Inverted planar heterojunction (PHJ) perovskite solar cells have attracted great attention due to their advantages of low-temperature fabrication on flexible substrates by solution processing with high efficiency. Poly(3,4ethylenedioxythiophene): polystyrenesulfonate (PEDOT:PSS) is the most widely used hole transport layer (HTL)in inverted PHJ perovskite solar cells; however, the acidic and hygroscopic nature of PEDOT: PSS can cause degradation and reduce the device stability. In this work, we demonstrated that low-cost solution-processed hydrophobic copper iodide (CuI) can serve as a HTL to replace PEDOT: PSS in inverted PHJ perovskite solar cells with high performance and enhanced device stability. Power conversion efficiency (PCE) of 13.58% was achieved by employing CuI as a HTL, slightly exceeding PEDOT: PSS based device with PCE of 13.28% under the same experimental conditions. Furthermore, the CuI based devices exhibited better air stability than that of PEDOT: PSS based devices. The results indicate that low-cost solution-processed CuI is a promising alternative to PEDOT: PSS HTL and could be widely used in inverted PHJ perovskite solar cells.

Low-temperature, solution-processed cerium oxide can serve as a promising electron transport layer to replace commonly used TiO2 in planar perovskite solar cells, with high efficiency and enhanced stability.

A novel rare earth hybrid electrocatalyst, consisting of a gadolinium-doped hierarchal NiFe-layered double hydroxide, is developed for improving the OER activity.

We report a heterometallic seed-mediated synthesis method for monodisperse penta-twinned Cu nanorods using Au nanocrystals as seeds. Elemental analyses indicate that resultant nanorods consist predominantly of copper with a gold content typically below 3 atom %. The nanorod aspect ratio can be readily adjusted from 2.8 to 13.1 by varying the molar ratio between Au seeds and Cu precursor, resulting in narrow longitudinal plasmon resonances tunable from 762 to 2201 nm. Studies of reaction intermediates reveal that symmetry-breaking is promoted by rapid nanoscale diffusion in Au−Cu alloys and the formation of a goldrich surface. The growth pathway features coevolving shape and composition whereby nanocrystals become progressively enriched with Cu concomitant with nanorod growth. The availability of uniform colloidal Cu nanorods with widely tunable aspect ratios opens new avenues toward the synthesis of derivative onedimensional metal nanostructures, and applications in surface-enhanced spectroscopy, bioimaging, and electrocatalysis, among others.

Annealing core@shell nanoparticles (NPs) yields high-entropy alloy NPs. Owing to their dispersed Pt/Pd content and low elemental diffusivity, they exhibit enhanced electrocatalytic performance and durability for the oxygen reduction reaction.

Combining Clarke's model with first‐principles calculation of average sound velocity, the minimum lattice thermal conductivities (κmin) of Y3Al5O12 (YAG), YAlO3 (YAP) and Y4Al2O9 (YAM) are predicted to be 1.59, 1.61, and 1.10 W·(m·K)−1, respectively. The weak Y–O polyhedra provide “weak zones” that scattering phonons and lead to the low κmin of ternary Y–Al–O compounds. In addition, the extremely low κmin of YAM is attributed to its higher levels of local disorder of crystal structure and weaker chemical bonding compared with those of YAG and YAP. Inspired by theoretical predictions, dense and phase‐pure YAM is synthesized and the experimental thermal conductivity is only 1.56 W·(m·K)−1at 1273 K. Finally, YAM is highlighted as a potential thermal barrier material for its low thermal conductivities at temperatures from 473 to 1273 K.

The discovery of atomically thin van der Waals magnets (e.g., CrI3 and Cr2Ge2Te6) has triggered a renaissance in the study of two-dimensional (2D) magnetism. Most of the 2D magnetic compounds discovered so far host only one single magnetic phase unless the system is at a phase boundary. In this work, we report the near degeneracy of magnetic phases in ultrathin chromium telluride (Cr2Te3) layers with strong perpendicular magnetic anisotropy highly desired for stabilizing 2D magnetic order. Single-crystalline Cr2Te3 nanoplates with a trigonal structure (space group P3̅1c) were grown by chemical vapor deposition. The bulk magnetization measurements suggest a ferromagnetic (FM) order with an enhanced perpendicular magnetic anisotropy, as evidenced by a coercive field as large as ∼14 kOe when the field is applied perpendicular to the basal plane of the thin nanoplates. Magneto-optical Kerr effect studies confirm the intrinsic ferromagnetism and characterize the magnetic ordering temperature of individual nanoplates. First-principles density functional theory calculations suggest the near degeneracy of magnetic orderings with a continuously varying canting from the c-axis FM due to their comparable energy scales, explaining the zero-field kink observed in the magnetic hysteresis loops. Our work highlights Cr2Te3 as a promising 2D Ising system to study magnetic phase coexistence and switches for ultracompact information storage and processing.

An emergent theme in mono-and multivalent ion batteries is to utilize nanoparticles (NPs) as electrode materials based on the phenomenological observations that their short ion diffusion length and large electrode−electrolyte interface can lead to improved ion insertion kinetics compared to their bulk counterparts. However, the understanding of how the NP size fundamentally relates to their electrochemical behaviors (e.g., charge storage mechanism, phase transition associated with ion insertion) is still primitive. Here, we employ spinel λ-MnO 2 particles as a model cathode material, which have effective Mg 2+ ion intercalation but with their size effect poorly understood to investigate their operating mechanism via a suite of electrochemical and structural characterizations. We prepare two differently sized samples, the small nanoscopic λ-MnO 2 particles (81 ± 25 nm) and big micron-sized ones (814 ± 207 nm) via postsynthesis size-selection. Analysis of the charge storage mechanisms shows that the stored charge from Mg 2+ ion intercalation dominates in both systems and is ∼10 times higher in small particles than that in the big ones. From both X-ray diffraction and atomic-resolution scanning transmission electron microscopy imaging, we reveal a fundamental difference in phase transition of the differently sized particles during Mg 2+ ion intercalation: the small NPs undergo a solid-solution-like phase transition which minimizes lattice mismatch and energy penalty for accommodating new phases, whereas the big particles follow conventional multiphase transformation. We show that this pathway difference is related to the improved electrochemical performance (e.g., rate capability, cycling performance) of small particles over the big ones which provides important insights in encoding within the particle dimension, that is, the single-phase transition pathway in high-performance electrode materials for multivalent ion batteries.