Fig. 3

a Absorbance spectrum acquired from a representative mechanically-exfoliated BP flake. It shows two clear bands in the UV region and a shoulder in the blue wavelength. b A schematic representation of the photo-oxidation mechanism, whereby reactive oxygen species are generated via the interaction of atmospheric oxygen and light. These reactive oxygen species result in the degradation of BP. c, d The generation of damaging reactive oxygen species (¹O₂ and OH^•) under, different excitation wavelengths (see experimental section for details about ROS generation). It is seen that the UV ligh t generates the maximum reactive oxygen species that degrade BP. This is in line with physical observations presented in the AFM results shown in Fig. 2. The error bars in c, d are standard deviations obtained from three independent experiments with each experiment comprised of four replicates