“…The band gaps of the samples could be deduced from plots ( Fig. 4b) of (αhν) 1/2 versus energy (hν), and were calculated to be 3.24, 2.70 and 1.79 eV for BiOCl, BiOBr and BiOI, respectively, which are consistent with those reported previously (Liu et al, 2014;Su et al, 2014;Hu et al, 2014). According to Fig.…”