  Fouling of surfaces leads to performance degradation in many energy-intensive
industrial processes, but the present solutions are either too complicated to
be routinely used or incomplete for eradication. Here we propose and
demonstrate that carbon-containing deposits can be catalytically wiped out in
an efficient way by roaming palladium nanoparticles with extreme shape
flexibility at relatively low temperatures. Surprisingly, during their dramatic
liquid-like migrations, these particles could still maintain crystalline
interior and conserve their initial crystal orientations through self-surface
diffusion. Moreover, these catalytic particles were even able to become
regenerated by other roaming particles after occasionally deactivated by
surface coking or multiple-particle sintering. These findings shed light on
metabolically driven, "living" nanocrystals, and also open a new avenue for
efficient catalysis.
