliation of Ti₃AlC₂,” Advanced Materials 37, no. 23 (2023): 4248–4253.

[7] M. Yi, S. Hu, N. Li, H. Wang, and J. Zhang, “Selenium Vacancy-Rich and Heteroatom-Doped CoSe/Mo₂CT MXene Prepared Using Ionic Liquid Dopants for pH-Universal Hydrogen Evolution and Flexible Supercapacitors,” Journal of Energy Chemistry 72 (2022): 453–464.

[8] Z. Ma, T. Wan, D. Zhang, et al., “Atomically Dispersed Cu Catalysts on Sulfide-Derived Defective Ag Nanowires for Electrochemical CO₂ Reduction,” ACS Nano 17, no. 17 (2023): 2387–2398.

[9] L. Shi, J. Chen, S. Zhao, L. Du, and S. Ye, “Proton-Exchange Membrane Water Electrolysis: From Fundamental Study to Industrial Application,” Chem Catalysis 3, no. 3 (2023): 100734.

[10] W. Bao, C. E. Shuck, W. Zhang, X. Guo, Y. Gogotsi, and G. Wang, “Boosting Performance of Na–S Batteries Using Sulfur-Doped Ti₃C₂T_X MXene Nanosheets With a Strong Affinity to Sodium Polysulfides,” ACS Nano 13, no. 13 (2019): 11500–11509.

[11] G. Jiang, N. Zheng, X. Chen, et al., “In-Situ Decoration of MOF-Derived Carbon on Nitrogen-Doped Ultrathin MXene Nanosheets to Multifunctionalize Separators for Stable Li-S Batteries,” Chemical Engineering Journal 373, no. 373 (2019): 1309–1318.

[12] X. Zhou, Y. Cui, X. Huang, X. Wu, H. Sun, and S. Tang, “Dual-Defect Engineering of Bidirectional Catalyst for High-Performing Lithium-Sulfur Batteries,” Small 19, no. 19 (2023): 2301545.

[13] S. Hao, H. Sheng, M. Liu, et al., “Torsion Strained Iridium Oxide for Efficient Acidic Water Oxidation in Proton Exchange Membrane Electrolyzers,” Nature Nanotechnology 16, no. 16 (2021): 1371–1377.

[14] Y. Song, Z. Sun, Z. Fan, et al., “Rational Design of Porous Nitrogen-Doped Ti₃C₂ Mxene as a Multifunctional Electrocatalyst for Li–S Chemistry,” Nano Energy 70 (2020): 104555.

[15] X. Zuo, Y. Qiu, M. Zhen, D. Liu, and Y. Zhang, “Review on Mxenes-Based Electrocatalysts for High-Energy-Density Lithium-Sulfur Batteries,” Nano-Micro Letters 17, no. 17 (2025): 209.

[16] T. A. Le, Q. V. Bui, N. Q. Tran, et al., “Synergistic Effects of Nitrogen Doping on MXene for Enhancement of Hydrogen Evolution Reaction,” ACS Sustainable Chemistry & Engineering 19, no. 7 (2019): 16879–16888.

[17] J. Wang, Z. Zhang, X. Yan, et al., “Rational Design of Porous N–Ti₃C₂ MXene@CNT Microspheres for High Cycling Stability in Li–S Battery,” Nano-Micro Letters 12, no. 12 (2020): 4.

[18] Z. Gu, H. Shen, Z. Chen, et al., “Efficient Electrocatalytic CO₂ Reduction to C2+ Alcohols at Defect-Site-Rich Cu Surface,” Joule 5, no. 5 (2021): 429–440.

[19] J. Zhu and S. Mu, “Defect Engineering in Carbon-Based Electrocatalysts: Insight Into Intrinsic Carbon Defects,” Advanced Functional Materials 30, no. 30 (2020): 2001097.

[20] C. Lu, L. Yang, B. Yan, et al., “Nitrogen-Doped Ti₃C₂ MXene: Mechanism Investigation and Electrochemical Analysis,” Advanced Functional Materials 30, no. 30 (2020): 2000852.

[21] X. Wu, Y. Wang, and Z. S. Wu, “Design Principle of Electrocatalysts for the Electrooxidation of Organics,” Chem 8, no. 8 (2022): 2594–2629.

