Screening of Intermetallic Compounds Based on Intermediate Adsorption Equilibrium for Electrocatalytic Nitrate Reduction to Ammonia.

Electrocatalytic nitrate (NO3-) reduction reaction (NO3RR) holds great potential for the conversion of NO3- contaminants into valuable NH3 in a sustainable method. Unfortunately, the nonequilibrium adsorption of intermediates and sluggish multielectron transfer have detrimental impacts on the electrocatalytic performance of the NO3RR, posing obstacles to its practical application. Herein, we initially screen the adsorption energies of three key intermediates, i.e., *NO3, *NO, and *H2O, along with the d-band centers on 21 types of transition metal (IIIV and IB)-Sb/Bi-based intermetallic compounds (IMCs) as electrocatalysts. The results reveal that hexagonal CoSb IMCs possess the optimal adsorption equilibrium for key intermediates and exhibit outstanding electrocatalytic NO3RR performance with a Faradaic efficiency of 96.3%, a NH3 selectivity of 89.1%, and excellent stability, surpassing the majority of recently reported NO3RR electrocatalysts. Moreover, the integration of CoSb IMCs/C into a novel Zn-NO3- battery results in a high power density of 11.88 mW cm-2.

Heterophase Intermetallic Compounds for Electrocatalytic Hydrogen Production at Industrial-Scale Current Densities.

Heterophase nanomaterials have sparked significant research interest in catalysis due to their distinctive properties arising from synergistic effects of different components and the formed phase boundary. However, challenges persist in the controlled synthesis of heterophase intermetallic compounds (IMCs), primarily due to the lattice mismatch of distinct crystal phases and the difficulty in achieving precise control of the phase transitions. Herein, orthorhombic/cubic Ru2Ge3/RuGe IMCs with engineered boundary architecture are synthesized and anchored on the reduced graphene oxide. The Ru2Ge3/RuGe IMCs exhibit excellent hydrogen evolution reaction (HER) performance with a high current density of 1000 mA cm-2 at a low overpotential of 135 mV. The presence of phase boundaries enhances charge transfer and improves the kinetics of water dissociation while optimizing the processes of hydrogen adsorption/desorption, thus boosting the HER performance. Moreover, an anion exchange membrane electrolyzer is constructed using Ru2Ge3/RuGe as the cathode electrocatalyst, which achieves a current density of 1000 mA cm-2 at a low voltage of 1.73 V, and the activity remains virtually undiminished over 500 h.

Continuous quality improvement project to reduce the downtime of medical linear accelerators: A case study at Zhejiang Cancer Hospital.

Objective: To analyse and continually improve existing issues in the quality improvement process of medical linear accelerators (LINACs) and enhance the quality control management of LINACs. Methods: Data were collected from eight LINACs (sourced from three manufacturers) at Zhejiang Cancer Hospital using Excel diaries between January 2019 and December 2020. The data description and analysis were performed using the analytic hierarchy process, SPSSAU and Excel software, and mean-time-to-repair (MTTR)/mean-time-between-failure (MTBF) metrics. Continuous quality improvement was executed using the quality control circle (QCC) quality management method. Results: After quality improvement, the risk frequency of 'LINAC down' events decreased by 43.63% and downtime was reduced by 40.45%. The weight of downtime risk improved by 73.69%. The MTTR recovery value increased by 31.90%, and MTBF reliability increased by 2.97 h. The simulation results demonstrated that the proposed quality improvement measures could effectively decrease the frequency and duration of downtimes, consequently extending the normal operational time of LINACs. Conclusion: Transitioning from instant repair to preventative maintenance can enhance the operational efficiency of equipment and yield economic benefits for hospitals. The QCC method and the event risk evaluation model are effective in reducing the downtime of LINACs and improving their quality control management.

Breaking Highly Ordered PtPbBi Intermetallic with Disordered Amorphous Phase for Boosting Electrocatalytic Hydrogen Evolution and Alcohol Oxidation.

