Role of organic/inorganic-sulfur doping on photocatalytic behavior of mesoporous bimetallic oxides heterojunction

Abstract A series of novel sulfur-doped mesoporous bimetallic oxides with controllable structure and property were synthesized for acid-induced photo-Fenton. The one-pot sol-gel strategy allowed high-dispersion and strong adhesion of different organic-/inorganic-sulfur species (including CH 4 N 2 S, C 5 H 11 NO 2 S, (NH 4 ) 2 SO 4 and Na 2 S 2 O 3 ) in host matrix to achieve highly active bimetallic heterojunction with stronger acid strength. It was found that organic-sulfur doping tended to simultaneously produce Bronsted and Lewis acid while inorganic-sulfur doping only generated Lewis acid. When two kinds of acid sites appeared on surface of solid, it made significant contributions toward superior performance either in absence of light (90.7% decoloration) or at pH of 10.0 (97.7% decoloration and 60.9% TOC removal). Possible sulfuration mechanism of S-doped bimetallic oxides for H 2 O 2 activation had been explored in details. The acidity of solids was inversely related to chain length of organic-sulfur but positively correlated with electronegativity of inorganic-sulfur. The study will not only make a facile and effective way for developing highly-efficient heterogeneous catalysts, but also provide valuable insights for understanding relationship between surface physicochemical properties and catalytic activity.