Unveiling a Redox-Assisted Electrocatalysis Approach for Efficient Azo-Based High-Energy Material Synthesis

Abstract

The azo reaction serves as a key approach for integrating high-energy ─N═N─ linkages into energetic materials, enabling precise modulation of their energy output and structural properties. Herein, we systematically explored efficient synthesis strategies for the key energetic material 3,3′-diamino-4,4′-azofurazan (DAAzF) through chemical, electrochemical, and coupled approaches. Chemical oxidation of 3,4-diaminofurazan (DAF) using Ce⁴⁺ achieved an optimal yield of 83.3% and 97.0% purity. A high-performance Ni‒Co₃O₄@CC anode catalyst was developed, demonstrating excellent electrocatalytic activity for DAF oxidation (118.7 mA·cm^‒2) and long-term stability (92.5% Faradaic efficiency after 15 h). To integrate the high yield of chemical synthesis with the environmental benefits of electrochemistry, an innovative coupled system based on the Ce³⁺/Ce⁴⁺ redox pair was constructed. This modular closed-loop design features an initial reaction chamber, a flow electrolysis cell, and a regeneration chamber, where Ce⁴⁺ is efficiently regenerated on Ni‒Co₃O₄@CC for continuous DAF oxidation. Within 120 min, this coupled system achieved a remarkable cumulative DAAzF yield of 87.46% with 79.95% Faradaic efficiency, significantly outperforming the single electrochemical route (1.62% yield) and the single chemical route (83.3% yield). This work not only provides an innovative and sustainable synthesis pathway for DAAzF but also establishes a versatile green paradigm for preparing other azo-containing energetic materials.

Keywords

azo compounds / electrosynthesis / energetic materials / green chemistry

References

[1] Y. Ma, C. Zhang, J. Li, C. Zhang, and H. Ma, “Green Electrosynthesis of CuN₃ Energetic Materials Coupled With Energy-Saving Hydrogen Production Reaction,” Composites Part B: Engineering 258 (2023): 110723.

[2] X. Wang, “Studies on the Hundred Grams-Scale Preparation and Technology of High-Purity DAOAF,” Southwest University of Science and Technology (2018).

[3] Y. Qin, F. Yang, S. Jiang, M. Lu, and P. Wang, “A New Breakthrough in Electrochemical Synthesis of Energetic Materials: Constructing Super Heat-Resistant Explosives,” Chemical Engineering Journal 486 (2024): 149968.

[4] J. Li, Y. Ma, C. Zhang, et al., “Green Electrosynthesis of 3,3′-Diamino-4,4′-Azofurazan Energetic Materials Coupled With Energy-Efficient Hydrogen Production Over Pt-Based Catalysts,” Nature Communications 14 (2023): 8146.

[5] K. Wang, X. Li, K. Yang, H. Li, and S. Pang, “A Novel Synthetic Method of 1,1,4,4-Tetramethyl-2-Tetrazene (TMTZ) via Photocatalytic Reaction,” Fire Physical Chemistry 2 (2022): 267–271.

[6] C. Yu, W. Zhang, S. Guo, et al., “A Safe and Efficient Liquid‒Solid Synthesis for Copper Azide Films With Excellent Electrostatic Stability,” Nano Energy 66 (2019): 104135.

[7] Y. Ma, Z. Zhao, C. Zhang, et al., “Synergistic Reaction Kinetics of Pt Single Atoms/MoS₂ and Nanoparticles for Energy-Saving Hydrogen Production Assisted by Green Electrosynthesis of Azotetrazolate Compound,” Chemical Engineering Journal 475 (2023): 146303.

[8] X. Fu, J. Du, B. Wu, et al., “Convenient Synthesis of 5,5′-Azotetrazolate Energetic Salts Through Electrochemical Oxidative-Coupling of 5-Amino-1H-Tetrazole Under Mild Conditions,” Journal of the Electrochemical Society 167 (2020): 065503.

[9] C. Zhang, C. Zhang, J. Li, et al., “Green N–N Oxidative Coupling Synthesis of Energetic Compounds and Energy-Saving Hydrogen Evolution Reaction,” Applied Surface Science 611 (2023): 155659.

[10] J. Li, C. Zhang, C. Zhang, et al., “Green Electrosynthesis of 5,5′-Azotetrazolate Energetic Materials Plus Energy-Efficient Hydrogen Production Using Ruthenium Single-Atom Catalysts,” Advanced Materials 34 (2022): 2203900.

[11] A. B. Sheremetev, B. V. Lyalin, A. M. Kozeev, N. V. Palysaeva, M. I. Struchkova, and K. Y. Suponitsky, “A Practical Anodic Oxidation of Aminofurazans to Azofurazans: An Environmentally Friendly Route,” RSC Advances 5 (2015): 37617–37625.

[12] Y. A. Sidunets, M. Krykin, A. N. Pivkina, and L. L. Fershtat, “Introduction of an Azoxy Moiety Into Advanced Energetic Materials: A Case of Azoxyfuroxans,” Organic Letters 28 (2026): 152–156.

