NiO Nanowire Arrays Based on AAO Templates for Photoelectrochemical Water Splitting
Article Sidebar
Main Article Content
Abstract
Herein, we report the effective preparation and characterization of well-ordered vertically aligned NiO nanowire (NW) arrays, showing potential as a photoactive material for photoelectrochemical (PEC) water splitting, which is an environmentally friendly approach to solar hydrogen energy. The synthesis was based on a precise multi-stage procedure that consisted of an optimized two-step anodization process to generate Anodic Aluminum Oxide (AAO) templates with tailor-made pore sizes (65–94 nm), deposition of Ni through nano-channels by electro-deposition, and subsequent thermal oxidation to generate crystalline NiO. Structural characterizations assured the success of the synthesis: scanning electron microscopy showed dense and uniform arrays of vertically aligned high-aspect-ratio NWs, X-ray diffraction confirmed a phase-pure face-centered cubic NiO structure free from impurities. UV-vis diffuse reflectance spectroscopy characterization revealed that as-prepared samples exhibited an in-tense ultraviolet absorption and band gaps of 3.77 to 4.18 eV. In particular, this bandgap was observed to depend strongly on the NW diameter. Performance, as measured through applied bias photon-to-current efficiency, was architecture dependent and increased systematically with increasing diameter of the nanowires from 65 nm to 94 nm. This trend is rationalized as the result of an optimum trade-off at higher diameters whereby larger diameters afford a greater surface area to promote catalysis, as well as more efficient light trapping and critically axial charge collection, minimizing bulk recombination. The good performance of these photo response properties is therefore attributed to the synergetic effect of a large available surface area, an ordered one-dimensional structure for efficient charge transfer, and a suitable band gap for UV light harvesting. Unlike previous studies, this work establishes a clear diameter-dependent structure–performance relationship in AAO-template NiO NW arrays, providing quantitative insight into the interplay between NW geometry, light harvesting, and axial charge transport. In summary, we provide a template-based, controllable, and scalable synthetic strategy for generating transition metal oxide nano-arrays, providing an explicit design principle for optimizing next-generation nanostructured photo- electrodes for effective solar-driven hydrogen generation.
Downloads
Article Details
This work is licensed under a Creative Commons Attribution 4.0 International License.
How to Cite
References
[1] Fujishima and K. Honda, “Electrochemical photolysis of water at a semiconductor electrode,” Nature, vol. 238, no. 5358, pp. 37–38, Jul. 1972, https://doi.org/10.1038/238037a0.
[2] M. G. Walter et al., “Solar water splitting cells,” Chem. Rev., vol. 110, no. 11, pp. 6446–6473, Nov. 2010, https://doi.org/10.1021/cr1002326.
[3] K. Sivula and R. van de Krol, “Semiconducting materials for photoelectrochemical energy conversion,” Nat. Rev. Mater., vol. 1, no. 2, 2016, https://doi.org/10.1038/natrevmats.2015.10.
[4] X. Chen, S. Shen, L. Guo, and S. S. Mao, “Semiconductor-based photocatalytic hydrogen generation,” Chem. Rev., vol. 110, no. 11, pp. 6503–6570, Nov. 2010, https://doi.org/10.1021/cr1001645.
[5] S. Rajendran et al., “Hydrogen adsorption properties of Ag-decorated TiO₂ nanomaterials,” Int. J. Hydrogen Energy, vol. 43, no. 5, pp. 2861–2868, 2018, https://doi.org/10.1016/j.ijhydene.2017.12.080.
[6] P. V. Rathod, P. P. More, J. M. C. Puguan, and H. Kim, “Phase-changing poly (ionic liquid) with electrolytic functionality for a single-layer ionogel-based smart window,” Sol. Energy Mater. Sol. Cells, vol. 230, 2021, https://doi.org/10.1016/j.solmat.2021.111202.
[7] V. Percec, “Introduction to frontiers in macromolecular and supramolecular science: Part 2,” Chem. Rev., vol. 116, no. 4, pp. 1671–1672, Feb. 2016, https://doi.org/10.1021/acs.chemrev.6b00069.
[8] Y. Ling et al., “Sn-doped hematite nanostructures for photoelectrochemical water splitting,” Nano Lett., vol. 11, no. 5, pp. 2119–2125, May 2011, https://doi.org/10.1021/nl200708y.
[9] A. Taroni, “Frosty reaction,” Nat. Mater., vol. 11, no. 11, p. 910, 2012, https://doi.org/10.1038/nmat3484.
[10] T. W. Kim and K. S. Choi, “Nanoporous BiVO₄ photoanodes with dual-layer oxygen evolution catalysts,” Science, vol. 343, no. 6174, pp. 990–994, Feb. 2014, https://doi.org/10.1126/science.1246913.
[11] W. Lee and S. J. Park, “Porous anodic aluminum oxide,” Chem. Rev., vol. 114, no. 15, pp. 7487–7556, Aug. 2014, https://doi.org/10.1021/cr500002z.
[12] Z. Zhou and S. S. Nonnenmann, “Progress in nanoporous templates,” Materials, vol. 12, no. 16, 2019, https://doi.org/10.3390/ma12162535.
[13] F. Keller, M. S. Hunter, and D. L. Robinson, “Structural features of oxide coatings on aluminum,” J. Electrochem. Soc., vol. 100, no. 9, 1953, https://doi.org/10.1149/1.2781142.
[14] H. Masuda and K. Fukuda, “Ordered metal nanohole arrays,” Science, vol. 268, no. 5216, pp. 1466–1468, Jun. 1995, https://doi.org/10.1126/science.268.5216.1466.
