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The absence of two-dimensional (2D) van der Waals (vdW) ferromagnetic crystals with both above-room-temperature strong intrinsic ferromagnetism and large perpendicular magnetic anisotropy (PMA) severely hinders practical applications of 2D vdW crystals in next-generation low-power magnetoelectronic and spintronic devices. Here, we report a vdW intrinsic ferromagnetic crystal Fe3GaTe2 that exhibits record-high above-room-temperature Curie temperature (Tc, ~350-380 K) for known 2D vdW intrinsic ferromagnets, high saturation magnetic moment (40.11 emu/g), large PMA energy density (~4.79 × 105 J/m3), and large anomalous Hall angle (3%) at room temperature. Such large room-temperature PMA is better than conventional widely-used ferromagnetic films like CoFeB, and one order of magnitude larger than known 2D vdW intrinsic ferromagnets. Room-temperature thickness and angle-dependent anomalous Hall devices and direct magnetic domains imaging based on Fe3GaTe2 nanosheet have been realized. This work provides an avenue for room-temperature 2D ferromagnetism, electrical control of 2D ferromagnetism and promote the practical applications of 2D-vdW-integrated spintronic devices.

their potential for applications in bioimaging, therapy, sensing, and catalysis. [4,5] For instance, ultrathin 2D noble metal nanomaterials have attracted increasing attention due to their ultrathin nature and 2D morphology. The ultrathin nature leads to high surface area-to-volume ratio and abundant exposed catalytically-active sites. [6][7][8] The 2D morphology confers a large interfacial area in contact with the substrate compared with either 1D or 3D nanostructures (e.g., nanowire or nanoparticles), which can enhance the interactions between reactants and the surface of catalysts, contributing to high activity. [8] In view of the fascinating attributes and numerous potential applications of ultrathin 2D metal nanomaterials associated with their unique structural features, it is essential to develop feasible facile and reliable synthesis routes. [2] However, the production of ultrathin 2D metal nanomaterials, free of a solid substrate, represents a significant challenge, due to the tendency of metal atoms to form a highly isotropic 3D close-packed crystal lattice. [9] This natural tendency toward 3D growth can be suppressed by the introduction of confinement to induce anisotropic growth. [4] To date, a range of synthesis strategies have been utilized to prohibit the free 2D metal nanomaterials offer exciting prospects in terms of their properties and functions. However, the ambient aqueous synthesis of atomicallythin, 2D metallic nanomaterials represents a significant challenge. Herein, freestanding and atomically-thin gold nanosheets with a thickness of only 0.47 nm (two atomic layers thick) are synthesized via a one-step aqueous approach at 20 °C, using methyl orange as a confining agent. Owing to the high surface-area-to-volume ratio, abundance of unsaturated atoms exposed on the surface and large interfacial areas arising from their ultrathin 2D nature, the as-prepared Au nanosheets demonstrate excellent catalysis performance in the model reaction of 4-nitrophenol reduction, and remarkable peroxidase-mimicking activity, which enables a highly sensitive colorimetric sensing of H 2 O 2 with a detection limit of 0.11 × 10 −6 m. This work represents the first fabrication of freestanding 2D gold with a sub-nanometer thickness, opens up an innovative pathway toward atomically-thin metal nanomaterials that can serve as model systems for inspiring fundamental advances in materials science, and holds potential across a wide region of applications. Sub-Nanometer Thick Gold Nanosheets

Singlet fission offers an opportunity to improve solar cell efficiency, but its practical use is hindered by the limited number of known efficient materials. We look for chromophores that satisfy the desirable but rarely encountered adiabatic energy conditions, E(T 2 ) − E(S 0 ) > E(S 1 ) − E(S 0 ) ≈ 2[E(T 1 ) − E(S 0 )], and are small enough to permit highly accurate calculations. We provide a rationale for the use of captodative biradicaloids, i.e., biradicals stabilized by direct interaction between their radical centers, which carry both an acceptor and a donor group. A computation of vertical excitation energies of 14 structures of this type by time-dependent density functional theory (TD-DFT) yielded 11 promising candidates. The vertical excitation energies from S 0 and T 1 were recalculated by complete-active-space second-order perturbation theory (CASPT2), and five of the compounds met the above energy criteria. Their adiabatic excitation energies from the S 0 into the S 1 , S 2 , T 1 , and T 2 excited states were subsequently calculated, and three of them look promising. For 2,3diamino-1,4-benzoquinone, adiabatic E(T 1 ) and E(S 1 ) energies were close to optimal (1.12 and 2.23 eV above the S 0 ground state, respectively), and for its more practical N-peralkylated derivative they were even lower (0.63 and 1.06 eV above S 0 , respectively). PCM/CASPT2 results suggested that the relative energies can be further tuned by varying the polarity of the environment.

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Time-resolved fluorescence and absorption measurements are performed on hypericin complexed with human serum albumin, HSA (1:4, 1:1 and approximately 5:1 hypericin: HSA complexes). Detailed comparisons with hypocrellin A/HSA complexes (1:4 and 1:1) are made. Our results are consistent with the conclusions of previous studies indicating that hypericin binds to HSA by means of a specific hydrogen-bonded interaction between its carbonyl oxygen and the N1-H of the tryptophan residue in the IIA subdomain of HSA. (They also indicate that some hypericin binds nonspecifically to the surface of the protein.) A single-exponential rotational diffusion time of 31 ns is measured for hypericin bound to HSA, indicating that it is very rigidly held. Energy transfer from the tryptophan residue of HSA to hypericin is very efficient and is characterized by a critical distance of 94 A, from which we estimate a time constant for energy transfer of approximately 3 x 10(-15) s. Although it is tightly bound to HSA, hypericin is still capable of executing excited-state intramolecular proton (or hydrogen atom) transfer in the approximately 5:1 complex, albeit to a lesser extent than when it is free in solution. It appears that the proton transfer process is completely impeded in the 1:1 complex. The implications of these results for hypericin (and hypocrellin A) are discussed in terms of the mechanism of intramolecular excited-state proton transfer, the mode of binding to HSA and the light-induced antiviral and antitumor activity.

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Very high power conversion efficiencies (PCEs) have been demonstrated by multijunction cells made of epitaxial III–V semiconductors; but they are too expensive to manufacture for terrestrial applications. Multijunction solar cells that can be fabricated with cheap and simple solution-processing techniques offer a lower-cost alternative to reach high PCEs. Here we demonstrate the solution processing of efficient all-perovskite triple-junction solar cells using optimal-bandgap perovskites. Monolithic all-perovskite triple-junction cells with an open-circuit voltage of 2.8 V and a fill factor of 81.1% are obtained by developing interconnecting layers that are compatible with the solution processing of perovskite absorbers. The concept and design here represent an important step toward efficient all-perovskite triple-junction solar cells.