Iron Atom-Cluster Strategy Synthesis of Hierarchically Porous Fe-N-C Catalysts for Proton Exchange Membrane Fuel Cells

Developing nonprecious metal-nitrogen-doped carbon(M-N-C)catalysts with high activity and stability is critical to their widespread use in fuel cells;however,these catalysts still face considerable challenges.Herein,a novel iron atom-cluster strategy for the synthesis of iron-based N-C catalyst comprising Fe nanoparticles(Fe NPs)surrounded by Fe-N_(x) sites is developed for oxygen reduction reactions in an acidic fuel cell.Iron oxide NPs were incorporated into zeolitic imidazolate framework-8(ZIF-8)-derived carbon materials and pyrolyzed at high temperatures using NaCl as a modifi er to produce Fe NPs and Fe-N_(x) composite active sites.The half-wave potential of the optimized Fe_(NP)/FeNC-NaCl material was substantially improved to 0.81 V.Furthermore,even after 15,000 cycles,the half-wave potential of the catalyst remained essentially unchanged.As a cathode catalyst for fuel cells,it realized a high peak power density of 436 mW/cm^(2)under a practical H_(2)-air atmosphere.Therefore,this study presents a new approach for designing and synthesizing electrocatalytic materials with high catalytic activity and stability.

Photoelectrocatalytic CO2 reduction based on metalloporphyrin-modified TiO2 photocathode

The conversion of CO2 and water to value-added chemicals under sunlight irradiation, especially by photoelectrocatalytic reduction process, is always a dream for human beings. A new artificial photosynthesis system composed of a metalloporphyrin-functionalized TiO2 photocathode and BiVO4 photoanode can efficiently transform CO2 and water to methanol, which is accompanied by oxygen release. This photoelectrocatalytic system smoothly produces methanol at a rate of 55.5 μM h^–1 cm^– 2, with 0.6 V being the membrane voltage in plants. The production of hydrogen can also be observed when the voltage is more than 0.75 V, due to photocatalysis. Our results evidently indicate that the molecules of metalloporphyrin attached onto the surface of anatase (TiO2) behave as chlorophyll, NADP, and Calvin cycle in plant cells.

Logistics Regression Analysis between TCM Constitution Types of Patients with Hypertension,Insomnia and ABPM,PSQI

[Objectives]The research aimed to explore the distribution characteristics of TCM constitution types of patients with hypertension and insomnia,and study the clinical characteristics of patients with different constitutions,in order to provide new ideas for the treatment of patients with hypertension and insomnia.[Methods]Cross sectional observation method was used,and 420 patients with hypertension and insomnia were selected.Required information was collected,and the constitution type of traditional Chinese medicine was determined,and relevant data were recorded.SPSS and Logistic regression analysis method were used to explore the correlation between the distribution of TCM constitution types and gender,age,24 h-SBP,24 h-DBP,24 h-BPV,PSQI score,etc.[Results]Among 420 patients,the proportion of gentleness constitution was the most,and others in turn were Qi deficiency constitution>Yang deficiency constitution>phlegm dampness constitution>Qi stagnation constitution>Yin deficiency constitution>blood stasis constitution>damp heat constitution>special constitution.Among male patients,the proportion of gentleness constitution was the most.Among female patients,the proportion of Qi deficiency constitution was the most.In each constitution,the proportion of men and women was different,and the difference in gentleness constitution,Qi deficiency constitution and Yin deficiency constitution had statistical significance(P<0.05).The proportion of gentleness constitution for young and middle-aged patients was the most,while elderly patients with Qi deficiency constitution was the most.There was difference in the distribution of TCM constitution in different age groups,and the difference had statistical significance(P<0.05).Compared with the patients with gentleness constitution,the patients with Qi deficiency constitution,Yang deficiency constitution,Yin deficiency constitution,damp heat constitution,blood stasis constitution and Qi stagnation constitution had different differences in terms of age,24 h-SBP,24 h-DBP,24 h-BPV and PSQI score,and there was statistical significance(P<0.05).Except damp heat constitution,blood stasis constitution and special constitution,other constitutions had certain correlation with age,24 h-SBP,24 h-DBP,24 h-BPV and PSQI score.[Conclusions]TCM constitution types of patients with hypertension and insomnia were dominant by gentleness constitution,Qi deficiency constitution and Yang deficiency constitution.The distribution of TCM constitution in different gender and age groups was different,and different TCM constitution was related to ABPM and PSQI.

Secondary reduction strategy synthesis of Pt-Co nanoparticle catalysts towards boosting the activity of proton exchange membrane fuel cells

Based on the volcanic relationship between catalytic activity and key adsorption energies,Pt-Co alloy materials have been widely studied as cathode oxygen reduction reaction(ORR)catalysts in proton exchange membrane fuel cells(PEMFCs)due to their higher active surface area and adjustable D-band energy levels compared to Pt/C.However,how to balance the alloying degree and ORR performance of Pt-Co catalyst remains a great challenge.Herein,we first synthesized a well-dispersed Pt/Co/C precursor by using a mild dimethylamine borane(DMAB)as the reducing agent.The precursor was calcined at high temperature under H_(2)/Ar mixed gas by a secondary reduction strategy to obtain an ordered Pt_(3)Co intermetallic compound nanoparticle catalyst with a high degree of alloying.The optimization of elec-tronic structure due to Pt-Co alloying and the strong metal-carrier interaction ensure the high kinetic activity of the cell membrane electrode.Additionally,the high degree of graphitization increases the electrical conductivity during the reaction.As a result,the activity and stability of the catalyst were significantly improved,with a half-wave potential as high as 0.87 V,which decreased by only 20 mV after 10000 potential cycles.Single-cell tests further validate the high intrinsic activity of the ordered Pt_(3)Co catalyst with mass activity up to 0.67 A mg_(pt)^(-1),exceeding the United States Department of Energy(US DOE)standard(0.44 A mg_(pt)^(-1)),and a rated power of 5.93 W mg_(pt)^(-1).

磷掺杂提升三氧化钨导带用于高效二氧化碳还原

光电催化还原二氧化碳是一种环境友好的高效方法,可将过量排放的CO_(2)转化为燃料与化学品,减少温室效应并存储太阳能为化学能.本研究设计制备了新型磷掺杂的WO_(3)催化剂,并将其用于CO_(2)和水转化为碳基化学品.通过X射线粉末衍射(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、顺磁共振(EPR)等证实了新型催化剂的成功制备;通过紫外可见(UV-vis)、线性扫描伏安曲线(LSV)、莫特-肖特基(Mott-Schottky)和电化学交流阻抗谱(EIS)表征了其光电性能.结果表明,随着P掺杂量的增加,其导带位置从WO_(3)的-0.13 V升高到30-P样品的-0.54 V,增强了其对CO_(2)的还原能力;所有样品X-P比纯WO_(3)有更高的活性,其中15-P电极还原CO_(2)的活性最高,其光电池的表观光量子效率为0.4%,与植物的光合作用相当,且导带位置越高越有利于甲酸和乙酸产物的生成,而相对较低的导带更有利于乙醇的生成.同时,氧空位对反应的正影响也通过设计H_(2)O_(2)猝灭实验进行了验证.