'Thermal substitution' for preparing ternary BCN nanosheets with enhanced and controllable nonlinear optical performance

Boron carbon nitride (BCN) nanosheets have gained increased attention as a novel semiconductor because of their controllable band-gap and environmentally-friendly properties. This study presents a facile 'thermal substitution' method for preparing BCN nanosheets through substitutional C doping into hexagonal boron nitride nanosheets (BNNSs) at 850 degrees C. 'Thermal substitution' is an effective method used to tune the band-gap of BCN nanosheets by adjusting the amount of carbon atoms incorporated. After irradiation by laser pulses at 1064 and 532 nm, the as-obtained BCN nanosheets exhibit excellent nonlinear optical (NLO) performance. The NLO absorption properties of the nanosheets shift from saturable absorption to reverse saturable absorption. The corresponding NLO performance can be adjusted by controlling the carbon content in the BCN nanosheets. The developed BCN nanosheets can be utilised as a new and advanced NLO material for sensitive optical components and laser protection.