Microbe-Mediated Precision Doping of Transition Metal Oxide in Alumina Nanorods for Highly Selective Catalysis

We present a novel, mild, and environmentally friendly strategy for one-pot precision doping of highly dispersed MO_x (M = Fe, Co, Ni, Cu) in Al₂O₃ nanorods by Sporosarcina pasteurii (S. pasteurii)-mediated urea enzymolysis. S. pasteurii shows better tolerance to the toxicity of M ions and ensures the complete enzymolysis of urea with the coexistence of those ions with Al(III), and thus facilitates the preparation of well-shaped M(OH)_x-NH₄Al(OH)₂CO₃ nanorods and uniform MO_x-doping Al₂O₃ nanorods after calcination. The growth process and structure of the proposed nanorods were fully discussed. The function of the typical Co₃O₄-Al₂O₃ nanorods was evaluated by activation of peroxymonosulfate (PMS) for selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD). The catalysis of Co₃O₄-Al₂O₃ nanorods gives BA conversion rate of 13.5 mmol g^-1 h^-1, with 81.7% BA conversion and 75.2% BAD selectivity for 5 h reaction, while the combination of Co₃O₄-Al₂O₃ nanorods and Br^- promotes the generation of carbon centered radicals, significantly increases BA conversion rate to 21.4 mmol g^-1 h^-1, with 90.0% BA conversion and 93.4% BAD selectivity for 3 h reaction. This work provides a novel approach to the biosynthesis of 1D nanomaterials and introduces a new concept of combination of Co₃O₄-Al₂O₃ nanorods and Br^- for PMS activation in selective catalytic oxidation.