[22] X. Chen, X. Zhai, J. Hou, et al., “Tunable Nitrogen-Doped Delaminated 2D Mxene Obtained by NH₃/Ar Plasma Treatment as Highly Efficient Hydrogen and Oxygen Evolution Reaction Electrocatalyst,” Chemical Engineering Journal 420, no. 420 (2021): 129832.

[23] C. E. Park, G. H. Jeong, J. Theerthagiri, H. Lee, and M. Y. Choi, “Moving Beyond Ti₂C₃T_x MXene to Pt-Decorated TiO₂@TiC Core-Shell via Pulsed Laser in Reshaping Modification for Accelerating Hydrogen Evolution Kinetics,” ACS Nano 17, no. 17 (2023): 7539–7549.

[24] K. Gu, D. Wang, C. Xie, et al., “Defect-Rich High-Entropy Oxide Nanosheets for Efficient 5-hydroxymethylfurfural Electrooxidation,” Angewandte Chemie 133, no. 133 (2021): 20415–20420.

[25] D. Guo, Q. Pan, T. Vietor, W. Lu, and Y. Gao, “MXene Based Non-Noble Metal Catalyst for Overall Water Splitting in Alkaline Conditions,” Journal of Energy Chemistry 87 (2023): 518–539.

[26] B. Wei, Z. Fu, D. Legut, et al., “Rational Design of Highly Stable and Active MXene-Based Bifunctional ORR/OER Double-Atom Catalysts,” Advanced Materials 33, no. 33 (2021): 2102595.

[27] D. S. Kouao, K. Grochowska, V. Stranak, et al., “Laser-Treated MXene as an Electrochemical Agent to Boost Properties of Semitransparent Photoelectrode Based on Titania Nanotubes,” ACS Nano 18, no. 18 (2024): 10165–10183.

[28] L. Tao, Y. Wang, Y. Zou, et al., “Charge Transfer Modulated Activity of Carbon-Based Electrocatalysts,” Advanced Energy Materials 10, no. 10 (2020): 1901227.

[29] M. Gao, Z. Y. Wang, Y. R. Yuan, W. W. Li, H. Q. Liu, and T. Y. Huang, “Ball-Milled Biochar for Efficient Neutral Electrosynthesis of Hydrogen Peroxide,” Chemical Engineering Journal 434, no. 434 (2022): 134788.

[30] X. Zhang, L. Hui, D. Yan, et al., “Defect Rich Structure Activated 3D Palladium Catalyst for Methanol Oxidation Reaction,” Angewandte Chemie International Edition 62, no. 62 (2023): e202308968.

[31] J. Qu, W. Liu, R. Liu, et al., “Evolution of Oxygen Vacancies in Cerium Dioxide at Atomic Scale Under CO₂ Reduction,” Chem Catalysis 3, no. 3 (2023): 100759.

[32] N. Chen, Y. Zhou, S. Zhang, et al., “Tailoring Ti₃CNT MXene via an Acid Molecular Scissor,” Nano Energy 85, no. 85 (2021): 106007.

[33] Y. Xue, J. Feng, S. Huo, et al., “Polyphosphoramide-Intercalated MXene for Simultaneously Enhancing Thermal Stability, Flame Retardancy and Mechanical Properties of Polylactide,” Chemical Engineering Journal 397, no. 397 (2020): 125336.

[34] Y. Fang, Y. Zhang, C. Miao, et al., “MXene-Derived Defect-Rich TiO₂@rGO as High-Rate Anodes for Full Na Ion Batteries and Capacitors,” Nano-Micro Letters 1, no. 12 (2020): 128.

[35] J. Liu, Z. Wei, Z. Gong, et al., “Single-Atom CoN₄ Sites With Elongated Bonding Induced by Phosphorus Doping for Efficient H₂O₂ Electrosynthesis,” Applied Catalysis, B: Environmental 324, no. 324 (2023): 122267.

[36] L. Yu, L. Lu, X. Zhou, L. Xu, Z. Alhalili, and F. Wang, “Strategies for Fabricating High-Performance Electrochemical Energy-Storage Devices by MXenes,” ChemElectroChem 8, no. 8 (2021): 1948–1987.

[37] K. Gong, F. Du, Z. Xia, M. Durstock, and L. Dai, “Nitrogen-Doped Carbon Nanotube Arrays With High Electrocatalytic Activity for Oxygen Reduction,” Science 323, no. 323 (2009): 760–764.

