So Should it be okay if I use SHA256 generate a 256 bit key than split the hex string of the key equally into 2 parts and use the first part as an IV in AES 256 bit encryption?
No, there are better ways.
First of all, when you create a key you need a cryptographically secure random number generator. If you derive a key from a master secret - sometimes called a seed - you need a key derivation function or KDF. In the latter case you could e.g. use HKDF with a good hash such as SHA-256. In principle you can create e.g. 384 bits output using HKDF - even when using SHA-256, but I don't think that's a good idea, because of the following part of the answer.
Second, reusing a key / IV combination is not a good idea; depending on the mode and message you may leak just some data or all of the message.
In general you can just use an all zero IV if the key is randomly generated for each message. That would be better than reusing part of the key. As indicated, an IV is generally not thought to be secret, so if you use key data as IV implementations may well leak it.'
If you need to encrypt multiple messages with the same key then you could use a synthetic IV or SIV. That way you would only leak data if messages are completely identical, at the cost of some performance, as SIV modes are multi-pass (messages need to be processed twice).
In general though you should just use a randomized IV and send it with the ciphertext. It isn't clear from the question if that has been considered; it would be the most common way of handling the IV generation.
Finally, keys are not alphanumerical; they consist of bits. Each time when a key is translated into text you are opening a security issue. So don't do that: keep keys binary. I'd rather use AES-128 with a fully random key and use the other 128 bits for the IV than revert to using hexadecimals.
Hexadecimals are only useful for human consumption, e.g. during testing or debugging when it comes to secret keys.