Machine-Learning-Assisted Design and Optimization of Single-Atom Transition Metal-Incorporated Carbon Quantum Dot Catalysts for Electrocatalytic Hydrogen Evolution Reaction

Abstract

Hydrogen evolution reaction (HER) in acidic media has been spotlighted for hydrogen production since it is a favourable kinetics with the supplied protons from a counterpart compared to that within alkaline environment. However, there is no choice but to use a platinum-based catalyst yet. As for a noble metal-free electrocatalyst, incorporation of earth-abundant transition metal (TM) atoms into nanocarbon platforms has been extensively adopted. Although a data-driven methodology facilitates the rational design of TM-anchored carbon catalysts, its practical application suffers from either a simplified theoretical model or the prohibitive cost and complexity of experimental data generation. Herein, an effective and facile catalyst design strategy is proposed based on machine learning (ML) and its model verification using electrochemical methods accompanied by density functional theory simulations. Based on a Bayesian genetic algorithm ML model, the Ni-incorporated carbon quantum dots (Ni@CQD) loaded on a three-dimensional reduced graphene oxide conductor are proposed as the best HER catalyst amongst the various TM-incorporated CQDs under the optimal conditions of catalyst loading, electrode type, and temperature and pH of electrolyte. The ML results are validated with electrochemical experiments, where the Ni@CQD catalyst exhibited superior HER activity, requiring an overpotential of 151 mV to achieve 10 mA cm⁻² with a Tafel slope of 52 mV dec⁻¹ and impressive durability in acidic media up to 100 h. This methodology can provide an effective route for the rational design of highly active electrocatalysts for commercial applications.

Keywords

carbon quantum dot / density functional theory / hydrogen evolution reaction / machine learning / transition metal doping

References

[1] J. Zhang, C. Ma, S. Jia, et al., “Electrocatalysts Design Guided by Active Intermediates of Hydrogen Evolution Reaction,” Advanced Energy Materials 13, no. 43 (2023): 2302436.

[2] L. Zhang, H. Jang, Y. Wang, et al., “Exploring the Dominant Role of Atomic- and Nano-Ruthenium as Active Sites for Hydrogen Evolution Reaction in Both Acidic and Alkaline Media,” Advanced Science 8, no. 15 (2021): 2004516.

[3] L. M. Salonen, D. Y. Petrovykh, and Y. V. Kolen'ko, “Sustainable Catalysts for Water Electrolysis: Selected Strategies for Reduction and Replacement of Platinum-Group Metals,” Materials Today Sustainability 11-12 (2021): 100060.

[4] Z. Pu, T. Liu, G. Zhang, et al, “General Synthesis of Transition- Sustainable Catalysts for Water Electrolysis: Selected Strategies for Reduction and Lytic Hydrogen Evolution in Wide pH Range,” Advanced Energy Materials 12, no. 20 (2022): 2200293.

[5] Y. Wei, R. A. Soomro, X. Xie, and B. Xu, “Design of Efficient Electrocatalysts for Hydrogen Evolution Reaction Based on 2D Mxenes,” Journal of Energy Chemistry 55 (2021): 244-255.

[6] B. Wang, L. Wang, J. H. Lee, T. T. Isimjan, H. M. Jeong, and X. Yang, “Enabling Built-In Electric Fields on Rhenium-Vacancy-Rich Heterojunction Interfaces of Transition-Metal Dichalcogenides for pH-Universal Efficient Hydrogen and Electric Energy Generation,” Carbon Energy 6, no. 9 (2024): e526.

[7] L. Tian, Z. Li, P. Wang, X. Zhai, X. Wang, and T. Li, “Carbon Quantum Dots for Advanced Electrocatalysis,” Journal of Energy Chemistry 55 (2021): 279-294.

[8] X. Wang, Y. Feng, P. Dong, and J. Huang, “A Mini Review on Carbon Quantum Dots: Preparation, Properties, and Electrocatalytic Application,” Frontiers in Chemistry 7 (2019): 671.

