Boosted Electrocatalytic Glucose Oxidation Reaction on Noble-Metal-Free MoO_(3)-Decorated Carbon Nanotubes

Electrocatalytic glucose oxidation reaction(GOR)has attracted much attention owing to its crucial role in biofuel cell fabrication.Herein,we load MoO_(3)nanoparticles on carbon nanotubes(CNTs)and use a discharge process to prepare a noblemetal-free MC-60 catalyst containing MoO_(3),Mo_(2)C,and a Mo_(2)C–MoO_(3)interface.In the GOR,MC-60 shows activity as high as 745μA/(mmol/L cm^(2)),considerably higher than those of the Pt/CNT(270μA/(mmol/L cm^(2)))and Au/CNT catalysts(110μA/(mmol/L cm^(2))).In the GOR,the response minimum on MC-60 is as low as 8μmol/L,with a steady-state response time of only 3 s.Moreover,MC-60 has superior stability and anti-interference ability to impurities in the GOR.The better performance of MC-60 in the GOR is attributed to the abundant Mo sites bonding to C and O atoms at the MoO_(3)–Mo_(2)C interface.These Mo sites create active sites for promoting glucose adsorption and oxidation,enhancing MC-60 performance in the GOR.Thus,these results help to fabricate more effi cient noble-metal-free catalysts for the fabrication of glucose-based biofuel cells.

Deciphering the linear relationship in the activity of the oxygen reduction reaction on Pt electrodes:A decisive role of adsorbates

Despite substantial efforts in developing high-performance catalysts for the oxygen reduction reaction(ORR),the persistent challenge lies in the high onset overpotential of the ORR,and the effect of the elec-trolyte solution cannot be ignored.Consequently,we have systematically investigated the impact of adsorbate species and concentration,as well as solution pH,on the ORR activity on Pt(111)and Pt(poly)electrodes.The results all tend to establish a linear quantitative relationship between the onset potential for ORR and the adsorption equilibrium potential of the adsorbate.This finding indicates the decisive role of adsorbates in the onset potential for ORR,suggesting that the adsorption potential of adsorbates can serve as an intuitive criterion for ORR activity.Additional support for this conclusion is derived from experimental results obtained from the oxygen evolution reaction on Pt(poly)with different adsorbate species and from the hydrogen evolution reaction on Pt(111)with iodine adsorption.We further propose both an empirical equation for the onset potential for ORR and the concept of a potential-regulated adsor-bate shielding effect to elucidate the influence of adsorbates on ORR activity.This study provides new insights into the high onset overpotential of the ORR and offers potential strategies for predicting and enhancingORRactivity inthefuture.

Fundamental Understanding of Hydrogen Evolution Reaction on Zinc Anode Surface:A First‑Principles Study

Hydrogen evolution reaction(HER)has become a key factor affecting the cycling stability of aqueous Zn-ion batteries,while the corresponding fundamental issues involving HER are still unclear.Herein,the reaction mechanisms of HER on various crystalline surfaces have been investigated by first-principle calculations based on density functional theory.It is found that the Volmer step is the ratelimiting step of HER on the Zn(002)and(100)surfaces,while,the reaction rates of HER on the Zn(101),(102)and(103)surfaces are determined by the Tafel step.Moreover,the correlation between HER activity and the generalized coordination number(CN)of Zn at the surfaces has been revealed.The relatively weaker HER activity on Zn(002)surface can be attributed to the higher CN of surface Zn atom.The atomically uneven Zn(002)surface shows significantly higher HER activity than the flat Zn(002)surface as the CN of the surface Zn atom is lowered.The CN of surface Zn atom is proposed as a key descriptor of HER activity.Tuning the CN of surface Zn atom would be a vital strategy to inhibit HER on the Zn anode surface based on the presented theoretical studies.Furthermore,this work provides a theoretical basis for the in-depth understanding of HER on the Zn surface.

