What are some applications of anti-ferromagnetism?
In short, this type of magnetism gives the material a net magnetisation of zero, however when the temperature increases, the magnetisation gets non-zero. This is what I understand now, please feel free to elaborate.
A possible way to trigger hydrogen evolution reaction (HER) activity of the basal‐plane sites and make a MoS2 monolayer a single‐atom‐layer catalyst, is through long‐range ferromagnetism order induced by magnetic cobalt ion doping. The effect of the doping promotes the hydrogen adsorption ability of basal S sites.
Abstract
Single‐atom‐layer catalysts with fully activated basal‐atoms will provide a solution to the low loading‐density bottleneck of single‐atom catalysts. Herein, we activate the majority of the basal sites of monolayer MoS2, by doping Co ions to induce long‐range ferromagnetic order. This strategy, as revealed by in situ synchrotron radiation microscopic infrared spectroscopy and electrochemical measurements, could activate more than 50 % of the originally inert basal‐plane S atoms in the ferromagnetic monolayer for the hydrogen evolution reaction (HER). Consequently, on a single monolayer of ferromagnetic MoS2 measured by on‐chip micro‐cell, a current density of 10 mA cm−2 could be achieved at the overpotential of 137 mV, corresponding to a mass activity of 28, 571 Ag−1, which is two orders of magnitude higher than the multilayer counterpart. Its exchange current density of 75 μA cm−2 also surpasses most other MoS2‐based catalysts. Experimental results and theoretical calculations show the activation of basal plane S atoms arises from an increase of electronic density around the Fermi level, promoting the H adsorption ability of basal‐plane S atoms.
https://ift.tt/3rWOW8Z
I learned that Fe, Co and Ni are all Ferromagnetic. But I was watching a youtube video today and they said that CoCl^(2) is paramagnetic. Why? Could you tell me how to tell the difference please?
Many times since I have been a child, I have found myself returning to play with my "Supermag" toy magnets. This week though, Ive come upon a gap of my understanding.
I know that energy is stored in a magnetic field. If I hold one magnet above another, it jumps through the air gaining kinetic energy and then changing into potential energy.
My question is, do the magnetic fields become weakened and hold less energy when there are other magnets in close proximity? This mechanical energy surely originates from the field, and conservation of energy says that an increase in gravitational potential energy requires some input of work, but I would not intuitively think that the field is weakened.
Thanks for any insight, Cheers!
Journal of the American Chemical SocietyDOI: 10.1021/jacs.0c04101
https://ift.tt/3dxpO10
Journal of the American Chemical SocietyDOI: 10.1021/jacs.9b13295
https://ift.tt/39lurt9
I was watching this video on how magnets work. They explain that while individual atoms can be magnetic based on whether or not their electron shell is filled, groups of atoms may not be, based on the atom configuration. That atom configuration apparently depends on least amount of energy required--if this were the case, how can an antiferromagnetic or paramagnetic configurations require less energy than a ferromagnetic one? In other words, what determines stability/how is stability defined?
Single‐atom‐layer catalysts with fully activated basal‐atoms will provide an ultimate solution to the low loading‐density bottleneck of single‐atom catalysts. Herein, we propose a strategy to activate the majority of basal sites of monolayer MoS 2 , by doping Co ions to induce long‐range ferromagnetic order. This strategy, as revealed by in‐situ synchrotron radiation microscopic infrared spectroscopy and electrochemical measurements, could activate more than 50% of the originally inert basal‐plane S atoms in the ferromagnetic monolayer for the hydrogen evolution reaction. Consequently, on a single monolayer of ferromagnetic MoS 2 measured by on‐chip micro‐cell, a current density of 10 mA cm ‐2 could be achieved at the overpotential of 137 mV, corresponding to a mass activity of 28, 571 A g ‐1 , which is two orders of magnitude higher than the multilayer counterpart. The exchange current density of 75 μA cm ‐2 for the monolayer also surpasses most of other MoS 2 ‐based catalysts reported so far. Experimental characterizations and theoretical calculations unravel that the activation of basal plane S atoms is due to the delocalization of spin states of d ‐electron and the increase of S‐ p electronic density around the Fermi level, and hence promotes the H adsorption ability of basal‐plane S atoms.
https://ift.tt/3rWOW8Z
