Sains Malaysiana 51(10)(2022): 3251-3259

http://doi.org/10.17576/jsm-2022-5110-11

Hydrogen Production from Water Splitting using TiO₂/CoS Composite Photocatalyst

(Penghasilan Hidrogen daripada Pemisahan Air menggunakan Komposit Fotomangkin TiO₂/CoS)

MUTIA AGUSTINA¹, SITI NURUL FALAEIN MORIDON², AMILIA LINGGAWATI¹, KHUZAIMAH ARIFIN^2,*, LORNA JEFFERY MINGGU² & MOHAMMAD B. KASSIM³

¹Department of Chemistry, Faculty of Mathematic and Natural Science, University of Riau, Kampus Binawidya, Km 12.5, Simpang Baru, Pekanbaru Riau, Indonesia

²Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

³Department of Chemical Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

Received: 8 February 2022/Accepted: 1 June 2022

Abstract

Photocatalytic water splitting reaction has been considered an ideal method for hydrogen generation. In this study, a composite of TiO₂/CoS photocatalyst prepared by hydrothermal synthesis method assisted by ball milling crushing process was used. The TiO₂/CoS composites prepared with three variation compositions of 90/10, 80/20, and 70/30 were named M-10, M-20, and M-30, respectively. Field-emission scanning electron microscopy images showed that the morphologies of the composites were porous and uniform of nanospheres. The X-ray diffraction and energy dispersive spectroscopy analyses confirmed the presence of CoS in the composites. Ultraviolet–visible absorption characterization demonstrated the smallest bandgap value of approximately 2.72 eV presented by sample M-30 with the photocurrent density of 0.32 mA cm⁻² at 0.9 V vs. Ag/AgCl. The presence of CoS in this study could increase the PC hydrogen generation of TiO₂ by nearly 2.5 times. The composites forming a p-n heterojunction between TiO₂ and CoS could prevent electron–hole recombination and increase the overall photoactivity of TiO₂.

Keywords: Composite; hydrogen production; hydrothermal; water splitting

Abstrak

Tindak balas pemisahan air secara fotokatalisis telah dianggap sebagai kaedah yang ideal untuk penjanaan hidrogen dengan menggunakan semikonduktor sebagai fotomangkin. Dalam kajian ini, komposit fotomangkin TiO₂/CoS yang disediakan melalui kaedah sintesis hidroterma dibantu oleh proses penghancuran penggilingan bebola telah digunakan. Komposit TiO₂/CoS yang disediakan dengan tiga komposisi variasi 90/10, 80/20 dan 70/30 masing-masing dinamakan M-10, M-20 dan M-30. Imej mikroskopi elektron pengimbasan pelepasan medan menunjukkan bahawa morfologi komposit adalah berliang dan nanosfera yang seragam. Analisis difraksi sinar-X dan spektroskopi penyebaran tenaga mengesahkan kehadiran CoS dalam komposit. Pencirian penyerapan cahaya ultraungu-nampak menunjukkan nilai celah jalur terkecil kira-kira 2.72 eV yang ditunjukkan oleh sampel M-30 dengan ketumpatan arus foto 0.32 mA cm⁻² pada 0.9 V lwn. Ag/AgCl. Kehadiran CoS dalam kajian ini boleh meningkatkan penjanaan hidrogen PC TiO₂ sebanyak hampir 2.5 kali ganda. Komposit yang membentuk hetero-simpang p-n antara TiO₂ dan CoS boleh mengurangkan penggabungan semula lohong dan elektron serta meningkatkan keseluruhan fotoaktiviti TiO₂.

Kata kunci: Hidroterma; komposit; pemisahan air; pengeluaran hidrogen

REFERENCES

Arifin, K., Yunus, R.M., Minggu, L.J. & Kassim, M.B. 2021. Improvement of TiO₂ nanotubes for photoelectrochemical water splitting: Review. International Journal Hydrogen Energy 46(7): 4998-5024. https://doi.org/10.1016/j.ijhydene.2020.11.063

Dincer, I. & Acar, C. 2015. Review and evaluation of hydrogen production methods for better sustainability, I. International Journal Hydrogen Energy 40: 11094-11111. https://doi.org/10.1016/j.ijhydene.2014.12.035

Dincer, I. & Bicer, Y. 2018. Photoelectrochemical energy conversion. In Comprehensive Energy Systems, Vol. 1. Energy Fundamental, edited by Ibrahim Dincer. pp. 816-855. https://doi.org/10.1016/B978-0-12-809597-3.00438-7

Franchi, G., Capocelli, M., De Falco, M., Piemonte, V. & Barba, D. 2020. Hydrogen production via steam reforming: A critical analysis of MR and RMM technologies. Membranes 10: 10. https://doi.org/10.3390/membranes10010010

