Boron Radicals Identified as the Source of the Unexpected Catalysis by Boron Nitride Nanosheets.

Atomically thin boron nitride (BN) nanosheets were generally considered to be chemically inert until the recent discovery of the surprising catalysis. However, the origin of this unusual catalytic activity remains unclear. We have observed the free boron radicals at the edges and defective sites of BN nanosheets and demonstrated with both experimental and theoretical approaches that the boron radicals in the nanosheets can catalyze the chromogenic reaction of 3,5,3',5'-tetramethylbenzidine and serve as a source of reactive radicals for the co-reactant electrogenerated chemiluminescence of tris(2,2'-bipyridine)ruthenium(2+). These findings suggest BN nanosheets as a type of nonmetal catalyst.