[15] H. Tsuchiya and P. Schmuki, “Self-organized porous hafnium oxide,” Electrochem. Commun., vol. 7, no. 1, pp. 49–52, 2005, https://doi.org/10.1016/j.elecom.2004.11.004.
[16] M. Spodaryk et al., “Electrochemical reduction of CO₂,” Electrochim. Acta, vol. 297, pp. 55–60, 2019, https://doi.org/10.1016/j.electacta.2018.11.124.
[17] Y. Liu, J. Goebl, and Y. Yin, “Templated synthesis of nanostructured materials,” Chem. Soc. Rev., vol. 42, no. 7, pp. 2610–2653, Apr. 2013, https://doi.org/10.1039/C2CS35369E.
[18] J. Zhou et al., “Surface-dependent activity of graphitic felts,” Appl. Surf. Sci., vol. 509, 2020, https://doi.org/10.1016/j.apsusc.2019.144875.
[19] Y. Wang et al., “Tuning optical band gap of NiO thin films,” RSC Adv., vol. 12, no. 34, pp. 21940–21945, Aug. 2022, https://doi.org/10.1039/D2RA01887J.
[20] X. Tao et al., “NiOx nanoplatelet-based films,” Mater. Adv., vol. 3, no. 21, pp. 7881–7893, 2022, https://doi.org/10.1039/D2MA00816E.
[21] K. Zhu et al., “Dual role of surface hydroxyl groups,” J. Am. Chem. Soc., vol. 144, no. 24, pp. 11010–11018, Jun. 2022, https://doi.org/10.1021/jacs.2c04301.
[22] L. Wei et al., “NiO nanosheets coupled with CdS nanorods,” Front. Chem., vol. 9, 2021, https://doi.org/10.3389/fchem.2021.655583.
[23] J. W. Lee et al., “Photoelectrochemical water splitting using nanostructures,” J. Mater. Chem. A, vol. 9, no. 38, pp. 21576–21606, 2021, https://doi.org/10.1039/D1TA04829E.
[24] L. Brock and J. Sheng, “Fabrication of polymeric nanowires,” Micromachines, vol. 11, no. 1, 2019, https://doi.org/10.3390/mi11010046.
[25] A. Al-Haddad et al., “Ultrathin alumina membranes,” ACS Nano, vol. 9, no. 8, pp. 8584–8591, Aug. 2015, https://doi.org/10.1021/acsnano.5b03789.
[26] D. Chidambaram et al., “Surface pretreatments of aluminum alloy,” J. Electrochem. Soc., vol. 151, no. 11, 2004, https://doi.org/10.1149/1.1806393.
[27] P. J. Kelly and R. D. Arnell, “Magnetron sputtering,” Vacuum, vol. 56, no. 3, pp. 159–172, 2000, https://doi.org/10.1016/S0042-207X(99)00189-X.
[28] H. Masuda and M. Satoh, “Gold nanodot array fabrication,” Jpn. J. Appl. Phys., vol. 35, no. 1B, 1996, https://doi.org/10.1143/JJAP.35.L126.
[29] P. Scherrer, “Bestimmung der Größe…,” Nachr. Ges. Wiss. Göttingen, Math. -Phys. Kl., vol. 1918, pp. 98–100, 1918, https://doi.org/10.1002/andp.19183610202.
[30] A. L. Patterson, “The Scherrer formula for X-ray particle size determination,” Phys. Rev., vol. 56, no. 10, pp. 978–982, 1939, https://doi.org/10.1103/PhysRev.56.978.
[31] G. K. Williamson and W. H. Hall, “X-ray line broadening from filed aluminum and wolfram,” Acta Metall., vol. 1, no. 1, pp. 22–31, 1953, https://doi.org/10.1016/0001-6160(53)90006-6.
[32] J. Zhu et al., “Optical absorption enhancement in silicon nanowires,” Nano Lett., vol. 9, no. 1, pp. 279–282, 2009, https://doi.org/10.1021/nl802886y.
[33] L. Cao et al., “Semiconductor nanowire optical antenna absorbers,” Nano Lett., vol. 10, no. 2, pp. 439–445, 2010, https://doi.org/10.1021/nl9036627.
[34] P. Makuła et al., “Determining band gap energy,” J. Phys. Chem. Lett., vol. 9, no. 23, pp. 6814–6817, 2018, https://doi.org/10.1021/acs.jpclett.8b02892.
[35] A. Al-Haddad et al., “Optical absorption band edge of TiO₂ nanotubes,” J. Phys. Chem. C, vol. 119, no. 28, pp. 16331–16337, 2015, https://doi.org/10.1021/acs.jpcc.5b02665.
[36] S. Tarish et al., “ZnO/ZnS core/shell nanotube arrays,” J. Phys. Chem. C, vol. 119, no. 3, pp. 1575–1582, 2015, https://doi.org/10.1021/jp510835n.
[37] S. Tarish et al., “Optical absorption band edge shift,” J. Mater. Chem. C, vol. 4, no. 7, pp. 1369–1374, 2016, https://doi.org/10.1039/C5TC04152J.
[38] Z. Chen, H. N. Dinh, and E. Miller, Photoelectrochemical Water Splitting. New York, NY, USA: Springer, 2013, https://doi.org/10.1007/978-1-4614-8298-7.
[39] Z. Li et al., “Tunable band alignment in Nb₃O₇F nanocrystals,” Nanotechnology, vol. 29, no. 22, 2018, https://doi.org/10.1088/1361-6528/aab68e.
[40] K. Zhu, G. Mul, and A. Huijser, “Dye-sensitized NiO photocathodes,” Chem. Phys. Rev., vol. 5, no. 2, 2024, https://doi.org/10.1063/5.0170022.