North-Caucasus Federal University (Stavropol, Russia)

I. S. Chikulina, Senior Researcher of the Department of Scientific Affairs, iraaaa@yandex.ru
D. S. Vakalov, Head of the Physicochemical Research Methods Department, Candidate of Physical and Mathematical Sciences, dvakalov@ncfu.ru
О. V. Vakalova, Senior Researcher of the Department of Scientific Affairs, Tigra55586@mail.ru
Е. D. Nazaretova, Laboratory Assistant of the Department of Functional Materials and Engineering Design, Student, ekaterina.nazaretova@mail.ru

The effect of the synthesis conditions of nickel oxide powders obtained from Ni(OH)₂ on the particle size distribution of the samples has been investigated. Precursor powders have been synthesized by direct precipitation using 0.5 M solutions of nickel chloride (NiCl₂·6H₂O) and nickel nitrate hexahydrate (Ni(NO₃)₂·6H₂O). Nickel hydroxide (Ni(OH)₂) has been precipitated from the nickel-containing salt solutions using a 3 M ammonia (NH₃) solution until a pH of 6.5 is reached. Precise control of the pH during synthesis ensures controlled particle growth and stability of the colloidal system. The obtained samples have been dried at 120 °C for 16 h, followed by a two-stage low-temperature synthesis of nickel oxide (NiO) from Ni(OH)₂ at 400 and 800 °C. It is established that heat treatment significantly affects particle agglomeration and the formation of aggregate structures. The particle size distribution of the samples obtained at different stages of the low-temperature synthesis has been determined using a Shimadzu SALD-7500 nano laser particle size analyzer. The smallest particles have been found to form when the NiCl₂ solution is used, which may be associated with differences in the precipitation mechanism and crystallite growth rate. Using the developed procedure, NiO nanopowders with a volume-based particle size distribution of D10 = 0.05 μm, D50 = 0.15 μm, and D90 = 0.69 μm have been obtained, confirming the effectiveness of the selected synthesis conditions. As a result of this study, a procedure for synthesizing NiO nanopowders with controlled particle size and morphology has been developed.

