The city shall have power to borrow money for the purpose of constructing, purchasing, improving, extending or repairing of public utilities, recreational facilities or facilities for any other self-liquidating municipal function not now or hereafter prohibited by any general laws of the state, and to issue revenue bonds to evidence the obligation created thereby. Such bonds shall be a charge upon and payable solely from the properties or interest therein acquired and the income therefrom, and shall never be a debt of the city. All revenue bonds issued by the city shall be in accordance with state law.