Sains Malaysiana 55(2)(2026): 293-304

http://doi.org/10.17576/jsm-2026-5502-09

 

Controlling the Hydrothermal Reaction and Unlocking the Potential of Porous Substrates for Enhanced Photoelectrochemical Activity in ZnO on Graphene/Nickel Foam

(Mengawal Tindak Balas Hidroterma dan Membuka Potensi Substrat Berliang untuk Peningkatan Aktiviti Fotoelektrokimia dalam ZnO pada Busa Grafin/Nikel)

 

NUR RABIATUL ADAWIYAH MOHD SHAH¹, NURUL NABILA ROSMAN², MOHAMAD AZUWA MOHAMED^1,3,4, KHUZAIMAH ARIFIN⁵, LORNA JEFFERY MINGGU¹, WAI YIN WONG¹ & ROZAN MOHAMAD YUNUS^1,*

 

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

²Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia

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

⁴Polymer Research Centre (PORCE), Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

⁵National Research and Innovation Agency (BRIN), Research Center for Advanced Materials, Building 224, KST BJ Habibie, South Tangerang 15314, Banten, Indonesia

 

Received: 4 September 2025/Accepted: 27 January 2026

 

Abstract

Zinc oxide (ZnO) is a promising photoanode material for photoelectrochemical (PEC) applications; however, its limitations, including a wide band gap and a high electron–hole recombination rate, hinder its performance. This study addresses these challenges by growing ZnO on graphene/nickel foam (Gr/Ni-foam) using a hydrothermal method, varying reaction parameters (time: 2, 4, 6, 8, 10 h; temperature: 150, 180 and 200 ºC). Results demonstrate significantly enhanced PEC activity via hydrothermal reaction temperature at 200 ºC for 8 h, attributed to the porous Ni-foam substrate, which improves electrolyte accessibility and light harvesting. Gr further reduces by about 50% the photocurrent onset potential, which in turn boosts charge transfer. Interestingly, ZnO on Gr/Ni-foam exhibits outstanding PEC activity (24.93 mA cm^-2 at 1.23 V vs RHE) compared to other tested substrates, primarily due to the advantages of the porous structure of Ni-foam. This research highlights the critical role of substrate selection, particularly the use of porous Ni-foam, in overcoming the intrinsic limitations of ZnO to enabling the development of high-performance photoelectrodes for efficient PEC water splitting.

Keywords: Graphene; nickel foam; photoelectrochemical activity; porous substrate; zinc oxide

 

Abstrak

Zink oksida (ZnO) adalah bahan fotoanod yang berpotensi dalam aplikasi fotoelektrokimia (PEC), tetapi prestasinya agak terhad disebabkan oleh beberapa kelemahan seperti sela jalur lebar dan kadar penggabungan semula pasangan elektron-lohong yang pantas. Untuk menangani isu yang dinyatakan, kajian ini menumbuhkan ZnO di atas grafin/busa nikel (Gr/Busa Ni) menggunakan kaedah hidroterma dengan mengubah parameter tindak balas (masa: 2, 4, 6, 8, 10 jam; suhu: 150, 180, 200 ºC). Keputusan menunjukkan peningkatan aktiviti PEC yang ketara menggunakan tindak balas hidroterma pada suhu 200 ºC selama 8 jam yang disebabkan oleh substrat Busa Ni yang berliang dan ia meningkatkan kebolehcapaian elektrolit dan penyerapan cahaya. Kehadiran Gr mengurangkan keupayaan onset fotoarus sebanyak 50% dan menyebabkan berlaku pemindahan cas yang lebih cekap. Menariknya, ZnO pada Gr/Busa Ni menunjukkan aktiviti PEC yang tinggi (24.93 mA cm^-2 pada 1.23 V vs RHE) berbanding dengan substrat yang lain disebabkan oleh kelebihan struktur Busa Ni yang berliang. Penyelidikan ini menekankan kepentingan pemilihan Busa Ni berliang sebagai substrat fotoelektrod bagi mengatasi batasan intrinsik ZnO, seterusnya membolehkan pembangunan fotoelektrod yang berpestasi tinggi untuk pembelahan molekul air yang cekap melalui PEC.

Kata kunci: Aktiviti fotoelektrokimia; busa nikel; grafin; substrat berliang; zink oksida

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*Corresponding author; email: rozanyunus@ukm.edu.my