Search

Heteroatom‐doping in metal‐nitrogen‐carbon single‐atom catalysts (SACs) is considered a powerful strategy to promote the electrocatalytic CO2 reduction reaction (CO2RR), but the origin of enhanced catalytic activity is still elusive. Here, we disclose that sulfur doping induces an obvious proton‐feeding effect for CO2RR. The model SAC catalyst with sulfur doping in the second‐shell of FeN4 (Fe1−NSC) was verified by X‐ray absorption spectroscopy and aberration‐corrected scanning transmission electron microscopy. Fe1−NSC exhibits superior CO2RR performance compared to sulfur‐free FeN4 and most reported Fe‐based SACs, with a maximum CO Faradaic efficiency of 98.6 % and turnover frequency of 1197 h−1. Kinetic analysis and in situ characterizations confirm that sulfur doping accelerates H2O activation and feeds sufficient protons for promoting CO2 conversion to *COOH, which is also corroborated by the theoretical results. This work deepens the understanding of the CO2RR mechanism based on SAC catalysts. [ABSTRACT FROM AUTHOR]

Heteroatom‐doping in metal‐nitrogen‐carbon single‐atom catalysts (SACs) is considered a powerful strategy to promote the electrocatalytic CO2 reduction reaction (CO2RR), but the origin of enhanced catalytic activity is still elusive. Here, we disclose that sulfur doping induces an obvious proton‐feeding effect for CO2RR. The model SAC catalyst with sulfur doping in the second‐shell of FeN4 (Fe1−NSC) was verified by X‐ray absorption spectroscopy and aberration‐corrected scanning transmission electron microscopy. Fe1−NSC exhibits superior CO2RR performance compared to sulfur‐free FeN4 and most reported Fe‐based SACs, with a maximum CO Faradaic efficiency of 98.6 % and turnover frequency of 1197 h−1. Kinetic analysis and in situ characterizations confirm that sulfur doping accelerates H2O activation and feeds sufficient protons for promoting CO2 conversion to *COOH, which is also corroborated by the theoretical results. This work deepens the understanding of the CO2RR mechanism based on SAC catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni electron depletion on NiPc/CNTs is alleviated by doping electron-deficient B. • Ni site in NiPc/B-CNTs is electron-enriched state, lowering CO 2 RR reaction barrier. • The NiPc/B-CNTs presents prominent CO 2 RR performance in neutral electrolytes. Dispersed nickel phthalocyanine (NiPc) on carbon nanotubes (CNTs) is the promising electrocatalyst for carbon dioxide reduction (CO 2 RR), but the strong interfacial electron interaction causes Ni electron depletion, limiting CO 2 RR performance. Herein, engineering the heteroatom doping in CNTs is proposed to alleviate electron depletion of Ni sites toward effective CO 2 RR. Boron heteroatoms induce electron-enriched Ni sites in NiPc/B-CNTs compared to phosphorus, nitrogen, and fluorine doped catalysts, resulting in superior CO 2 RR performance. Impressively, the NiPc/B-CNTs presents high CO Faraday efficiency (FE CO) of >98 % from −20 to −80 mA cm−2 and excellent stability up to 37 h with sustained FE CO of > 90 % in neutral electrolyte. Theoretical and experimental investigation reveals that implanting B heteroatoms alleviates Ni electron depletion via weakening electron transfer from NiPc to CNTs and thus reduces reaction barrier of *COOH formation, facilitating CO 2 RR. This study highlights importance of modifying carbon substrate in development of supported molecular catalysts for practical applications. [ABSTRACT FROM AUTHOR]

Electrochemical production of hydrogen peroxide (H2O2) through two‐electron (2 e−) oxygen reduction reaction (ORR) is an on‐site and clean route. Oxygen‐doped carbon materials with high ORR activity and H2O2 selectivity have been considered as the promising catalysts, however, there is still a lack of direct experimental evidence to identify true active sites at the complex carbon surface. Herein, we propose a chemical titration strategy to decipher the oxygen‐doped carbon nanosheet (OCNS900) catalyst for 2 e− ORR. The OCNS900 exhibits outstanding 2 e− ORR performances with onset potential of 0.825 V (vs. RHE), mass activity of 14.5 A g−1 at 0.75 V (vs. RHE) and H2O2 production rate of 770 mmol g−1 h−1 in flow cell, surpassing most reported carbon catalysts. Through selective chemical titration of C=O, C−OH, and COOH groups, we found that C=O species contributed to the most electrocatalytic activity and were the most active sites for 2 e− ORR, which were corroborated by theoretical calculations. [ABSTRACT FROM AUTHOR]

Electrochemical production of hydrogen peroxide (H2O2) through two‐electron (2 e−) oxygen reduction reaction (ORR) is an on‐site and clean route. Oxygen‐doped carbon materials with high ORR activity and H2O2 selectivity have been considered as the promising catalysts, however, there is still a lack of direct experimental evidence to identify true active sites at the complex carbon surface. Herein, we propose a chemical titration strategy to decipher the oxygen‐doped carbon nanosheet (OCNS900) catalyst for 2 e− ORR. The OCNS900 exhibits outstanding 2 e− ORR performances with onset potential of 0.825 V (vs. RHE), mass activity of 14.5 A g−1 at 0.75 V (vs. RHE) and H2O2 production rate of 770 mmol g−1 h−1 in flow cell, surpassing most reported carbon catalysts. Through selective chemical titration of C=O, C−OH, and COOH groups, we found that C=O species contributed to the most electrocatalytic activity and were the most active sites for 2 e− ORR, which were corroborated by theoretical calculations. [ABSTRACT FROM AUTHOR]

• Monolithic multiple surfaces simplifies the alignment by "freezing" surfaces. • Multiple surfaces including form and orientation are measured simultaneously by a single CGH. • Null test is used as feedback after mapping distortion correction. • Higher accuracy is achieved by corrective machining with fast axis servo. • Null fringes are experimentally observed for monolithic two mirrors in final test. Monolithic multiple freeform mirrors integrate two or more surfaces on a single substrate. Alignment of these surfaces is no longer required because they are frozen there as they are machined. Null test is then critical as a feedback to corrective machining which is indispensable for high accuracy optics. This paper presents a methodology for corrective machining of monolithic multiple freeform mirrors based on holographic null test capable of measuring multiple surfaces simultaneously. The surfaces are firstly related and modeled by coordinate transformation. A single computer generated hologram is then proposed with different regions to compensate aberrations of different surfaces. A combined tilt and power carrier is designed to separate the disturbance orders of diffraction. Mapping distortion in the null test is corrected through a pure ray tracing procedure by introducing a virtual reference sphere. The surface error including the orientation error is then superposed on the nominal surface to generate the tool path for corrective machining with fast axis servo. The tool radius and decenter is recognized by pre-cutting a spherical surface. The remounted workpiece is aligned with the machine tool by using an on-machine probe. Finally the proposed method is experimentally verified by corrective machining monolithic two mirrors with surface error effectively reduced and null fringes observed for both surfaces. [ABSTRACT FROM AUTHOR]