Constructing amorphous/intermetallic (A/IMC) heterophase structures by breaking the highly ordered IMC phase with disordered amorphous phase is an effective way to improve the electrocatalytic performance of noble metal-based IMC electrocatalysts because of the optimized electronic structure and abundant heterophase boundaries as active sites. In this study, we report the synthesis of ultrathin A/IMC PtPbBi nanosheets (NSs) for boosting hydrogen evolution reaction (HER) and alcohol oxidation reactions. The resulting A/IMC PtPbBi NSs exhibit a remarkably low overpotential of only 25 mV at 10 mA cm-2 for the HER in an acidic electrolyte, together with outstanding stability for 100 h. In addition, the PtPbBi NSs show high mass activities for methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR), which are 13.2 and 14.5 times higher than those of commercial Pt/C, respectively. Density functional theory calculations demonstrate that the synergistic effect of amorphous/intermetallic components and multimetallic composition facilitate the electron transfer from the catalyst to key intermediates, thus improving the catalytic activity of MOR. This work establishes a novel pathway for the synthesis of heterophase two-dimensional nanomaterials with high electrocatalytic performance across a wide range of electrochemical applications.

2D MOF based-heterostructure with hierarchical architecture as antibacterial wound dressing.

Bacterial infections pose a huge threat to human health due to the inevitable emergency of drug resistance. Metal-organic frameworks (MOFs) consisting of metal ions and organic linkers, as emerging efficient antibacterial material, have the merits of structural flexibility and adjustable physicochemical property. With assistance of photosensitive agents as organic linkers, MOFs have great potential in antibacterial application through photocatalytic therapy by the generation of reactive oxygen species (ROS). However, the limited light use efficiency and short lifespan of ROS are two obstacles for their applications. Inspired by the semiconductor heterostructure in photocatalysis, we rationally design and precisely synthesize MOFs based heterostructures, in which the TiO2 nanoclusters are filled into the pores of Cu-TCPP nanosheets (i.e. TiO2 NCs@Cu-TCPP HSs). And the composite materials possess three-dimensional (3D) hierarchical architectures, which have advantages of large surface area, excellent light-absorbing ability and photocatalytic efficiency. Significantly, this novel material displays >99.99 % antibacterial efficiency against E. coli and S. aureus within 30 min and preserves the excellent antibacterial ability during reusing three times, which is superior to recently reported photocatalystic-based antibacterial materials. Our study provides new insights into the energy band engineering for enhanced antibacterial performance, paving a way for designing advanced clinical wound dressings.

Pulsed electroreduction of low-concentration nitrate to ammonia.

Electrocatalytic nitrate (NO3-) reduction to ammonia (NRA) has emerged as an alternative strategy for effluent treatment and ammonia production. Despite significant advancements that have been achieved in this field, the efficient conversion of low-concentration nitrate to ammonia at low overpotential remains a formidable challenge. This challenge stems from the sluggish reaction kinetics caused by the limited distribution of negatively charged NO3- in the vicinity of the working electrode and the competing side reactions. Here, a pulsed potential approach is introduced to overcome these issues. A good NRA performance (Faradaic efficiency: 97.6%, yield rate: 2.7 mmol-1 h-1 mgRu-1, conversion rate: 96.4%) is achieved for low-concentration (≤10 mM) nitrate reduction, obviously exceeding the potentiostatic test (Faradaic efficiency: 65.8%, yield rate: 1.1 mmol-1 h-1 mgRu-1, conversion rate: 54.1%). The combined results of in situ characterizations and finite element analysis unveil the performance enhancement mechanism that the periodic appearance of anodic potential can significantly optimize the adsorption configuration of the key *NO intermediate and increase the local NO3- concentration. Furthermore, our research implies an effective approach for the rational design and precise manipulation of reaction processes, potentially extending its applicability to a broader range of catalytic applications.

Recent Progress on Phase Engineering of Nanomaterials.

