It’s unwarranted that writers begin drafting introductions minus having a good topic.
Quick ways to solve this problem is to browse the internet, do a quick search and come up with a good one that feeds your interests.
It is then the job of the Introduction section to ensure that they start reading it and keep reading it, to pull them in and to show them around as it were, guiding them to the other parts of the paper (Methods, Results, Discussion, and Conclusion).
Put simply, the Introduction should answer the question ‘Why:’ why you choose that topic for research; why it is important; why you adopted a particular method or approach; and so on.
However, the 4-step approach described in this article should ease the task.
A final tip: although the Introduction is the first section of the main text of your paper, you don’t have to write that section first.
Once the first sentence has introduced the broad field, the next sentence can point to the specific area within that broad field.
As you may have noticed, the papers in the examples mentioned above introduced the subfield by mentioning 1) remission of some types cancer following accidental infection by Streptococcus pyogenes, 2) organic matter in soil as a source of nutrients for plants and of energy for microorganisms, and 3) imaging techniques to visualize the 3-dimensional structure of the materials and components of batteries on nanoscale.
This concluding part of the Introduction should include specific details or the exact question(s) to be answered later in the paper.
At the same time, the introductory statement should not be too broad: note that in the examples above, the Introduction did not begin by talking about agriculture, cancer, or batteries in general, but by mentioning organic matter in soil, the role of bacteria, and lithium ion batteries.