Guo, W., Zhang, X., Yu, R., Que, M., Zhang, Z., Wang, Z., Hua, Q., Wang, C., Wang, Z.L. & Pan, C. 2015. CoS NWs/Au hybridized networks as efficient counter electrodes for flexible sensitized solar cells. Advanced Energy Materials 5: 1500141. https://doi.org/10.1002/aenm.201500141

Hankin, A., Bedoya-Lora, F.E., Alexander, J.C., Regoutz, A. & Kelsall, G.H. 2019. Flat band potential determination: Avoiding the pitfalls. Journal of Materials Chemistry A  7: 26162-26176. https://doi.org/10.1039/C9TA09569A

Herkert, E., Sterl, F., Strohfeldt, N., Walter, R. & Giessen, H. 2020. Low-cost hydrogen sensor in the PPM range with purely optical readout. ACS Sensors 5(4): 978-983. https://doi.org/10.1021/acssensors.9b02314

Liu, Y., Wang, Z. & Huang, W. 2016. Influences of TiO₂ phase structures on the structures and photocatalytic hydrogen production of CuO_x/TiO₂ photocatalysts. Applied Surface Science 389: 760-767. https://doi.org/10.1016/j.apsusc.2016.07.173.

Liu, C., Yang, Y., Lie, J. & Chen, S. 2018. Phase transformation synthesis of TiO₂/CdS heterojunction film with high visible-light photoelectrochemical activity. Nanotechnology 29: 265401. https://doi.org/10.1088/1361-6528/aabd6e

Makuła, P., Pacia, M. & Macyk, W. 2018. How to correctly determine the band gap energy of modified semiconductor photocatalysts based on UV–Vis spectra. The Journal of Physical Chemistry Letters 9(23): 6814-6817. https://doi.org/10.1021/acs.jpclett.8b02892

Molinari, R., Lavorato, C., Argurio, P., Szymański, K., Darowna, D. & Mozia, S. 2019. Overview of photocatalytic membrane reactors in organic synthesis, energy storage and environmental applications. Catalysts 9: 239. https://doi.org/10.3390/catal9030239

Moridon, S.N.F., Salehmin, M.N.I., Arifin, K., Minggu, L.J. & Kassim, M.B. 2021. Synthesis of cobalt oxide on FTO by hydrothermal method for photoelectrochemical water splitting application. Applied Sciences 11: 3031. https://doi.org/10.3390/app11073031

Moridon, S.N.F., Salehmin, M.I., Mohamed, M.A., Arifin, K., Minggu, L.J. & Kassim, M.B. 2019. Cobalt oxide as photocatalyst for water splitting: Temperature-dependent phase structures. International Journal Hydrogen Energy 44: 25495-25504. https://doi.org/10.1016/j.ijhydene.2019.08.075

Niu, Y., Li, F., Yang, K., Wu, Q., Xu, P. & Wang, R. 2018. Highly efficient photocatalytic hydrogen on CoS/TiO₂ photocatalysts from aqueous methanol solution.
International Journal of Photoenergy 2018: Article ID. 8143940. https://doi.org/10.1155/2018/8143940

Ouyang, W., Liu, S., Yao, K., Zhao, L., Cao, L., Jiang, S. & Hou, H. 2018. Ultrafine hollow TiO₂ nanofibers from core-shell composite fibers and their photocatalytic properties. Composites Communications 9: 76-80. https://doi.org/10.1016/j.coco.2018.06.006

Rambey, M.N., Arifin, K., Minggu, L.J. & Kassim, M.B. 2020. Cobalt sulfide as photoelectrode of photoelectrochemical hydrogen generation from water.  Sains Malaysiana  49(12): 3117-3123. http://dx.doi.org/10.17576/jsm-2020-4912-24

Rosen, M.A. & Koohi-Fayegh, S. 2016. The prospects for hydrogen as an energy carrier: An overview of hydrogen energy and hydrogen energy systems. Energy, Ecology and Environment 1: 10-29. https://doi.org/10.1007/s40974-016-0005-z

Scott, K. 2019. Chapter 1: Introduction to electrolysis, electrolysers and hydrogen production, in electrochemical methods for hydrogen production. The Royal Society of Chemistry’s Books pp. 1-27. https://doi.org/10.1039/9781788016049-00001

Wang, Q., An, N., Bai, Y., Hang, H., Li, J., Lu, X., Liu, Y., Wang, F., Li, Z. & Lei, Z. 2013. High photocatalytic hydrogen production from methanol aqueous solution using the photocatalysts CuS/TiO₂. International Journal of Hydrogen Energy 38(25): 10739-10745. https://doi.org/10.1016/j.ijhydene.2013.02.131

^*Corresponding author; email: khuzaim@ukm.edu.my