Harnessing photocatalytic efficacy of SnO 2 nanoparticles via Bi doping toward degradation of recalcitrant organic pollutants

Abstract We report a simple, atom economy co-precipitation route expanding the repertoire for the preparation of Bi doped SnO 2 (Bi-SnO 2 ) nanoparticles (NPs) with the usage of oxalic acid as cost effective photocatalyst for elimination of model organic pollutants, rose Bengal (RB) dye and ciprofloxacin (CP), under stimulated UV irradiation addressing the urgent need for waste water treatment. We investigate the effect of Bi dopant in tetragonal rutile SnO 2 host tuning geometrical, optical, and electronic structures, influencing photocatalysis capability, in this research. TEM measurement revealed the as-synthesized SnO 2 and Bi-SnO 2 (1:3 = Bi: Sn weight ratio) particles to be nearly spherical with an average size of ~18 nm and 12 nm, respectively. Furthermore, the calculated optical band gap for SnO 2 and Bi-SnO 2 NPs were 2.71 eV and 2.43 eV respectively. The results demonstrated Bi-SnO 2 NP had enhanced photocatalytic reaction values where its efficiencies toward RB and CP were 2.27 and 3.16 fold higher than that of the pristine SnO 2 NPs counterpart (38.95% and 29.16%) upon illuminating for 4 h and 15 h respectively. Superoxide anion radical and/or singlet oxygen were involved as the main species during the degradation reactions. More importantly, this remarkably improved photocatalytic performance stemmed mainly from the small size, lower optical band gap, alleviating photo-induced electron and hole recombination rate as well as the creation of higher density oxygen vacancy in Bi-SnO 2 NPs.