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 assynthesized 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℃ and remaining stable over a period of 52 h of reaction time.

State of arts on the bio-synthesis of noble metal nanoparticles and their biological application

Nanomaterials are materials in which at least one of the dimensions of the particles is 100 nm and below.There are many types of nanomaterials,but noble metal nanoparticles are of interest due to their uniquely large surface-to-volume ratio,high surface area,optical and electronic properties,high stability,easy synthesis,and tunable surface functionalization.More importantly,noble metal nanoparticles are known to have excellent compatibility with bio-materials,which is why they are widely used in biological applications.The synthesis method of noble metal nanoparticles conventionally involves the reduction of the noble metal salt precursor by toxic reaction agents such as NaBH4,hydrazine,and formaldehyde.This is a major drawback for researchers involved in biological application researches.Hence,the bio-synthesis of noble metal nanoparticles(NPs)by bio-materials via bio-reduction provides an alternative method to synthesize noble metal nanoparticles which are potentially non-toxic and safer for biological application.In this review,the bio-synthesis of noble metal nanoparticle including gold nanoparticle(AuNPs),silver nanoparticle(AgNPs),platinum nanoparticle(PtNPs),and palladium nanoparticle(PdNPs)are first discussed.This is followed by a discussion of these biosynthesized noble metal in biological applications including antimicrobial,wound healing,anticancer drug,and bioimaging.Based on these,it can be concluded that the study on bio-synthesized noble metal nanoparticles will expand further involving bio-reduction by unexplored bio-materials.However,many questions remain on the feasibility of bio-synthesized noble metal nanoparticles to replace existing methods on various biological applications.Nevertheless,the current development of the biological application by bio-synthesized noble metal NPs is still intensively ongoing,and will eventually reach the goal of full commercialization.