Nonlinear edge enhancement imaging based on Laguerre-Gaussian superimposed vortex filters.

Nonlinear reconstruction, which is based on the principle of cross correlation, is a commonly employed reconstruction technique in incoherent correlated digital holography systems. However, the modulation of phase masks in these systems is suppressed during the reconstruction process, resulting in an inability to express the characteristics of the phase masks. Consequently, achieving edge enhancement within these systems is constrained. We propose a nonlinear reconstruction method utilizing Laguerre-Gaussian superimposed vortex filters, which modulates the spectrum of the target during the reconstruction process. Experimental results demonstrate that this method performs well in reconstructing image edges for various phase-masked incoherent imaging systems and effectively suppresses noise. Additionally, this method enables directional edge enhancement.

Focusing through scattering media by a single polarization transmission matrix with binary polarization modulation.

Wavefront distortion induced by scattering media seriously affects optical focusing. Wavefront shaping based on a transmission matrix (TM) is useful in controlling light propagation in highly scattering media. Traditional TM generally studies amplitude and phase, but the stochastic nature of the light propagation in the scattering medium also affects its polarization. Based on the binary polarization modulation, we propose a single polarization transmission matrix (SPTM) and achieve single-spot focusing through scattering media. We anticipate that the SPTM will be widely used in wavefront shaping.

Photocatalytic Applications of ReS2-Based Heterostructures.

ReS2-based heterostructures, which involve the coupling of a narrow band-gap semiconductor ReS2 with other wide band-gap semiconductors, have shown promising performance in energy conversion and environmental pollution protection in recent years. This review focuses on the preparation methods, encompassing hydrothermal, chemical vapor deposition, and exfoliation techniques, as well as achievements in correlated applications of ReS2-based heterostructures, including type-I, type-II heterostructures, and Z-scheme heterostructures for hydrogen evolution, reduction of CO2, and degradation of pollutants. We believe that this review provides an overview of the most recent advances to guide further research and development of ReS2-based heterostructures for photocatalysis.

Mimicking Photosynthesis: A Natural Z-Scheme Photocatalyst Constructed from Red Mud Bauxite Waste for Overall Water Splitting.

All-solid-state Z-Scheme photocatalysts have attracted significant attention due to their great potential for solar fuel production. However, delicately coupling two individual semiconductors with a charge shuttle by a material strategy remains a challenge. Herein, we demonstrate a new protocol of natural Z-Scheme heterostructures by strategically engineering the component and interfacial structure of red mud bauxite waste. Advanced characterizations elucidated that the hydrogen-induced formation of metallic Fe enabled the effective Z-Scheme electron transfer from γ-Fe2 O3 to TiO2 , leading to the significantly boosted spatial separation of photo-generated carriers for overall water splitting. To the best of our knowledge, it is the first Z-Scheme heterojunction based on natural minerals for solar fuel production. Thus our work provides a new avenue toward the utilization of natural minerals for advanced catalysis applications.

Recording point spread functions by wavefront modulation for interferenceless coded aperture correlation holography.

Coded aperture correlation holography (COACH) needs the point spread function (PSF) for image reconstruction. Utilizing a pinhole to generate a point light source is the most frequently adopted method for measuring PSF, which, however, has significant issues to resolve. One of the problems is that the resolution of the reconstructed result is limited by the cutoff frequency of the pinhole. The other is that the far-field PSF is undetectable because the amount of light illuminance decreases with the distance. In this work, we present a method for recording the PSF based on wavefront modulation. By modulating a plane wave with both the carrier spherical wave and the coded phase mask, we obtain a virtual point spread function (VPSF) that is used for image reconstruction. It is shown that the resolution of reconstructed results is not limited by the pinhole. We experimentally demonstrate high-resolution reconstruction by the VPSF.

Facilitating Molecular Activation and Proton Feeding by Dual Active Sites on Polymeric Carbon Nitride for Efficient CO2 Photoreduction.

Photoreduction of CO2 provides an appealing way to alleviate the energy crisis and manage the global carbon balance but is limited by the high activation energy and the rate-limiting proton transfer. We now develop a dual-site strategy for high-efficiency CO2 conversion through polarizing CO2 molecules at pyridine N vacancies and accelerating the intermediate protonation by protonated pyridine N adjacent to nitrogen vacancies on polymeric carbon nitride. Our photocatalysts with atomic-level engineered active sites manifest a high CO production rate of 1835 µmol g-1 h-1 , 183 times higher than the pristine bulk carbon nitride. Theoretical prediction and experimental studies confirm that such excellent performance is attributed to the synergistic effect between vacant and protonated pyridine N in decreasing the formation energy of the key *COOH intermediates and the efficient electron transfer relay facilitated by the defect-induced shallow trap state and homogeneous charge mediators.