Freeform optical surfaces are advantageous to optical designers, as they provide additional degrees of freedom for optimization. The loss of rotational symmetry, however, makes measurement of freeforms more challenging. Herein, advances in interferometric areal measurement of freeform optical surfaces, including null tests, non‐null tests, near‐null tests, and adaptive null tests, are reviewed. Some new developments, in the Hartmann test, deflectometry, and phase retrieval, as representatives of non‐interferometric areal measurement, are then presented. Overall, the focus is on single‐point‐probe‐based profilometry categorized into coordinate measurements and slope‐ or curvature‐based measurements. Innovative measurement technology is trying to bridge the gap between high accuracy and high dynamic range as freeform optical surfaces are finding more applications in visible and shorter‐wavelength optics. [ABSTRACT FROM AUTHOR]

Highlights • We present a novel flatness test which only using two flats. • Multi-shift and rotation steps are needed. • A pixel level spatial resolution can be achieved. • Analysis to tilt error and rotation error is presented. • Simulations and experimental absolute results are given. Abstract In classical three-flat test, error in reference surface can not be identified fully. What we obtain is only the absolute radial profile instead. In addition, at least three flats with similarly high accuracy are required. The test procedures are very complex and it takes a long time and requires high precision adjustment. In this paper, we proposed a new method for absolute test of flatness. There are only two flats used in our method and it does not need precise alignment of the specimens. The method requires multiple translations of the test surface and one 90° rotation step. The relative tilt during translation is measured by a compact wavefront interferometer. We analyze the effect of noise, tilt estimation error and rotation error on reconstruction result. The method is experimentally verified and compared with the direct interferometric result using high precision reference surface. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials have attracted great attention due to their unique physical and chemical properties derived from the dimensionality effect and modulation in their band structure. Herein, an important industrial catalytic material, gamma alumina (γ-Al 2 O 3 ) with well-defined two-dimensional nanosheet structure was fabricated by a designed crown ether induced assembly approach. The obtained γ-Al 2 O 3 nanosheets with a thickness of ∼4 nm possess high surface area (351 m 2 /g) and 16% pentacoordinate Al 3+ sites which are the main catalytic active sites for ethanol dehydration to ethylene, compared to almost no pentacoordinate Al 3+ sites for the commercial γ-Al 2 O 3 nanoparticles. Furtherly, systematical investigation reveals that the crown ether plays the key role in the assembly of nanosheet structure. As a catalyst for ethanol dehydration to ethylene, the obtained alumina nanosheets with easily-accessible surface and more active sites, exhibit a superior catalytic performance to the commercial alumina with a much higher yield at large space velocity. [ABSTRACT FROM AUTHOR]

Because of its high sensitivity to misalignment, precision grinding of free-form surfaces with micron accuracy requires accurate registration of the surface measurement point cloud. Registration of point clouds obtained with a coordinate measuring machine (CMM) is generally an iterative process of finding optimal coordinate transformation between the CMM frame and the model frame of the workpiece by minimizing the point-to-surface distances with probe radius compensation. For free-form surfaces, frequent calculation of point-to-surface distances consumes very much time, and a trade-off has to be made between the efficiency and the accuracy. This paper presents a method for fast registration of free-form surface point clouds based on the point-to-triangle distance which involves only Delaunay triangulation of a two-dimensional dataset, and the surface normal is quickly calculated from cross product. Probe radius compensation is realized by registering the probe center points with the offset surface. We prove that it is equivalent to registering the probe contact points with the nominal surface through theoretical analysis. The registration problem is then formulated as sequential linear least-square problems with properly defined ball constraints. To validate the method, numerical simulations are presented to show the accuracy of the point-to-triangle distance. The registration algorithm also shows excellent robustness against misalignment of tens of millimeters/degrees. Finally measurement, registration, and grinding of a free-form optical surface are experimentally demonstrated. The surface error obtained after registration is used for compensatory grinding which reduces it to micron level. [ABSTRACT FROM AUTHOR]

In traditional three flat test, it only provides the absolute profile along one surface diameter. In this paper, an absolute testing algorithm based on shift-rotation with three flat test has been proposed to reconstruct two-dimensional surface exactly. Pitch and yaw error during shift procedure is analyzed and compensated in our method. Compared with multi-rotation method proposed before, it only needs a 90° rotation and a shift, which is easy to carry out especially in condition of large size surface. It allows pixel level spatial resolution to be achieved without interpolation or assumption to the test surface. In addition, numerical simulations and optical tests are implemented and show the high accuracy recovery capability of the proposed method. [ABSTRACT FROM AUTHOR]

An improved zonal algorithm based on the multi-shear interferometry with different tilts is proposed to reconstruct two-dimensional wavefront exactly. The method allows large shear and high lateral resolution be achieved simultaneously. Due to environment vibration and mechanical misalignment, different tilt errors added in the measured wavefront will result in unknown and mismatch bias in the difference wavefronts. The effect of tilt errors in multi-shear method is analyzed and an improved zonal method is proposed to deal with tilt errors, which is easy to implement. Numerical simulations are executed and the results indicate that the improved algorithm is immune to tilt errors and has good noise suppression capabilities. In the experiment, we combine multi-shear method but using a Fizeau interferometer. The result demonstrates the effectiveness of the proposed algorithm. [ABSTRACT FROM AUTHOR]

Fluorescent probes can detect fluoride ion and carbon dioxide to ensure their concentrations at reasonable levels to protect human health. Although numerous fluorescent probes have been developed in the last decades, these probes still face some performance challenges: complicated molecular structures, unremarkable changes and long responsive times. Moreover, the detections of fluoride ion and carbon dioxide are usually separated and fluorescent probes which can detect fluoride ion and carbon dioxide simultaneously are rare. To improve this situation, in this work, an indolo[3,2 -b ]carbazole derivative, DP-ICZ, was designed. This compound had simple structure and facile preparation procedure. It displayed high selectivity toward fluoride ion over other ions. Obvious changes of color, fluorescence band and intensity happened in a few seconds after the addition of fluoride ion. Meanwhile, after activated by fluoride ion, DP-ICZ was also suitable for carbon dioxide detection. Its detection limits for fluoride ion and carbon dioxide were 23.3 μM and 1.07 μM respectively. Through PL spectra and NMR analysis, its detection mechanisms were proved to be deprotonation by fluoride ion and recovery by carbon dioxide respectively. Our study presents an effective basic group based on which researchers can develop new fluorescent probes with simple structures, high sensitivities, short responsive times and the abilities to detect fluoride ion and carbon dioxide simultaneously. [ABSTRACT FROM AUTHOR]

