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

Icosahedral boron arsenide B12As2 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 B12As2 nanocrystals with a boron transformation rate of similar to 70%. Nano-B12As2 of 40-50 nm could be self-doped with Fe element and purified by aqua regia. Fe accounts from similar to 0.00-1.77 at% with rotational speeds. Based on nano-size effects and Fe-doping effects, the photo-luminescence 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 mu mol center dot h(-1) center dot g(-1) vs. 92.2 mu mol center dot h(-1) center dot g(-1)) and photocurrent density (similar to 6 times) indicate that Fe-doping enhances the photo-excitement and the separation of the photo-induced carrier. First-principles calculations reveal a robust B12As2 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 B12As2 crystals under extreme conditions.