Oxygen Vacancy-Enhanced Photoelectrochemical Water Splitting of WO3/NiFe-Layered Double Hydroxide Photoanodes.

Photoelectrochemical (PEC) water splitting serves as one of the promising approaches for producing clean and renewable energy, and their solar-hydrogen energy conversion efficiency depends on the interfacial charge separation and carrier mobility. Herein, we report an effective strategy to promote the PEC performance by fabricating a WO3 photoanode rich in oxygen vacancies (Ov) modified by NiFe-based layered double hydroxide (LDH). When WO3-Ov/NiFe-LDH is used as a photoanode, the maximum photocurrent density at 1.8 V versus RHE has been significantly enhanced to 2.58 mA·cm-2, which is 4.3 times higher than that of WO3. In addition, analogues were studied in controlled experiments without Ov, which further demonstrated that the synergistic effect of NiFe-LDH and Ov resulted in increased carrier concentration and driving force. According to electrical impedance spectroscopy, X-ray photoelectron spectroscopy, and Mott-Schottky analysis, the built-in electronic field in WO3 homojunction, along with the accelerated hole capture by the NiFe-LDH cocatalyst contributes to the improved charge separation and transport in the WO3-Ov/NiFe-LDH electrode. This work proposes an efficient and valuable strategy for designing the structure of WO3-based photoelectrodes.

Efficient compressive holographic reconstruction based on hologram segmentation.

Compressive holography can successfully reconstruct a three-dimensional layered object from a two-dimensional hologram. However, the extremely time-consuming reconstruction limits its range of applications. We propose a dimension reduction of measurement matrix (DRMM) method to accelerate compressive holographic reconstruction. The calculation time is substantially reduced while the reconstruction quality is improved by DRMM, which is implemented by a hologram segmentation approach and a parallel computing technique. Holograms of specific target objects are segmented from the hologram of a three-dimensional layered object, and the reconstruction can be implemented in parallel using multicore processors. We present both simulation and experimental results to show the feasibility and effectiveness of the proposed method.

Combination of the mutations for improving activity of TEV protease in inclusion bodies.

Tobacco etch virus protease (TEVp) is an enzymatic reagent to remove fusion tag, but additional purification steps are required for removing the TEVp after cleavage reaction is finished. Use of carrier-free and dependent TEVp immobilizates can eliminate protease contamination. In this work, we identified that, among the four constructed missense variants, the insoluble variant with the highest activity was correspondent with the soluble one tested formerly. The activities of the insoluble 15 codon variants were assayed and the variant with highest activity was selected. The K45F and/or E106G mutations have been reported on slightly improving protein stability of the wild-type TEVp, but only E106G mutation enhanced soluble production and activity of the selected TEVp variant, and it increased soluble amounts of two codon variants with the impaired folding. The decreased activity and use efficiency of the optimized TEVp variant in inclusion bodies was balanced by the determined high level production, lower leaking amounts of the protein, the enhanced resistance to the limited proteolysis mediated by protease K and trypsin, and the increased inhibition of auto-cleavage, as comparison to those of the immobilized soluble one. Thus, the TEVp construct is a potential alternate for simplifying protein purification protocols after tag-removal.

Decorating g-C3N4 Nanosheets with Ti3C2 MXene Nanoparticles for Efficient Oxygen Reduction Reaction.

One of the major challenges associated with fuel cells is exploring highly efficient and low-cost electrocatalysts for the oxygen reduction reaction (ORR). Herein, the feasibility of using Ti3C2 MXene nanoparticles (NPs) to enhance the electrocatalytic activity of g-C3N4 for ORR was investigated. By varying the content of Ti3C2 NPs, a series of g-C3N4/Ti3C2 heterostructures were obtained, displaying enhanced electrocatalytic activity, including a positive shift in both onset and peak potentials toward ORR, compared to the original g-C3N4 in basic solution. We attribute the improvement to the favorable electrical conductivity of well-dispersed Ti3C2 MXene nanoparticles and also enhanced O2 adsorption due to the electronic coupling effect between g-C3N4 and Ti3C2 in the heterostructures. This work demonstrates the potential of earth-abundant MXene family materials to construct low-cost and high-performance electrocatalysts.

Quantitative detection of procalcitonin using an electrochemical immunosensor based on MoO3/Au@rGO nanocomposites.

In this work, a sandwich-type electrochemical immunosensor for the detection of procalcitonin (PCT) is constructed layer-by-layer with a novel label based on MoO3/Au@rGO nanocomposites. The high surface area and electroconductivity of graphene contributes to the transfer of electrons. Besides, the introduction of Au modulates the morphology of the MoO3@rGO nanocomposites from hexagonal prisms to agglomerated particles. Compared to rGO, Au@rGO and MoO3@rGO, the synergistic effect of MoO3/Au@rGO nanocomposites leads to the highest electrocatalytic activity towards H2O2 reduction. The electrochemical immunosensor exhibits a wide working range from 0.01 pg mL-1 to 10 ng mL-1 and a detection limit of 0.002 pg mL-1 at a signal-to-noise ratio of 3. Additionally, we also obtain excellent sensing performance for the immunosensor, including excellent selectivity, good reproducibility and stability. This work will give insight into the application of the nanocomposites based on noble metals combined with transition metal oxides in the fields of electroanalytical chemistry and biosensors.

