Facile synthesis of porous Pd nanoflowers with excellent catalytic activity towards CO oxidation

Microorganism-mediated, hexadecyltrimethylammonium chloride (CTAC)-directed (MCD) method was employed in this work to synthesize Pd nanoflowers (PdNFs). Proper Pichia pastoris cells (PPCs) dosage, ascorbic acid (AA), Pd(NO 3 ) 2 and CTAC concentrations were essential for the growth of the PdNFs. The size of the as-synthesized PdNFs could be tuned by adjusting the amount of Pd(NO 3 ) 2 solution and dosage of PPCs used. Characterization techniques such as X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy were used to verify the nature of the PdNFs. Finally the PdNF/PPC nanocomposites were immobilized onto TiO 2 supports to obtain bio-PdNF/TiO 2 catalysts which showed excellent catalytic activity for CO oxidation, obtaining 100% conversion at 100 °C and remaining stable over a period of 52 h of reaction time.