[38] Q. Wu, H. Zou, X. Mao, et al., “Unveiling the Dynamic Active Site of Defective Carbon-Based Electrocatalysts for Hydrogen Peroxide Production,” Nature Communications 14, no. 14 (2023): 6275.

[39] J. Liu, D. Wang, K. Huang, et al., “Iodine-Doping-Induced Electronic Structure Tuning of Atomic Cobalt for Enhanced Hydrogen Evolution Electrocatalysis,” ACS Nano 15, no. 15 (2021): 18125–18134.

[40] C. Zhu, Y. Hao, H. Wu, et al., “Self-Assembly of Binderless MXene Aerogel for Multiple-Scenario and Responsive Phase Change Composites With Ultrahigh Thermal Energy Storage Density and Exceptional Electromagnetic Interference Shielding,” Nano-Micro Letters 16, no. 16 (2024): 57.

[41] S. Chen, T. Luo, X. Li, et al., “Identification of the Highly Active Co–N₄ Coordination Motif for Selective Oxygen Reduction to Hydrogen Peroxide,” Journal of the American Chemical Society 144, no. 144 (2022): 14505–14516.

[42] X. Wang, Y. Jia, X. Mao, et al., “A Directional Synthesis for Topological Defect in Carbon,” Chem 6, no. 6 (2020): 2009–2023.

[43] X. Wang, Y. Q. Wang, Y. C. Feng, D. Wang, and L. J. Wan, “Insights Into Electrocatalysis by Scanning Tunnelling Microscopy,” Chemical Society Reviews 50, no. 50 (2021): 5832–5849.

[44] L. Xu, K. G. Papanikolaou, B. A. J. Lechner, et al., “Formation of Active Sites on Transition Metals Through Reaction-Driven Migration of Surface Atoms,” Science 380, no. 380 (2023): 70–76.

[45] Y. Jia, L. Zhang, A. Du, et al., “Defect Graphene as a Trifunctional Catalyst for Electrochemical Reactions,” Advanced Materials 28, no. 28 (2016): 9532–9538.

[46] R. Amirbeigiarab, J. Tian, A. Herzog, et al., “Atomic-Scale Surface Restructuring of Copper Electrodes Under CO₂ Electroreduction Conditions,” Nature Catalysis 9, no. 6 (2023): 837–846.

[47] K. Xu, M. Holbrook, L. N. Holtzman, et al., “Validating the Use of Conductive Atomic Force Microscopy for Defect Quantification in 2D Materials,” ACS Nano 17, no. 17 (2023): 24743–24752.

[48] D. Kim, M. Chung, S. Kim, et al., “Defect Dynamics at a Single Pt Nanoparticle During Catalytic Oxidation,” Nano Letters 19, no. 19 (2019): 5044–5052.

[49] X. Yan, Y. Jia, and X. Yao, “Defective Structures in Metal Compounds for Energy-Related Electrocatalysis,” Small Structures 2, no. 2 (2021): 2000067.

[50] S. Mo, Q. Zhang, J. Li, et al., “Highly Efficient Mesoporous MnO₂ Catalysts for the Total Toluene Oxidation: Oxygen-Vacancy Defect Engineering and Involved Intermediates Using In Situ DRIFTS,” Applied Catalysis, B: Environmental 264, no. 264 (2020): 118464.

[51] J. Liu, Z. Gong, M. Yan, et al., “Electronic Structure Regulation of Single-Atom Catalysts for Electrochemical Oxygen Reduction to H₂O₂,” Small 18, no. 18 (2022): 2103824.

[52] Y. Liu and S. Zhao, “Identifying the Geometric Symmetry Role of Single-Atom Chlorine Evolution Electrocatalyst,” Chem Catalysis 3, no. 3 (2023): 100755.

[53] L. Fu, H. N. Nam, J. Zhou, et al., “Mesoporous High-Entropy Alloy Films,” ACS Nano 18, no. 18 (2024): 27617–27629.

[54] J. Li, Y. Wang, H. Song, et al. N-doped Rutile TiO₂ Composite g–C₃N₄ With Z-Scheme Boosts Photocatalytic Hydrogen Production Under Visible Light. 2023, https://doi.org/10.21203/rs.3.rs-2497545/v1.

[55] Y. Zhang, D. Wang, and S. Wang, “High-Entropy Alloys for Electrocatalysis: Design, Characterization, and Applications,” Small 18, no. 18 (2022): 2104339.

