I agree that "please join me in welcoming..." is a better formula here. Also, maybe instead of a list of titles, it would be useful to look into some of his publications and notable talks. When someone introduces a speaker, I always think it's very well done when they point out some of the earlier work that other people may have overlooked or some combination of research interests that makes the speaker unique. It shows that you've taken time to look into their work, and makes them feel special.