Interferometric test of large convex aspheres with high accuracy is still an urgent problem. Adopting a large-aperture null corrector is usually inevitable, and it is imperative to certify the large-aperture null optics in case incorrect final shape of the aspheric mirror is obtained. Moreover, it is necessary to calibrate and remove errors of the large-aperture null lens and trace errors to surfaces that are easy to obtain high accuracy. For these purpose, this paper presents an in situ calibrated null test method. The large-aperture null corrector for convex aspheric mirror is verified and calibrated by a wisely designed small aperture certifying null whose surfaces are either flat or spherical which are easy to be fabricated, measured and assembled. A redundant test is implemented by a Zygo VeriFire Asphere interferometer for cross test. Compared with existing methods of certificating null correctors which utilize an expensive CGH or a self-aligning aspherical mirror, the presented method finally traces errors of a large-aperture null corrector to small aperture flat and spherical surfaces thus costs are expected to be saved dramatically. [ABSTRACT FROM AUTHOR]

Silver nanowire (AgNW) ink has great influence on the performance of the resulting AgNW-based conductive film, especially for the large-scale roll-to-roll processed films. However, AgNW inks made by researchers are almost immature because there is not a clear research procedure for the development of qualified inks. In this work, electric double layer model, Young equation, bubble theory, percolation theory, Rhodes & Orchäd equation, Kelvin equation and other theoretical models were introduced successively to describe those processes which additives in inks should adjust. Based on the guidance of these theories, additives were determined successively and an optimized light grey ink with the composition of 0.4% AgNW + 0.2% 2-amino-2-methyl-1-propanol + 0.01% Zonyl FSO-100 + 1.5% diacetone alcohol + 5% 1,4-dioxane + 92.89% isopropyl alcohol was obtained. Except for trace amount of Zonyl FSO-100, other additives could be easily eliminated at low temperature (110 °C), which could retain the original properties of AgNW furthest and greatly lower the dosage of AgNW in inks. Based on this ink, excellent AgNW/PET composite film was prepared. The sheet resistance, transmittance and haze of this film were 29.5 Ω/sq, 88.9% and 1.49% respectively. Finally, touch screens (180 mm × 105 mm) and tablets (10 inches) were prepared from our films and showed good performance. These results demonstrated that excellent AgNW ink could be developed through our research procedure. Our studies not only produce an excellent AgNW ink, but also provide a systematic research procedure and series of theoretical models for many kinds of conductive inks. [ABSTRACT FROM AUTHOR]

Subaperture stitching test in combination of the reconfigurable optical null we proposed recently provides flexible solutions to various surfaces including convex aspheres and even aspheres of large aperture. However it is challenging for the stitching optimization to get the real surface error because the surface error is strongly coupled with misalignment-induced aberrations in near-null subaperture measurements. Aiming at this challenge, we first figure out the property of aberrations induced by misalignment of optical null or test surface. It shows that identical misalignment of the optical null introduces nearly identical aberrations to subapertures with different off-axis distances, while misalignment of the test surface introduces little aberrations to the central subaperture. The stitching algorithm is then proposed with focus on decoupling surface error and induced aberrations. The major step is to calibrate out the effect of misaligned near-null optics before stitching optimization by using the central subaperture measurement. We also present the through-the-back null test for the purpose of cross test. The axial distance is precisely monitored by a low coherence interferometer, which enables accurate determination of the spherical aberration component of surface error. Final experimental results show consistent spherical aberration obtained by stitching test and by the through-the-back null test. It is a big step towards instrumentation of subaperture stitching test for aspheres with rather big amount of misalignments in surface metrology practice. [ABSTRACT FROM AUTHOR]

With the research focus of subaperture stitching interferometry shifting from flat wavefronts to aspheric ones, a variety of algorithms for stitching optimization have been proposed. We try to category and compare the algorithms in this paper by their modeling of misalignment-induced subaperture aberrations which are of low orders. A simple way is to relate the aberrations to misalignment by linear approximation with small angle assumption. But it can not exactly model the induced aberrations of aspheres. In general, the induced aberrations can be fitted to free polynomials and then removed from subaperture measurements. However, it is at the risk of mixing up the surface error and the induced aberrations. The misalignment actually introduces different terms of aberrations with certain proportions. The interrelation is then determined through analytical modeling or ray tracing. The analytical model-based algorithm and the ray tracing-based algorithm both are tedious, aperture shape-related and surface type-specific. While the configuration space-based algorithm we proposed numerically calculates the surface height change under rigid body transformation, it is generally applicable to various surface types and different aperture shapes. Simulations and experiments are presented to compare the stitching results when different algorithms are applied to null cylindrical subapertures measured with a computer generated hologram. The configuration space-based algorithm shows superior flexibility and accuracy. [ABSTRACT FROM AUTHOR]

A new zonal wavefront reconstruction algorithm with pixel-level spatial resolution and high accuracy is proposed, which is able to reconstruct the original wavefront of general aperture shape from only two difference wavefronts measured at two orthogonal shear directions with shear amounts equaling arbitrary moderate integral multiples of the sample interval. Based on this algorithm, a quasi-absolute surface figure test method is presented, which requires only two additional translational measurements with shifts of arbitrary moderate integral multiples of sample interval along x and y directions besides the original position measurement. Optical schemes of the proposed method for testing flat, spherical and cylindrical surfaces are investigated, and special considerations and challenges for calibrating spheres and cylinders are also briefly formulated theoretically. Thorough errors analysis is formulated for obtaining high accuracy test result. Simulations and experiments on a flat surface are conducted to validate the proposed algorithm and method. Compared with existing absolute test methods with Pseudo-Shear Interferometry (PSI) technique, the presented method has advantages, like, less number of measurements, arbitrary moderate shear amounts and the high signal-to-noise ratio it can reach. [ABSTRACT FROM AUTHOR]

A diphenylamino-substituted bicarbazole derivative (BCZDA) with high glass-transition temperature (170 °C) has been developed. The introduction of the strongly electron-donating diphenylamino group endows this compound with high HOMO (−4.94 eV), LUMO (−1.94 eV) and triplet energy (2.65 eV) levels which are beneficial for hole injection and electron/triplet exciton blocking. By adopting this compound as the hole-transporting layer, both fluorescent and phosphorescent devices with good performance have been realized. Through the device study, the performance of this compound is proved to be comparable to that of NPB. The utility of this compound as a host has also been evaluated. [ABSTRACT FROM AUTHOR]

• Multi-scale measurement of DOEs based on stitching interference microscopy. • Inherited advantages of high resolution and high accuracy. • Extended lateral range of measurement to 10 mm scale via subaperture stitching. • Simultaneous correction of 6-dof scanning motion error for seamless data fusion. • Full aperture fabrication error map obtained with undercut effect verification. The development of diffractive optical elements (DOEs)enables fascinatingly compact design and chromatic aberration correction. Fabrication errors of DOEs include periodic pattern error, relief profile error and roughness which affect imaging quality and diffraction efficiency. Characterization of the DOE requires thus multi-scale measurement of the surface topography over the full aperture of 10 mm scale. This paper presents a method based on the white light interferometry in combination of subaperture stitching. Firstly, the principle of measurement and subaperture layout design is introduced. The measuring system is easily set up by integrating a scanning platform with the interference microscope. Subaperture stitching algorithm is developed based on the surface height change related to the scanning motion error. The slope of the relief profile is used to model the deviations of overlapping point pairs induced by lateral shift and rotation. Finally, the topography and fabrication error of a Fresnel lens surface are experimentally obtained and characterized over the full aperture through stitching of totally 67 subapertures. [ABSTRACT FROM AUTHOR]

