Coupling ferromagnetic ordering electron transfer channels and surface reconstructed active species for spintronic electrocatalysis of water oxidation

Sluggish reaction kinetics of oxygen evolution reaction(OER), resulting from multistep proton-coupled electron transfer and spin constriction, limits overall efficiency for most reported catalysts. Herein, using modeled ZnFe_(2-x)Ni_xO_(4)(0 ≤ x ≤ 0.4) spinel oxides, we aim to develop better OER electrocatalyst through combining the construction of ferromagnetic(FM) ordering channels and generation of highly active reconstructed species. The number of symmetry-breaking Fe–O–Ni structure links to the formation of FM ordering electron transfer channels. Meanwhile, as the number of Ni^(3+)increases, more ligand holes are formed, beneficial for redirecting surface reconstruction. The electro-activated ZnFe_(1.6)Ni_(0.4)O_(4) shows the highest specific activity, which is 13 and 2.5 times higher than that of ZnFe_(2)O_(4) and unactivated ZnFe_(1.6)Ni_(0.4)O_(4), and even superior to the benchmark IrO_(2) under the overpotential of 350 mV. Applying external magnetic field can make electron spin more aligned, and the activity can be further improved to 39 times of ZnFe_(2)O_(4). We propose that intriguing FM exchange-field interaction at FM/paramagnetic interfaces can penetrate FM ordering channels into reconstructed oxyhydroxide layers, thereby activating oxyhydroxide layers as spin-filter to accelerate spin-selective electron transfer. This work provides a new guideline to develop highly efficient spintronic catalysts for water oxidation and other spin-forbidden reactions.

Bimetal MOF-derived NiFe-P nanocomposites coupled with Cu_(3)P nanoparticles to construct tandem electron transfer channels for photocatalytic hydrogen evolution

Finely modulated light-induced charge separation and transfer is a central challenge to achieve efficient photocatalysis.Although progress has been made in this field,most of the previous research works focused on the separation or migration of photogenerated carriers but did not build a bridge between the two.How to realize the strong driving and precise migration of carriers has become the focus of our work.We report an ingeniously designed ternary heterojunction.Taking NiFe-MOF as the“parent material”,the FeP_(4)/Ni_(x)P_(y)heterojunction is derived in situ while maintaining the frame structure through gas-solid reaction,and finally the Z-type electron transfer is realized.With Cu_(3)P anchoring spindle matrix,an electron transport tunnel is opened up in Cu_(3)P/FeP_(4)/Ni_(x)P_(y)ternary heterojunction under the action of p-n heterojunction built-in electric field driving and accurate energy band matching.The strong driving force of the built-in electric field provides an inexhaustible power for the transmission of electrons,and the fine series of electron transmission channels realizes the precise transmission of electrons.The above fine design makes the perfect fit between the built-in electric field and the electron transfer channel,which not only effectively improves the embarrassing situation of insufficient electron driving force of hydrogen evolution reaction in the previous research,but also makes up for the weakening of semi-conductor reduction ability caused by the construction of traditional p-n heterostructures.This research work provides a new idea for the construction of multiple heterostructures and the design of fine interface engineering in the future.

Effect of mass transfer channels on flexural strength of C/SiC composites fabricated by femtosecond laser assisted CVI method with optimized laser power

In this study,femtosecond laser assisted-chemical vapor infiltration(LA-CVI)was employed to produce C/SiC composites with 1,3,and 5 rows of mass transfer channels.The effect of laser machining power on the quality of produced holes was investigated.The results showed that the increase in power yielded complete hole structures.The as-obtained C/SiC composites with different mass transfer channels displayed higher densification degrees with flexural strengths reaching 546±15 MPa for row mass transfer channel of 3.The strengthening mechanism of the composites was linked to the increase in densification and formation of"dense band"during LA-CVI process.Multiphysics finite element simulations of the dense band and density gradient of LA-CVI C/SiC composites revealed C/SiC composites with improved densification and lower porosity due to the formation of"dense band"during LA-CVI process.In sum,LA-CVI method is promising for future preparation of ceramic matrix composites with high densities.