[9] Z. Zhang, T. Zheng, X. Li, J. Xu, and H. Zeng, “Progress of Carbon Quantum Dots in Photocatalysis Applications,” Particle & Particle Systems Characterization 33, no. 8 (2016): 457-472.

[10] T. Gong, Y. Liu, K. Cui, et al., “Binary Molten Salt in Situ Synthesis of Sandwich-Structure Hybrids of Hollow Β-Mo₂C Nanotubes and N-Doped Carbon Nanosheets for Hydrogen Evolution Reaction,” Carbon Energy 5, no. 12 (2023): e349.

[11] Y. Li, M.-C. Kim, C. Xia, et al., “A Natural Molecule-Driven Organometallic Conformal Overlayer for High Efficiency Photoelectrochemical Water Splitting,” Applied Catalysis, B: Environmental 343 (2024): 123516.

[12] S. Daniel, M. G. Praveena, and E. M. Mohammed, “Exploration of Highly Photoluminescent First-Row Transition Metals (Manganese, Iron, Cobalt, Nickel, Copper and Zinc) Co-Doped Nano Carbon Dots as Energy Storage Materials,” Materials Science and Engineering: B 269 (2021): 115145.

[13] X.-L. Guo, Z.-Y. Ding, S.-M. Deng, et al., “A Novel Strategy of Transition-Metal Doping to Engineer Absorption of Carbon Dots for Near-Infrared Photothermal/Photodynamic Therapies,” Carbon 134 (2018): 519-530.

[14] S. A. Rub Pakkath, S. S. Chetty, P. Selvarasu, et al., “Transition Metal Ion (Mn²⁺, Fe²⁺, Co²⁺, and Ni²⁺)-Doped Carbon Dots Synthesized Via Microwave-Assisted Pyrolysis: A Potential Nanoprobe for Magneto-Fluorescent Dual-Modality Bioimaging,” ACS Biomaterials Science & Engineering 4, no. 7 (2018): 2582-2596.

[15] J. Zheng, X. Sun, J. Hu, et al., “Symbolic Transformer Accelerating Machine Learning Screening of Hydrogen and Deuterium Evolution Reaction Catalysts in MA₂Z₄ Materials,” ACS Applied Materials & Interfaces 13, no. 43 (2021): 50878-50891.

[16] M. Kim, B. C. Yeo, Y. Park, H. M. Lee, S. S. Han, and D. Kim, “Artificial Intelligence to Accelerate the Discovery of N₂ Electroreduction Catalysts,” Chemistry of Materials 32, no. 2 (2020): 709-720.

[17] X. Chen, H.-J. Peng, R. Zhang, et al., “An Analogous Periodic Law for Strong Anchoring of Polysulfides on Polar Hosts in Lithium Sulfur Batteries: S- or Li-Binding on First-Row Transition-Metal Sulfides?,” ACS Energy Letters 2, no. 4 (2017): 795-801.

[18] Y. Yang, J. Liu, F. Liu, Z. Wang, and D. Wu, “FeS₂-Anchored Transition Metal Single Atoms for Highly Efficient Overall Water Splitting: A DFT Computational Screening Study,” Journal of Materials Chemistry A 9, no. 4 (2021): 2438-2447.

[19] B. C. Yeo, H. Nam, H. Nam, et al., “High-Throughput Computational-Experimental Screening Protocol for the Discovery of Bimetallic Catalysts,” npj Computational Materials 7, no. 1 (2021): 137.

[20] J. Wei, X. Chu, X. Y. Sun, et al., “Machine Learning in Materials Science,” InfoMat 1, no. 3 (2019): 338-358.

[21] D. Tian, S. R. Denny, K. Li, H. Wang, S. Kattel, and J. G. Chen, “Density Functional Theory Studies of Transition Metal Carbides and Nitrides as Electrocatalysts,” Chemical Society Reviews 50, no. 22 (2021): 12338-12376.