Effects of acid-rock reaction on physical properties during CO_(2)-rich industrial waste gas(CO_(2)-rich IWG)injection in shale reservoirs

"Carbon peaking and carbon neutrality"is an essential national strategy,and the geological storage and utilization of CO_(2)is a hot issue today.However,due to the scarcity of pure CO_(2)gas sources in China and the high cost of CO_(2)capture,CO_(2)-rich industrial waste gas(CO_(2)-rich IWG)is gradually emerging into the public's gaze.CO_(2)has good adsorption properties on shale surfaces,but acidic gases can react with shale,so the mechanism of the CO_(2)-rich IWG-water-shale reaction and the change in reservoir properties will determine the stability of geological storage.Therefore,based on the mineral composition of the Longmaxi Formation shale,this study constructs a thermodynamic equilibrium model of water-rock reactions and simulates the regularity of reactions between CO_(2)-rich IWG and shale minerals.The results indicate that CO_(2)consumed 12%after reaction,and impurity gases in the CO_(2)-rich IWG can be dissolved entirely,thus demonstrating the feasibility of treating IWG through water-rock reactions.Since IWG inhibits the dissolution of CO_(2),the optimal composition of CO_(2)-rich IWG is 95%CO_(2)and 5%IWG when CO_(2)geological storage is the main goal.In contrast,when the main goal is the geological storage of total CO_(2)-rich IWG or impurity gas,the optimal CO_(2)-rich IWG composition is 50%CO_(2)and 50%IWG.In the CO_(2)-rich IWG-water-shale reaction,temperature has less influence on the water-rock reaction,while pressure is the most important parameter.SO2 has the greatest impact on water-rock reaction in gas.For minerals,clay minerals such as illite and montmorillonite had a significant effect on water-rock reaction.The overall reaction is dominated by precipitation and the volume of the rock skeleton has increased by 0.74 cm3,resulting in a decrease in shale porosity,which enhances the stability of CO_(2)geological storage to some extent.During the reaction between CO_(2)-rich IWG-water-shale at simulated temperatures and pressures,precipitation is the main reaction,and shale porosity decreases.However,as the reservoir water content increases,the reaction will first dissolve and then precipitate before dissolving again.When the water content is less than 0.0005 kg or greater than 0.4 kg,it will lead to an increase in reservoir porosity,which ultimately reduces the long-term geological storage stability of CO_(2)-rich IWG.

Theoretical insights into oxygen reduction reaction on Au-based single-atom alloy cluster catalysts

Developing highly active alloy catalysts that surpass the performance of platinum group metals in the oxygen reduction reaction(ORR)is critical in electrocatalysis.Gold-based single-atom alloy(AuSAA)clusters are gaining recognition as promising alternatives due to their potential for high activity.However,enhancing its activity of AuSAA clusters remains challenging due to limited insights into its actual active site in alkaline environments.Herein,we studied a variety of Au_(54)M_(1) SAA cluster catalysts and revealed the operando formed MO_(x)(OH)_(y) complex acts as the crucial active site for catalyzing the ORR under the basic solution condition.The observed volcano plot indicates that Au_(54)Co_(1),Au_(54)M_(1),and Au_(54)Ru_(1) clusters can be the optimal Au_(54)M_(1) SAA cluster catalysts for the ORR.Our findings offer new insights into the actual active sites of AuSAA cluster catalysts,which will inform rational catalyst design in experimental settings.

α-OXOKETENE CYCLIC DITHIOACETAL CHEMISTRY(XⅢ)-THE ETHERIFYING REACTION ON THE ADDUCTS OF ALIPHATIC α-OXO KETENE CYCLIC DITHIOACETALS WITH ALLYL MAGNESIUM BROMIDE

Aliphatic α-oxo ketene cyclic dithioacetals 1 were reacted with allyl magne- sium bromide to afford the 1,2-addition products 2.Catalyzed by boron trifluoride etherate,the adducts 2 were etherified by methanol to afford the corresponding methyl ethers 3.This process provides a new method for the protection of the acid sensitive hydroxyl group in 2 under mild condition.

Effects of stress dependent electrochemical reaction on voltage hysteresis of lithium ion batteries

Intercalation of lithium ions into the electrodes of lithium ion batteries is affected by the stress of active materials, leading to energy dissipation and stress dependent voltage hysteresis. A reaction-diffusion-stress coupling model is established to investigate the stress effects under galvanostatic and potentiostatic operations. It is found from simulations that the stress hysteresis contributes to the voltage hysteresis and leads to the energy dissipation. In addition, the stress induced voltage hysteresis is small in low rate galvanostatic operations but extraordinarily significant in high rate cases. In potentiostatic operations, the stresses and stress induced overpotentials increase to a peak value very soon after the operation commences and decays all the left time. Therefore,a combined charge-discharge operation is suggested, i.e., first the galvanostatic one and then the potentiostatic one. This combined operation can not only avoid the extreme stress during operations so as to prevent electrodes from failure but also reduce the voltage hysteresis and energy dissipation due to stress effects.