Interfacial Charge Transfer in MoS2/TiO2 Heterostructured Photocatalysts: The Impact of Crystal Facets and Defects.

One of the most challenging issues in photocatalytic hydrogen evolution is to efficiently separate photocharge carriers. Although MoS2 loading could effectively improve the photoactivity of TiO2, a fundamental understanding of the charge transfer process between TiO2 and MoS2 is still lacking. Herein, TiO2 photocatalysts with different exposed facets were used to construct MoS2/TiO2 heterostructures. XPS, ESR, together with PL measurements evidenced the Type II electron transfer from MoS2 to {001}-TiO2. Differently, electron-rich characteristic of {101}-faceted TiO2 were beneficial for the direct Z-scheme recombination of electrons in TiO2 with holes in MoS2. This synergetic effect between facet engineering and oxygen vacancies resulted in more than one order of magnitude enhanced hydrogen evolution rate. This finding revealed the elevating mechanism of constructing high-performance MoS2/TiO2 heterojunction based on facet and defect engineering.

Controllable synthesis of Co3O4 nanocrystals as efficient catalysts for oxygen reduction reaction.

The electrochemical oxygen reduction reaction (ORR) has received great attention due to its importance in fuel cells and metal-air batteries. Here, we present a simple approach to prepare non-noble metal catalyst-Co3O4 nanocrystals (NCs). The particle size and shape were simply controlled by different types and concentrations of metal precursor. Furthermore, different sizes and shapes of Co3O4 NCs are explored as electrocatalysts for ORR, and it has been observed that particles with a similar shape, and smaller particle size led to greater catalytic current densities because of the greater surface area. For particles with a comparable size, the shape or crystalline structure governed the activity of the electrocatalytic reactions. Most importantly, the 9 nm-Co3O4 were demonstrated to act as low-cost catalysts for the ORR with a similar performance to that of Pt catalysts.

The synergetic effects of Ti3C2 MXene and Pt as co-catalysts for highly efficient photocatalytic hydrogen evolution over g-C3N4.

Co-catalyst loading provides an effective way to enhance the efficiency of photocatalysts for solar hydrogen production. From a sustainability point of view, it has immense scientific and technological values to explore more efficient co-catalytic systems by using multi-cocatalysts, because of potential synergetic effects between different components. Herein, the feasibility of using Ti3C2 MXene nanoparticles and Pt nanoclusters as dual co-catalysts to enhance the photoactivity of g-C3N4 for H2 production was investigated. Due to the improved electrical conductivity and increased reactive sites for photoreduction reactions, Ti3C2 and Pt co-modified photocatalysts exhibited a high photocatalytic hydrogen production activity of 5.1 mmol h-1 g-1. Compared to g-C3N4/Ti3C2 and g-C3N4/Pt, the 3- and 5-fold increased photoactivity demonstrated great potential of Ti3C2 MXene nanoparticles to construct high-performance photocatalysts. The synergetic effects between Ti3C2 and Pt were fundamentally investigated, indicating that the specific transfer of electrons not only contributed to the inhibited recombination of charge carriers but also resulted in good stability of heterostructured photocatalysts. Our results have demonstrated an approach worthy for the design and fabrication of high-efficiency heterostructures with superior photoactivity for hydrogen energy production.

An ultrasensitive electrochemical immunosensor based on the synergistic effect of quaternary Cu2SnZnS4 NCs and cyclodextrin-functionalized graphene.

In this study, highly monodispersed Cu2SnZnS4 NCs with a quasi-spherical structure were prepared to construct a sandwich-type electrochemical immunosensor for alpha-fetoprotein detection. Quaternary Cu2SnZnS4 NCs as novel biomimetic catalysts show an efficient intrinsic peroxidase-like activity for H2O2 reduction. This excellent catalytic activity is ascribed to the higher electroconductivity than those of the binary Cu2S and ternary Cu2SnS3 NCs. Moreover, ß-cyclodextrin-functionalized graphene sheets are used as substrate materials that can capture large amounts of primary antibodies due to host-guest interaction and high surface area. Under the optimized conditions, the electrochemical immunosensor exhibites a wide working range from 0.5 pg mL-1 to 10 ng mL-1 and a detection limit of 0.16 pg mL-1 at a signal-to-noise ratio of 3. Good sensitivity, reproducibility, and stability demonstrate its potential application in clinical diagnostics.