In this work, a novel deep-red (642 nm) iridium complex, Ir(bp4b) 2 (dend), is developed. The introduction of alkyl groups in ligands weakens the intermolecular interactions and endows Ir(bp4b) 2 (dend) with favorable physical properties: short photoluminescence lifetime (271.6 ns), low concentration sensitivity (10−6 to 10−4 M) and balanced charge-transporting ability. Ir(bp4b) 2 (dend)-doped phosphorescent device displays high efficiencies (9.62 cd/A, 12.25 lm/W, 15.29%), low roll-off of efficiencies (from 10 to 1000 cd/m2: no decrease; from 1000 to 5000 cd/m2: 10.6%), relatively low concentration sensitivity (from 5% to 15%), long device lifetime (T 80 : 5225 h at 100 cd/m2) and very stable electroluminescent spectra (from 1 cd/m2 to maximum luminance). This performance is comparable to those of previous record deep-red (around 640 nm) phosphorescent emitters. More importantly, compared with previous record emitters, Ir(bp4b) 2 (dend) reports more kinds of excellent parameters and such comprehensive deep-red emitter is rare at present. [Display omitted] • A novel deep-red (642 nm) iridium complex with favorable physical properties is developed. • Ir(bp4b) 2 (dend)-doped phosphorescent device displays high and comprehensive performance. • This device performance is comparable to those of previous record deep-red (around 640 nm) phosphorescent emitters. [ABSTRACT FROM AUTHOR]

Aiming to develop a prototype swing arm profilometer for several meter-class aspheres, we first present detailed error analysis including error motions of the swing rotary table and the part rotary table, and misalignment of the axes of the two rotary tables. The induced probing error in the normal direction of the reference sphere is calculated by considering the error motions in the coordinate transformation. A surface reconstruction algorithm is then proposed to separate the error motions of the part rotary table by stitching multiple traces. The error motions are optimally recognized and then removed from the trace measurement based on the least squares principle. We model the objective function by relating the normal error to the rigid body transformation of each trace. The basic idea is to minimize the inconsistency of all intersection points of different traces simultaneously. Finally the algorithm is verified through simulations. It shows that error motions of sub-milliradian scale are even tolerant with the surface reconstruction algorithm. [ABSTRACT FROM AUTHOR]

Development of high-performance and stable electrocatalysts for hydrogen evolution reaction (HER) is crucial for hydrogen economy. Inspired by hydrogen evolution behavior on hydrogenase enzyme, in which the azadithiolate bridging ligand of active center facilitates fast proton shuttling and catalytic turnover, here we present an efficient approach to enhance both HER kinetics and stability realizing on an IrNi@N,O-C catalyst with individual IrNi nanoparticle separately confined in N and O co-doped carbon (N,O-C) nanocage. Experimental and theoretical investigations indicate that the N,O-C nanocage provides proton-adsorbing functionality on raising H* coverage over IrNi active centers, resulting in much accelerated HER kinetics. The IrNi@N,O-C presents superior HER performances compared to all reported Ir-based catalysts, with overpotential of 22 mV at 100 mA cm−2, ultrahigh mass activity of 9.82 A mg Ir −1 (−0.050 V vs. RHE) and outstanding durability of 200 h at large current density. This work affords fresh insights/strategies for design of high-performance electrocatalysts [Display omitted] • The IrNi@N,O-C prepared via reactive template route features nanoreactor structure. • The IrNi@N,O-C presents record-high hydrogen evolution reaction performances. • The N,O-C nanocage-mediated HER pathway contributes to enhanced HER performances. • The HER pathway on IrNi@N,O-C is similar to that of hydrogenase enzyme. [ABSTRACT FROM AUTHOR]

It is necessary to quantitatively compare two measurement results which are typically in the form of error maps of the same surface figure for the purpose of cross test. The error maps are obtained by different methods or even different instruments. Misalignment exists between them including the tip-tilt, lateral shift, clocking and scaling. A fast registration algorithm is proposed to correct the misalignment before we can calculate the pixel-to-pixel difference of the two maps. It is formulated as simply a linear least-squares problem. Sensitivity of registration error to the misalignment is simulated with low-frequency features and mid-frequency features in the surface error maps represented by Zernike polynomials and spatially correlated functions, respectively. Finally by applying it to two cases of real datasets, the algorithm is validated to be comparable in accuracy to general non-linear optimization method based on sequential quadratic programming while the computation time is superiorly incomparable. [ABSTRACT FROM AUTHOR]

• Optical surface metrology based on stitching interference microscopy. • Flexible adaptability to sophisticated variation of the aspheric surface shape. • "One-stop" measurement of surface form, waviness and roughness simultaneously. • Applied to even asphere, "gull-wing" surface and microstructured curved surface. • Verified with CGH null test and stylus profilometry for 10 mm-class optics. Small optics of 10 mm-scale are widely used in miniature cameras with increasingly sophisticated surface shape. The surface features ranging from low to high frequency need to be measured efficiently for in-process quality control. Wavefront interferometry is applicable with specifically designed null optics for each surface, but not preferred for small optics because the surface radius is approaching the shortest measurable radius limited by the interferometer optics. We present a strategy for flexible surface metrology based on stitching interference microscopy. The full aperture surface is divided into a series of small subapertures with reduced size and slope which are then measurable with a standard interference microscope. The measurement principle is introduced and a method for subaperture design is proposed by checking the subaperture size and slope after coordinate transformation. A simultaneous stitching algorithm is proposed to minimize the overlapping deviations with overlapping points and subaperture configurations determined automatically in a way of alternating optimization. Instrumentation is easy by integrating a multi-axis platform with a commercial interference microscope. Both the lateral and the vertical scales need to be calibrated to give accurate subaperture measurement of three coordinates. The capability of the instrument is finally verified through a series of experiments compared with cross tests such as the null test and the stylus profilometry. It shows high flexibility to measure a variety of complex surfaces including the high-order even asphere, the "gull-wing" surface and microstructured curved surfaces without using any auxiliary null optics. The instrument enables "one-stop" measurement of surface form, waviness and roughness simultaneously. [ABSTRACT FROM AUTHOR]

