First-Principles Study on Magnetism of Manganese Dithiolene-diamine and Dihydroxyl-diamine Nanosheets

We perform first-principles simulations on a type of two-dimensional metal-organic nanosheet derived from the recently reported manganese bis-dithiolene Mn3C12S12 [Nanoscale 5, 10404 （2013）] and manganese bis-diamine Mn3C12N12H12 [ChemPhysChem 16, 614 （2015）] mono-layers. By coordinating chalcogen （S or O） atoms and -NH- group to Mn atoms with trans- or cis-structures and preserving space inversion symmetry, four configurations of this type of nanosheet are obtained： trans-manganese dithiolene-diamine Mn3（C6S3N3H3）2, cis- manganese dithiolene-diamine Mn3（C6S6）（C6N6H6）, trans-manganese dihydroxyl-diamine Mn3（C6O3N3H3）2, and cis-manganese dihydroxyl-diamine Mn3（C6O6）（C6N6H6）. The ge- ometric con guration, electronic structure and magnetic properties of these metal-organic nanosheets are systematically explored by density functional theory calculations. The cal- culated results show that Mn3（C6S3N3H3）2, Mn3（C6O3N3H3）2 and Mn3（C6O6）（C6N6H6） monolayers exhibit half-metallicity and display strong ferromagnetism with Curie transition temperatures near and even beyond room temperature, and Mn3（C6S6）（C6N6H6） monolayer is a semiconductor with small energy gap and spin frustration ground state. The mechanisms for the above properties, especially in uences of diflerent groups （atoms） substitution and coordination style on the magnetism of the nanosheet, are also discussed. The predicted two-dimensional metal-organic nanosheets have great promise for the future spintronics ap-plications.

Strain effect on the electronic properties of III-nitride nanosheets:Ab-initio study

In this study the structural and electronic properties of III-nitride monolayers XN(X=B, Al, Ga and In) under different percentages of homogeneous and shear strain are investigated using the full potential linearized augmented plane wave within the density functional theory. Geometry optimizations indicate that GaN and InN monolayers get buckled under compressive strain.Our calculations show that the free-strains of these four monolayers have an indirect band gap. By applying compressive biaxial strain, a transition from indirect to direct band gap occurs for GaN and InN, while the character of band gap for BN and AlN is not changed. Under tensile strain, only BN monolayer behaves as direct band gap semiconductor. In addition, when the shear strain is applied, only InN undergoes an indirect to direct band gap transition. Furthermore, the variations of band gap versus strain for III-nitride monolayers have been calculated. When a homogeneous uniform strain, in the range of [.10%, +10%], is applied to the monolayers, the band gap can be tuned for from 3.92 eV to 4.58 eV for BN, from 1.67 eV to 3.46 eV for AlN, from0.24 eV to 2.79 eV for GaN and from 0.60 eV to 0.90 eV for InN.

Non-covalent interaction of atomically dispersed dual-site catalysts featuring Co and Ni nascent pair sites for efficient electrocatalytic overall water splitting

The scarcity of highly effective and economical catalysts is a major impediment to the widespread adop-tion of electrochemical water splitting for the generation of hydrogen.MoS_(2),a low-cost candidate,suffers from inefficient catalytic activity.Nonetheless,a captivating strategy has emerged,which involves the en-gineering of heteroatom doping to enhance electrochemical proficiency.This investigation demonstrates a successful implementation of the strategy by combining ultrathin MoS_(2) nanosheets with Co and Ni dual single multi-atoms(DSMAs)grown directly on 2D N-doped carbon nanosheets(CoNi-MoS_(2)/NCNs)for the purpose of improving hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).With the aid of a dual-atom doped bifunctional electrocatalyst,effective water splitting has been achieved across a broad pH range in electrolytes.The double doping of Co and Ni strengthens their interactions,thereby altering the electromagnetic composition of the host MoS_(2) and ultimately leading to improved electrocat-alytic activity.Additionally,the synergistic effect between NCNs and MoS_(2) nanosheets provided efficient electron transport channels for ions and an ample surface area with open voids for ion diffusion.Con-sequently,the CoNi-MoS_(2)/NCNs catalysts demonstrated exceptional stability and activity,producing low degree overpotentials of 180.5,124.9,and 196.4 mV for HER and 200,203,and 207 mV for OER in neu-tral,alkaline,and acidic mediums,respectively,while also exhibiting outstanding overall water-splitting performance,durability,and stability when used as an electrolyzer at universal pH.