Oxygen reduction reaction on single Pt nanoparticle

Nanocollision electrochemistry is employed to evaluate the ORR’s activity of one single Pt nanoparticle,the effect of the size and ligand is investigated.The size-normalized activity of the Pt nanoparticle of 4 nm is two times higher than that of 25 nm,confirming that the intrinsic activity does depend on the size of the nanoparticles.It is further found that the adsorbed ligand does yield effect on electrocatalysis,and the adsorption strength follows the order of PVP>CTAB>citrate.This work is of significance to understand the nature of the ORR’s electrocatalysis at the level of an individual entity,which makes the structure-activity correlation in a more reliable way.

Mass Transfer of MHD Nanofluid in Presence of Chemical Reaction on A Permeable Rotating Disk with Convective Boundaries, Using Buongiorno’s Model

This communiquéis opted to study the flow of nanofluid because of heated disk rotation subjected to the convective boundaries with chemical reaction of first order.Wherein Buongiorno’s model for nanofluids is used due to its wide range of applications and the rotating disk under investigation is permeable.Small magneto Reynolds parameter and boundary layer assumptions are carried out to formulate the problem.The system of nonlinear partial differential equations governing the flow problem is converted into the set of ordinary differential equations by using particular relations known as Von Karman transformations.The complicated set of coupled ordinary differential equations with complicated boundary conditions is set to solve by an analytical technique Homotopy Analysis Method(HAM).Whereby the results obtained by the aforementioned method are provided analytically and analyzed graphically.Also validation of the work is confirmed by providing comparison of previous works in tabular form.Effect of chemical reaction parameter on mass transfer rate is also highlighted tabularly for its increament.Nusselt and Sherwood numbers calculated and compared to the like literature and found in good agreement.

Oxygen reduction reaction on Pt‐based electrocatalysts:Four‐electron vs.two‐electron pathway

Oxygen reduction reaction(ORR)has attracted extensive attention as an important component for sustainable energy storage and conversion technologies.However,the sluggish kinetics has hampered the practical application.Pt‐based nanomaterials have triggered much interest as the most promising electrocatalyst to facilitate the kinetics of ORR.Nonetheless,a major challenge for Pt‐based electrocatalysts is to precisely control the selectivity of reaction pathways and possible products(H2O or H2O2)with a reduced loading amount of precious Pt.This review systematically summarizes the strategies to regulate the ORR performances of Pt‐based electrocatalysts by accommodating the adsorption energy and spatial structure.Further discussion is implemented about the key factors to accelerate the kinetics of ORR and control the 4e‐ORR and 2e‐ORR pathways.Finally,we demonstrate the challenges and perspectives for further development of novel Pt‐based electrocatalysts.

Effect of a Slight Interfacial Reaction on Mechanical Properties of SiCp/Al Composites

A slight interfacial reaction in squeeze-cast SiCp/6061AI composites has been studied. It is found that this kind of reaction has a particular effect on the mechanical properties of the composites. The results of fie-cure tests show that this reaction in the composites obviously increases the elastic properties, but is not beneficial to the fracture strength and ductility.This phenomenon can be interpreted in terms of two different micromechanisms which have been analyzed using TEM and HREM observations, acoustic emission (AE) technique and SEM fractography. In addition, a new method of SiC surface modification which can control the interface state is initially presented.

Influence of chemical reaction on heat and mass transfer of non-Newtonian fluid with yield stress by free convection from vertical surface in porous medium considering Soret effect

The effect of chemical reaction on free convection heat and mass transfer for a non-Newtonian power law fluid over a vertical flat plate embedded in a fluid-saturated porous medium has been studied in the presence of the yield stress and the Soret effect. The governing boundary layer equations and boundary conditions are cast into a dimen- sionless form by similarity transformations, and the resulting system of equations is solved by a finite difference method. The results are preSented and discussed for concentration profiles, as well as the Nusselt number and the Sherwood number for various values of the parameters, which govern the problem. The results obtained show that the flow field is influenced appreciably by the presence of the chemical reaction parameter γ the order of.the chemical reaction parameter m, the Soret number St, the buoyancy ratio N, the Lewis number Le, and the dimensionless rheological parameter Ω.

