There are several options for publishing a journal article Open Access:
Published in a journal that isn't Gold Open Access? Check Sherpa/RoMEO for your publisher's Green Open Access (self-archiving) policy:
A predatory publisher exploits the gold open access model in order to gain a profit from authors' fees. In addition, predatory publishers frequently do not adhere to academic standards, such as rigorous peer review, during the publication process. Many are not transparent about their operations and use official sounding names in order to recruit authors.
If you are unsure about the quality of an open access journal in your discipline, please contact your subject liaison.