genera
But good question. There's actually been a ton of plants identified as "hyperaccumulators" (which is distinguished from regular "accumulators") of various heavy metals. You can actually find a good list on Wikipedia[0] organized by the contaminant. There's entire journals dedicated to this research. If you peruse that Wikipedia list you'll see Salix spp in general listed as being a noted accumulator of a large variety of contaminants.
Given that there's over 400 species of willows though I doubt this holds uniformally for all species and I also doubt that all 400 species have been rigorously tested for their phytoremediative potential. Common osier (aka S. viminalis) is a common tree in Europe so it's likely that it's just a readily available type species to study
Maybe that same mechanism helps here? If it pulls out water, and the water is contaminated, the willow evaporates the water and keeps the contaminants.
It could then be used as a biofuel in a fluidized bed reactor specifically created to handle such heavy metal dense fuel, as suggested in this paper.[1] Most of the heavy metals remain in the ash, the cadmium needs to be trapped in the exhaust.
1 - https://sci-hub.se/https://doi.org/10.1016/j.biombioe.2011.12.025