Boosting the water gas shift reaction on Pt/CeO_(2)-based nanocatalysts by compositional modification: Support doping versus bimetallic alloying

The water gas shift reaction is of vital significance for the generation and transition of energy due to the application in hydrogen production and industries such as ammonia synthesis and fuel cells.The influence of support doping and bimetallic alloying on the catalytic performance of Pt/Ce O_(2)-based nanocatalysts in water gas shift reaction was reported in this work.Various lanthanide ions and 3d transition metals were respectively introduced into the Ce O_(2)support or Pt to form Pt/Ce O_(2):Ln(Ln=La,Nd,Gd,Tb,Yb)and Pt M/Ce O_(2)(M=Fe,Co,Ni)nanocatalysts.The sample of Pt/Ce O_(2):Tb showed the highest activity(TOF at 200℃=0.051 s^(-1))among the Pt/Ce O_(2):Ln and the undoped Pt/Ce O_(2)catalysts.Besides,the sample of Pt Fe/Ce O_(2)exhibited the highest activity(TOF at 200℃=0.12 s^(-1))among Pt M/Ce O_(2)catalysts.The results of the multiple characterizations indicated that the catalytic activity of Pt/Ce O_(2):Ln catalysts was closely correlated with the amount of oxygen vacancies in doped ceria support.However,the different activity of Pt M/Ce O_(2)bimetallic catalysts was owing to the various Pt oxidation states of the bimetals dispersed on ceria.The study of the reaction pathway indicated that both the samples of Pt/Ce O_(2)and Pt/Ce O_(2):Tb catalyzed the reaction through the formate pathway,and the enhanced activity of the latter derived from the increased concentration of oxygen vacancies along with promoted water dissociation.As for the sample of Pt Fe/Ce O_(2),its catalytic mechanism was the carboxyl route with a higher reaction rate due to the moderate valence of Pt along with improved CO activation.

First-principles Calculations of H_2O Adsorption Reaction on the GaN(0001) Surface

The adsorption and decomposition of H2O on GaN（0001） surface have been explored employing density functional theory （DFT）. Two distinct adsorption features of H2O on GaN（0001） corresponding to molecular adsorption and H-OH dissociative adsorption are revealed by our calculations. The activities of the surface reactions of H2O on GaN（0001） surface are investigated. For the stepwise processes of H2O decomposition into H2 in gas phase and adsorbed O atom （H2O（g）→H2O（chem）→OH（chem） ＋ H（chem）→2H（chem） ＋ O（chem）→H2（g） ＋ O（chem））, the first and second steps are facile and can even occur at room temperature; while the last two have high barriers and thus are difficult to proceed, especially the fourth step is endothermic. In short, H2O adsorption and decomposition into H2 in gas phase and adsorbed O atom on GaN（0001） surface are exothermic by -43.98 kcal/mol.

Current trending and beyond for solar-driven water splitting reaction on WO_(3)photoanodes

This review shows the importance of WO_(3)photoanode as a potentially low-cost,efficient,stable,and photoactive material for light-driven water splitting.For such,this manuscript aims to review the most recent publications regarding the strategies to improve the phoelectroactivity of WO_(3)films for water oxidation.In addition,this review aims to graphically highlight and discuss the general trendings of the photocurrent density response and stability test of the recent outstanding studies in the literature for photoelectrochemical water splitting application.The strategies covered in this review will not only concern the WO_(3)morphology and crystal plane growth,but also the many arrangements possibilities to improve the WO_(3)efficiency for water photoelectrooxidation,such as defect engineering based on oxygen vacancies,doping,decorations,and homo and heterojunctions.All these strategies are compared by the photocurrent density results and by the stability of these photocatalysts.The best results in this sense were observed in cases where the use of heterojunction was applied together with a desired morphology and crystal plane of the WO_(3)photoanode.However,the modifications that caused a decrease in the photocurrent density reaching values that are even lower than the pure WO_(3)were also discussed.In this way,this review intends to improve the knowledge about the synthesis and design of WO_(3)photoanodes to further obtain an efficient photocatalyst to minimize the recombination losses or losses across the interfaces and improve the photoelectroactivity for water splitting in the large-scale application.

Blocking backward reaction on hydrogen evolution cocatalyst in a photosystem Ⅱ hybrid Z-scheme water splitting system

Photocatalytic Z-scheme water splitting is considered as a promising approach to produce solar hydrogen.However,the forward hydrogen production reaction is often impeded by backward reactions.In the present study,in a photosystem Ⅱ-integrated hybrid Z-scheme water splitting system,the backward hydrogen oxidation reaction was significantly suppressed by loading a PtCrOx cocatalyst on a ZrO2/TaON photocatalyst.Due to the weak chemisorption and activation of molecular hydrogen on PtCrOx,where Pt is stabilized in the oxidized forms,Pt^Ⅱ and Pt^Ⅳ,hydrogen oxidation is inhibited.However,it is remarkably well-catalyzed by the metallic Pt cocatalyst,thereby rapidly consuming the produced hydrogen.This work describes an approach to inhibit the backward reaction in the photosystem Ⅱ-integrated hybrid Z-scheme water splitting system using Fe(CN)6^3-/Fe(CN)6^4-redox couple as an electron shuttle.