[22] Y. A. Alsunni, A. W. Alherz, and C. B. Musgrave, “Electrocatalytic Reduction of CO₂ to CO over Ag(110) and Cu(211) Modeled by Grand-Canonical Density Functional Theory,” Journal of Physical Chemistry C 125, no. 43 (2021): 23773-23783.

[23] E. B. Carneiro-Neto, M. C. Lopes, and E. C. Pereira, “Simulation of Interfacial pH Changes During Hydrogen Evolution Reaction,” Journal of Electroanalytical Chemistry 765 (2016): 92-99.

[24] A. Lasia, “Mechanism and Kinetics of the Hydrogen Evolution Reaction,” International Journal of Hydrogen Energy 44, no. 36 (2019): 19484-19518.

[25] A. R. Kucernak and C. Zalitis, “General Models for the Electrochemical Hydrogen Oxidation and Hydrogen Evolution Reactions: Theoretical Derivation and Experimental Results under Near Mass-Transport Free Conditions,” Journal of Physical Chemistry C 120, no. 20 (2016): 10721-10745.

[26] J. I. Martinez Alvarado, J. M. Meinhardt, and S. Lin, “Working at the Interfaces of Data Science and Synthetic Electrochemistry,” Tetrahedron Chem 1 (2022): 100012.

[27] S. Hammami, N. Oturan, N. Bellakhal, M. Dachraoui, and M. A. Oturan, “Oxidative Degradation of Direct Orange 61 by Electro-Fenton Process Using a Carbon Felt Electrode: Application of the Experimental Design Methodology,” Journal of Electroanalytical Chemistry 610, no. 1 (2007): 75-84.

[28] C. García-Gómez, P. Drogui, F. Zaviska, et al., “Experimental Design Methodology Applied to Electrochemical Oxidation of Carbamazepine Using Ti/PbO₂ and Ti/BDD Electrodes,” Journal of Electroanalytical Chemistry 732 (2014): 1-10.

[29] D. M. Deaven and K. M. Ho, “Molecular Geometry Optimization With a Genetic Algorithm,” Physical Review Letters 75, no. 2 (1995): 288-291.

[30] J. Zhang, J. Chen, P. Hu, and H. Wang, “Identifying the Composition and Atomic Distribution of Pt-Au Bimetallic Nanoparticle With Machine Learning and Genetic Algorithm,” Chinese Chemical Letters 31, no. 3 (2020): 890-896.

[31] A. Chen, X. Zhang, and Z. Zhou, “Machine Learning: Accelerating Materials Development for Energy Storage and Conversion,” InfoMat 2, no. 3 (2020): 553-576.

[32] S. Steiner, J. Wolf, S. Glatzel, et al., “Organic Synthesis in a Modular Robotic System Driven by a Chemical Programming Language,” Science 363, no. 6423 (2019): eaav2211.

[33] R. M. Maceiczyk, I. G. Lignos, and A. J. deMello, “Online Detection and Automation Methods in Microfluidic Nanomaterial Synthesis,” Current Opinion in Chemical Engineering 8 (2015): 29-35.

[34] D. E. Goldberg, “Real-Coded Genetic Algorithms, Virtual Alphabets, and Blocking,” Complex Systems 5, no. 2 (1991): 139-167.

[35] B. J. Moon, Y. Oh, D. H. Shin, et al., “Facile and Purification-Free Synthesis of Nitrogenated Amphiphilic Graphitic Carbon Dots,” Chemistry of Materials 28, no. 5 (2016): 1481-1488.

[36] B. J. Moon, S. J. Kim, A. Lee, et al., “Structure-Controllable Growth of Nitrogenated Graphene Quantum Dots Via Solvent Catalysis for Selective C-N Bond Activation,” Nature Communications 12, no. 1 (2021): 5879.

[37] S. Ueno, N. Chatani, and F. Kakiuchi, “Ruthenium-Catalyzed Carbon−Carbon Bond Formation via the Cleavage of an Unreactive Aryl Carbon−Nitrogen Bond in Aniline Derivatives with Organoboronates,” Journal of the American Chemical Society 129, no. 19 (2007): 6098-6099.

