Magnetite (FeO) nanocrystals (MNCs) are among the most-studied magnetic nanomaterials, and many reports of solution-phase synthesis of monodisperse MNCs have been published. However, lack of reproducibility of MNC synthesis is a persistent problem, and the keys to producing monodisperse MNCs remain elusive. Here, we define and explore synthesis parameters in this system thoroughly to reveal their effects on the product MNCs. We demonstrate the essential role of benzaldehyde and benzyl benzoate produced by oxidation of benzyl ether, the solvent typically used for MNC synthesis, in producing monodisperse MNCs. This insight allowed us to develop stable formulas for producing monodisperse MNCs and propose a model to rationalize MNC size and shape evolution. Solvent polarity controls the MNC size, while short ligands shift the morphology from octahedral to cubic. We demonstrate preparation of specific assemblies with these MNCs. This standardized and reproducible synthesis of MNCs of well-controlled size, shape, and magnetic properties demonstrates a rational approach to stabilizing and expanding existing protocols for nanocrystal syntheses and may drive practical advances including enhanced MRI contrast, higher catalytic selectivity, and more accurate magnetic targeting.

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Conversion of carbon dioxide (CO 2 ) and water (H 2 O) to methanol (CH 3 OH) is achieved through an artificial photosynthesis procedure utilizing cobalt (Co) micro-particle based photocatalyst and solar energy in a simple, closed reactor. The photocatalyst is fabricated by exposing the surfaces of cobalt microparticles to femtosecond laser irradiation in a gold chloride (AuCl) solution. The morphology and composite of the photocatalyst surfaces were observed and detected to be a layer of cobalt dioxide (CoO) nano-flakes on which some gold (Au) nanoparticles were deposited. The Au nanoparticles harvest the Sunlight energy through a plasmonic effect. The energy absorbed by Au nanoparticles creates electrons and holes which excite the H 2 O and CO 2 molecules adsorbed on CoO nanostructure surfaces to form excited hydrogen (H 2 ) * and excited carbon monoxide (CO) * on the CoO surface. The excited molecules combine to form CH 3 OH on the CoO surface. The Au/CoO/Co nanostructured surfaces are useful for developing a low-cost method to convert solar energy to chemical energy in the form of methanol.

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