Monolayer Graphitic Carbon Nitride as Metal-Free Catalyst with Enhanced Performance in Photo- and Electro-Catalysis

The exfoliation of bulk graphitic carbon nitride(g-C_(3)N_(4))into monolayer has been intensively studied to induce maximum sur-face area for fundamental studies,but ended in failure to realize chemi-cally and physically well-defined monolayer of g-C_(3)N_(4)mostly due to the difficulty in reducing the layer thickness down to an atomic level.It has,therefore,remained as a challenging issue in two-dimensional(2D)chemistry and physics communities.In this study,an“atomic monolayer of g-C_(3)N_(4)with perfect two-dimensional limit”was successfully prepared by the chemically well-defined two-step routes.The atomically resolved monolayer of g-C_(3)N_(4)was also confirmed by spectroscopic and micro-scopic analyses.In addition,the experimental Cs-HRTEM image was collected,for the first time,which was in excellent agreement with the theoretically simulated;the evidence of monolayer of g-C_(3)N_(4)in the perfect 2D limit becomes now clear from the HRTEM image of orderly hexagonal symmetry with a cavity formed by encirclement of three adjacent heptazine units.Compared to bulk g-C_(3)N_(4),the present g-C_(3)N_(4)monolayer showed significantly higher photocatalytic gen-eration of H2O2 and H2,and electrocatalytic oxygen reduction reaction.In addition,its photocatalytic efficiency for H2O2 production was found to be the best for any known g-C_(3)N_(4)nanomaterials,underscoring the remarkable advantage of monolayer formation in optimizing the catalyst performance of g-C_(3)N_(4).

Fresnel incoherent correlation holography with single camera shot

Fresnel incoherent correlation holography(FINCH)is a self-interference based super-resolution three-dimensional imaging technique.FINCH in inline configuration requires an active phase modulator to record at least three phase-shifted camera shots to reconstruct objects without twin image and bias terms.In this study,FINCH is realized using a randomly multiplexed bifocal binary diffractive Fresnel zone lenses fabricated using electron beam lithography.The object space is calibrated by axially scanning a point object along the optical axis and recording the corresponding point spread holograms(PSHs).An object is mounted within the calibrated object space,and the object hologram was recorded under identical experimental conditions used for recording the PSHs.The image of the object at different depths was reconstructed by a cross-correlation between the object hologram and the PSHs.Application potential including bio-medical optics is discussed.

Single-shot mid-infrared incoherent holography using Lucy-Richardson-Rosen algorithm

In recent years,there has been a significant transformation in the field of incoherent imaging with new possibilities of compressing three-dimensional(3D)information into a two-dimensional intensity distribution without two-beam interference(TBI).Most of the incoherent 3D imagers without TBI are based on scattering by a random phase mask exhibiting sharp autocorrelation and low cross-correlation along the depth.Consequently,during reconstruction,high lateral and axial resolutions are obtained.Imaging based on scattering requires an astronomical photon budget and is therefore precluded in many power-sensitive applications.In this study,a proof-of-concept 3D imaging method without TBI using deterministic fields has been demonstrated.A new reconstruction method called the Lucy-Richardson-Rosen algorithm has been developed for this imaging concept.We believe that the proposed approach will cause a paradigm-shift in the current state-of-the-art incoherent imaging,fluorescence microscopy,mid-infrared fingerprinting,astronomical imaging,and fast object recognition applications.

Review of engineering techniques in chaotic coded aperture imagers

Coded aperture imaging(CAI)is a technique to image three-dimensional scenes with special controlled abilities.In this review,we survey several recently proposed techniques to control the parameters of CAI by engineering the aperture of the system.The prime architectures of these indirect methods of imaging are reviewed.For each design,we mention the relevant application of the CAI recorders and summarize this overview with a general perspective on this research topic.

Machine-learning-assisted discovery of polymers with high thermal conductivity using a molecular design algorithm

The use of machine learning in computational molecular design has great potential to accelerate the discovery of innovative materials.However,its practical benefits still remain unproven in real-world applications,particularly in polymer science.We demonstrate the successful discovery of new polymers with high thermal conductivity,inspired by machine-learning-assisted polymer chemistry.This discovery was made by the interplay between machine intelligence trained on a substantially limited amount of polymeric properties data,expertise from laboratory synthesis and advanced technologies for thermophysical property measurements.Using a molecular design algorithm trained to recognize quantitative structure—property relationships with respect to thermal conductivity and other targeted polymeric properties,we identified thousands of promising hypothetical polymers.From these candidates,three were selected for monomer synthesis and polymerization because of their synthetic accessibility and their potential for ease of processing in further applications.The synthesized polymers reached thermal conductivities of 0.18–0.41 W/mK,which are comparable to those of state-of-the-art polymers in non-composite thermo-plastics.

Review of Fresnel incoherent correlation holography with linear and non-linear correlations

Fresnel incoherent correlation holography(FINCH)is a well-established incoherent imaging technique.In FINCH,three selfinterference holograms are recorded with calculated phase differences between the two interfering,differently modulated object waves and projected into a complex hologram.The object is reconstructed without the twin image and bias terms by a numerical Fresnel back propagation of the complex hologram.A modified approach to implement FINCH by a single camera shot by pre-calibrating the system involving recording of the point spread function library and reconstruction by a nonlinear cross correlation has been introduced recently.The expression of the imaging characteristics from the modulation functions in original FINCH and the modified approach by pre-calibration in spatial and polarization multiplexing schemes are reviewed.The study reveals that a reconstructing function completely independent of the function of the phase mask is required for the faithful expression of the characteristics of the modulating function in image reconstruction.In the polarization multiplexing method by non-linear cross correlation,a partial expression was observed,while in the spatial multiplexing method by non-linear cross correlation,the imaging characteristics converged towards a uniform behavior.

Laser polymerized photonic wire bonds approach 1 Tbit/s data rates

Microelectronics has solved the challenge of packaging different functional elements with integrated chips(ICs)in modern computing and communication by wire bonding.Miniaturization was a trend guided by the requirements for faster,more portable and less expensive(smaller amount of materials)solutions,where wire bonding evolved to accommodate increasingly more complex 3D architectures of chips and printed circuit boards.

Tunable vertical ferroelectricity and domain walls by interlayer sliding inβ-ZrI_(2)

Vertical ferroelectricity where a net dipole moment appears as a result of in-plane ionic displacements has gained enormous attention following its discovery in transition metal dichalcogenides.Based on first-principles calculations,we report on the evidence of robust vertical ferroelectricity upon interlayer sliding in layered semiconductingβ-ZrI_(2),a sister material of polar semimetals MoTe_(2)and WTe_(2).The microscopic origin of ferroelectricity in ZrI_(2)is attributed to asymmetric shifts of electronic charges within a trilayer,revealing a subtle interplay of rigid sliding displacements and charge redistribution down to ultrathin thicknesses.We further investigate the variety of ferroelectric domain boundaries and predict a stable charged domain wall with a quasi-twodimensional electron gas and a high built-in electric field that can increase electron mobility and electromechanical response in multifunctional devices.Semiconducting behaviour and a small switching barrier of ZrI_(2)hold promise for various ferroelectric applications,and our results provide important insights for further development of slidetronics ferroelectricity.