Advanced development of grain boundaries in TMDs from fundamentals to hydrogen evolution application

Grain boundary(GB),as a kind of lattice defect,widely exists in two-dimensional transition metal dichalcogenides(2D TMDs),which has complex and diverse influences on the physical/chemical properties of 2D TMDs.GBs are universally considered to be a double-edged sword,although some electrical and mechanical properties of 2D TMDs would be adversely affected leading to the reduced overall quality,certain structure-oriented applications could be realized based on its unique properties.In this review,we first detailed the atomic structure characteristics of GBs and the corresponding techniques,then we systematically summarized the methods of introducing GBs into 2D TMDs.Next,we expounded unique electrical,mechanical,and chemical properties of the GBs in 2D TMDs and clarified its internal relationship with the atomic structure.Moreover,the application of GB structure in hydrogen evolution reaction(HER)is also discussed.In the end,we make a conclusion and put forward outlooks,hoping to further promote the basic research of GB and boost the wide application of 2D TMDs.

Tailoring activation sites of metastable distorted 1T′-phase MoS_(2) by Ni doping for enhanced hydrogen evolution

Heteroatom doping is a promising approach to enhance catalytic activity by modulating physical properties,electronic structure,and reaction pathway.Herein,we demonstrate that appropriate Ni-doping could trigger a preferential transition of the basal plane from 2H(trigonal prismatic)to 1T′(clustered Mo)by inducing lattice distortion and S vacancy(SV)and thus dramatically facilitate its catalytic hydrogen evolution activity.It is noteworthy that the unique catalysts did possess superior catalytic performance of hydrogen evolution reaction(HER).The rate of photocatalytic hydrogen evolution could reach 20.45 mmol·g^(−1)·h^(−1) and reduced only slightly in the long period of the photocatalytic process.First-principles calculations reveal that the distorted Ni-1T′-MoS_(2) with SV could generate favorable water adsorption energy(Ead(H_(2)O))and Gibbs free energy of hydrogen adsorption(∆GH).This work exhibits a facile and promising pathway for synergistically regulating physical properties,electronic structure,or wettability based on the doping strategy for designing HER electrocatalysts.

Reversibly sensitizing-storing-releasing ^(1)O_(2) within a single platinum(Ⅱ)-acetylide-based metallacycle molecule via laser power modulation

Tumor hypoxia severely limits the therapeutic efficacy of photodynamic therapy(PDT) for solid tumors,which is highly dependent on tissue oxygen concentration.In this study,we developed a platinum(Ⅱ)-acetylide-based metallacycle compound bearing six 1,4-dimethylnaphthalenes(DMN) groups,and controlled the photodynamic and photothermal effects of the compound by adjusting the power of 730 nm laser to achieve reversible sensitization,storage and release of 1~O_(2) within a single molecule.The compound formed nanoparticles by self-assembly and exhibited good water solubility and biocompatibility.Under laser irradiation,the strong spin-orbit coupling of platinum atoms in the metallacycle facilitated 1~O_(2) generation.The produced 1~O_(2) was captured by the DMN carriers and transported into the hypoxic tumor,where 1~O_(2) release was triggered owing to the good photothermal effect of the extended conjugation of the metallacycle.During therapy,the metallacycle serving as a photosensitizer,1~O_(2) carrier,and photothermal reagent,achieved the synergistic therapy of PDT/PTT,demonstrating the versatility of the metallacycle.This study proposes a new strategy to develop phototherapy agents that are suitable for hypoxic tumors.

Chiral induction and Sb3+doping in indium halides to trigger second harmonic generation and circularly polarized luminescence

Recently,organic-inorganic hybrid metal halides(HMHs)have attracted extensive attention as promis-ing multifunctional materials by virtue of their structural diversity and tunable photophysical properties.However,it remains a challenge to design HMHs with specific functions on demand.Herein,by introduc-ing R/S-methylbenzylamine(R/S-MBA)and doping Sb^(3+),we have achieved both second harmonic gen-eration(SHG)and circularly polarized luminescence(CPL)properties in lead-free indium halides.The introduction of chiral organic cations can break the symmetry and induce the indium halides to crys-tallize in the chiral space group.The Sb^(3+)with ns2 electronic configuration can serve as the dopants to promote the formation of self-trapped excitons,so as to activate highly efficient luminescence.As a re-sult,the as-prepared Sb3+doped(R/S-MBA)3 InCl6 show not only SHG responses but also CPL signals with luminescence dissymmetry factor of−5.3×10^(−3) and 4.7×10^(−3).This work provides a new inspiration for the exploitation of chiral multifunctional materials.

