Generating highly active oxide-phosphide heterostructure through interfacial engineering to break the energy scaling relation toward urea-assisted natural seawater electrolysis

Urea-assisted natural seawater electrolysis is an emerging technology that is effective for grid-scale carbon-neutral hydrogen mass production yet challenging.Circumventing scaling relations is an effective strategy to break through the bottleneck of natural seawater splitting.Herein,by DFT calculation,we demonstrated that the interface boundaries between Ni_(2)P and MoO_(2) play an essential role in the selfrelaxation of the Ni-O interfacial bond,effectively modulating a coordination number of intermediates to control independently their adsorption-free energy,thus circumventing the adsorption-energy scaling relation.Following this conceptual model,a well-defined 3D F-doped Ni_(2)P-MoO_(2) heterostructure microrod array was rationally designed via an interfacial engineering strategy toward urea-assisted natural seawater electrolysis.As a result,the F-Ni_(2)P-MoO_(2) exhibits eminently active and durable bifunctional catalysts for both HER and OER in acid,alkaline,and alkaline sea water-based electrolytes.By in-situ analysis,we found that a thin amorphous layer of NiOOH,which is evolved from the Ni_(2)P during anodic reaction,is real catalytic active sites for the OER and UOR processes.Remarkable,such electrode-assembled urea-assisted natural seawater electrolyzer requires low voltages of 1.29 and 1.75 V to drive 10 and600 mA cm^(-2)and demonstrates superior durability by operating continuously for 100 h at 100 mA cm^(-2),beyond commercial Pt/C||RuO_(2) and most previous reports.

Durable hierarchical phosphorus‐doped biphase MoS_(2)electrocatalysts with enhanced H^(*)adsorption

Phase engineering is an efficient strategy for enhancing the kinetics of electrocatalytic reactions.Herein,phase engineering was employed to prepare high‐performance phosphorous‐doped biphase(1T/2H)MoS_(2)(P‐BMS)nanoflakes for hydrogen evolution reaction(HER).The doping of MoS_(2)with P atoms modifies its electronic structure and optimizes its electrocatalytic reaction kinetics,which significantly enhances its electrical conductivity and structural stability,which are verified by various characterization tools,including X‐ray photoelectron spectroscopy,high‐resolution transmission electron microscopy,X‐ray absorption near‐edge spectroscopy,and extended X‐ray absorption fine structure.Moreover,the hierarchically formed flakes of P‐BMS provide numerous catalytic surface‐active sites,which remarkably enhance its HER activity.The optimized P‐BMS electrocatalysts exhibit low overpotentials(60 and 72 mV at 10 mA cm^(−2))in H_(2)SO_(4)(0.5 M)and KOH(1.0 M),respectively.The mechanism of improving the HER activity of the material was systematically studied using density functional theory calculations and various electrochemical characterization techniques.This study has shown that phase engineering is a promising strategy for enhancing the H*adsorption of metal sulfides.

Effect of circumferential strain rate on dynamic recrystallization and texture of Mg-13Gd-4Y-2Zn-0.5Zr alloy during rotary backward extrusion

Gleeble-3500 thermal simulator was applied to realize the rotary backward extrusion forming of Mg-13Gd-4Y-2Zn-0.5Zr(wt%)alloy at different circumferential strain rate from 0.009 s^(-1)to 0.027 s^(-1)at 400℃and the dynamic recrystallization mechanism and texture evolution were studied.The results show that the grain size of the alloy was obviously refined after rotary backward extrusion.As the circumferenlial strain rate increased,the dynamic recrystallization fraction gradually increased causing the grain size decreased and the distribution of microstructure became more uniform.At the same time,the texture of{0001},{10-10},{11-20}was weakened and the grain orientation distribution became more random.With the increase of circumferential strain rate,the discontinuous dynamic recrystallization mechanism became dominant,which promoted the weakening of texture and grain refinement of the alloy.