Tobacco etch virus protease mediating cleavage of the cellulose-binding module tagged colored proteins immobilized on the regenerated amorphous cellulose.

In this study, four fusion proteins were designed, in which the N-terminal cellulose-binding module as the affinity tag was immobilized on the regenerated amorphous cellulose (RAC), and the release of the C-terminal colored proteins was detected easily and rapidly after on-resin cleavage using the free tobacco etch virus protease (TEVp) variant, or the immobilized cognate protease with a binding capacity of up to 220 mg protein per gram of RAC. The enhanced stability and repetitive use of the immobilized TEVp compensated slight loss of the catalytic efficiency toward the soluble protein substrate. On-resin cleavage and purity of the released target proteins are related to the context of the fusion tag, the incorporated linker composition, and the colored protein. Owing to low cost and high binding capacity of the RAC, the TEVp immobilized on the resin is an ideal alternative for removing fusion tag. The colored proteins are easily monitored in the on-resin process of fusion proteins, and rapid separation from RAC.

Synthesis of Bi2S3-Au Dumbbell Heteronanostructures with Enhanced Photocatalytic and Photoresponse Properties.

In this article, novel types of Bi2S3-Au heterostructures are fabricated through rationally controlling the growth atmosphere. Under argon, Au nanoparticles are preferentially deposited onto the tips of Bi2S3 nanorods to form Bi2S3-Au dumbbell heterostructures. In contrast, because of the etching effect by amine, Au nanoparticles are randomly anchored onto the surface of nanorods to form Bi2S3-Au nanocorns in the presence of oxygen. Furthermore, the size of gold nanoparticles can be controlled through adjusting the concentration of reaction precursors. Bi2S3-Au dumbbells show superior activity for the photodegradation of organic pollutants and an enhanced photoresponse compared to the Bi2S3-Au nanocorns. The significantly improved photocatalytic performance of Bi2S3-Au dumbbells is ascribed to the more efficient charge separation compared to that of Bi2S3-Au nanocorns. These heterostructures composed of environmentally friendly elements are expected to be promising for applications in the field of clean energy.

Biomolecule-assisted synthesis of defect-mediated Cd1-xZnxS/MoS2/graphene hollow spheres for highly efficient hydrogen evolution.

Moderate efficiency and the utilization of noble metal cocatalysts are the key factors that restrict the large-scale application of photocatalytic hydrogen production. To develop more efficient photocatalysts based on earth abundant elements, either a new material strategy or a fundamental understanding of the semiconductor/cocatalyst interfaces is highly desirable. In this paper, we studied the feasibility of in situ formation of defect-rich cocatalysts on graphene-based photocatalysts. A facile biomolecule-assisted strategy was used to self-assmble Cd1-xZnxS/MoS2/graphene hollow spheres. The defect-mediated cocatalyst and synergetic charge transfer around heterostructured interfaces exhibit a significant impact on the visible-light-driven photocatalytic activity of multicomponent solid solutions. With engineered interfacial defects, Cd0.8Zn0.2S/MoS2/graphene hollow spheres exhibited a 63-fold improved H2 production rate, which was even 2 and 3.8 times higher than those of CdS/MoS2/graphene hollow spheres and Cd0.8Zn0.2S/Pt. Therefore, our research provides a promising approach for the rational design of high-efficiency and low-cost photocatalysts for solar fuel production.

Cu2ZnSnS4-Ag2S Nanoscale p-n Heterostructures as Sensitizers for Photoelectrochemical Water Splitting.

A cation exchange-based route was used to produce Cu2ZnSnS4 (CZTS)-Ag2S nanoparticles with controlled composition. We report a detailed study of the formation of such CZTS-Ag2S nanoheterostructures and of their photocatalytic properties. When compared to pure CZTS, the use of nanoscale p-n heterostructures as light absorbers for photocatalytic water splitting provides superior photocurrents. We associate this experimental fact to a higher separation efficiency of the photogenerated electron-hole pairs. We believe this and other type-II nanoheterostructures will open the door to the use of CZTS, with excellent light absorption properties and made of abundant and environmental friendly elements, to the field of photocatalysis.

Cu(2)ZnSnS(4)-Pt and Cu(2)ZnSnS(4)-Au heterostructured nanoparticles for photocatalytic water splitting and pollutant degradation.

Cu2ZnSnS4, based on abundant and environmental friendly elements and with a direct band gap of 1.5 eV, is a main candidate material for solar energy conversion through both photovoltaics and photocatalysis. We detail here the synthesis of quasi-spherical Cu2ZnSnS4 nanoparticles with unprecedented narrow size distributions. We further detail their use as seeds to produce CZTS-Au and CZTS-Pt heterostructured nanoparticles. Such heterostructured nanoparticles are shown to have excellent photocatalytic properties toward degradation of Rhodamine B and hydrogen generation by water splitting.