[13] S. Wang, Y. Xu, S. Jiang, et al., “4,4′-Bis(Trinitromethyl)-3,3′-Azo/Azoxy-Furazan: High-Energy Dense Oxidizers,” Chemical Engineering Journal 454 (2023): 140358.

[14] J. Guo, Z. Lin, G. Li, and X. Peng, “Density Functional Theory (DFT) Study on the Structures and Energy Properties of High Energy Density Materials Based on Polynitroazofurazan Derivatives,” Materials Today Communications 40 (2024): 109759.

[15] J. Tang, H. Yang, and G. Cheng, “Nitrogen-Rich Tetracyclic-Based Heterocyclic Energetic Materials,” Energetic Materials Frontiers 4 (2023): 110–122.

[16] W. Cao, Q. Tariq, Z. Li, J. Yang, and J. Zhang, “Recent Advances on the Nitrogen-Rich 1,2,4-Oxadiazole-Azoles-Based Energetic Materials,” Defence Technology 18 (2022): 344–367.

[17] C. Luo, X. Ji, S. Hou, et al., “Azo Compounds Derived From Electrochemical Reduction of Nitro Compounds for High-Performance Li-Ion Batteries,” Advanced Materials 30 (2018): 1706498.

[18] V. G. Andrianov and A. V. Eremeev, “Synthesis and Properties of 4-Amino-3-Cyanofurazan,” Chemistry of Heterocyclic Compounds 30 (1994): 608–611.

[19] G. D. Solodyuk, M. D. Boldyrev, B. V. Gidaspov, et al., “Oxidation of 3,4-Diaminofurazan by Some Peroxide Reagents,” Journal of Organic Chemistry of the USSR 17 (1981): 756–759.

[20] D. E. Chavez and E. G. Francois, “Preparation of 3,3′-Diamino-4,4′-Azoxyfurazan, 3,3′-4,4′-Azofurazan, and Pressed Articles,” US Patent (2009): 20090306355.

[21] S. E. Semenov, A. M. Churakov, S. L. Loffe, E. A. Vinogradova, S. G. Zlotin, and O. A. Luk'yanov, “Dibromoisocyanuric Acid—A New Reagent for the Preparation of Azo Compounds From Heterocyclic Amines,” Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science 40 (1991): 1727.

[22] M. Labaj, Z. Jalový, R. Matyáš, J. Nesveda, J. Mikuláštík, and A. Votýpka, “One-Pot Synthesis of Guanidinium 5,5′-Azotetrazolate Avoiding Isolation of Hazardous Sodium 5,5′-Azotetrazolate,” Organic Process Research & Development 28 (2024): 4091–4098.

[23] Z. Zeng, Y. Tang, H. Yang, and G. Cheng, “Synthetic Chemistry of Energetic Materials: Evolution, Current Trends, and AI-Driven Future,” Energetic Materials Frontiers 6 (2025): 267–276.

[24] G. Awasthi, C. Sonne, P. Kumar, and P. Jha, “Development of Anti-TNT@Cu-BTC MOF Thin Film Using Drop Caste Method for Trinitrotoluene (TNT) Sensing,” Microchemical Journal 200 (2024): 110400.

[25] D. Kyprianou, M. Berglund, G. Emma, et al., “Synthesis of 2,4,6-Trinitrotoluene (TNT) Using Flow Chemistry,” Molecules 25 (2020): 3586.

[26] F. Ding, W. Wang, B. Zhao, J. Liu, and Y. Li, “Synthesis and Properties of Diazido Linear Ether Plasticizers,” Chinese Journal of Energetic Materials 27 (2019): 1043–1049.

[27] X. Cao, F. Nan, W. Fan, et al., “Preparation, Formation Mechanism, and Performance of Nitrocellulose Aqueous Coating Based on the Anti-Solvent Method,” Colloids and Surfaces A 684 (2024): 133214.

[28] L. Chen, J. Zhang, D. Meng, et al., “Construction of Nitrate Glycerol Ether Cellulose/RDX Energetic Composite in Gun Propellants and Its Comprehensive Performance,” Cellulose 31 (2024): 5725–5745.

[29] Y. Q. Wang, A. J. Tang, M. Lu, S. Jiang, H. Yang, and G. Cheng, “Electrochemical Nitration to Synthesize 1,3,4-Trinitropyrazole,” Energetic Materials Frontiers (2025).

[30] S. P. Blum, C. Nickel, L. Schäffer, T. Karakaya, and S. R. Waldvogel, “Electrochemical Nitration With Nitrite,” Chemsuschem 14 (2021): 4936–4940.

[31] W. Du, L. Yang, J. Feng, et al., “Advancements in Methodologies and Techniques for the Synthesis of Energetic Materials: A Review,” Energetic Materials Frontiers 5 (2024): 175–190.