Grain refinement impact on the mechanical properties and wear behavior of Mg-9Gd-3Y-2Zn-0.5Zr alloy after decreasing temperature reciprocating upsetting-extrusion

Based on the deforming technique of severe plastic deformation(SPD), the grain refinement of a Mg-9Gd-3Y-2Zn-0.5Zr alloy treated with decreasing temperature reciprocating upsetting-extrusion(RUE) and its influence on the mechanical properties and wear behavior of the alloy were studied. The RUE process was carried out for 4 passes in total, starting at 0 ℃ and decreasing by 10 ℃ for each pass. The results showed that as the number of RUE passes increased, the grain refinement effect was obvious, and the second phase in the alloy was evenly distributed. Room temperature tensile properties of the alloy and the deepening of the RUE degree showed a positive correlation trend, which was due to the grain refinement, uniform distribution of the second phase and texture weakening. And the microhardness of the alloy showed that the microhardness of RUE is the largest in 2 passes. The change in microhardness was the result of dynamic competition between the softening effect of DRX and the work hardening effect. In addition, the wear resistance of the alloy showed a positive correlation with the degree of RUE under low load conditions. When the applied load was higher, the wear resistance of the alloy treated with RUE decreased compared to the initial state alloy. This phenomenon was mainly due to the presence of oxidative wear on the surface of the alloy, which could balance the positive contribution of severe plastic deformation to wear resistance to a certain extent.

Recent research and development on forming for large magnesium alloy components with high mechanical properties

The lightweight of high-end equipment relies on high mechanical properties magnesium(Mg) alloy structural components, because it is the best way to improve equipment service performance and reduce energy consumption. This article summarizes the current progress and characteristics of large-scale high-performance Mg alloy components by analyzing the strengthening-toughening mechanisms, characteristics of plastic forming, and the preparation of large high mechanical properties forging blanks. Due to the lack of breakthroughs in the key technologies for forming large-scale Mg alloy components, their uniformity of mechanical properties and consistency are poor, the forming accuracy of components is low, and the production cost is high, which limit their engineering application and restrict the lightweight level of high-end equipment. In view of the above problems, the forming trends and research directions of large-scale and high mechanical properties Mg alloy components are proposed in this paper. It can provide help for the breakthrough of the key technology of large-scale Mg alloy components with high mechanical properties and expand the application of Mg alloy in high-end products.

Effect of aging treatment on the precipitation transformation and age hardening of Mg-Gd-Y-Zn-Zr alloy

In this study, the precipitation transformation and age hardening of solution-treated Mg-9Gd-4Y-2Zn-0.5Zr(wt.%) alloy were investigated at different aging treatment parameters. The precipitation sequences of the alloy aged at 200℃, 250℃ and 300℃ are β’’(DO19) → β’(BCO) → β(FCC), β’’(DO19) → β’(BCO) → β_(1)(FCC) → β(FCC) and β(FCC), respectively. The streaks sequences of the alloy aged at 200℃, 250℃ and 300℃ are SF, SF → 14H-LPSO and SF → 14H-LPSO, respectively. For the alloy aged at 200℃ and 250℃, the increase in hardness with increasing aging time is contributed from the increase in precipitate volume fraction and the transformation from β’’ to β’ phase with basal → prismatic and spherical → spindle-like precipitate changes. The decrease in hardness after the peak-aging stage is attributed to the appearance of micro-sized β precipitates. Because of the smaller size of precipitates and the triangular arrangement of β’ precipitate, the hardness of the alloy aged at 200℃ is higher than that aged at 250℃. For the alloy aged at 300℃, the appearance of only micro-sized β precipitate and its coarsening with increasing aging time leads to the lowest hardness and an overall decrease in hardness with the aging time.