[56] L. Tao, M. Qiao, R. Jin, et al., “Bridging the Surface Charge and Catalytic Activity of a Defective Carbon Electrocatalyst,” Angewandte Chemie International Edition 58, no. 58 (2019): 1019–1024.

[57] Y. Wang, X. Hu, H. Song, et al., “Oxygen Vacancies in Actiniae-Like Nb₂O₅/Nb₂C Mxene Heterojunction Boosting Visible Light Photocatalytic NO Removal,” Applied Catalysis, B: Environmental 299 (2021): 120677.

[58] J. Zhang, E. Wang, S. Cui, S. Yang, X. Zou, and Y. Gong, “Single-Atom Pt Anchored on Oxygen Vacancy of Monolayer Ti₃C₂T_x for Superior Hydrogen Evolution,” Nano Letters 22, no. 22 (2022): 1398–1405.

[59] X. Zhong, E. Yuan, F. Yang, et al., “Optimizing Oxygen Vacancies Through Grain Boundary Engineering to Enhance Electrocatalytic Nitrogen Reduction,” Proceedings of the National Academy of Sciences 120, no. 120 (2023): e2306673120.

[60] X. Wang, J. Ding, W. Song, et al., “Cation Vacancy Clusters in Ti₃C₂T_x MXene Induce Ultra-Strong Interaction With Noble Metal Clusters for Efficient Electrocatalytic Hydrogen Evolution,” Advanced Energy Materials 13, no. 13 (2023): 2300148.

[61] Y. Zhang, J. Xu, Y. Long, L. Tao, M. Ding, and C. Jia, “Defect Chemistry on Electrode Materials for Electrochemical Energy Storage and Conversion,” ChemNanoMat 6, no. 6 (2020): 1589–1600.

[62] Y. Wang and Y. Wang, “MXene Ink Printing of High-Performance Micro-Supercapacitors,” Carbon Neutralization 3, no. 3 (2024): 798–817.

[63] Y. Yan, J. Lin, T. Xu, et al., “Atomic-Level Platinum Filling Into Ni-Vacancies of Dual-Deficient NiO for Boosting Electrocatalytic Hydrogen Evolution,” Advanced Energy Materials 12, no. 12 (2022): 2200434.

[64] Z. Kou, W. Zang, W. Pei, et al., “A Sacrificial Zn Strategy Enables Anchoring of Metal Single Atoms on the Exposed Surface of Holey 2D Molybdenum Carbide Nanosheets for Efficient Electrocatalysis,” Journal of Materials Chemistry A 8, no. 8 (2020): 3071–3082.

[65] B. Du, J. Li, S. Ma, et al., “Recent Advances of Engineering Multiple Vacancies In Electrocatalyst for Promoting Water Splitting,” Materials Today Chemistry 46 (2025): 102717.

[66] Y. Zhang, P. Guo, S. Guo, et al., “Gradient Heating Epitaxial Growth Gives Well Lattice-Matched Mo₂C-Mo₂N Heterointerfaces That Boost Both Electrocatalytic Hydrogen Evolution and Water Vapor Splitting,” Angewandte Chemie International Edition 61, no. 61 (2022): e202209703.

[67] V. Ramalingam, P. Varadhan, H. C. Fu, et al., “Heteroatom-Mediated Interactions Between Ruthenium Single Atoms and an MXene Support for Efficient Hydrogen Evolution,” Advanced Materials 31, no. 31 (2019): 1903841.

[68] T. Sun, G. Zhang, D. Xu, et al., “Defect Chemistry In 2D Materials for Electrocatalysis,” Materials Today Energy 12 (2019): 215–238.

[69] J. Liu, C. Tang, Z. Ke, et al., “Optimizing Hydrogen Adsorption by d–d Orbital modulation for Efficient Hydrogen Evolution Catalysis,” Advanced Energy Materials 12, no. 12 (2022): 2103301.

[70] Q. Qin, H. Jang, X. Jiang, et al., “Constructing Interfacial Oxygen Vacancy and Ruthenium Lewis Acid-Base Pairs to Boost the Alkaline Hydrogen Evolution Reaction Kinetics,” Angewandte Chemie International Edition 63, no. 63 (2024): e202317622.

[71] W. Ni, Z. Liu, Y. Zhang, et al., “Electroreduction of Carbon Dioxide Driven by the Intrinsic Defects In the Carbon Plane of a Single Fe–N₄ Site,” Advanced Materials 33, no. 33 (2021): 2003238.

