From a lighting stand point I would have added a large softbox right behind the camera to act as an on axis fill to put some more detail in the shadows, set about a stop below the main light, depending. Then perhaps a reflector under the subject to put a catch light in the bottom of their eyes as well.
For the background I think doing something that wasn't pure black would add depth and breathe some life in to the photos, perhaps make it environmental and find a spot on campus with a pretty background you can throw out of focus. I tend to relate pure black background to moodier photos more so than school photos.
My suggestions wouldn't necessarily make anything better, just different. Lighting and background choices are very subjective, of course.
What light setup did you use? I see two catch lights in their eyes both from camera left. Looks like maybe a larger umbrella and a smaller softbox?