[32] Q. Xue, M. Zhang, L. He, F. Bi, B. Wang, and B. Liu, “An Environment Friendly Electrochemical Synthesis of 1,1,4,4-Tetramethyl-2-Tetrazene Energetic Materials From Undimethylhydrazine,” Chemical Communications 59 (2023): 14261–14264.

[33] J. R. Yount and D. G. Piercey, “Electrochemical Synthesis of High-Nitrogen Materials and Energetic Materials,” Chemical Reviews 122 (2022): 8809–8840.

[34] C. Yu, Z. Zheng, W. Zhang, et al., “Sustainable Electrosynthesis of Porous CuN₃ Films for Functional Energetic Chips,” ACS Sustainable Chemistry & Engineering 8 (2020): 3969–3975.

[35] Y. Wang, G. Zhang, S. Jiang, M. Lu, and P. Wang, “Continuous Synthesis of Hexanitrostilbene Using a Difunctional Electrochemical Reactor,” Reaction Chemistry & Engineering 9 (2024): 2419–2426.

[36] J. Li, Y. Li, Y. Ma, et al., “Electrochemical N–N Oxidatively Coupled Dehydrogenation of 3,5-Diamino-1H-1,2,4-Triazole for Value-Added Chemicals and Bipolar Hydrogen Production,” Journal of the American Chemical Society 147 (2025): 9505–9518.

[37] N. Fu, G. S. Sauer, A. Saha, A. Loo, and S. Lin, “Metal-Catalyzed Electrochemical Diazidation of Alkenes,” Science 357 (2017): 575–579.

[38] Y. Q. Wang, Y. H. Dong, Y. Q. Qin, S. Jiang, H. Yang, and G. Cheng, “Construction of Electrochemical Flow Reactor: Static Mixing and Micro-Cell for Dehydrogenation Oxidation From TNT to 2,2′,4,4′,6,6′-Hexanitrostilbene,” Energetic Materials Frontiers 6 (2025): 383–391.

[39] L. Chen, L. M. Barton, J. C. Vantourout, et al., “Electrochemical Cyclobutane Synthesis in Flow: Scale-Up of a Promising Melt-Castable Energetic Intermediate,” Organic Process Research & Development 25 (2021): 2639–2645.

[40] W. Qiao, I. Waseem, G. Shang, et al., “Paired Electrochemical N–N Coupling Employing a Surface-Hydroxylated Ni₃Fe‒MOF‒OH Bifunctional Electrocatalyst With Enhanced Adsorption of Nitroarenes and Anilines,” ACS Catalysis 11 (2021): 13510–13518.

[41] Y. F. Zhang and M. Mellah, “Convenient Electrocatalytic Synthesis of Azobenzenes From Nitroaromatic Derivatives Using SmI₂,” ACS Catalysis 7 (2017): 8480–8486.

[42] M. Cheraghveisi, B. Maddah, and M. Najafi, “Electrosynthesis of Perchlorate Using Neodymium-Doped PbO₂ Electrode: Application of Experimental Design Methodology for Optimization of the Effective Parameters,” Materials Research Express 9 (2022): 025801.

[43] J. Llanos, I. Moraleda, C. Sáez, M. A. Rodrigo, and P. Cañizares, “Electrochemical Production of Perchlorate as an Alternative for the Valorization of Brines,” Chemosphere 220 (2019): 637–643.

[44] F. Wang, M. Rafiee, and S. S. Stahl, “Electrochemical Functional-Group-Tolerant Shono-Type Oxidation of Cyclic Carbamates Enabled by Aminoxyl Mediators,” Angewandte Chemie International Edition 57 (2018): 6686–6690.

[45] Y. Pan, Y. Zou, C. Ma, et al., “Electrocatalytic Coupling of Nitrate and Formaldehyde for Hexamethylenetetramine Synthesis via C–N Bond Construction and Ring Formation,” Journal of the American Chemical Society 146 (2024): 19572–19579.

[46] M. Feng, S. Li, H. He, L. Xi, S. Chen, and X. Yu, “Electrochemically Initiated Intermolecular C–N Formation/Cyclization of Ketones With 2-Aminopyridines: An Efficient Method for the Synthesis of Imidazo[1,2-a]Pyridines,” Green Chemistry 21 (2019): 1619–1624.

[47] S. Patra, I. Mosiagin, R. Giri, T. Nauser, and D. Katayev, “Electron-Driven Nitration of Unsaturated Hydrocarbons,” Angewandte Chemie International Edition 62 (2023): e202300533.

[48] Y. Wang, L. Miao, R. Shi, M. Lu, and P. Wang, “Unraveling the Synergistic Effect of Hollow Sea Urchin-Like Ag–Co₃O₄ Heterostructures in Electrochemical Dehydrogenation Reactions: Interface-Enhanced Electron Transfer and Desorption Process,” ACS Catalysis 15 (2025): 7966–7978.

[49] K. Karaghiosoff, T. M. Klapötke, and M. B. R. Völkl, “Energetic Material Synthesis: Scale-Up Using a Novel Modular Microflow Reactor Setup,” Organic Process Research & Development 28 (2024): 1458–1463.

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