Single-image night haze removal based on color channel transfer and estimation of spatial variation in atmospheric light

The visible-light imaging system used in military equipment is often subjected to severe weather conditions, such as fog, haze, and smoke, under complex lighting conditions at night that significantly degrade the acquired images. Currently available image defogging methods are mostly suitable for environments with natural light in the daytime, but the clarity of images captured under complex lighting conditions and spatial changes in the presence of fog at night is not satisfactory. This study proposes an algorithm to remove night fog from single images based on an analysis of the statistical characteristics of images in scenes involving night fog. Color channel transfer is designed to compensate for the high attenuation channel of foggy images acquired at night. The distribution of transmittance is estimated by the deep convolutional network DehazeNet, and the spatial variation of atmospheric light is estimated in a point-by-point manner according to the maximum reflection prior to recover the clear image. The results of experiments show that the proposed method can compensate for the high attenuation channel of foggy images at night, remove the effect of glow from a multi-color and non-uniform ambient source of light, and improve the adaptability and visual effect of the removal of night fog from images compared with the conventional method.

Enhancing heat transfer at the micro-scale using elastic turbulence

Small concentrations of a high-molecular-weight polymer have been used to create so-called ＂elastic tur- bulence＂ in a micro-scale serpentine channel geometry. It is known that the interaction of large elastic stresses created by the shearing motion within the fluid flow with streamline curvature of the serpentine geometry leads initially to a purely-elastic instability and then the generation of elastic turbulence. We show that this elastic turbulence enhances the heat transfer at the micro-scale in this geometry by up to 300% under creeping flow conditions in comparison to that achieved by the equivalent Newtonian fluid flow.

Boosting interfacial S-scheme charge transfer and photocatalytic H_(2)-production activity of 1D/2D WO_(3)/g-C_(3)N_(4)heterojunction by molecular benzene-rings integration

A novel benzene-ring engineered 1D/2D WO_(3)/g-C_(3)N_(4)S-scheme photocatalyst(BCNW)was rationally de-signed and successfully synthesized by the electrostatic self-assembly method.Experimental and Density Functional Theory results reveal that the integration of molecular benzene-ring in the framework of g-C_(3)N_(4)can not only narrow its bandgap and accelerate charge separation by forming a mid-state at the top of its valence band but more importantly open up a new additional bridge for speeding up the interfacial S-scheme charge transfer in BCNW.Benefitting from those multiple positive effects of benzene-ring inte-gration,as expected,BCNW S-scheme photocatalysts show superior photocatalytic H_(2)-production activity and reach 2971μmol h^(-1)g^(-1)under visible-light illumination,which is 3.35 times WO_(3)/g-C_(3)N_(4)S-scheme photocatalyst without benzene-ring integration.This work supplies an innovative strategy for the design of a high-efficiency S-scheme photocatalytic system by constructing a facile and additional molecular charge transfer channel at the interface.

Prospects for High-quality Development of Water Resources

The water resources of rivers and reservoirs with a five-meter drop are used to discuss the technical theory and the cost and practical value of equipment cases.The high-quality development technology of water resources explored in this paper provides a feasible plan for achieving the goal of innovation to zero.

The Wireless Power Transmission on the Wristto-Forehead Path Based on the Body Channel

The body channel based wireless power transfer(BC-WPT)method utilizes the human body as the medium to transfer power for bioelectronics,which can achieve a lower transmission loss due to its higher conductivity.However,except for the channel length,different on-body loca-tions of the transmitter and receiver also influence the power supply performance.This paper fo-cuses on the wrist-to-forehead path to show the potential of BC-WPT for the brain bioelectronics such as the brain computer interface device.The channel characteristics from 10 MHz to 60 MHz are measured by a vector network analyzer(VNA)and a prototype BC-WPT system with differ-ent copper electrodes and the lowest power loss locates between-22 dB and-33 dB.Furthermore,the minimum path loss limit is simulated in Advanced Design System(ADS)software and the low-est optimum path loss can reach nearly-13 dB.Finally,a rectifier circuit is also built at the receiv-er side to harvest d.c.voltage.The results show that the open-circuit voltage(OCV)can reach 1.75 V with the transmitter of 50Ωoutput impedance supplying 5V_(pp)sine voltage at 60 MHz when adopt-ing 1 cm-diameter circular electrodes.

Construction of atomic-level charge transfer channel in Bi_(12)O_(17)C_(l2)/MXene heterojunctions for improved visible-light photocatalytic performance

