Pyridinic-N doping carbon layers coupled with tensile strain of FeNi alloy for activating water and urea oxidation

Exploitation of oxygen evolution reaction(OER)and urea oxidation reaction(UOR)catalysts with high activity and stability at large current density is a major challenge for energy-saving H_(2) production in water electrolysis.Herein,we use the pyridinic-N doping carbon layers coupled with tensile strain of FeNi alloy activated by NiFe_(2)O_(4)(FeNi/NiFe_(2)O_(4)@NC)for efficiently increasing the performance of water and urea oxidation.Due to the tensile strain effect on FeNi/NiFe_(2)O_(4)@NC,it provides a favorable modulation on the electronic properties of the active center,thus enabling amazing OER(η_(100)=196 mV)and UOR(E_(10)=1.32 V)intrinsic activity.Besides,the carbon-coated layers can be used as armor to prevent FeNi alloy from being corroded by the electrolyte for enhancing the OER/UOR stability at large current density,showing high industrial practicability.This work thus provides a simple way to prepare high-efficiency catalyst for activating water and urea oxidation.

Ferroelectric order in hybrid organic-inorganic perovskite NH_(4)PbI_(3) with non-polar molecules and small tolerance factor

The appropriate theoretical picture of describing the ferroelectric order in hybrid organic-inorganic perovskite remains attractive and under intense debate.We rationalize the interaction between organic molecule sublattice and inorganic frame from first-principles.Through systematic investigations on the NH_(4)PbI_(3),we show that the non-polar octahedral rotation dominates the process of stabilizing of the lattice with small value of tolerance factor.The direct coupling between molecules is negligible.With the help of hydrogen bonding to the inorganic cage,molecule sublattice will eventually build long-range ferroelectric or anti-ferroelectric order under the constrain of the inorganic cage and further polarize the inorganic frame as the feedback.These results also clarify that to build ferroelectricity the polar molecule is helpful but not crucial.As the general rule for hybrid organic-inorganic perovskite,we identified the fundamental mechanism that can be considered as a critical pre-step forward to further controlling the related physics in functional materials.

Tunable ferromagnetic Weyl fermions from a hybrid nodal ring

Realization of nontrivial band topology in condensed matter systems is of great interest in recent years.Using first-principles calculations and symmetry analysis,we propose an exotic topological phase with tunable ferromagnetic Weyl fermions in a halfmetallic oxide CrP_(2)O_(7).In the absence of spin–orbit coupling(SOC),we reveal that CrP_(2)O_(7) possesses a hybrid nodal ring.When SOC is present,the spin-rotation symmetry is broken.As a result,the hybrid nodal ring shrinks to discrete nodal points and forms different types of Weyl points.The Fermi arcs projected on the(100)surface are clearly visible,which can contribute to the experimental study for the topological properties of CrP_(2)O_(7).In addition,the calculated quasiparticle interference patterns are also highly desirable for the experimental study of CrP_(2)O_(7).Our findings provide a good candidate of ferromagnetic Weyl semimetals,and are expected to realize related topological applications with their attracted features.