Two-dimensional (2D) metal-organic framework nanosheets (MOF NSs) play a vital role in catalysis, but the most preparation is ultrasonication or solvothermal. Herein, a liquid-liquid interfacial synthesis method has been developed for the efficient fabrication of a series of 2D Ni MOF NSs. The active sites could be modulated by readily tuning the ratios of metal precursors and organic linkers (R M/L ). The Ni MOF NSs display highly R M/L dependent activities towards 2e oxygen reduction reaction (ORR) to hydrogen peroxide (H 2 O 2 ), where the Ni MOF NSs with the R M/L of 6 exhibit the optimal nearzero overpotential, ca. 98 % H 2 O 2 selectivity and production rate of ca. 80 mmol g cat À1 h À1 in 0.1 M KOH. As evidenced by X-ray absorption fine structure spectroscopy, the coordination environment of active sites changed from saturation to unsaturation, and the partially unsaturated metal atoms are crucial to create optimal sites for enhancing the electrocatalysis.

Photocatalytic hydrogenation of biomass‐derived organic molecules transforms solar energy into high‐energy‐density chemical bonds. Reported herein is the preparation of a thiophene‐containing covalent triazine polymer as a photocatalyst, with unique donor‐acceptor units, for the metal‐free photocatalytic hydrogenation of unsaturated organic molecules. Under visible‐light illumination, the polymeric photocatalyst enables the transformation of maleic acid into succinic acid with a production rate of about 2 mmol g−1 h−1, and furfural into furfuryl alcohol with a production rate of about 0.5 mmol g−1 h−1. Great catalyst stability and recyclability are also measured. Given the structural diversity of polymeric photocatalysts and their readily tunable optical and electronic properties, metal‐free photocatalytic hydrogenation represents a highly promising approach for solar energy conversion.

Here, we show the fabrication of the carbon dots (CDs) with green and orange emissions from PTCDA (perylene‐3,4,9,10‐tetracarboxylic dianhydride). Using these CDs as emitters, the orange (or green) CDs LEDs were fabricated, which show electroluminescence (EL) spectra centered at 560 nm (or 498 nm) with an external quantum efficiency (EQE) of 1.98 % (1.76 %) adhering a luminescence of 626 cd m−2 (or 519 cd m−2). The machine learning was successfully used to predict PL CCT value. With the model, the white photoluminescence (PL) emission with adjustable correlated color temperature (CCT) from 3093 to 11018 K via combining blue, green, and orange CDs was achieved. Then, we obtained the warm white CDs LEDs with CCT of 3107, 4071 and 4548 K, and cold white CDs LEDs with CCT of 5632 (CIE coordinates of (0.33, 0.33), EQE: 1.18 %, luminescence: 598 cd m−2) and 6034 K accurately.

For emerging perovskite quantum dots (QDs), understanding the surface features and their impact on the materials and devices is becoming increasingly urgent. In this family, hybrid FAPbI 3 QDs (FA: formamidium) exhibit higher ambient stability, nearinfrared absorption and sufficient carrier lifetime. However, hybrid QDs suffer from difficulty in modulating surface ligand, which is essential for constructing conductive QD arrays for photovoltaics. Herein, assisted by an ionic liquid formamidine thiocyanate, we report a facile surface reconfiguration methodology to modulate surface and manipulate electronic coupling of FAPbI 3 QDs, which is exploited to enhance charge transport for fabricating high-quality QD arrays and photovoltaic devices. Finally, a record-high efficiency approaching 15 % is achieved for FAPbI 3 QD solar cells, and they retain over 80 % of the initial efficiency after aging in ambient environment (20-30 % humidity, 25 °C) for over 600 h.

We present seeing measurements of the Guoshoujing Telescope (formerly named the Large Sky Area Multi-Object Fiber Spectroscopic Telescope-LAMOST) site at Xinglong station during the period from 2007 March 12 to April 25. The measurements were carried out with the Differential Image Motion Monitor (DIMM), and a total of 9259 data sets was obtained. The median seeing was measured to be 1.1 ′′ , with 25% being better than 0.8 ′′ and 75% better than 1.5 ′′. The experiment shows that the DIMM exposure time has significant effects on the results of seeing measurements. An SBIG Polaris seeing monitor, which had been planned to be installed on the LAMOST site for long-term monitoring, was also employed during the DIMM observations. The results show that the SBIG seeing monitor is easily affected by gusty wind, resulting in larger seeing values. Considering the previous seeing measurements at Xinglong station over the last 15 yr, we conclude that an acceptable seeing condition at Xinglong station is around 1 ′′-2 ′′ .