Sains Malaysiana 52(12)(2023): 3841-3851

http://doi.org/10.17576/jsm-2023-5212-16

A Coral-Like Mo₂C/TiO₂ Photoelectrode for Photoelectrochemical Water Splitting

(Fotoelektrod Mo₂C/TiO₂ Berstruktur Karang untuk Aplikasi Pembelahan Air Fotoelektrokimia)

SITI NURUL FALAEIN MORIDON¹, KHUZAIMAH ARIFIN^1,3,*, LORNA JEFFERY MINGGU¹,  MOHAMAD AZUWA MOHAMED², MASLIANA MUSLIMIN⁴, AHMAD ZAKI ZAINI² & MOHAMMAD B. KASSIM^1,2

¹Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

²Department of Chemical Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

³Research Center for Advanced Materials, National Research and Innovation Agency (BRIN), Tangerang Selatan 15314, Indonesia

⁴Agensi Nuklear Malaysia, 43000 Kajang, Bangi, Selangor, Malaysia

Diserahkan: 21 Jun 2023/Diterima: 4 Disember 2023

Abstract

Titanium dioxide (TiO₂) is one of the most explored photoelectrode materials of water splitting for hydrogen generation. However, TiO₂ has a bandgap of 3.2 eV, which restricts its energy absorption to UV light, and the photoexcited electrons and holes swiftly recombine. Thus, alteration of the band structure, such as by adding materials as cocatalysts, is needed. 2D molybdenum carbide (Mo₂C) has been researched extensively as an excellent non-noble cocatalyst owing to its Pt-like H⁺ adsorption capacity and high conductivity. In this work, composites of TiO₂ and Mo₂C with four different compositions were produced using the sol-gel method, and their photoelectrochemical activity for water splitting was assessed. The composites were spin-coated onto FTO conducting glass, and FESEM analysis indicated that TiO₂ nanoparticles are widely disseminated across Mo₂C to form coral-like structures. Analysis via X-ray diffraction verified the existence of peaks composed of TiO₂ and Mo₂C. The sample containing 3% Mo₂C had the greatest increase in photocurrent density, which was approximately 1.56 mA cm^-2 at a potential of 1.0 V against Ag/AgCl (1.59 vs. RHE), which is five times that of bare TiO₂. In addition, the composite's onset potential moved to a lower potential. Our findings suggest that adding Mo₂C increases the photoelectrochemical performance of the TiO₂ photoelectrode. This work indicates the feasibility of employing Mo₂C as a cocatalyst to improve the performance of TiO₂ for photoelectrochemical H₂ production.

Keywords: Molybdenum carbide (Mo₂C); photoanode and water-splitting; titanium dioxide (TiO₂)

Abstrak

Titanium dioksida (TiO₂) merupakan salah satu bahan fotoelektrod yang paling diterokai untuk aplikasi pembelahan molekul air bagi penjanaan gas hidrogen. Namun, TiO₂ mempunyai jurang jalur lebar 3.2 eV yang mengehadkan penyerapan tenaganya kepada cahaya UV serta elektron dan lohong foto teruja bergabung semula dengan cepat. Oleh itu, pengubahan struktur jalur dengan kaedah seperti penambahan bahan tambah sebagai ko-pemangkin amat diperlukan. Molibdenum karbida 2D (Mo₂C) telah dikaji secara meluas sebagai ko-pemangkin kerana kapasiti penyerapan H⁺ seperti Pt dan kekonduksian yang tinggi. Dalam kajian ini, komposit TiO₂ dan Mo₂C dengan empat komposisi berbeza dihasilkan menggunakan kaedah sol-gel dan aktiviti fotoelektrokimia bagi proses pembelahan air dinilai. Komposit ini disapukan pada kaca konduktif FTO melalui kaedah salutan putaran dan analisis FESEM menunjukkan bahawa nanozarah TiO₂ tersebar luas di sekitar Mo₂C untuk membentuk struktur seperti karang. Analisis melalui difraksi sinar-X mengesahkan kewujudan puncak yang terdiri daripada TiO₂ dan Mo₂C. Sampel yang mengandungi 3% Mo₂C menunjukkan peningkatan ketumpatan fotoarus yang terbesar, iaitu sekitar 1.56 mA cm-2 pada keupayaan 1.0 V berbanding dengan Ag/AgCl (1.59 berbanding RHE), yang merupakan lima kali ganda TiO₂ kosong. Selain itu, keupayaan permulaan komposit bergerak ke keupayaan yang lebih rendah. Penemuan kami menunjukkan bahawa penambahan Mo₂C meningkatkan prestasi fotoelektrokimia fotoelektrod TiO₂. Kajian ini menunjukkan kerealisasian penggunaan Mo₂C sebagai ko-pemangkin untuk meningkatkan prestasi TiO₂ dalam penghasilan H₂ secara fotoelektrokimia.

Kata kunci: Fotoarus dan pembelahan air; molibdenum karbida (Mo₂C); titanium dioksida (TiO₂)

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*Pengarang untuk surat-menyurat; email: khuzaim@ukm.edu.my