[38] T. Akiyama, Y. Wada, M. Yamada, et al., “Self-Assembled Multilayer Iron(0) Nanoparticle Catalyst for Ligand-Free Carbon-Carbon/Carbon-Nitrogen Bond-Forming Reactions,” Organic Letters 22, no. 18 (2020): 7244-7249.

[39] S. M. Tan and M. Pumera, “Two-Dimensional Materials on the Rocks: Positive and Negative Role of Dopants and Impurities in Electrochemistry,” ACS Nano 13, no. 3 (2019): 2681-2728.

[40] K. Li, Q. Liu, H. Cheng, M. Hu, and S. Zhang, “Classification and Carbon Structural Transformation From Anthracite to Natural Coaly Graphite by XRD, Raman Spectroscopy, and HRTEM,” Spectrochimica Acta, Part A: Molecular and Biomolecular Spectroscopy 249 (2021): 119286.

[41] Y. Li, Z.-S. Wu, P. Lu, et al., “High-Valence Nickel Single-Atom Catalysts Coordinated to Oxygen Sites for Extraordinarily Activating Oxygen Evolution Reaction,” Advanced Science 7, no. 5 (2020): 1903089.

[42] M. Wahid, G. Parte, D. Phase, and S. Ogale, “Yogurt: A Novel Precursor for Heavily Nitrogen Doped Supercapacitor Carbon,” Journal of Materials Chemistry A 3, no. 3 (2015): 1208-1215.

[43] F. Wu, H. Su, X. Zhu, K. Wang, Z. Zhang, and W.-K. Wong, “Near-Infrared Emissive Lanthanide Hybridized Carbon Quantum Dots for Bioimaging Applications,” Journal of Materials Chemistry B 4, no. 38 (2016): 6366-6372.

[44] L. Wang, W. Li, L. Yin, et al., “Full-Color Fluorescent Carbon Quantum Dots,” Science Advances 6, no. 40 (2020): eabb6772.

[45] Y. G. Cao, X. L. Chen, Y. C. Lan, J. Y. Li, Y. P. Xu, and T. Xu, “A New Method for Synthesis of Amorphous Carbon Nitride Powders,” Applied Physics A: Materials Science & Processing 71, no. 4 (2000): 465-467.

[46] B. Zhao, J. Liu, C. Xu, et al., “Hollow NiSe Nanocrystals Heterogenized With Carbon Nanotubes for Efficient Electrocatalytic Methanol Upgrading to Boost Hydrogen Co-Production,” Advanced Functional Materials 31, no. 8 (2021): 2008812.

[47] Y. Cheng, S. Zhao, H. Li, et al., “Unsaturated Edge-Anchored Ni Single Atoms on Porous Microwave Exfoliated Graphene Oxide for Electrochemical CO₂,” Applied Catalysis, B: Environmental 243 (2019): 294-303.

[48] C. Zhang, Z. Fu, Q. Zhao, Z. Du, R. Zhang, and S. Li, “Single-Atom-Ni-Decorated, Nitrogen-Doped Carbon Layers for Efficient Electrocatalytic CO₂ Reduction Reaction,” Electrochemistry Communications 116 (2020): 106758.

[49] G. Di Liberto, L. Giordano, and G. Pacchioni, “Predicting the Stability of Single-Atom Catalysts in Electrochemical Reactions,” ACS Catalysis 14, no. 1 (2024): 45-55.

[50] S. Li, R. Ma, J. Hu, et al., “Coordination Environment Tuning of Nickel Sites by Oxyanions to Optimize Methanol Electro-Oxidation Activity,” Nature Communications 13, no. 1 (2022): 2916.

[51] Z. Chen, C. Wang, X. Zhong, et al., “Achieving Efficient CO₂ Electrolysis to CO by Local Coordination Manipulation of Nickel Single-Atom Catalysts,” Nano Letters 23, no. 15 (2023): 7046-7053.