[72] Q. Gong, P. Ding, M. Xu, et al., “Structural Defects on Converted Bismuth Oxide Nanotubes Enable Highly Active Electrocatalysis of Carbon Dioxide Reduction,” Nature Communications 1, no. 10 (2019): 2807.

[73] Y. Li, W. Wang, M. Cheng, et al., “Arming Ru With Oxygen-Vacancy-Enriched Ruo₂ Sub-Nanometer Skin Activates Superior Bifunctionality for Ph-Universal Overall Water Splitting,” Advanced Materials 35, no. 35 (2023): 2206351.

[74] X. Bai and J. Guan, “MXenes for Electrocatalysis Applications: Modification and Hybridization,” Chinese Journal of Catalysis 43, no. 43 (2022): 2057–2090.

[75] N. Li, X. Chen, W. J. Ong, et al., “Understanding of Electrochemical Mechanisms for CO₂ Capture and Conversion Into Hydrocarbon Fuels In Transition-Metal Carbides (Mxenes),” ACS Nano 11, no. 11 (2017): 10825–10833.

[76] C. Cheng, X. Zhang, Z. Yang, and K. Hermansson, “Identification of High-Performance Single-Atom MXenes Catalysts for Low-Temperature CO Oxidation,” Advanced Theory and Simulations 2, no. 2 (2019): 1900006.

[77] Z. Lv, W. Ma, M. Wang, et al., “Co-Constructing Interfaces of Multiheterostructure on MXene (Ti₃C₂T_x)-Modified 3D Self-Supporting Electrode for Ultraefficient Electrocatalytic HER in Alkaline Media,” Advanced Functional Materials 31, no. 31 (2021): 2102576.

[78] C. Y. Liu and E. Y. Li, “Termination Effects of Pt/V–Ti_n+1C_nT₂ Mxene Surfaces for Oxygen Reduction Reaction Catalysis,” ACS Applied Materials & Interfaces 1, no. 11 (2018): 1638–1644.

[79] P. Wang, D. Zhao, X. Hui, et al., “Bifunctional Catalytic Activity Guided by Rich Crystal Defects in Ti₃C₂ MXene Quantum Dot Clusters for Li–O₂ Batteries,” Advanced Energy Materials 11, no. 11 (2021): 2003069.

[80] T. Xu, Y. Wang, Z. Xiong, Y. Wang, Y. Zhou, and X. Li, “A Rising 2D Star: Novel MBenes With Excellent Performance In Energy Conversion and Storage,” Nano-Micro Letters 15, no. 15 (2023): 6.

[81] Z. Liu, Z. Xiao, G. Luo, et al., “Defects-Induced In-Plane Heterophase in Cobalt Oxide Nanosheets for Oxygen Evolution Reaction,” Small 15, no. 15 (2019): 1904903.

[82] Y. Wu, J. Yang, T. Tu, et al., “Evolution of Cationic Vacancy Defects: A Motif for Surface Restructuration of OER Precatalyst,” Angewandte Chemie International Edition 60, no. 60 (2021): 26829–26836.

[83] Z. Xiao, Y. C. Huang, C. L. Dong, et al., “Operando Identification of the Dynamic Behavior of Oxygen Vacancy-Rich Co₃O₄ for Oxygen Evolution Reaction,” Journal of the American Chemical Society 142, no. 142 (2020): 12087–12095.

[84] Y. Zhu, Y. Wang, Y. Wang, T. Xu, and P. Chang, “Research Progress on Carbon Materials as Negative Electrodes In Sodium-And Potassium-Ion Batteries,” Carbon Energy 4, no. 14 (2022): 1182–1213.

[85] J. Wang, T. Liao, Z. Wei, J. Sun, J. Guo, and Z. Sun, “Heteroatom-Doping of Non-Noble Metal-Based Catalysts for Electrocatalytic Hydrogen Evolution: An Electronic Structure Tuning Strategy,” Small Methods 5, no. 5 (2021): 2000988.

[86] S. Chae, S. Yi, J. Yoon, et al., “Highly Defective Ti₃CNT-Mxene-Based Fiber Membrane Anode for Lithium Metal Batteries,” Energy Storage Materials 52 (2022): 76–84.