Aspheres and freeform surfaces are well measured with null optics but the transverse coordinates on the test surface are not linear with the pixels on the imaging plane. Such a mapping distortion must be corrected before the measured surface error map is used for corrective figuring process. Conventional mapping distortion correction involves tediously finding the coordinates of a sequence of fiducial marks on both the test surface and the imaging plane. This paper presents a pure ray tracing method without use of fiducial marks by introducing a dummy spherical surface between the point source and the null optics, acting like a virtual reference sphere (RS). It is linearly mapped to the imaging plane with the linear scale easily calibrated. On the other hand, the virtual RS is exactly mapped to the test surface by tracing a bundle of dense rays. This virtual surface thus bridges the gap between coordinates on the imaging plane and those on the test surface. Two experimental examples of null test of on-axis and off-axis aspheres demonstrate the effectiveness of mapping distortion correction. • Pure ray tracing method for mapping distortion correction. • A dummy virtual reference sphere introduced for coordinate mapping. • No need of fiducial marks except two feature points for linear calibration. • No need of polynomial fitting because tracing rays can be dense as possible. • Effectiveness verified by experimental examples of asphere and freeform surfaces. [ABSTRACT FROM AUTHOR]

Abstract: Subaperture stitching interferometry combined with a test plate is attractive for testing large convex aspheres, but the stitching algorithm is challenging because the aberrations induced by misaligned test surface or test plate are coupled with the surface figure. By relating the subaperture configuration to the overlapping deviations through ray trace and coordinate transformation, the subaperture misalignment is optimally recognized and corrected to give a minimal overlapping inconsistency in an iterative way. Allowing for misaligned test plate, we decompose the induced aberrations into three parts which are corrected by the stitching algorithm, removed in the form of the Zernike polynomials and left uncorrected as residuals. Finally we present simulation results of testing a convex aspheric mirror with a computer generated hologram which shows the algorithm successfully retrieves the surface figure with the test mirror or the hologram misaligned. [Copyright &y& Elsevier]

Abstract: Stitching test of large optical flats is still quite challenging. In this paper, aiming to reduce the 2nd order error accumulation effect, separation of the reference surface error from the subaperture measurements is proposed in stitching of large flats. The reference error is decomposed into power and astigmatism, residual Zernike polynomial surface and high frequency component, which are estimated or calibrated, respectively. The error separation procedure is then incorporated into the subaperture stitching algorithm. Finally experiments are presented to show the effect of error reductions in stitching test of a 600mm-aperture flat, with reference surface separated and verified by the factory report of the transmission flat. [Copyright &y& Elsevier]

The alkaline oxygen evolution reaction (OER) is a promising avenue for producing clean fuels and storing intermittent energy. However, challenges such as excessive OH− consumption and strong adsorption of oxygen‐containing intermediates hinder the development of alkaline OER. In this study, we propose a cooperative strategy by leveraging both nano‐scale and atomically local electric fields for alkaline OER, demonstrated through the synthesis of Mn single atom doped CoP nanoneedles (Mn SA‐CoP NNs). Finite element method simulations and density functional theory calculations predict that the nano‐scale local electric field enriches OH− around the catalyst surface, while the atomically local electric field improves *O desorption. Experimental validation using in situ attenuated total reflection infrared and Raman spectroscopy confirms the effectiveness of the nano‐scale and atomically electric fields. Mn SA‐CoP NNs exhibit an ultra‐low overpotential of 189 mV at 10 mA cm−2 and stable operation over 100 hours at ~100 mA cm−2 during alkaline OER. This innovative strategy provides new insights for enhancing catalyst performance in energy conversion reactions. [ABSTRACT FROM AUTHOR]

The alkaline oxygen evolution reaction (OER) is a promising avenue for producing clean fuels and storing intermittent energy. However, challenges such as excessive OH− consumption and strong adsorption of oxygen‐containing intermediates hinder the development of alkaline OER. In this study, we propose a cooperative strategy by leveraging both nano‐scale and atomically local electric fields for alkaline OER, demonstrated through the synthesis of Mn single atom doped CoP nanoneedles (Mn SA‐CoP NNs). Finite element method simulations and density functional theory calculations predict that the nano‐scale local electric field enriches OH− around the catalyst surface, while the atomically local electric field improves *O desorption. Experimental validation using in situ attenuated total reflection infrared and Raman spectroscopy confirms the effectiveness of the nano‐scale and atomically electric fields. Mn SA‐CoP NNs exhibit an ultra‐low overpotential of 189 mV at 10 mA cm−2 and stable operation over 100 hours at ~100 mA cm−2 during alkaline OER. This innovative strategy provides new insights for enhancing catalyst performance in energy conversion reactions. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) presents a promising approach for combating periodontitis, an infectious disease triggered by bacteria. However, the hypoxic environment within periodontal pockets poses challenges for PDT efficacy. In this study, novel purine‐based C^N ligands are utilized to develop Ir(III) complexes with enhanced reactive oxygen species (ROS) generation capacity for periodontitis treatment. The type I/II PDT performance of Ir(III) is greatly enhanced by the purine ligands, which leads to potent bactericidal and biofilm elimination efficacy. In a rat model of periodontitis, local application of these purine‐based Ir(III) complexes effectively achieves antibacterial and anti‐inflammatory effects while promoting tissue repair under clinical luminaire exposure. This PDT strategy utilizing purine‐based Ir(III) complexes circumvents the need for antibiotics and surgical intervention, emerging as a promising, non‐invasive approach for managing periodontitis. [ABSTRACT FROM AUTHOR]

A hybrid biomimetic imaging system combining the advantages of a fish eye and a compound eye is proposed. It uses a single ball lens as objective lens followed by an array of microcameras, which makes it possible to achieve high resolution in a wide field of view (FOV). Unlike conventional monocentric designs, a single ball lens is enough for the purpose of intermediate imaging. Its geometric aberrations are rather big but still able to be corrected by the subsequent microcameras with ordinary spherical lenses. Optomechanical design of the imaging system is presented and the alignment tolerance is easily guaranteed by machining fitting elements on an integrative housing assembly. Imaging performance of the single ball lens-based system is experimentally verified to be comparable with that of conventional two-shell objective-based system. Moreover, its microcamera has larger FOV which facilitates the extension of FOV with overlap between sub-images. Finally, a row of 9microcameras and 3 × 3 array of microcameras are integrated to capture and then stitch sub-images for wide FOV imaging with high resolution. • Hybrid biomimetic design combining a fish eye and a compound eye. • A single ball lens used as objective lens followed by an array of microcameras. • Optomechanical design facilitating assembly without laborious adjustment. • Imaging performance comparable with conventional monocentric design. • Extended FOV with high resolution achieved by stitching 9 sub-images. [ABSTRACT FROM AUTHOR]