As a key structural parameter, phase depicts the arrangement of atoms in materials. Normally, a nanomaterial exists in its thermodynamically stable crystal phase. With the development of nanotechnology, nanomaterials with unconventional crystal phases, which rarely exist in their bulk counterparts, or amorphous phase have been prepared using carefully controlled reaction conditions. Together these methods are beginning to enable phase engineering of nanomaterials (PEN), i.e., the synthesis of nanomaterials with unconventional phases and the transformation between different phases, to obtain desired properties and functions. This Review summarizes the research progress in the field of PEN. First, we present representative strategies for the direct synthesis of unconventional phases and modulation of phase transformation in diverse kinds of nanomaterials. We cover the synthesis of nanomaterials ranging from metal nanostructures such as Au, Ag, Cu, Pd, and Ru, and their alloys; metal oxides, borides, and carbides; to transition metal dichalcogenides (TMDs) and 2D layered materials. We review synthesis and growth methods ranging from wet-chemical reduction and seed-mediated epitaxial growth to chemical vapor deposition (CVD), high pressure phase transformation, and electron and ion-beam irradiation. After that, we summarize the significant influence of phase on the various properties of unconventional-phase nanomaterials. We also discuss the potential applications of the developed unconventional-phase nanomaterials in different areas including catalysis, electrochemical energy storage (batteries and supercapacitors), solar cells, optoelectronics, and sensing. Finally, we discuss existing challenges and future research directions in PEN.

Silver nanoparticle-decorated AlN whiskers hybrids for enhancing the thermal conductivity of nanofibrillated cellulose composite films.

By depositing silver nanoparticles (AgNPs) on the surface of aluminum nitride whiskers (AlNw), an AlNw-AgNPs heterogeneous structural filler was rationally designed from the perspective of interface engineering, which was further combined with nanofibrillated cellulose (NFC) to prepare anisotropic composite films by a facile vacuum-assited filtration method. Due to the synergistic effect of cross-linking AlNw and "thermal conducting micro-bridges" of AgNPs, the composite films exhibited an extraordinary in-plane thermal conductivity of 31.329 W m-1 K-1, showing a promising application as thermal management materials.

Enhanced In-Plane Thermal Conductivity and Mechanical Strength of Flexible Films by Aligning and Interconnecting Si3N4 Nanowires.

As the rapid development of advanced foldable electronic devices, flexible and insulating composite films with ultra-high in-plane thermal conductivity have received increasing attention as thermal management materials. Silicon nitride nanowires (Si3N4NWs) have been considered as promising fillers for preparing anisotropic thermally conductive composite films due to their extremely high thermal conductivity, low dielectric properties, and excellent mechanical properties. However, an efficient approach to synthesize Si3N4NWs in a large scale still need to be explored. In this work, large quantities of Si3N4NWs were successfully prepared using a modified CRN method, presenting the advantages of high aspect ratio, high purity, and easy collection. On the basis, the super-flexible PVA/Si3N4NWs composite films were further prepared with the assistance of vacuum filtration method. Due to the highly oriented Si3N4NWs interconnected to form a complete phonon transport network in the horizontal direction, the composite films exhibited a high in-plane thermal conductivity of 15.4 W·m-1·K-1. The enhancement effect of Si3N4NWs on the composite thermal conductivity was further demonstrated by the actual heat transfer process and finite element simulations. More significantly, the Si3N4NWs enabled the composite film presenting good thermal stability, high electrical insulation, and excellent mechanical strength, which was beneficial for thermal management applications in modern electronic devices.

Adaptive vibration control method for double-crystal monochromator base on VMD and FxNLMS.

Double-crystal monochromators (DCMs) are one of the most critical optical devices in beamlines at synchrotron sources, directly affecting the quality of the beam energy and position. As the performance of synchrotron light sources continues to improve, higher demands are placed on the stability of DCMs. This paper proposes a novel adaptive vibration control method combining variational modal decomposition (VMD) and filter-x normalized least mean squares (FxNLMS), ensuring DCM stability under random engineering disturbance. Firstly, the sample entropy of the vibration signal is selected as the fitness function, and the number of modal components k and the penalty factor α are optimized by a genetic algorithm. Subsequently, the vibration signal is decomposed into band frequencies that do not overlap with each other. Eventually, each band signal is individually governed by the FxNLMS controller. Numerical results have demonstrated that the proposed adaptive vibration control method has high convergence accuracy and excellent vibration suppression performance. Furthermore, the effectiveness of the vibration control method has been verified with actual measured vibration signals of the DCM.

Filter design and color correction for the X-cube prism 3CCD camera.

