A particle approaching an attractive potential can be partially reflected — not by a barrier, but because the wavefunction cannot adapt fast enough to the rapidly varying potential (breakdown of the WKB approximation).
This occurs when the de Broglie wavelength changes significantly within one wavelength — i.e., at very low energies near evanescent potentials.
Observed experimentally: ultra-cold atoms reflecting from van der Waals surfaces (He* from glass), anti-hydrogen experiments at CERN.