Null test is preferred for measuring surface error of aspheres. However for large convex aspheres, it is challenging to fabricate larger null optics. Subaperture stitching is hence introduced but requires different null optics for subapertures of different off-axis distances. It gets easier by using replaceable computer generated holograms (CGHs). In this paper, a convex high-order even asphere is taken as an example and multiple CGHs are designed for null test of different subapertures. The same transmission flat and tilt carrier are used to facilitate alignment of CGHs. Disturbance orders of diffraction are confirmed to be separated by the tilt carrier without ghost interference. A configuration-based stitching algorithm is applied to successfully retrieve the full aperture surface error. The CGH substrate error is calibrated out before stitching optimization by measuring its transmitted wavefront with a high precision reference flat. Finally, the stitching result is verified by through-the-back null test of the same asphere. • Measurement of large convex aspheres with null subaperture stitching. • Different subaperture aberrations compensated by replaceable multiple CGHs. • Tilt carrier designed for separation of disturbance orders of diffraction. • CGH substrate error calibrated out before stitching optimization. • Experimental cross test of an even asphere with through-the-back test. [ABSTRACT FROM AUTHOR]

• Measurement of large area micro topography with subaperture stitching. • Detection of edge features with slope threshold and projection on OXY plane. • Fast correction of 2D lateral coordinates by solving a linear least-squares. • Correction of height coordinates by solving a linear least-squares problem. • No need for high precision scanning stages with "sliding" eliminated by stitching. Microstructured surfaces over large areas are typical in diffractive optics and biomimetic surfaces. The topography measurement is challenging due to the multi-scale nature. In this paper, an efficient stitching method is proposed for fusion of multiple subapertures to produce a large area topography. The first step is detecting edge features and then projecting them on the OXY plane. The next step is correction of lateral coordinates by registering the edge curves in overlapping regions. The change of lateral coordinates is linearly related to the lateral shifts and clocking angle which are estimated by simply solving a linear least-squares problem. In the final step, height change is also linearly related to the piston and tip-tilt of subapertures. Hence it is corrected by minimizing the height difference in overlapping regions, which is again modeled as a linear least-squares problem. The stitching method is experimentally verified on a holographic sample. Totally seven by seven subapertures are measured with an interference microscope and seamlessly stitched together. [ABSTRACT FROM AUTHOR]

Large aperture acylinders are typical optical elements in synchrotron radiation systems and laser shaping devices. The manufacture of such ultra-precision optical elements requires ultra-precision measurement of the surface figure. The use of computer-generated hologram (CGH) customized for the acylindrical surface can only achieve a "one-to-one" test. Limited by the aperture of CGH, it also cannot meet the requirements for large aperture acylinders. In order to realize flexible test of large aperture acylinders with mild aspherical departure, a method of surface figure reconstruction for subaperture measurements under near-null test is proposed. It is based on ray tracing and rigid body transformation. By using a general CGH for cylindrical surface, near-null test for various acylindrical surfaces can be realized. Subaperture stitching test can overcome the problem of the limited CGH aperture which cannot meet the requirement of large aperture acylinders. Finally an elliptical cylindrical mirror with an aperture of 240mm (sagittal) × 350mm (tangential) is measured. And the cross test is realized by using a customized CGH to verify the validity and precision of the proposed method. [ABSTRACT FROM AUTHOR]

Inducing calcium carbonate (CaCO3) precipitation is an active research field for its functional extension. Herein, we presented a simple but efficient method for fast preparation of CaCO3 thin film induced by 1-naphthoic acid (1 N) at organic-aqueous interface. The film structure was characterized by scanning electron microscopy (SEM) and X-ray powder diffractometry. Grain growth and morphology of the quickly formed thin film are described. The results indicate the thickness of the film can reach 5–20 µm, with promotion and acceleration of mineralization between liquid–liquid interface induced by 1 N. These results shed light on the importance of organic molecule-induced crystallization of CaCO3 and open a novel synthetic route for its precipitation. [ABSTRACT FROM AUTHOR]

The computer-generated holograms (CGH) are the core component to solve the problem of complex surface measurement. Pattern distortion is an important error source that affects its testing accuracy. This paper presents an evaluation method for the influence of pattern distortion on wavefront error. Firstly, the technical means of characterizing pattern information of CGH by optical element detection system was expounded. Then, the simulation model of wavefront error distribution was established to study the effect of pattern distortion on CGH testing accuracy. Finally, we verified the feasibility of the evaluation method based on the experimental research. [ABSTRACT FROM AUTHOR]

[Display omitted] • An electro-production and detection of H 2 O 2 system is constructed by Ni-SAC. • In-situ electro-detection of H 2 O 2 is more reliable than spectrophotometry. • The sensor displays a low detection limit of 6.87 pM towards H 2 O 2 detection. • NiOOH on single Ni site is an intermediate for H 2 O 2 detection in alkaline medium. Electrochemical oxygen reduction reaction (ORR) to hydrogen peroxide (H 2 O 2) is a common method to address the growing demands of H 2 O 2. To map a clear understanding of structure–activity relationship of electrocatalyst for H 2 O 2 production, it is necessary to real-time quantitative monitor of H 2 O 2 in the initial production process. However, we found that the common off-line methods such as spectrophotometry, titration, etc., are not reliably during in-situ ORR process. Here, a simple and real-time simultaneous electrochemical production and determination of H 2 O 2 system is constructed by using a dual-functional nickel (Ni) single-atom electrocatalyst. The electro-production part is conducted with a DC power supply, air pump, and dual-electrode system, while the electro-detection part consists of a three-electrode system. Compared with traditional off-line H 2 O 2 measure methods, the present on-line determination of H 2 O 2 protocol provides more reliable results in the quantitative monitoring of H 2 O 2 , and with a wide detection concentration range from 20 pM to 22.2 mM and a low detection limit of 6.87 pM. NiOOH on single Ni site is an important intermediate for efficient detection of H 2 O 2 in alkaline medium. The Ni-SAC sensor also shows well anti-interferential and selective ability, high reproducibility and stability of H 2 O 2 sensing up to 12 days. This simple-to-operate method offers a new window to record a reliable structure–activity relationship on electrocatalyst engineering in electrochemistry. [ABSTRACT FROM AUTHOR]

To realize the quasi-quantitative Schlieren measurement of the shock train structure across the cylindrical isolator in the supersonic flow field, based on the theory of Schlieren measurement and light transmission, we propose the design scheme of conformal windows and discuss the machining feasibility with the window's parameters. The relationship between the Schlieren imaging effect, the deflection of parallel light in the Schlieren apparatus, and the conformal optical window aberrations was researched, putting forward the optical simulation model of the conformal optical windows and the quasi-quantitative Schlieren measurement. Moreover, considering the actual wind tunnel test conditions, under the speed of Mach 2 at the isolator's inlet, the distortion brought by conformal optical windows in the Schlieren observation region was simulated by the computational fluid dynamics method. Finally, the image correction algorithm for the distorted picture caused by the conformal windows was presented, and the quasi-quantitative Schlieren measurement through the conformal optical window pair was conducted for the experimental verification. The results reveal the quasi-quantitative Schlieren measurement effect across the high-precision conformal optical window pair of the cylindrical isolator, providing guidance on maintaining the balance between the manufacturing feasibility and the observation performance of conformal windows. [ABSTRACT FROM AUTHOR]