For the X-cube prism three-charge-coupled-device (3CCD) camera, the spectra of the designed dichroic films in the X-cube prism shift with changes in the angle of incident light, producing non-uniformity of color on the image plane. We considered the influence of the incident angle on color performance in filter design and directly optimized the thin film to improve color consistency. An optical model was constructed to calculate the distribution of camera spectral sensitivity and independently correct the non-uniform color on the image plane. Results showed that the optimization and correction methods could significantly improve the color performance of the X-cube prism 3CCD camera.

In situ fabrication of MIL-68(In)@ZnIn2S4 heterojunction for enhanced photocatalytic hydrogen production.

Metal-organic frameworks (MOFs), as a class of semiconductor-like materials, are widely used in photocatalysis. However, the limited visible light absorption and poor charge separation efficiency are the main challenges restricting their photocatalytic performance. Herein, the type II heterojunction MIL-68(In)@ZIS was successfully fabricated by in situ growth of ZnIn2S4 (ZIS) on the surface of a representative MOF, i.e. MIL-68(In). After composition optimization, MIL-68(In)-20@ZIS shows an extraordinary photocatalytic hydrogen production efficiency of 9.09 mmol g-1 h-1 and good photochemical stability, which far exceeds those of most photocatalysts. The hierarchical loose structure of MIL-68(In)-20@ZIS is conducive to the adsorption of reactants and mass transfer. Meanwhile, a large number of tight 2D contact interfaces significantly reduce the obstruction of charge transfer, paving the way for high-perform photocatalytic hydrogen evolution. The experimental results demonstrate that the MIL-68(In)@ZIS heterojunction achieves intensive photoresponse and effective charge separation and transfer benefiting from unique charge transport paths of a type II heterojunction. This study opens an avenue toward MOF-based heterojunctions for solar energy conversion.

Unveiling selective nitrate reduction to ammonia with Co3O4 nanosheets/TiO2 nanobelt heterostructure catalyst.

Electrochemical nitrate (NO3-) reduction reaction (NO3RR) possesses two-pronged properties for sustainable ammonia (NH3) synthesis and mitigating NO3- contamination in water. However, the sluggish kinetics for the direct eight-electron NO3--to-NH3 conversion makes a formidable challenge to develop efficient electrocatalysts. Herein, we report a heterostructure of Co3O4 nanosheets decorated TiO2 nanobelt array on titanium plate (Co3O4@TiO2/TP) as an efficient NO3RR electrocatalyst. Both experimental and density theory calculations reveal that the heterostructure of Co3O4@TiO2 establishes a built-in electric field which can optimize the electron migration kinetics, as well as facilitate the adsorption and fixation of NO3- on the electrode surface, ensuring the selectivity to NH3. As expected, the designed Co3O4@TiO2/TP exhibits a remarkable Faradaic efficiency of 93.1 % and a remarkable NH3 yield as high as 875 µmol h-1 cm-2, superior to Co3O4/TP and TiO2/TP. Significantly, it also demonstrates strong electrochemical durability.

Isolated Electron-Rich Ruthenium Atoms in Intermetallic Compounds for Boosting Electrochemical Nitric Oxide Reduction to Ammonia.

The direct electrochemical nitric oxide reduction reaction (NORR) is an attractive technique for converting NO into NH3 with low power consumption under ambient conditions. Optimizing the electronic structure of the active sites can greatly improve the performance of electrocatalysts. Herein, we prepare body-centered cubic RuGa intermetallic compounds (i.e., bcc RuGa IMCs) via a substrate-anchored thermal annealing method. The electrocatalyst exhibits a remarkable NH4 + yield rate of 320.6 µmol h-1 mg-1 Ru with the corresponding Faradaic efficiency of 72.3 % at very low potential of -0.2 V vs. reversible hydrogen electrode (RHE) in neutral media. Theoretical calculations reveal that the electron-rich Ru atoms in bcc RuGa IMCs facilitate the adsorption and activation of *HNO intermediate. Hence, the energy barrier of the potential-determining step in NORR could be greatly reduced.

High-Efficiency Electrochemical Nitrate Reduction to Ammonia on a Co3O4 Nanoarray Catalyst with Cobalt Vacancies.

