Yes, you can use the same approval notice but you must provide evidence that you are now a US citizen. The petition automatically changes to an Immediate Relative petition once you become a US citizen. The underlying question though is whether or not your husband is eligible to adjust his status in the United States. If he entered illegally, for example, he cannot adjust in the US unless he is protected by a law that you have probably come across generally referred to as 245(i) (its the section number of the law). There are other things that could make him ineligible and there are creative ways to find people eligible under 245(i). Generally, if he has ever been arrested and/or you are not sure if he is eligible to apply, you should definitely speak to an immigration attorney. Good luck.
Disclaimer: This answer does not constitute legal advice, and should not be relied on as each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.