Abstract: We present a method for calibrating the position error of phase retrieval with transverse translation diversity in optical wavefront in situation where the position error sharply influences algorithm precision. This method involves testifying that the essence of the position error in phase retrieval is the translation in frequency domain and the minimum of iterative error against position error reaches when there is no position error. Then the least square method is used for fitting the relationship between the iterative error and the assumed position error in polynomial function. The computer simulations used to prove the validity of this method are described. The results indicated that this method can calibrate the position error to approximately 1/500mm which nearly has no influence on the phase retrieval. [Copyright &y& Elsevier]

[Display omitted] • The method of improving dispersion of indium polyphthalocyanine (InPPc) has been proposed. • The sodium dodecylbenzenesulfonate (SDBS) modification induces the matched surface hydrophilicity of carbon nanotubes (CNT) with InPPc. • The InPPc/SDBS@CNT exhibits the increased exposure of active site and electron-deficient In center. Molecular catalysts have emerged as the promising candidate for oxygen reduction to hydrogen peroxide (H 2 O 2). Dispersing homogeneously molecular catalyst on carbon support is the prerequisite for actual electrocatalysis application. Herein, we proposed a novel strategy of modification with sodium dodecylbenzenesulfonate (SDBS) to improve dispersion of indium polyphthalocyanine (InPPc) on carbon nanotube (CNT). The SDBS modification induces the matched surface hydrophilicity of CNT with InPPc, preventing InPPc aggregation. As a result, the InPPc/SDBS@CNT exhibits a remarkable onset potential of 0.84 V vs. RHE and selectivity of > 95 %, superior to InPPc/CNT and most recently reported catalysts. In situ Raman spectrum identifies the critical *OOH intermediate during H 2 O 2 formation on InPPc/SDBS@CNT. Importantly, the InPPc/SDBS@CNT presents a prominent H 2 O 2 production rate of 24.88 mg/cm2/h over 12 h in flow cell. This work provides an effective strategy to promote practical application of molecular catalysts. [ABSTRACT FROM AUTHOR]

The effective removal of 99TcO 4 − in the radioactive waste is very important and ReO 4 − was often used as the substitute of TcO 4 − for research. In this paper, an imidazolyl-based polymer TIB-TBPB was successfully synthesized and exhibited excellent adsorption performance for ReO 4 − . The results showed that the framework of TIB-TBPB is benzene-rich structure, which enhances its hydrophobicity and allows it to exhibit excellent thermal stability and acid-base stability. It could maintain the excellent recyclability even in 3 M HNO 3. TIB-TBPB possessed the high capacity of 882 mg g−1 and the superb removal depth for ReO 4 − and TcO 4 − with K d of 2.34 × 106 mL g − 1 and 1.35 × 106 mL g − 1, respectively. Furthermore, TIB-TBPB has the advantages of excellent selectivity, recyclability and could remove 65.7 % and 86.4 % of ReO 4 − from 3 M HNO 3 and the Hanford LAW simulated nuclear waste, respectively. DFT calculation explained the selectivity of TIB-TBPB for ReO 4 − over NO 3 − and verified the experimental results. In a word, the excellent performance suggested TIB-TBPB would be a promising material for TcO 4 − /ReO 4 − removal. [Display omitted] [ABSTRACT FROM AUTHOR]

• Mechanical behaviors of AuPt alloys are investigated from atomic level. • Monocrystalline AuPt alloy is susceptible to work hardening at low temperature. • Mechanical properties of AuPt alloy are improved greatly by twining boundary. • Mechanical behavior of nanocrystalline AuPt alloy depends on grain size strongly. AuPt alloys are widely applied in electronics, aerospace, and precision equipment fields. A thorough understanding of the mechanical behavior of AuPt alloys is critical for their potential applications. Here, we leverage molecular dynamics (MD) method to for the first reveal the effects of microstructure and temperature on mechanical behavior of AuPt alloys from atomic level. The nanoindentation of monocrystalline (MC), nanotwinned (NT), and nanocrystalline (NC) AuPt alloys are performed. The results demonstrate that the mechanical properties of the MC AuPt alloy are excellent at 77 K because of dislocation strengthening while poor at high temperature due to amorphous behavior. The introduction of twinning boundary (TB) greatly improves the mechanical properties of AuPt alloy by preventing the stress spread and promoting dislocation activity. The mechanical behavior of NC AuPt alloy is strongly dependent on grain size. With increasing average grain size, the dominant plastic deformation mechanism of NC AuPt alloy changes from GB migration to dislocation motion and then to GB destruction. An appropriate grain size should be selected to inhibit GB migration or GB destruction, thereby achieving the enhancement of NC AuPt alloy through dislocation strengthening. This work provides an important theoretical basis for the subsequent design of AuPt alloys with desirable mechanical performances to extend the application prospects of noble metals. [Display omitted] [ABSTRACT FROM AUTHOR]

Ruthenium (Ru)‐based catalysts, with considerable performance and desirable cost, are becoming highly interesting candidates to replace platinum (Pt) in the alkaline hydrogen evolution reaction (HER). The hydrogen binding at Ru sites (Ru−H) is an important factor limiting the HER activity. Herein, density functional theory (DFT) simulations show that the essence of Ru−H binding energy is the strong interaction between the 4dz2 orbital of Ru and the 1s orbital of H. The charge transfer between Ru sites and substrates (Co and Ni) causes the appropriate downward shift of the 4dz2 ‐band center of Ru, which results in a Gibbs free energy of 0.022 eV for H* in the RuCo system, much lower than the 0.133 eV in the pure Ru system. This theoretical prediction has been experimentally confirmed using RuCo alloy‐nanosheets (RuCo ANSs). They were prepared via a fast co‐precipitation method followed with a mild electrochemical reduction. Structure characterizations reveal that the Ru atoms are embedded into the Co substrate as isolated active sites with a planar symmetric and Z‐direction asymmetric coordination structure, obtaining an optimal 4dz2 modulated electronic structure. Hydrogen sensor and temperature program desorption (TPD) tests demonstrate the enhanced Ru−H interactions in RuCo ANSs compared to those in pure Ru nanoparticles. As a result, the RuCo ANSs reach an ultra‐low overpotential of 10 mV at 10 mA cm−2 and a Tafel slope of 20.6 mV dec−1 in 1 M KOH, outperforming that of the commercial Pt/C. This holistic work provides a new insight to promote alkaline HER by optimizing the metal‐H binding energy of active sites. [ABSTRACT FROM AUTHOR]

