Anisotropy is an important and widely present characteristic of materials that provides desired direction-dependent properties. In particular, the introduction of anisotropy into magnetic nanoparticles (MNPs) has become an effective method to obtain new characteristics and functions that are critical for many applications. In this review, we first discuss anisotropy-dependent ferromagnetic properties, ranging from intrinsic magnetocrystalline anisotropy to extrinsic shape and surface anisotropy, and their effects on the magnetic properties. We further summarize the syntheses of monodisperse MNPs with the desired control over the NP dimensions, shapes, compositions, and structures. These controlled syntheses of MNPs allow their magnetism to be finely tuned for many applications. We discuss the potential applications of these MNPs in biomedicine, magnetic recording, magnetotransport, permanent magnets, and catalysis. CONTENTS 4.5.1. Co-Based Rare-Earth Metal Alloy Nanoparticles 3917 4.5.2. Fe-Based Rare-Earth Metal Alloy Nanoparticles 4.6. Rare-Earth-Metal-Free Nanoparticles 4.6.1. MnBi and MnAl Nanoparticles 4.6.2. Metal Carbide Nanoparticles 5. Magnetic Nanoparticles with Enhanced Anisotropy for Biomedical Applications 5.1. Magnetic Nanoparticles for MRI 5.1.1. MRI in General 5.1.2. Magnetic Nanoparticles as MRI Contrast AgentS 5.1.3. Cubic Ferrite Nanoparticles as T 2 -Weighted MRI Contrast Agents 5.1.4. Cubic Ferrite Nanoparticles as T 1 -Weighted MRI Contrast Agents 5.

We report a new form of catalyst based on ferromagnetic hexagonal-close-packed (hcp) Co nanosheets (NSs) for selective CO2RR to ethanal, CH3CHO. In all reduction potentials tested from −0.2 to −1.0 V (vs RHE) in 0.5 M KHCO3 solution, the reduction yields ethanal as a major product and ethanol/methanol as minor products. At −0.4 V, the Faradaic efficiency (FE) for ethanal reaches 60% with current densities of 5.1 mA cm–2 and mass activity of 3.4 A g–1 (total FE for ethanal/ethanol/methanol is 82%). Density functional theory (DFT) calculations suggest that this high CO2RR selectivity to ethanal on the hcp Co surface is attributed to the unique intralayer electron transfer, which not only promotes [OC–CO]* coupling but also suppresses the complete hydrogenation of the coupling intermediates to ethylene, leading to highly selective formation of CH3CHO.

By co-precipitating a nanoscale blocking agent, SmCo5 nanoparticles around 300 nm were synthesized and room-temperature coercivity of 7.2 T was obtained.