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Hydrogen production from methanol decomposition to syngas (H 2 + CO) is a promising alternative route for clean energy transition. One major challenge is related to the quest for stable, cost-effective, and selective catalysts operating below 400 °C. We illustrate an investigation of the surface reactivity of a Ni 3 Sn 4 catalyst working at 250 °C, by combining density functional theory, operando X-ray absorption spectroscopy, and high-resolution transmission electron microscopy. We discovered that the catalytic reaction is driven by surface tin-oxide phases, which protects the underlying Ni atoms from irreversible chemical modifications, increasing the catalyst durability. Moreover, we found that Sn content plays a key role in enhancing the H 2 selectivity, with respect to secondary products such as CO 2 . These findings open new perspectives for the engineering of scalable and low-cost catalysts for hydrogen production.

Geometrically frustrated lattices combined with magnetism usually host quantum fluctuations that suppress magnetic orders and generate highly entangled ground states. Three-dimensionally (3D) frustrated magnets generally exist in the diamond and pyrochlore lattices, while two-dimensionally (2D) frustrated geometries contain Kagomé, triangular, and honeycomb lattices. In this work, we reported using chemical pressure to tune the magnetism of the pyrochlore lattice in LiYbSe 2 into a triangular lattice by doping Ga or In. Li 3- x Ga x Yb 3 Se 6 and Li 3- x In x Yb 3- y In y Se 6 /Li 3- x In x Yb 3- y □ y Se 6 crystallize in a trigonal α-NaFeO 2 structure-type (space group R 3̅ m ) and can be synthesized using either LiCl or Se flux. In Li 3- x Ga x Yb 3 Se 6 , Ga 3+ and Li + are mixed, leaving Yb 3+ on the triangular plane. Instead of just Li + being replaced in Li 3- x Ga x Yb 3 Se 6 , In 3+ was observed in both the Li + and Yb 3+ layers in Li 3- x In x Yb 3- y In y Se 6 depending on the reaction conditions. Dominant antiferromagnetic interactions are revealed by magnetic measurements in both Li 3- x Ga x Yb 3 Se 6 and Li 3- x In x Yb 3- y In y Se 6 /Li 3- x In x Yb 3- y □ y Se 6 . However, no long-range magnetic order is detected in thermomagnetic measurements above 1.8 K due to geometrical frustration. Thus, Li 3- x Ga x Yb 3 Se 6 , Li 3- x In x Yb 3- y In y Se 6 /Li 3- x In x Yb 3- y □ y Se 6 , and the LiYbSe 2 previously discovered by our group provide an ideal platform to understand the complex structure-magnetism correlations from 3D to 2D frustrated lattices.

The metal-metal bond in metal-rich chalcogenide is known to exhibit various structures and interesting physical properties. Ta 2 Se can be obtained by both arc-melting and solid-state pellet methods. Ta 2 Se crystallizes a layered tetragonal structure with space group P 4/ nmm (No. 129; Pearson symbol tP 6). Each unit cell consists of four layers of body-centered close-packing Ta atoms sandwiched between two square nets of Se atoms, forming the Se-Ta-Ta-Ta-Ta-Se networks. Herein, we present magnetic susceptibility, resistivity, and heat capacity measurements on Ta 2 Se, which together indicate bulk superconductivity with T c = 3.8(1) K. According to first-principles calculations, the d orbitals in Ta atoms dominate the Fermi level in Ta 2 Se. The flat bands at the Γ point in the Brillouin zone yield the van Hove singularities in the density of states around the Fermi level, which is intensified by introducing a spin-orbit coupling effect, and thus could be critical for the superconductivity in Ta 2 Se. The physical properties, especially superconductivity, are completely different from those of Ta-rich alloys or transition-metal dichalcogenide TaSe 2 .

While exploring novel magnetic semiconductors, the new phase Cr 0.65 Al 1.35 Se 3 was discovered and characterized by both structural and physical properties. Cr 0.65 Al 1.35 Se 3 was found to crystallize into orthorhombic CrGeTe 3 -type structure with space group Pnma (no. 62). Vacancies and mixed occupancies were tested, and the results show that one of the 4 c sites accommodates a mixture of Cr and Al atoms, while the other 4 c site is fully occupied by Al atoms. Unique structural features include a T-shaped channel network created from the edge-sharing Cr/Al@Se 6 and Al@Se 4 polyhedra and a zipper effect of the puckered Se atoms inside the columnar channels. The round peak observed in the temperature-dependent magnetic susceptibility (χ g ) plot at ∼8(1) K corresponds to the antiferromagnetic-type transition in Cr 0.65 Al 1.35 Se 3 . However, the positive θ CW indicates an additional ferromagnetic interaction, which is highly likely due to the complex magnetic structure arising from the mixed Cr/Al occupancies on the 4 c site. Electrical resistivity measurements confirm that Cr 0.65 Al 1.35 Se 3 is a semimetal with a positive magnetoresistance. Here we present the characterization and determination of the crystal structure and physical properties for this new material.

Herein, the synthesis and application of functionalized quantum dot-based protease probes is described. Such probes are composed of nontoxic ZnO nanocrystals decorated by amino groups followed by linker and labeled peptide attachment. Spherical NH 2 -terminated ZnO quantum dots (QDs) with the average size ranging from 4 to 8 nm and strong emission centered at 530 nm were prepared using the sol-gel method. The fluorescence of ZnO QDs was quenched by the BHQ1 moiety present on the N-terminal amino group of the peptide. The enzymatic cleavage of the peptide mediated by the proteinase 3 (PR3) bond resulted in an increase in the QD probe fluorescence. This observation was verified using both model and biological systems; and the picomolar detection limit was found to be more than 30 times lower than that of the previously reported internally quenched peptide (a decrease in detection limit from 43 to 1.3 pmol was observed).