PhD scholarship in nanoporous material; how to advertise?
Are there discussion boards, social media accounts, or email lists for societies or interest groups that are directly/indirectly part of your field? Can you email the links to other researchers (the ones you cite or who cite you)? Perhaps there are researchers who are particularly adept at their internet presence (websites, social media accounts etc) who would be willing to share the information.

In my field, there are numerous opportunities for free advertising on all of the above-mentioned areas. Most faculty I know of are happy to share opportunities like that for students, since they recognize funded opportunities are increasingly rare.