Contents lists available at ScienceDirect Microelectronic Engineering journal homepage: www.elsevier.com/locate/mee Research paper Efect of zinc oxide nucleation on fexible bio based carbon nanotube cotton via chemical bath deposition method Juraina Md Yusof a,b, ⁎ , Ismayadi Ismail b , Muhammad Rahimi Yusop c , Suraya Abdul Rashid a , Mohd Ali Mat Nong a , Mohamed Husham Mohamed Ali a a Materials Processing and Technology Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, UPM, Serdang, Selangor 43400, Malaysia b Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, UPM, Serdang, Selangor 43400, Malaysia c School of Chemical Sciences and Food Technology, Universiti Kebangsaan Malaysia, UKM, Bangi, Selangor 43600, Malaysia ARTICLE INFO Keywords: Waste cooking oil Zinc oxide nanorods Carbon nanotubes sponge Aqueous chemical growth ABSTRACT The preparation and characterization of zinc oxide nanorods on fexible bio-based carbon nanotubes cotton (CNTC) was investigated. CNTC was synthesized via foating catalyst chemical vapor deposition reactor using waste cooking palm oil as hydrocarbon source. One sided CNTC facet was used as substrate hosting the growth of zinc oxide nanorods. The zinc oxide (ZnO) nucleation seed layer was deposited onto the CNTC using 99.9% Zn target and ZnO nanorods were synthesized via chemical bath deposition method. It was observed that the average diameter and length of nanorods increased proportionally to the increase of seed layer thickness. However, the aspect ratio decreased with the escalation of seed layer thickness due to its diameter signifcant enlargement. The highest aspect ratio is 9.4 and the lowest is 6.3 for seed layer thickness at 117 nm and 282 nm respectively. The electrical conductivity measurement showed that sample with thicker seed layer yielded better conductive value due to the ease of electrical charges movement with lower energy gap. Conclusively, ZnO nanorods have been successfully grown on CNTC surface via facile synthesis route with minimal sample pre- preparation exertion. The hybrid of ZnO/CNTC ofers promising future as CNTC is fexible, readily available and incurs lower cost than other substrates. 1. Introductıon Nowadays the usage of cooking palm oil has tremendously escalated due to the infux of small and medium enterprises into the food and beverages manufacturing industry. Hence, the amount of waste cooking oil has increased simultaneously which leads to uncontrolled dumping and discharging to the environment. In order to solve this problem, waste cooking palm oil (WCPO) has been recycled and turned into products with economic potential. Most research converts WCPO into inexpensive feedstock in biodiesel production. For instance, refned vegetable oil was replaced by WCPO as a source of triglycerides for biodiesel production [1,2]. Further research used WCPO as carbon precursor to synthesize carbon nanotubes (CNTs) by modifying double- stages thermal chemical vapor deposition set-up [3]. CNTs from WCPO with high purity and crystallinity were studied for compact energy storage application in supercapacitor [4]. Another study focused on the production of nano‑carbon, one of carbon allotropes in nanometer- scaled particle sizes using WCPO as carbon precursor [5]. Carbon nanotubes cotton or sponge is a bulk form of either multi walls, single walls or both types of CNTs that appeared in lengthy three- dimensional network threads. Physically, it resembles cotton fber used in the clothing industry, which is soft, fufy and lightweight. Previously, multi walls carbon nanotubes (MWCNTs) sponges synthe- sized in a domestic microwave oven were fabricated as light emitting transistor and feld efect transistor [6]. Another research reported on CNTs sponges used for fltration and water treatment, as well as for soft magnetic memories and magnetic targeted drug delivery platforms, due to its highly porous structure and superlight weight density [7]. A study reported on the yield of nitrogen doped CNTs sponges by including acetone in the carbon precursors for an ethanol-benzylamine synthe- sized in aerosol-assisted chemical vapor deposition experiment [8]. Another study reported on CNTC synthesized from ethanol via a foating catalyst chemical vapor deposition (FCCVD) reactor and was used to examine the efects of ferrocene as catalyst to the diameter and electrical properties of CNTC. It was found that the variation of ferro- cene concentration afected CNTs diameter formation and its electrical https://doi.org/10.1016/j.mee.2020.111439 Received 7 July 2020; Received in revised form 17 September 2020; Accepted 28 September 2020 ⁎ Corresponding author at: Materials Processing and Technology Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, UPM, Serdang, Selangor 43400, Malaysia. E-mail address: juraina@upm.edu.my (J.M. Yusof). Microelectronic Engineering 234 (2020) 111439 Available online 02 October 2020 0167-9317/ © 2020 Elsevier B.V. All rights reserved. T