It claims the dust is likely charged by solar radiation, but doesn't say the polarity. The paper mostly talks about using "dielectrophoretic forces"–forces experienced by any dielectric (polarizable) particle in a non-uniform electric field regardless of its net charge.
For negative charges, electrons must be captured. There is a minor component of the cosmic radiation that consists of electrons and it is also possible to capture photoelectrons emitted by nearby particles, but in most cases there should be much less opportunities to capture electrons than to emit them.
Even an incoming electron from the cosmic radiation would first expel a great number of electrons from dust particles before slowing enough to be captured by some particle.
EDIT: As explained in the document linked by another poster, what is written above is correct only for the day side of the Moon.
On the night side, electrons are no longer emitted, but only captured, so the sign of the charge is reversed.
https://ntrs.nasa.gov/api/citations/20220007230/downloads/Fi...
I wonder if it would work for dry snow too. Ie when the flakes are falling that it could be repelled.