MoS_(x) nanowire networks derived from[Mo_(3)S_(13)]^(2−) clusters for efficient electrocatalytic hydrogen evolution

Precise design and synthesis of sub-nano scale catalysts with controllable electronic and geometric structures are pivotal for enhancing the hydrogen evolution reaction(HER)performance of molybdenum sulfide(MoS_(2))and unraveling its structure−activity relationship.By leveraging transition molybdenum polysulfide clusters as functional units for multi-level ordering,we successfully designed and synthesized MoS_(x)nanowire networks derived from[Mo_(3)S_(13)]^(2−) clusters via evaporationinduced self-assembly,which exhibit enhanced HER activity attributed to a high density of active sites and dynamic evolution behavior under cathodic potentials.MoS_(x) nanowire networks electrode yields a current density of 100 mA·cm^(−2) at 142 mV in 0.5 M H_(2)SO_(4).This work provides an attractive prospect for optimizing catalysts at the sub-nano scale and offers insights into a strategy for designing catalysts in various gas evolution reactions.

调控分子间的电子耦合效应实现多彩超长有机室温磷光

有机超长室温磷光聚合物因其优异的可加工性、灵活性和可重复性等特点,在各种光电应用中表现出巨大的应用潜力.然而,实现全彩的室温磷光仍然是一个挑战.在本文中,我们通过在聚乙烯醇中掺杂不同浓度的三苯基膦盐,成功制备了一系列余晖颜色可调的有机室温磷光聚合物(从蓝色到红色).实验和理论计算证明:室温磷光聚合物颜色的宽范围调控归因于掺杂体膦盐分子间的电子耦合作用大小.此外,这些多彩的磷光聚合物可应用于柔性3D显示和防伪.

Circularly polarized luminescence from organic micro-/nano-structures

Circularly polarized light exhibits promising applications in future displays and photonic technologies.Circularly polarized luminescence(CPL)from chiral luminophores is an ideal approach to directly generating circularly polarized light,in which the energy loss induced by the circularly polarized filters can be reduced.Among various chiral luminophores,organic micro-/nano-structures have attracted increasing attention owing to the high quantum efficiency and luminescence dissymmetry factor.Herein,the recent progress of CPL from organic micro-/nano-structures is summarized.Firstly,the design principles of CPL-active organic micro-/nano-structures are expounded from the construction of micro-/nano-structure and the introduction of chirality.Based on these design principles,several typical organic micro-/nano-structures with CPL activity are introduced in detail,including self-assembly of small molecules,self-assembly ofπ-conjugated polymers,and self-assembly on micro-/nanoscale architectures.Subsequently,we discuss the external stimuli that can regulate CPL performance,including solvents,pH value,metal ions,mechanical force,and temperature.We also summarize the applications of CPL-active materials in organic light-emitting diodes,optical information processing,and chemical and biological sensing.Finally,the current challenges and prospects in this emerging field are presented.It is expected that this review will provide a guide for the design of excellent CPL-active materials.

Ingeniously designed Ni-Mo-S/ZnIn_(2)S_(4) composite for multi-photocatalytic reaction systems

Molybdenum disulfide (MoS_(2)) with low cost, high activity and high earth abundance has been found to be a promising catalyst for the hydrogen evolution reaction (HER), but its catalytic activity is considerably limited due to its inert basal planes. Here, through the combination of theory and experiment, we propose that doping Ni in MoS_(2) as catalyst can make it have excellent catalytic activity in different reaction systems. In the EY/TEOA system, the maximum hydrogen production rate of EY/Ni-Mo-S is 2.72 times higher than that of pure EY, which confirms the strong hydrogen evolution activity of Ni-Mo-S nanosheets as catalysts. In the lactic acid and Na_(2)S/Na_(2)SO_(3) systems, when Ni-Mo-S is used as co-catalyst to compound with ZnIn_(2)S_(4) (termed as Ni-Mo-S/ZnIn_(2)S_(4)), the maximum hydrogen evolution rates in the two systems are 5.28 and 2.33 times higher than those of pure ZnIn_(2)S_(4), respectively. The difference in HER enhancement is because different systems lead to different sources of protons, thus affecting hydrogen evolution activity. Theoretically, we further demonstrate that the Ni-Mo-S nanosheets have a narrower band gap than MoS_(2), which is conducive to the rapid transfer of charge carriers and thus result in multi-photocatalytic reaction systems with excellent activity. The proposed atomic doping strategy provides a simple and promising approach for the design of photocatalysts with high activity and stability in multi-reaction systems.