Industrial Consultancy & Sponsored Research (IC&SR) , IIT Madras

AAO Template-assisted Synthesis Process Coupled with Alkali Etching to Develop Zinc Oxide Branched Superstructures

Technology Category/Market

Technology: Zinc Oxide branched superstructures

Industry: Chemical, Renewable energy, Pharmaceutical

Applications: Catalysis, Sensing, Electronics

Market: The global nano zinc oxide market was valued at $0.3 billion in 2021, projected to reach $1.1 billion by 2031, growing at a CAGR of 13.2% from 2022 to 2031.

Targeted Industries

Watermarking IP design,

Electronic circuits

Image Gallery

Problem Statement

  • In the prior arts, patent and non patent literature, there are few processes discussed for production of zinc oxide superstructures which incur high initial equipment cost & requires modifiers, seed layers, or surface directing agents which can compromise the purity of the developed nanostructures.
  • Further, the above prior art techniques require variety of organic or inorganic ingredients with time-consuming processing steps, including heat treatment. Hence, there is a requirement of a simple process to address the above issues efficiently.


Present Patent talks about a process for preparation of zinc oxide (ZnO) superstructures by coupling Anodic Aluminum Oxide (AAO) template-assisted synthesis with alkali etching, wherein the process comprises a step of:

  • Electro polishing ultrasonicallycleaned aluminum strips.
  • Conducting first anodizationfor 1 hour;
  • Oxide etching at 60ºC for 1 hour.
  • Conducting second anodization for 2 hours.
  • Thinning the alumina dielectric barrier layer by sequentially reducing the anodization voltage.
  • Etching the sample in 5 wt. % phosphoric acids at 20°C for 45 min to widen the pores.
  • Electrochemical deposition of zinc oxide (ZnO) nanowires within the AAO nanochannels.
  • Hydroxide etching of ZnO nanowires embedded in the AAO template to obtain ZnO superstructures.

Further, it talks about various features for obtaining ZnO superstructure as shown: 

  1. The Electro-polishing step is done at 20V DC, at 100C for 60s including a mixture of perchloric acid & ethanol in 1:4 v/v ratio.
  2. First & second anodization steps are conducted in an electrolyte of 0.3M oxalic acid solution at 20°C with a constant voltage of 45V DC.
  3. In the hydroxide etching step, the nanowires are etched further for a period of 0 to 60 minutes under concentration range of 0.5 to 2M NaOH at a Temp. between 5 to 50°C.

In this instant, the process of obtaining ZnO superstructure along with outcomes are depicted in the figures.

Key Features/Value Proposition

Technical Perspective:

Claimed Patent provides simple fabrication process to develop zinc oxide (ZnO) superstructures, by coupling anodic aluminum oxide template-assisted synthesis with alkali etching.

Industrial Perspective: 

Patented Process is cost-effective, less time taking, scalable technique to grow zinc oxide (ZnO) SSs with file tunable morphologies and modifier/catalysts/seed layers free.

Questions about this Technology?

Contact for Licensing

Research lab

Prof. Lakshman Neelakantan,

Prof. Parasuraman Swaminathan

Department of Metallurgical & Materials Engineering

Intellectual Property

  • IITM IDF Ref. 2249.

  • IN Patent No: 421576 (Granted)

Technology Readiness Level

TRL- 3/4

Proof of Concept Ready & tested and validated in Laboratory stage.  

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