The Application of Suzuki Coupling Reaction on the Preparation of Carbosilane Dendrimers with 4-(Naphthalen-1-yl)phenyl Core

Carbosilane dendrimers with p-bromophenyl core were synthesized by alternating Grignard and hydrosilylation reaction. And the α-naphthalenyl was connected to the core by the Suzuki coupling reaction. A new carbosilane dendrimer with big π-conjugated structure [4-（naphthalen-l-yl）phenyl core] was given. It shows Suzuki coupling reaction is an effective and powerful core-functionalization method and the satisfactory result can be obtained through prolonging the reaction time with the increase of the generation of dendrimer.

Mapping the kinetics of hydrogen evolution reaction on Ag via pseudo-single-crystal scanning electrochemical cell microscopy

Elucidating the structure-activity relationship in electrocatalysis is of fundamental interest for electrochemical energy conversion and storage.However,the heterogeneity in the surface structure of electrocatalysts,including the presence of various facets,poses an analytical challenge in revealing the true structure-activity relationship because the activity is conventionally measured on ensemble,resulting in an averaged activity that cannot be unequivocally associated with a single structural motif.Scanning electrochemical cell microscopy(SECCM)[1]combined with colocalized electron backscatter diffraction(EBSD)offers a direct way to reveal the correlative local electrochemical and structural information.Herein,we measured the hydrogen evolution reaction(HER)activity on Ag and its dependence on the crystal orientation.From the combined EBSD and SECCM mapping,it is found that Ag grains closer to{111}show a higher exchange current density,while those closer to{110}show a lower Tafel slope.The Tafel slope is also found to decrease with the step density increase.The ability to measure the electrocatalytic activity under a high mass-transfer rate allows us to reveal the activity difference at a high current density(up to 200 mA/cm^(2)).The approach reported here can be expanded to other systems to reveal the nature of active sites of electrocatalysis.

Effects of Partially N-acetylated Chitosans to Elicit Resistance Reaction on Brassica napus L.

The effects to elicit resistance reaction on oilseed rape (Brassica napus L. cv Xinongchangjiao ) by four partially N-acetylated chitosan 7B, 8B, 9B and 10B (Degree of acetylation (D. A.) is 30% , 20% , 10%, 0%, respectively) and Glycol chitosan (GC, D.A. is 0%) were investigated and compared. Results showed that chitosan were similar to salicylic acid (SA), and could induce resistance reaction, but the reaction was influenced by the degree of acetylation of chitosan. Fully deacetylated chitosans, 10B and GC, elicited chitinase activity, but partially acetylated chitosan, 7B, 8B and 9B, inhibited chitinase activity. Phenyalanine ammonia-lyase (PAL) was also elicited. Elicitor activity increased with on increasing degree of acetylation, 7B induced highest PAL activity among all chitosans. All chitosans induced peroxidase (POD) in a similar level. After elicited by glycol chitosan, like SA treatment, the seedlings increased disease resistance to Sclerotinia sclerotiorum significantly.

Recent advances in regulating the performance of acid oxygen reduction reaction on carbon-supported non-precious metal single atom catalysts

Developing high performance and low-cost catalysts for oxygen reduction reaction(ORR)in challenging acid condition is vital for proton-exchange-membrane fuel cells(PEMFCs).Carbon-supported nonprecious metal single atom catalysts(SACs)have been identified as potential catalysts in the field.Great advance has been obtained in constructing diverse active sites of SACs for improving the performance and understanding the fundamental principles of regulating acid ORR performance.However,the ORR performance of SACs is still unsatisfactory.Importantly,microenvironment adjustment of SACs offers chance to promote the performance of acid ORR.In this review,acid ORR mechanism,attenuation mechanism and performance improvement strategies of SACs are presented.The strategies for promoting ORR activity of SACs include the adjustment of center metal and its microenvironment.The relationship of ORR performance and structure is discussed with the help of advanced experimental investigations and theoretical calculations,which will offer helpful direction for designing advanced SACs for ORR.