Engineering of visible light photocatalytic activity in SnO2 nanoparticles: Cu2+-integrated Li+, Y3+ or Zr4+ dopants

Abstract

Integration between Cu 2+ ions and Li + , Y 3+ or Zr 4+ ions was strongly enhanced the visible light absorption and the sunlight photocatalytic properties of nanocrystalline SnO 2 . Nanopowders of SnO 2 , Sn 0.97 Cu 0.03 O 2 , Sn 0.95 Cu 0.03 Li 0.02 O 2 , Sn 0.95 Cu 0.03 Y 0.02 O 2 and Sn 0.95 Cu 0.03 Zr 0.02 O 2 compositions were synthesized via coprecipitation method. Dominant crystallographic planes of SnO 2 tetragonal rutile structure were clearly detected in the XRD patterns with absence of any secondary phases or impurities. The FTIR profiles show a strong appearance of the characteristic vibrational absorption modes of SnO 2 in all compositions which prove their good crystallinity. The TEM images demonstrate that the agglomerated nanoparticles observed for pure SnO 2 were converted to regular nanospherical-shaped with slight degree of agglomeration due to Cu doping or (Cu, Li), (Cu, Y) and (Cu, Zr) codoping. Pure SnO 2 possesses UV band gap energy of 3.6 eV while Sn 0.97 Cu 0.03 O 2 , Sn 0.95 Cu 0.03 Li 0.02 O 2 , Sn 0.95 Cu 0.03 Y 0.02 O 2 and Sn 0.95 Cu 0.03 Zr 0.02 O 2 compositions exhibit visible light band gap energies of 2.97 eV, 2.7 eV, 2.6 eV and 2.6 eV, respectively. The photocatalytic tests confirmed that 97% of Congo red and 91% of Rhodamine B dyes were decomposed in the presence of Sn 0.95 Cu 0.03 Li 0.02 O 2 catalyst after 90 min of solar irradiation. Sn 0.95 Cu 0.03 Li 0.02 O 2 has considerable activity above 87% over long photodegradation time for four successive tests. For Sn 0.95 Cu 0.03 Li 0.02 O 2 catalyst, the high generation of the charge carriers due to extending of the band gap to visible light spectrum plus suppression of charge carriers’ recombination by Cu 2+ -Cu + trap states and high defects formation lead to its high photocatalytic activity. • Cu 2+ based Li + , Y 3+ or Zr 4+ codoped SnO 2 exhibit visible band gap. • Sn 0.95 Cu 0.03 Li 0.02 O 2 is a perfect solar photocatalyst. • High degradation for Congo red (97%) and Rhodamine B (91%) dyes. • The efficiency is above 87% after four repeated test.