Electrocatalytic nitrate reduction reaction (NO3RR) affords a bifunctional character in the carbon-free ammonia synthesis and remission of nitrate pollution in water. Here, we fabricated the Co3O4 nanosheet array with cobalt vacancies on carbon cloth (vCo-Co3O4/CC) by in situ etching aluminum-doped Co3O4/CC, which exhibits an excellent Faradaic efficiency of 97.2% and a large NH3 yield as high as 517.5 µmol h-1 cm-2, better than the pristine Co3O4/CC. Theoretical calculative results imply that the cobalt vacancies can tune the local electronic environment around Co sites of Co3O4, increasing the charge and reducing the electron cloud density of Co sites, which is thus conducive to adsorption of NO3- on Co sites for greatly enhanced nitrate reduction. Furthermore, the vCo-Co3O4 (311) facet presents excellent NO3RR activity with a low energy barrier of about 0.63 eV on a potential-determining step, which is much smaller than pristine Co3O4 (1.3 eV).

Unexpected High-Performance Photocatalytic Hydrogen Evolution in Co@NCNT@ZnIn2 S4 Triggered by Directional Charge Separation and Transfer.

The structural design of photocatalysts is highly related to the separation and transfer of photogenerated carriers, which is essential for the improvement of photocatalytic hydrogen evolution performance. Here, the hybrid photocatalyst M@NCNT@ZIS (M: Fe, Co, Ni; NCNT: nitrogen-doped carbon nanotube; ZIS: ZnIn2 S4 ) with a hierarchical structure is rationally designed and precisely synthesized. The unique hollow structure with a large specific surface area offers abundant reactive sites, thus increasing the adsorption of reactants. Importantly, the properly positioned metal nanoparticles realize the directional charge migration from ZIS to M@NCNT, which significantly improves the efficiency of charge separation. Furthermore, the intimate interface between M@NCNT and ZIS effectively facilitates charge migration by shortening the transfer distance and providing numerous transport channels. As a result, the optimized Co@NCNT@ZIS exhibits a remarkable photocatalytic hydrogen evolution efficiency (43.73 mmol g-1 h-1 ) without Pt as cocatalyst. Experimental characterizations and density functional theory calculations demonstrate that the synergistic effect between hydrogen adsorption and interfacial charge transport is of great significance for improving photocatalytic hydrogen production performance.

Filling Mesopores of Conductive Metal-Organic Frameworks with Cu Clusters for Selective Nitrate Reduction to Ammonia.

The electrocatalytic nitrate reduction reaction (NO3-RR) to ammonia (NH3) under ambient conditions not only has the benefit of lowering energy consumption, but also helps remove nitrate contamination. Inspired by the unique structure of nitrate/nitrite reductase with the active spheroproteins encapsulated by larger enzymes, herein, we develop an in situ synthetic strategy for the construction of metal cluster-conductive metal-organic framework (MOF) composite electrocatalysts. The metallic Cu clusters are filled into the mesopores of a conductive copper-based MOF (i.e., CuHHTP); meanwhile, CuHHTP with a porous structure provides an internal environment to limit the growth of metallic Cu clusters with an ultrasmall size (i.e., 1.5 ± 0.2 nm) and restrains their aggregation. The obtained Cu@CuHHTP exhibits superb performance for NO3-RR. In a neutral electrolyte with 500 ppm NO3-, Cu@CuHHTP shows a high NO3- conversion of 85.81% and a selectivity for NH3 of 96.84%. 15N isotope labeling experiments confirm that the formation of NH3 originates from the process of NO3-RR. Theoretical calculations confirm that Cu clusters are the active sites in the composite electrocatalysts, in which the proper d-band center and the "accept-donate" mechanism in charge transfer are the key factors for the improvement of the electrocatalytic performance.

Design and Optimization for Mounting Primary Mirror with Reduced Sensitivity to Temperature Change in an Aerial Optoelectronic Sensor.