[87] L. Li, Z. Qin, L. Ries, et al., “Role of Sulfur Vacancies and Undercoordinated Mo Regions in MoS₂ Nanosheets Toward the Evolution of Hydrogen,” ACS Nano 13, no. 13 (2019): 6824–6834.

[88] C. Cheng, X. Zhang, M. Wang, S. Wang, and Z. Yang, “Single Pd Atomic Catalyst on Mo₂CO₂ Monolayer (MXene): Unusual Activity for CO Oxidation by Trimolecular Eley-Rideal Mechanism,” Physical Chemistry Chemical Physics 20, no. 20 (2018): 3504–3513.

[89] Y. Wang and Y. Wang, “Recent Progress in MXene Layers Materials for Supercapacitors: High-Performance Electrodes,” SmartMat 4, no. 4 (2023): e1130.

[90] Y. Jin and Y. Wang, “Preparation, Integration, and Piezoresistive Performance of MXene Materials for Multifunctional Pressure Sensor Design,” Chemical Engineering Journal 514 (2025): 163035.

[91] X. Chen, D. Vione, and Y. Gao, “Conversion of Vacancy Defects In Fe-Polyoxometalates@Ti₃C₂ Mxene Promotes Broad-Spectrum Degradation of Bisphenols,” Applied Catalysis B: Environment and Energy 379, no. 379 (2025): 125728.

[92] T. Xu, Y. Wang, Y. Xue, J. Li, and Y. Wang, “MXenes@Metal-Organic Framework Hybrids for Energy Storage and Electrocatalytic Application: Insights Into Recent Advances,” Chemical Engineering Journal 470 (2023): 144247.

[93] V. R. Stamenkovic, B. S. Mun, M. Arenz, et al., “Trends in Electrocatalysis on Extended and Nanoscale Pt-Bimetallic Alloy Surfaces,” Nature Materials 6, no. 6 (2007): 241–247.

[94] X. Wang, Y. Jia, X. Mao, et al., “Edge-Rich Fe–N₄ Active Sites In Defective Carbon for Oxygen Reduction Catalysis,” Advanced Materials 16, no. 32 (2020): 2000966.

[95] Y. Wang, Y. Wang, M. Jian, Q. Jiang, and X. Li, “MXene Key Composites: A New Arena for Gas Sensors,” Nano-Micro Letters 16, no. 16 (2024): 209.

[96] M. Ren, J. Li, D. Guo, et al., “Lattice Coherency Engineering Trigger Rapid Charge Transport At the Heterointerface of Te/In₂O₃@MXene Photocatalysts for Boosting Photocatalytic Hydrogen Evolution,” Journal of Colloid and Interface Science 685 (2025): 733–742.

[97] X. Li, X. Wang, M. Yang, et al., “Interlayer Expanded MXene Film Cathodes With Rich Defects for Flexible 2-Electron Oxalate-Based Li–CO₂ Batteries: A New Path to Enhanced Energy Efficiency and Durability,” Advanced Materials 37, no. 37 (2025): 2500064.

[98] K. Wang, Y. Wang, B. Yang, et al., “Highly Active Ruthenium Sites Stabilized by Modulating Electron-Feeding for Sustainable Acidic Oxygen-Evolution Electrocatalysis,” Energy & Environmental Science 6, no. 15 (2022): 2356–2365.

[99] X. Fu, N. Li, B. Ren, et al., “Tailoring FeN₄ Sites With Edge Enrichment for Boosted Oxygen Reduction Performance In Proton Exchange Membrane Fuel Cell,” Advanced Energy Materials 9, no. 9 (2019): 1803737.

[100] F. Pan, B. Li, E. Sarnello, et al., “Pore-Edge Tailoring of Single-Atom Iron-Nitrogen Sites on Graphene for Enhanced CO₂ Reduction,” ACS Catalysis 10, no. 10 (2020): 10803–10811.

[101] C. Ling, L. Shi, Y. Ouyang, Q. Chen, and J. Wang, “Transition Metal-Promoted V₂CO₂ (MXenes): A New and Highly Active Catalyst for Hydrogen Evolution Reaction,” Advanced Science 3, no. 3 (2016): 1600180.

[102] L. Li, X. Wang, H. Guo, et al., “Theoretical Screening of Single Transition Metal Atoms Embedded in MXene Defects as Superior Electrocatalyst of Nitrogen Reduction Reaction,” Small Methods 3, no. 3 (2019): 1900337.

