An investor will put money into a business that they think will give them a profitable return. To convince then you will need to explain why or prove that people with use your app in large enough numbers to make it investment worthy.
Who are your target users?
Why will they use use your app over the alternatives?
Have you tested the MVP or at least the concept with users and what were the results?
These are the preliminary questions I would ask as an investor in deciding whether to continue the conversation.
Good luck with your venture!