1. Narender S. S. et al. Nickel oxide nanoparticles: a brief review of their synthesis, characterization, and applications. Chemical Engineering & Technology. 2022. Vol. 45, Iss. 3. pp. 397–409.
2. Diao C. C. et al. Morphological, optical, and electrical properties of p-type nickel oxide thin films by nonvacuum deposition. Nanomaterials. 2020. Vol. 10, Iss. 4. pp. 636.
3. Kaur N. Nickel oxide nanostructures for gas sensing: recent advances, challenges, and future perspectives. ACS sensors. 2025. Vol. 10, Iss. 3. pp. 1641–1674.
4. Sviridenko N. N., Urazov Kh. Kh., Sudarev E. A. The effect of nickel oxide on the composition of products of catalytic cracking of heavy oil from the Zyuzeevsky deposit. Vestnik Tomskogo gosudarstvennogo universiteta. Khimiia. 2022. No. 28. pp. 22–33.
5. Abbas M. et al. Structural, optical and electrical properties of NiO thin films for hole transport layer in chalcogenide and perovskite materials based solar cells. Chalcogenide Letters. 2025. Vol. 22, Iss. 7. pp. 381–390.
6. Yu X. et al. Controlled NiO x defect engineering to harnessing redox reactions in perovskite photovoltaic cells via atomic layer deposition. ACS Applied Materials & Interfaces. 2024. Vol. 16, Iss. 24. pp. 31114–31125.
7. Shkerin S. N. et al. Defective structure of lithium-doped nickel oxide. Fizika tverdogo tela. 2023. Vol. 65, No. 10. pp. 1795–1801.
8. Karpov I. V. et al. Investigation of electrochemical properties of a nickel oxide-based supercapacitor electrode by vacuum-arc synthesis. Pisma v Zhurnal tekhnicheskoy fiziki. 2024. Vol. 50, No. 3. pp. 7–9.
9. Dhas S. D. et al. Sol-gel synthesized nickel oxide nanostructures on nickel foam and nickel mesh for a targeted energy storage application. Journal of Energy Storage. 2022. Vol. 47. 103658.
10. Tran T. T. B., Park E. J., Son J. T. Optimization of hydrothermal synthesis of nickel oxide with flower-like structure. Korean Journal of Chemical Engineering. 2024. Vol. 41, Iss. 2. pp. 473–478.
11. Ahmaruzzaman M. Metal oxides (ZnO, CuO and NiO)-based nanostructured materials for photocatalytic remediation of organic contaminants. Nanotechnology for Environmental Engineering. 2023. Vol. 8, Iss. 1. pp. 219–235.
12. Salleh N. A. et al. Microwave assisted synthesis of nickel oxide nanoparticles at different pH via sol gel method: Experimental and first-principles investigations. Inorganic Chemistry Communications. 2024. Vol. 164. 112415.
13. Zelensky V. A. et al. Micro- and nanomodification of the structure during cyclic redox treatment of porous nickel sintered using a pore forming agent. Perspektivnye materialy. 2022. No. 11. pp. 69–78
14. Skundin A.M. et al. Effect of lithium-containing electrolyte composition on electrochemical characteristics of layered nickel, cobalt and aluminum oxide. Zhurnal fizicheskoy khimii. 2025. Vol. 99, No. 10. pp. 1589–1594.
15. Ivanova T., Harizanova A., Petkov N. Optical, electrical, and structural properties of nio thin films, derived by sol–gel method. Gels. 2025. Vol. 11, Iss. 12. 944.
16. Praveenkumar V. et al. Effect of fuel concentration on structural, vibrational, morphological properties and particle stability of NiO nanoparticles. Ceramics International. 2022. Vol. 48, Iss. 24. pp. 37027–37031.
17. Ozmen O. et al. Efficient and controlled nano-catalyst solid-oxide fuel cell electrode infiltration with poly-norepinephrine surface modification. Journal of Power Sources. 2021. Vol. 485. 229232.
18. Nizam N. S. A. M. et al. Strategies for enhancing the stability and performance of nickel-based catalysts in solid oxide fuel cells: A review. Journal of Alloys and Compounds. 2025. Vol. 1033. 181263.
19. Lee H., Baek J., Choi M. Recent advances and challenges in degradation issues of direct ammonia solid oxide fuel cells: comprehensive review. Journal of Materials Chemistry A. 2025. Vol. 13, Iss. 26. pp. 20080–20103.
20. Simonenko T. L. et al. Triethanolamine-assisted hydrothermal synthesis of hierarchically organized nickel oxide particles. Zhurnal neorganicheskoy khimii. 2022. Vol. 67, No. 5. pp. 575–581.
21. Zhang Z. et al. Achieving high stability in nickel-based solid oxide fuel cell stacks with direct internal reforming of methane. International Journal of Hydrogen Energy. 2025. Vol. 106. pp. 1285–1295.
22. Timurkutluk B., Ucar E. A route for enhancing the performance of solid oxide fuel cell anodes produced from commercial powders. Journal of Power Sources. 2025. Vol. 625. 235715.
12. Maccato C. et al. Plasma-assisted fabrication of NiO nanoarchitectures: from design to oxygen evolution electrocatalysis. Catalysis Science & Technology. 2025. Vol. 15, Iss. 21. pp. 6358–6371.
24. Sun Z. et al. Hard lewis acid sites modulate competitive adsorption in nickel oxide for efficiency 5-hydroxymethylfurfural oxidation. Advanced Functional Materials. 2026. Vol. 36, Iss. 11. e16593.
25. Mahmud M. et al. A concise review on applications of nickel oxide nanoparticles and their extraction parts. International Journal of Advanced Biological and Biomedical Research. 2025. Vol. 13, Iss. 3. pp. 317–340.
26. Ahmad W. et al. A review on current trends in the green synthesis of nickel oxide nanoparticles, characterizations, and their applications. Environmental Nanotechnology, Monitoring & Management. 2022. Vol. 18. 100674.
27. Silva F. A., Salim V. M. M., Rodrigues T. S. Controlled nickel nanoparticles: a review on how parameters of synthesis can modulate their features and properties. Applied Chem. 2024. Vol. 4, Iss. 1. pp. 86–106.
28. Mou J. et al. Nickel oxide nanoparticle synthesis and photocatalytic applications: evolution from conventional methods to novel microfluidic approaches. Microfluidics and Nanofluidics. 2022. Vol. 26, Iss. 4. 25.
29. Hassan M. R. et al. Synthesis and applications of nickel nanoparticles (NiNPs)—comprehensive review. JUC. 2023. Vol. 19. pp. 9–37.