Authors: Parsa Borhani | Erfan Kamali | Kenneth D. Harris | Shiva Mohajernia
Source: ECS Meeting Abstracts (article, 2025-07-11)
Field: Materials Science — Materials Chemistry

Nanostructured Nickel Oxide Electrodes Fabricated Using Glancing Angle Deposition for Electrochemical Water Splitting Green hydrogen is considered a key sustainable energy source and is emphasized in the United Nations Sustainable Development Goals (SDGs) (Morton et al., 2017). It is offered as a clean alternative to fossil fuels, playing an important role in reducing carbon emissions. Currently, it is estimated that most hydrogen—about 95%—is produced through “grey hydrogen” methods, in which hydrogen is extracted from fossil fuels without capturing the resulting carbon dioxide. Significant amounts of CO₂ are released in this process, contributing to climate change (Gunathilake et al., 2024). Green hydrogen, which is produced by splitting water using renewable energy, is considered much cleaner, but it is priced significantly higher at USD 2.28–7.39 per kilogram compared to grey hydrogen, which is priced below USD 1.00 per kilogram. A major barrier to large-scale green hydrogen adoption is posed by this cost-gap (Arcos &amp; Santos, 2023). To address this challenge, we made enhancements to nickel oxide electrodes for water splitting via engineered nanostructure. Specifically, glancing angle deposition (GLAD), an advanced physical vapor deposition technique, was employed (Hawkeye &amp; Brett, 2007). In this method, thin films are deposited at an oblique angle, typically above 70°, and nanostructures such as rods or helices are created during this process. With GLAD, a significant increase in the surface area of the electrodes is achieved, enhancing catalytic activity. Electrolytic efficiency is improved by the larger surface area, and precise control over the structure and thickness of the deposited film is also enabled by GLAD, making it a powerful tool for optimizing electrode surface morphology and catalytic efficiency. In this study, the effects of deposition angle, film thickness, and deposition rate over the oxygen evolution reaction (OER) performance of nickel oxide GLAD-fabricated electrodes were investigated. Thicknesses of 300 nm, 500 nm, 700 nm, and 1000 nm were considered, while deposition angles of 74°, 78°, 83°, and 86° were tested. Among these parameters, the best performance was achieved at a deposition angle of 78° and a thickness of 500 nm, where an optimal balance of surface area and mass transfer was achieved, resulting in an overpotential of 355 mV at 10 mA/cm². It was observed that increasing the deposition angle caused a decrease in areal density of the nanocolumnar NiO structures. To further optimize electrode performance, the effect of deposition rate was examined under four different scenarios, all tested at a deposition angle of 78° and a thickness of 500 nm: (1) a constant deposition rate of 0.2 nm/s, (2) a constant deposition rate of 0.4 nm/s, (3) a deposition rate starting at 0.2 nm/s and gradually increasing to 0.4 nm/s, and (4) a deposition rate starting at 0.4 nm/s and gradually decreasing to 0.2 nm/s. The results revealed that the fourth scenario, where the deposition rate started at 0.4 nm/s and decreased to 0.2 nm/s, yielded the best performance. Under these conditions, an overpotential of 300 mV was achieved at 10 mA/cm². X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the crystal structure and morphology of the electrodes. These findings highlight the critical role of fine-tuning deposition parameters in optimizing electrode performance and advancing cost-effective green hydrogen production. Arcos, J. M. M., &amp; Santos, D. M. F. (2023). The Hydrogen Color Spectrum: Techno-Economic Analysis of the Available Technologies for Hydrogen Production. Gases , 3 (1), 25–46. https://doi.org/10.3390/gases3010002 Gunathilake, C., Soliman, I., Panthi, D., Tandler, P., Fatani, O., Ghulamullah, N. A., Marasinghe, D., Farhath, M., Madhujith, T., Conrad, K., Du, Y., &amp; Jaroniec, M. (2024). A comprehensive review on hydrogen production, storage, and applications. Chemical Society Reviews , 53 (22), 10900–10969. https://doi.org/10.1039/D3CS00731F Hawkeye, M. M., &amp; Brett, M. J. (2007). Glancing angle deposition: Fabrication, properties, and applications of micro- and nanostructured thin films. Journal of Vacuum Science &amp; Technology A , 25 (5), 1317–1335. https://doi.org/10.1116/1.2764082 Morton, S., Pencheon, D., &amp; Squires, N. (2017). Sustainable Development Goals (SDGs), and their implementation: A national global framework for health, development and equity needs a systems approach at every level. British Medical Bulletin , 124 (1), 81–90. https://doi.org/10.1093/bmb/ldx031 Figure 1 Materials science ; Nickel ; Electrode ; Electrochemistry ; Deposition (geology) ; Nickel oxide ; Water splitting ; Oxide ; Chemical engineering ; Nanotechnology ; Optoelectronics ; Metallurgy ; Chemistry ; Catalysis Copper-based nanomaterials and applications ; Semiconductor materials and devices ; Electronic and Structural Properties of Oxides