Unlike the general databases, literature (or any subject) specific databases generally focus solely on journal articles as a publication type and do not have a broad, multidisciplinary approach.
In addition looking at Graphic Novels and Comics from a literary perspective, it is helpful to broaden your research and venture into other disciplines. Here is a brief list of databases that may enhance your research:
Cartoon America: James Arthur Wood, Jr., began collecting original cartoon art as a childhood hobby. Wood worked diligently throughout his professional life as an editorial cartoonist to showcase his collection. He ultimately turned to the Library of Congress to preserve and present his collection to the American people and the world. The Library's Art Wood Collection of Cartoon and Caricature contains more than 36,000 original cartoon drawings. The 102 drawings selected for this exhibition reflect Woods primary collecting interests and the vitality of an innovative and evolving art form
The online exhibition "Wonderfully Vulgar" presents a selection of British comics from the 1870s (the Ally Sloper era) to the 1930s (knockabout comics). The phrase "wonderfully vulgar" used in the exhibition title is taken from an interview in which Charlie Chaplin recalled his pleasure in reading comics as a boy in 1890s London.
The exhibition is based on a collection of around 5000 historical British comics housed in the Library (BIS) of the University of Oldenburg in Germany.