How to supply an op-amp from a 9V Battery?
According to page 4 of the LM741 datasheet, the minimum supply voltage is +/- 10V, so powering it with +/-9V isn't guaranteed to work. The LM741 is a very old design, and its characteristics are not as good as modern op amps (that being said, it works fine, but it's not what I'd pick for a new design). I'd recommend getting a more modern op amp, you probably want one with rail to rail inputs and outputs as well as a lower minimum supply voltage. I've narrowed down the listing here, you still will want to make sure whatever you pick can use the supply you're planning to use.