[103] D. Kan, D. Wang, X. Zhang, et al., “Rational Design of Bifunctional ORR/OER Catalysts Based on Pt/Pd-Doped Nb₂CT₂ MXene by First-Principles Calculations,” Journal of Materials Chemistry A 8, no. 8 (2020): 3097–3108.

[104] L. Xiu, Z. Wang, M. Yu, X. Wu, and J. Qiu, “Aggregation-Resistant 3D MXene-Based Architecture as Efficient Bifunctional Electrocatalyst for Overall Water Splitting,” ACS Nano 12, no. 12 (2018): 8017–8028.

[105] J. Halim, J. Palisaitis, J. Lu, et al., “Synthesis of Two-Dimensional Nb_1.33C (MXene) With Randomly Distributed Vacancies by Etching of the Quaternary Solid Solution (Nb_2/3Sc_1/3)₂AlC MAX Phase,” ACS Applied Nano Materials 1, no. 1 (2018): 2455–2460.

[106] X. Wang, C. Wang, S. Ci, et al., “Accelerating 2D MXene Catalyst Discovery for the Hydrogen Evolution Reaction by Computer-Driven Workflow and An Ensemble Learning Strategy,” Journal of Materials Chemistry A 8, no. 8 (2020): 23488–23497.

[107] Y. Zhu, G. Xu, W. Song, et al. RETRACTED: Anchoring Single Ni Atoms on Defected 2D MXene Nanosheets as an Efficient Electrocatalyst for Enhanced Hydrogen Evolution Reaction. 21, no. 47 (2021): 30005–30011.

[108] S. Zhang, H. Ying, P. Huang, T. Yang, and W. Q. Han, “Hierarchical Utilization of Raw Ti₃C₂T_x MXene for Fast Preparation of Various Ti₃C₂T_x MXene Derivatives,” Nano Research 15, no. 15 (2022): 2746–2755.

[109] D. Kan, R. Lian, D. Wang, et al., “Screening Effective Single-Atom ORR and OER Electrocatalysts From Pt Decorated MXenes by First-Principles Calculations,” Journal of Materials Chemistry A 8, no. 8 (2020): 17065–17077.

[110] M. Zhang, W. Zhao, T. Yang, et al., “Vacancy and Growth Modulation of Cobalt Hexacyanoferrate by Porous MXene for Zinc Ion Batteries,” Advanced Energy Materials 14, no. 14 (2024): 2400543.

[111] J. Duan, S. Chen, C. A. Ortíz-Ledón, M. Jaroniec, and S. Z. Qiao, “Phosphorus Vacancies That Boost Electrocatalytic Hydrogen Evolution by Two Orders of Magnitude,” Angewandte Chemie 132, no. 132 (2020): 8258–8263.

[112] Y. Wang, R. Du, Z. Li, et al., “Rationally Designed Cds/Ti₃C₂ MXene Electrocatalysts for Efficient CO₂ Reduction in Aqueous Electrolyte,” Ceramics International 47, no. 47 (2021): 28321–28327.

[113] X. Xu, Y. Zhang, H. Sun, et al., “Orthorhombic Cobalt Ditelluride With Te Vacancy Defects Anchoring on Elastic MXene Enables Efficient Potassium-Ion Storage,” Advanced Materials 33, no. 33 (2021): 2100272.

[114] L. Deng, B. Chang, D. Shi, et al., “Mxene Decorated by Phosphorus-Doped TiO₂ for Photo-Enhanced Electrocatalytic Hydrogen Evolution Reaction,” Renewable Energy 170 (2021): 858–865.

[115] Q. Yang, Y. Jia, F. Wei, et al., “Understanding the Activity of Co-N_4−xC_x in Atomic Metal Catalysts for Oxygen Reduction Catalysis,” Angewandte Chemie 132, no. 132 (2020): 6178–6183.

[116] D. Yan, C. Xia, W. Zhang, et al., “Cation Defect Engineering of Transition Metal Electrocatalysts for Oxygen Evolution Reaction,” Advanced Energy Materials 12, no. 12 (2022): 2202317.

[117] J. Zhang, X. Wu, W. C. Cheong, et al., “Cation Vacancy Stabilization of Single-Atomic-Site Pt₁/Ni(OH)_x Catalyst for Diboration of Alkynes and Alkenes,” Nature Communications 1, no. 9 (2018): 1002.

