In this study, we, for the first time, report a high Cu solubility of 11.8% in single crystal SnSe microbelts synthesized via a facile solvothermal route.

The platinum single‐atom‐catalyst is verified as a very successful route to approach the size limit of Pt catalysts, while how to further improve the catalytic efficiency of Pt is a fundamental scientific question and is challenging because the size issue of Pt is approached at the ultimate ceiling as single atoms. Here, a new route for further improving Pt catalytic efficiency by cobalt (Co) and Pt dual‐single‐atoms on titanium dioxide (TiO2) surfaces, which contains a fraction of nonbonding oxygen‐coordinated Co–O–Pt dimers, is reported. These Co–Pt dimer sites originate from loading high‐density Pt single‐atoms and Co single‐atoms, with them anchoring randomly on the TiO2 substrate. This dual‐single‐atom catalyst yields 13.4% dimer sites and exhibits an ultrahigh and stable photocatalytic activity with a rate of 43.467 mmol g−1 h−1 and external quantum efficiency of ≈83.4% at 365 nm. This activity far exceeds those of equal amounts of Pt single‐atom and typical Pt clustered catalysts by 1.92 and 1.64 times, respectively. The enhancement mechanism relies on the oxygen‐coordinated Co–O–Pt dimer coupling, which can mutually optimize the electronic states of both Pt and Co sites to weaken H* binding. Namely, the “mute” Co single‐atom is activated by Pt single‐atom and the activity of the Pt atom is further enhanced through the dimer interaction. This strategy of nonbonding interactive dimer sites and the oxygen‐mediated catalytic mechanisms provide emerging rich opportunities for greatly improving the catalytic efficiency and developing novel catalysts with creating new electronic states.

Enhanced thermoelectric performance by band convergence and superlattice precipitates combined with geometry optimization by computer-aided design produced a segmented thermoelectric device with a record-high conversion efficiency.

Potassium-ion batteries (KIBs) are emerging as one of the most promising candidates for large-scale energy storage owing to the natural abundance of the materials required for their fabrication and the fact that their intercalation mechanism is identical to that of lithium-ion batteries. However, the larger ionic radius of K + is likely to induce larger volume expansion and sluggish kinetics, resulting in low specific capacity and unsatisfactory cycle stability. A new Ni/ Mn-based layered oxide, P2-type K 0.44 Ni 0.22 Mn 0.78 O 2 , is designed and synthesized. A cathode designed using this material delivers a high specific capacity of 125.5 mAh g −1 at 10 mA g −1 , good cycle stability with capacity retention of 67% over 500 cycles and fast kinetic properties. In situ X-ray diffraction recorded for the initial two cycles reveals single solid-solution processes under P2-type framework with small volume change of 1.5%. Moreover, a cathode electrolyte interphase layer is observed on the surface of the electrode after cycling with possible components of K 2 CO 3 , RCO 2 K, KOR, KF, etc. A full cell using K 0.44 Ni 0.22 Mn 0.78 O 2 as the cathode and soft carbon as the anode also exhibits exceptional performance, with capacity retention of 90% over 500 cycles as well as superior rate performance. These findings suggest P2-K 0.44 Ni 0.22 Mn 0.78 O 2 is a promising candidate as a high-performance cathode for KIBs.

Numerous trap states and low conductivity of compact TiO 2 layers are major obstacles for achieving high power conversion efficiency and high-stability perovskite solar cells. Here we report an effective Na 2 S-doped TiO 2 layer, which can improve the conductivity of TiO 2 layers, the contact of the TiO 2 /perovskite interface, and the crystallinity of perovskite layers. Comprehensive investigations demonstrate that Na cations increase the conductivity of TiO 2 layers while S anions change the wettability of TiO 2 layers, thus improving the crystallinity of perovskite layers and passivate defects at the TiO 2 /PVK interface. The synergetic effects of dopants lead to a champion efficiency as high as 21.25% in unencapsulated perovskite solar cells (PSCs), with much-improved stability. Our work provides new insights on anion dopants in TiO 2 layers, which is usually neglected in previous reports, and also proposes a simple approach to produce low-cost and highperformance electron transport layers for high-performance PSCs.

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Recently, single‐atom catalysts have aroused extensive attention in fields of clean energy and environmental protection due to their unique activity and efficient utilization of the active atoms. It is of great importance but still remains a great challenge to unveil the effect of single atoms on precise catalysis. Herein, it is reported that doping TiO2 hollow microspheres (TiO2‐HMSs) with single atomic Fe can boost the photoreactivity of TiO2‐HMSs towards NO oxidation due to the synergistic effects of atomically dispersed Fe and bonded Ti atom which act as dual active sites. The atomically dispersed Fe atoms occupy the subsurface Ti vacancies, and the interaction between Ti 3d and Fe 3d orbitals result in the formation of FeTi bond. Single atomic Fe modulates the electronic structure of the bonded Ti atoms by electron transfer, which facilitates the adsorption and activation of NO and O2 at Fe and bonded Ti sites, respectively. In addition, the introduction of single atomic Fe sharply suppresses the production of toxic NO2 byproduct. The synergistic effects of the dual active sites then cause a drastic promotion in photocatalytic oxidation of NO.

Programmable magnetic field-free manipulation of perpendicular magnetization switching is essential for the development of ultralow-power spintronic devices. However, the magnetization in a centrosymmetric single-layer ferromagnetic film cannot be switched directly by passing an electrical current in itself. Here, we demonstrate a repeatable bulk spin-orbit torque (SOT) switching of the perpendicularly magnetized CoPt alloy single-layer films by introducing a composition gradient in the thickness direction to break the inversion symmetry. Experimental results reveal that the bulk SOT-induced effective field on the domain walls leads to the domain walls motion and magnetization switching. Moreover, magnetic field-free perpendicular magnetization switching caused by SOT and its switching polarity (clockwise or counterclockwise) can be reversibly controlled in the IrMn/Co/Ru/CoPt heterojunctions based on the exchange bias and interlayer exchange coupling. This unique composition gradient approach accompanied with electrically controllable SOT magnetization switching provides a promising strategy to access energy-efficient control of memory and logic devices.