Influence of strain rate on grain refinement and texture evolution under complex shear stress conditions

The effects of different complex shear stress conditions on grain refinement and texture evolution of Mg-13Gd-4Y-2Zn-0.5Zr alloy were investigated.With increasing strain rate,the average grain size of compression-shear(CS)and compression-torsion(CT)samples are decreased,and the grain size of dynamic recrystallization(DRX)grains is also decreased.This is because that the precipitation number ofβphases is increased,and the hindering effect on grain growth can be significantly enhanced.The DRX fractions of CS and CT samples are decreased with increased strain rate.The low DRX fraction at high strain rate is related to the insufficient time for grains to nucleate.The DRX process can be promoted by the PSN mechanism of second phases,and the grain growth can be restricted by the pinning effect.At the same time,the texture strength is enhanced as the strain rate increased.Besides,the kinking degree of lamellar long-period stacking ordered(LPSO)phases is increased.Under complex shear stress conditions,non-basal slip,especially pyramidal slip,is easily activated and the texture is deflected greatly.Compared with the CS samples,CT samples have smaller average grain size,higher DRX fraction,and lower texture strength for a certain strain rate.This is because that the equivalent stress of the CT sample is larger,the stress triaxiality is smaller,so more serious dislocations are piled up near grain boundaries and second phases.At the same time,since CT sample was sheared with torsion,the dislocation movement path can be called“rotational dislocation accumulation”,and the longer distribution path of the CT sample is generated,so more sub-grains and low-angle grain boundaries(LAGBs)are formed.Compared with the CS sample,more huge-angle grain boundaries(HAGBs)and DRX grains are formed from grain boundary to grain interior,so better grain refinement effect is achieved.

Exploring catalytic behaviors of CoS_(2)-ReS_(2) heterojunction by interfacial engineering

Herein, a stable and efficient CoS_(2)-ReS_(2) electrocatalyst is successfully constructed by using the different molar ratios of CoS_(2) on ReS_(2). The size and morphology of the catalysts are significantly changed after the CoS_(2) is grown on ReS_(2), providing regulation of the catalytic activity of ReS_(2). Particularly, the optimized CoS_(2)-ReS_(2) shows superior electrocatalytic properties with a low voltage of 1.48 V at 20 mA cm^(-2) for overall water splitting in 1.0 M KOH, which is smaller than the noble metal-based catalysts(1.77 V at 20 mA cm^(-2)). The XPS, XAS, and theoretical data confirm that the interfacial regulation of ReS_(2) by CoS_(2) can provide rich edge catalytic sites, which greatly optimizes the catalytic kinetics and drop the energy barrier for oxygen/hydrogen evolution reactions. Our results demonstrated that interfacial engineering is an efficient route for fabricating high-performance water splitting electrocatalysts.

A Soft Robotic Fish with Variable-stiffness Decoupled Mechanisms

A Body and/or Caudal Fin （BCF） fish modulate its body stiffness by mechanisms consisting of antagonistic muscles. The mecha- nisms can be considered as Redundant Planar Rotational Parallel Mechanisms （RPRPM） with antagonistic flexible elements. For a typical RPRPM, its stiffness consists of the adjustable stiffness resulting from internal forces and the inherent stiffness caused by inherent com- pliances of flexible elements. In order to decouple the adjustable stiffness from the inherent stiffness and expand the range of stiffness variation, a variable-stiffness decoupled mechanism based on the Mechanically Adjustable Compliance and Controllable Equilibrium Position Actuator （MACCEPA） is presented and used to construct a soft robotic fish with large stiffness variation. According to the analysis of the evolution from RPRPM to MACCEPA, it can be found that MACCEPA is just a special type of RPRPM with only an adjustable stiffness. In addition, MACCEPA existed before RPRPM mechanism. The prototype of the soft robotic fish with variable- stiffness decoupled mechanisms is built to explore the relationships between the body stiffness and the swimming performance. It is validated experimentally that the stiffness variation multiple of the robotic fish is raised, the swimming performance of the robotic fish is improved when the stiffness is modulated to match the driving frequency.

Serum thioredoxin activity:a promising biomarker for assessment of coronary stenosis severity in patients with coronary artery disease

Coronary artery disease(CAD)is one of the major death causes worldwide.Therapeutic methods may improve the progress of CAD.Thus,specific biomarkers are required for detecting coronary stenosis severity and monitoring therapy.Although spiral computed tomography(CT)angiography or coronary angiography may accurate detect coronary stenosis,the both techniques