[118] J. Zhang, Y. Zhao, X. Guo, et al., “Single Platinum Atoms Immobilized on an MXene as an Efficient Catalyst for the Hydrogen Evolution Reaction,” Nature Catalysis 1, no. 1 (2018): 985–992.

[119] D. Zhao, Z. Chen, W. Yang, et al., “MXene (Ti₃C₂) Vacancy-Confined Single-Atom Catalyst for Efficient Functionalization of Co₂,” Journal of the American Chemical Society 141, no. 141 (2019): 4086–4093.

[120] Z. Zeng, G. Fu, H. B. Yang, et al., “Bifunctional N–Cose₂/3D–MXene as Highly Efficient and Durable Cathode for Rechargeable Zn–Air Battery,” ACS Materials Letters 1, no. 1 (2019): 432–439.

[121] X. Wei, X. Wen, Y. Liu, et al., “Oxygen Vacancy-Mediated Selective C–N Coupling Toward Electrocatalytic Urea Synthesis,” Journal of the American Chemical Society 26, no. 144 (2024): 11530–11535.

[122] X. Sang, Y. Xie, M. W. Lin, et al., “Atomic Defects in Monolayer Titanium Carbide (Ti₃C₂T_X) MXene,” ACS Nano 10, no. 10 (2016): 9193–9200.

[123] Y. Kang, O. Cretu, J. Kikkawa, et al., “Mesoporous Multimetallic Nanospheres With Exposed Highly Entropic Alloy Sites,” Nature Communications 1, no. 14 (2023): 4182.

[124] I. C. Onyia, S. O. Ezeonu, D. Bessarabov, and K. O. Obodo, “Density Functional Theory Studies of Transition Metal Doped Ti₃N₂ Mxene Monolayer,” Computational Materials Science 197, no. 197 (2021): 110613.

[125] R. Zheng, C. Shu, Z. Hou, et al., “Interfacial Electronic Structure Design of MXene-Based Electrocatalyst via Vacancy Modulation for Lithium-Oxygen Battery,” Carbon 166, no. 166 (2020): 273–283.

[126] H. Zhou, S. J. Han, H. D. Lee, et al., “Overcoming the Limitations of MXene Electrodes for Solution-Processed Optoelectronic Devices,” Advanced Materials 34, no. 34 (2022): 2206377.

[127] J. Li, Y. Wang, Y. Wang, et al., “MXene Ti₃C₂ Decorated g–C₃N₄/ZnO Photocatalysts With Improved Photocatalytic Performance for Co₂ Reduction,” Nano Materials Science 5, no. 5 (2023): 237–245.

[128] Y. Kang, M. K. Masud, Y. Guo, et al., “Au-Loaded Superparamagnetic Mesoporous Bimetallic Cofeb Nanovehicles for Sensitive Autoantibody Detection,” ACS Nano 17, no. 17 (2023): 3346–3357.

[129] S. Wang, A. Robertson, and J. H. Warner, “Atomic Structure of Defects and Dopants In 2D Layered Transition Metal Dichalcogenides,” Chemical Society Reviews 47, no. 47 (2018): 6764–6794.

[130] H. He, Y. Wang, Y. Qi, Z. Xu, Y. Li, and Y. Wang, “From Prediction to Design: Recent Advances in Machine Learning for the Study of 2D Materials,” Nano Energy 118 (2023): 108965.

[131] S. Liu, Z. Lin, R. Wan, et al., “Cobalt Phosphide Supported by Two-Dimensional Molybdenum Carbide (MXene) for the Hydrogen Evolution Reaction, Oxygen Evolution Reaction, and Overall Water Splitting,” Journal of Materials Chemistry A 9, no. 9 (2021): 21259–21269.

[132] Y. Kuai and Y. Wang, “Innovative COF@MXene Composites for High Performance Energy Applications,” Carbon Neutrality 3, no. 3 (2024): 36.

[133] P. Chang, Y. Wang, Y. Wang, and Y. Zhu, “Current Trends on In₂O₃ Based Heterojunction Photocatalytic Systems in Photocatalytic Application,” Chemical Engineering Journal 450 (2022): 137804.

[134] Q. Hu, S. Qi, Q. Huo, et al., “Designing Efficient Nitrate Reduction Electrocatalysts by Identifying and Optimizing Active Sites of Co-Based Spinels,” Journal of the American Chemical Society 146, no. 146 (2024): 2967–2976.

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