Reinforced photoinduced behavior of a low-cost mechanochemical synthesized Fe-doped B12As2 nanocrystals

Icosahedral boron arsenide B 12 As 2 is a self-healing semiconductor potentially applied in harshly irradiated environments. However, doping effects were rarely investigated to expand their applications. Hereby, a low-cost mechanochemical strategy is proposed to synthesize B 12 As 2 nanocrystals with a boron transformation rate of ∼70%. Nano-B 12 As 2 of 40–50 nm could be self-doped with Fe element and purified by aqua regia. Fe accounts from ∼0.00–1.77 at% with rotational speeds. Based on nano-size effects and Fe-doping effects, the photoluminescence process shows an indirect band-gap at E g = 2.81 eV and the presence of impurity energy level at E′= 2.11 eV. The optical absorption is red-shifted from the reported UV region to the visible region. The multiply increased photocatalytic hydrogen production (249 μmol∙h −1 ∙g −1 vs. 92.2 μmol∙h −1 ∙g −1 ) and photocurrent density (∼6 times) indicate that Fe-doping enhances the photo-excitement and the separation of the photoinduced carrier. First-principles calculations reveal a robust B 12 As 2 structure doped by Fe, bonding to icosahedral B 12 clusters and its nearest As via the Fe(III) style. Doped-Fe alters HOMO and LUMO orbital components, reduces the optical band-gap and becomes the activated carrier-separation center. Overall, a novel synthetic method and mechanism of Fe-doping are revealed that would facilitate optical applications of B 12 As 2 crystals under extreme conditions.