Q: How to publish a novel idea in a journal?

That is indeed an interesting idea! Most research articles require not just an idea, but also either a theory or a research study to show how the idea can be applied in the real world. For e.g., if you are able to demonstrate how a car can run entirely on water as fuel, you can write a manuscript explaining the rationale, methods applied and your findings, and then discussing your novel ideas with those previously published in literature. You may review other published articles in your field and select suitable journals that publish similar work.

Related reading:

Finding the right journal to disseminate your research

How can I select a suitable journal for submitting my manuscript?

Manuscript structure: How to convey your most important ideas through your paper