Exploring efficient co-catalysts to accurately steer the charge separation of semiconductor photocatalysts is highly desired yet remains challenging.Here,we tackle the significant challenge by in situ growing the Bi_(12)O_(17)C_(l2)photocatalyst onto two-dimensional(2D)Cl-terminated Ti_(3)C_(2)MXene to construct 2D/2D heterojunction of Bi_(12)O_(17)C_(l2)and Ti_(3)C_(2).Firstly,2D few-layered Ti_(3)C_(2)MXene with chlorine groups has been successfully syn-thesized by Lewis acidic etching strategy with subsequent ultrasonic exfoliation.The grafting of chlorine terminations on the surface of MXene serves as nucleating centers and growth platform,resulting in the formation of strong interfacial bonds(Bi-Cl-Ti)between Bi_(12)O_(17)C_(l2)and Ti_(3)C_(2).These strong bonds can facilitate the separation and transfer of photo-generated charge carriers between Bi_(12)O_(17)C_(l2)photocatalyst and Ti_(3)C_(2)cocatalyst.As expec-ted,the photocatalytic degradation rate of Bi_(12)O_(17)C_(l2)/Ti_(3)C_(2)hybrids is 9.7 times higher than that of bare Bi_(12)O_(17)C_(l2)nanosheets.This work not only exhibits a new design concept to effectively steer the charge separation for photocatalysis,but also gives a reference for constructing efficient MXene-based photocatalytic systems.

Efficient removal for multiple pollutants via Ag_(2)O/BiOBr heterojunction:A promoted photocatalytic process by valid electron transfer pathway

Multiple pollutants including pathogenic microorganism contaminations and emerging organic contaminations(EOCs)have shown a growing threat to the environment,especially the natural waters.However,the control and removal of pathogenic microorganism contaminations and EOCs have been greatly limited since limited knowledge of their environmental behaviors.Thus,a novel and efficient photocatalyst Ag_(2)O/BiOBr heterojunction was synthesized and used for removal of multiple pollutants including Escherichia coli(E.coli),Staphylococcus aureus(S.aureus),tetracycline and acetaminophen under visible light.The results showed that there were valid electron transfer pathways between BiOBr and Ag_(2)O,the main electron transfer direction was the BiOBr to Ag_(2)O.Photo-generated electrons were stored in Ag_(2)O and thus separation efficiency between holes and photo-generated electrons was obviously enhanced.Active oxygen species were highly produced and eventually end up with the high efficiency of removal of multiple pollutants.For Ag_(2)O/BiOBr with Ag_(2)O content at 3%(the best performance)under visible light,log decrease of E.coli was 7.16(removal efficiency was 100%)in 120 min,log decrease of S.aureus was 7.23(removal efficiency was 100%)in 160 min,C/C0 of tetracycline was 0.06 in 180 min,C/C0 of acetaminophen was 0.17 in 180 min.This work could provide a promising candidate in the actual contaminated natural waters for cleaning multiple pollutants.

Constructing charge transfer channel between dopants and oxygen vacancies for enhanced visible-light-driven water oxidation

Photocatalytic water oxidation is a crucial step in water splitting,but is generally restricted by the slow kinetics.Therefore,it is necessary to develop high-performance water oxidation photocatalysts.Herein,the Fe-doped Bi2WO6 nanosheets with oxygen vacancies(OVs)were synthesized for enhanced photocatalytic water oxidation efficiency,showing a synergistic effect between Fe dopants and OVs.When a molar fraction of 2%Fe was doped into the Bi2WO6 nanosheets,the visible-light-driven photocatalytic oxygen evolution rate was increased up to 131.3μmol·h^(-1)·g_(cat)^(-1)under ambient conditions,which was more than 3 times that of pure Bi2WO6 nanosheets.The proper doping concentration of Fe could promote the formation of OVs and at the same time modulate the band structure of catalysts,especially the position of the valence band maximum(VBM),leading to effective visible-light absorption and enhanced oxidizing ability of photogenerated holes.With ameliorated localized electron distribution,fast charge transfer channel emerged between the OVs and adjacent metal atoms,which accelerated the charge carrier transfer and promoted the separation of photoexcited electrons and holes.This work provides feasible approaches for designing efficient two-dimensional semiconductor water oxidation photocatalysts that could utilize visible-light,which will make more use of solar energy.

Charge transfer efficiency improvement of a 4-T pixel by the optimization of electrical potential distribution under the transfer gate

The charge transfer efficiency improvement method is introduced by optimizing the electrical potential distribution under the transfer gate along the charge transfer path. A non-uniform doped transfer transistor chan- nel is introduced to provide an ascending electrical potential gradient in the transfer transistor channel. With the adjustments to the overlap length between the R1 region and the transfer gate, the doping dose of the R1 region, and the overlap length between the anti-punch-through （APT） implantations and transfer gate, the potential barrier and potential pocket in the connecting region of transfer transistor channel and the pinned photodiode （PPD） are reduced to improve the electrical potential connection. The simulation results show that the percentage of residual charges to total charges drops from 1/10^4 to 1/10^7, and the transfer time is reduced from 500 to 110 ns. This means the charge transfer efficiency is improved.