Nickel is widely used in industrial fields such as electrocatalysis and energy storage devices. Although micron-sized nickel particles exhibit excellent mechanical durability, their low specific surface area limits their reactivity. We modified the surface of micron-sized nickel particles with nanostructured nickel oxalate and investigated the effects of the solvent dielectric constant, surfactant, and thermal treatment atmosphere on the resulting particle morphology and phase transformation. Rietveld refinement analysis confirmed that changes in the solvent dielectric constant led to increased or diminished crystallinity of specific planes in nickel oxalate, resulting in diffraction patterns distinct from standard JCPDS data. These structural changes were also found to influence the morphology of the synthesized nickel oxalate. The results demonstrate that nickel oxalate serves as an effective precursor for producing Ni and NiO phases, and shape control of the final product can increase the surface reactivity of micron-sized nickel materials.

1. Introduction 
2. Experimental Section 
3. Results and Discussion 
4. Conclusions 
Funding
Conflict of Interest 
Data Availability Statement 
Author Information and Contribution 
Acknowledgments
References

• Eunbi Park(Department of Hydrogen Energy, Dankook University, Cheonan 31116, Republic of Korea)
• Jongwon Bae(Department of Hydrogen Energy, Dankook University, Cheonan 31116, Republic of Korea)
• Sera Kang(Department of Hydrogen Energy, Dankook University, Cheonan 31116, Republic of Korea)
• Minsu Kang(Department of Hydrogen Energy, Dankook University, Cheonan 31116, Republic of Korea)
• Kun-Jae Lee(Department of Hydrogen Energy, Dankook University, Cheonan 31116, Republic of Korea, Department of Energy Engineering, Dankook University, Cheonan 31116, Republic of Korea) Corresponding author
• Suseong Lee(Department of Energy Engineering, Dankook University, Cheonan 31116, Republic of Korea)