[52] T. K. C. Phu, W. T. Hong, H. Han, et al., “Conformal Surface Intensive Doping of Low-Valence Bi on Cu₂O for Highly Efficient Electrochemical Nitrate Reduction to Ammonia Production,” Materials Today 76 (2024): 52-63.

[53] C. Xia, S. Surendran, S. Ji, et al., “A Sulfur Self-Doped Multifunctional Biochar Catalyst for Overall Water Splitting and a Supercapacitor From Camellia japonica Flowers,” Carbon Energy 4, no. 4 (2022): 491-505.

[54] J. K. Nørskov, T. Bligaard, A. Logadottir, et al., “Trends in the Exchange Current for Hydrogen Evolution,” Journal of the Electrochemical Society 152, no. 3 (2005): J23-J27.

[55] D. Strmcnik, K. Kodama, D. van der Vliet, J. Greeley, V. R. Stamenkovic, and N. M. Marković, “The Role of Non-Covalent Interactions in Electrocatalytic Fuel-Cell Reactions on Platinum,” Nature Chemistry 1, no. 6 (2009): 466-472.

[56] X. Chen, I. T. McCrum, K. A. Schwarz, M. J. Janik, and M. T. M. Koper, “Co-Adsorption of Cations as the Cause of the Apparent pH Dependence of Hydrogen Adsorption on a Stepped Platinum Single-Crystal Electrode,” Angewandte Chemie International Edition 56, no. 47 (2017): 15025-15029.

[57] C. Pei, M.-C. Kim, Y. Li, et al., “Electron Transfer-Induced Metal Spin-Crossover at NiCo₂S₄/ReS₂ 2D-2D Interfaces for Promoting pH-Universal Hydrogen Evolution Reaction,” Advanced Functional Materials 33, no. 4 (2023): 2210072.

[58] X. Liu, S. Xi, H. Kim, et al., “Restructuring Highly Electron-Deficient Metal-Metal Oxides for Boosting Stability in Acidic Oxygen Evolution Reaction,” Nature Communications 12, no. 1 (2021): 5676.

[59] B. Hammer and J. K. Norskov, “Why Gold is the Noblest of all the Metals,” Nature 376, no. 6537 (1995): 238-240.

[60] D. N. Nguyen, G. S. Gund, M. G. Jung, et al., “Core-Shell Structured MXene@Carbon Nanodots as Bifunctional Catalysts for Solar-Assisted Water Splitting,” ACS Nano 14, no. 12 (2020): 17615-17625.

[61] G. Kresse and J. Furthmüller, “Efficiency of Ab-Initio Total Energy Calculations for Metals and Semiconductors Using a Plane-Wave Basis Set,” Computational Materials Science 6, no. 1 (1996): 15-50.

[62] G. Kresse and D. Joubert, “From Ultrasoft Pseudopotentials to the Projector Augmented-Wave Method,” Physical Review B 59, no. 3 (1999): 1758-1775.

[63] J. P. Perdew, K. Burke, and M. Ernzerhof, “Generalized Gradient Approximation Made Simple,” Physical Review Letters 77, no. 18 (1996): 3865-3868.

[64] S. Grimme, J. Antony, S. Ehrlich, and H. Krieg, “A Consistent and Accurate Ab Initio Parametrization of Density Functional Dispersion Correction (DFT-D) for the 94 Elements H-Pu,” Journal of Chemical Physics 132, no. 15 (2010): 154104.

[65] K. Mathew, R. Sundararaman, K. Letchworth-Weaver, T. A. Arias, and R. G. Hennig, “Implicit Solvation Model for Density-Functional Study of Nanocrystal Surfaces and Reaction Pathways,” Journal of Chemical Physics 140, no. 8 (2014): 084106.

[66] M.-C. Kim, E. Sim, and K. Burke, “Understanding and Reducing Errors in Density Functional Calculations,” Physical Review Letters 111, no. 7 (2013): 073003.

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