dnd 5e – A new ki idea for increasing monk damage 5th edition

Is this idea for a Ki option for a monk starting at 2nd level balanced? Based on playing experience, are there any foreseeable problems with it?

Iron Palm

Immediately before you take the attack action on your turn, you can spend 1 ki point to increase your unarmed strike damage dice to the next rank. This lasts until the end of your turn, and does not effect hand held weapons or other monk weapons only the unarmed strikes.