In order to improve the image quality of the aerial optoelectronic sensor over a wide range of temperature changes, high thermal adaptability of the primary mirror as the critical components is considered. Integrated optomechanical analysis and optimization for mounting primary mirrors are carried out. The mirror surface shape error caused by uniform temperature decrease was treated as the objective function, and the fundamental frequency of the mirror assembly and the surface shape error caused by gravity parallel or vertical to the optical axis are taken as the constraints. A detailed size optimization is conducted to optimize its dimension parameters. Sensitivities of the optical system performance with respect to the size parameters are further evaluated. The configuration of the primary mirror and the flexure are obtained. The simulated optimization results show that the size parameters differently affect the optical performance and which factors are the key. The mirror surface shape error under 30 °C uniform temperature decrease effectively decreased from 26.5 nm to 11.6 nm, despite the weight of the primary mirror assembly increases by 0.3 kg. Compared to the initial design, the value of the system's modulation transfer function (0° field angle) is improved from 0.15 to 0.21. Namely, the optical performance of the camera under thermal load has been enhanced and thermal adaptability of the primary mirror has been obviously reinforced after optimization. Based on the optimized results, a prototype of the primary mirror assembly is manufactured and assembled. A ground thermal test was conducted to verify difference in imaging quality at room and low temperature, respectively. The image quality of the camera meets the requirements of the index despite degrading.

Selective Epitaxial Growth of Rh Nanorods on 2H/fcc Heterophase Au Nanosheets to Form 1D/2D Rh-Au Heterostructures for Highly Efficient Hydrogen Evolution.

Phase engineering of nanomaterials (PEN) enables the preparation of metal nanomaterials with unconventional phases that are different from their thermodynamically stable counterparts. These unconventional-phase nanomaterials can serve as templates to construct precisely controlled metallic heterostructures for wide applications. Nevertheless, how the unconventional phase of templates affects the nucleation and growth of secondary metals still requires systematic explorations. Here, two-dimensional (2D) square-like Au nanosheets with an unconventional 2H/face-centered cubic (fcc) heterophase, composing of two pairs of opposite edges with 2H/fcc heterophase and fcc phase, respectively, and two 2H/fcc heterophase basal planes, are prepared and then used as templates to grow one-dimensional (1D) Rh nanorods. The effect of different phases in different regions of the Au templates on the overgrowth of Rh nanorods has been systematically investigated. By tuning the reaction conditions, three types of 1D/2D Rh-Au heterostructures are prepared. In the type A heterostructure, Rh nanorods only grow on the fcc defects including stacking faults and/or twin boundaries (denoted as fcc-SF/T) and 2H phases in two 2H/fcc edges of the Au nanosheet. In the type B heterostructure, Rh nanorods grow on the fcc-SF/T and 2H phases in two 2H/fcc edges and two 2H/fcc basal planes of the Au nanosheet. In the type C heterostructure, Rh nanorods grow on four edges and two basal planes of the Au nanosheet. Furthermore, the type C heterostructure shows promising performance toward the electrochemical hydrogen evolution reaction (HER) in acidic media, which is among the best reported Rh-based and other noble-metal-based HER electrocatalysts.

Preparation of CdSy Se1- y -MoS2 Heterostructures via Cation Exchange of Pre-Epitaxially Synthesized Cu2- χ Sy Se1- y -MoS2 for Photocatalytic Hydrogen Evolution.

Construction of 2D transition metal dichalcogenide (TMD)-based epitaxial heterostructures with different compositions is important for various promising applications, including electronics, photonics, and catalysis. However, the rational design and controlled synthesis of such kind of heterostructures still remain challenge, especially for those consisting of layered TMDs and other non-layered materials. Here, a facile one-pot, wet-chemical method is reported to synthesize Cu2- χ Sy Se1- y -MoS2 heterostructures in which two types of different epitaxial configurations, i.e., vertical and lateral epitaxies, coexist. The chalcogen ratio (S/Se) in Cu2- χ Sy Se1- y and the loading amount of MoS2 in the heterostructures can be tuned. Impressively, the obtained Cu2- χ Sy Se1- y -MoS2 heterostructures can be transformed to CdSy Se1- y -MoS2 without morphological change via cation exchange. As a proof-of-concept application, the obtained CdSy Se1- y -MoS2 heterostructures with controllable compositions are used as photocatalysts, exhibiting distinctive catalytic activities toward the photocatalytic hydrogen evolution under visible light irradiation. The method paves the way for the synthesis of different TMD-based lateral epitaxial heterostructures with unique properties for various applications.