Ruthenium (Ru)‐based catalysts, with considerable performance and desirable cost, are becoming highly interesting candidates to replace platinum (Pt) in the alkaline hydrogen evolution reaction (HER). The hydrogen binding at Ru sites (Ru−H) is an important factor limiting the HER activity. Herein, density functional theory (DFT) simulations show that the essence of Ru−H binding energy is the strong interaction between the 4dz2 orbital of Ru and the 1s orbital of H. The charge transfer between Ru sites and substrates (Co and Ni) causes the appropriate downward shift of the 4dz2 ‐band center of Ru, which results in a Gibbs free energy of 0.022 eV for H* in the RuCo system, much lower than the 0.133 eV in the pure Ru system. This theoretical prediction has been experimentally confirmed using RuCo alloy‐nanosheets (RuCo ANSs). They were prepared via a fast co‐precipitation method followed with a mild electrochemical reduction. Structure characterizations reveal that the Ru atoms are embedded into the Co substrate as isolated active sites with a planar symmetric and Z‐direction asymmetric coordination structure, obtaining an optimal 4dz2 modulated electronic structure. Hydrogen sensor and temperature program desorption (TPD) tests demonstrate the enhanced Ru−H interactions in RuCo ANSs compared to those in pure Ru nanoparticles. As a result, the RuCo ANSs reach an ultra‐low overpotential of 10 mV at 10 mA cm−2 and a Tafel slope of 20.6 mV dec−1 in 1 M KOH, outperforming that of the commercial Pt/C. This holistic work provides a new insight to promote alkaline HER by optimizing the metal‐H binding energy of active sites. [ABSTRACT FROM AUTHOR]

In this paper, porphyrin-based cationic conjugated network (PCCN) nanosheets were synthesized, and its adsorption for TcO4−/ReO4− was investigated. This material was stacked with AB dislocation, with an aperture of 1.2 nm. The Re(VII)/Tc(VII) adsorption kinetics of PCCN is extremely fast, and the adsorption capacity is relatively large, the selective order is ReO4− > NO3− > Cl−. XPS and DFT revealed that the exchange of Cl− on PCCN with ReO4−, while the hydrophobic pore of PCCN are the keys to improve adsorption selectivity. It could be used to remove Tc from groundwater around nuclear facilities. [ABSTRACT FROM AUTHOR]

Atomically dispersed transition metal sites have been extensively studied for CO2 electroreduction reaction (CO2RR) to CO due to their robust CO2 activation ability. However, the strong hybridization between directionally localized d orbits and CO vastly limits CO desorption and thus the activities of atomically dispersed transition metal sites. In contrast, s‐block metal sites possess nondirectionally delocalized 3s orbits and hence weak CO adsorption ability, providing a promising way to solve the suffered CO desorption issue. Herein, we constructed atomically dispersed magnesium atoms embedded in graphitic carbon nitride (Mg‐C3N4) through a facile heat treatment for CO2RR. Theoretical calculations show that the CO desorption on Mg sites is easier than that on Fe and Co sites. This theoretical prediction is demonstrated by experimental CO temperature program desorption and in situ attenuated total reflection infrared spectroscopy. As a result, Mg‐C3N4 exhibits a high turnover frequency of ≈18 000 per hour in H‐cell and a large current density of −300 mA cm−2 in flow cell, under a high CO Faradaic efficiency ≥90 % in KHCO3 electrolyte. This work sheds a new light on s‐block metal sites for efficient CO2RR to CO. [ABSTRACT FROM AUTHOR]

Atomically dispersed transition metal sites have been extensively studied for CO2 electroreduction reaction (CO2RR) to CO due to their robust CO2 activation ability. However, the strong hybridization between directionally localized d orbits and CO vastly limits CO desorption and thus the activities of atomically dispersed transition metal sites. In contrast, s‐block metal sites possess nondirectionally delocalized 3s orbits and hence weak CO adsorption ability, providing a promising way to solve the suffered CO desorption issue. Herein, we constructed atomically dispersed magnesium atoms embedded in graphitic carbon nitride (Mg‐C3N4) through a facile heat treatment for CO2RR. Theoretical calculations show that the CO desorption on Mg sites is easier than that on Fe and Co sites. This theoretical prediction is demonstrated by experimental CO temperature program desorption and in situ attenuated total reflection infrared spectroscopy. As a result, Mg‐C3N4 exhibits a high turnover frequency of ≈18 000 per hour in H‐cell and a large current density of −300 mA cm−2 in flow cell, under a high CO Faradaic efficiency ≥90 % in KHCO3 electrolyte. This work sheds a new light on s‐block metal sites for efficient CO2RR to CO. [ABSTRACT FROM AUTHOR]

A series of regioregular head-to-tail oligo(3-hexylthiophene)-functionalized dicyano-ethylene substituted quinacridone derivatives DCN-Tn-QA (n = 1–3) were designed and synthesized. These linear π-conjugated donor–acceptor–donor (D–A–D) molecules with different length of the oligothiophene chain have been achieved in good yields via iterative iodination and Suzuki cross-coupling reactions followed by Knoevenagel condensations. Their photophysical and electrochemical properties, as well as density functional theory (DFT) calculations, were systematically investigated. The compounds of DCN-Tn-QA (n = 1–3) with an intense absorption range from 350–750 nm, suitable LUMO levels at around −4.0 eV and considerable film formation properties, were suitable for application in organic solar cells (OSCs) as acceptors. The organic bulk heterojunction (BHJ) solar cell based on the blend film of P3HT/DCN-T2-QA (1 : 1, w/w) (P3HT = poly(3-hexylthiophene)) showed a power conversion efficiency (PCE) of 0.51% under the illumination of AM.1.5, 100 mW cm−2. Compared with P3HT/PCBM (PCBM = [6,6]-phenyl-C61-butyric acid methyl ester), the blend film of P3HT/DCN-T2-QA displayed a stronger response to the solar spectrum in the long wavelength range from 665–750 nm. [ABSTRACT FROM AUTHOR]

• Complete characterization of surface error and thickness variation for hemispherical shells. • Interpretation and correction of pixel misalignment and mapping distortion. • Full aperture error map available through subaperture stitching. • Polar harmonics decomposition related to resonator performance. Geometric errors including the surface error and thickness variation of a hemispherical shell are determinant of the system performance, e.g. the frequency splitting of a hemispherical resonator gyroscope. Therefore, complete characterization at 0.1 µm level of accuracy is required which is difficult with current roundness measuring instruments. This paper presents an interferometric method for axially eccentric hemispherical shells. The outer surface and inner surface are measured individually by simply translating the shell along its anchor axis. The two measurements are registered after correction of pixel misalignment and mapping distortion through ray tracing. Thickness variation is then calculated from their difference. A multi-axis platform is designed to scan multiple subapertures covering the hemispherical shell. All subapertures are stitched together with misalignment corrected, according to the minimized inconsistency in the overlapping region of neighboring subapertures. The full aperture map is thus obtained for both the surface error and thickness variation. Polar harmonic representation is suggested by applying annular Zernike polynomial fitting. The method is experimentally demonstrated and validated with roundness cross test. [ABSTRACT FROM AUTHOR]