Although Pt Ni catalyst possesses good oxygen reduction activity, its poor stability is the main obstacle for the commercialization of proton exchange membrane fuel cells(PEMFCs). In this work, we introduce the acid-r...Although Pt Ni catalyst possesses good oxygen reduction activity, its poor stability is the main obstacle for the commercialization of proton exchange membrane fuel cells(PEMFCs). In this work, we introduce the acid-resistant refractory Mo to enhance the structure stability and modify the electronic structure of Pt in the prepared PtNi catalyst, improving the catalytic activity for oxygen reduction reaction(ORR). In addition, near-surface Pt content in the nanoparticle is also optimized to balance the ORR activity and stability. The electrochemical results show that the alloy formed by Mo and Pt Ni is obviously more stable than the PtNi alloy alone, because the acid-resistant Mo and its oxides effectively prevent the dissolution of Pt. Especially, the Pt3 Ni3 MoN/C exhibits the optimal ORR catalytic performance in O2-saturated 0.1 mol L^(-1) HClO4 aqueous solutions, with mass activity(MA) of 900 m A mg^(-1) Pt at 0.90 V vs. RHE, which is 3.75 times enhancement compared with the commercial Pt/C(240 mA mg^(-1) Pt). After 30 k accelerated durability tests, its MA(690 m A mg^(-1) Pt) is still 2.88 times higher than the pristine Pt/C. This study thus provides a valuable method to design stable ORR catalysts with high efficiency and has great significance for the commercialization of PEMFCs.展开更多
We demonstrated a unique synthesis approach of graphene（GR）-wrapped AgPO/LaCOOH（APO/LCO）heterostructures by an in-situ wet chemical method. FESEM analysis reveals the formation of rhombic dodecahedrons of APO deco...We demonstrated a unique synthesis approach of graphene（GR）-wrapped AgPO/LaCOOH（APO/LCO）heterostructures by an in-situ wet chemical method. FESEM analysis reveals the formation of rhombic dodecahedrons of APO decorated with LCO and later wrapped with GR flakes. Optical studies shows two absorption edges corresponding to the band gap energies of APO（2.41 eV） and LCO（4.1 eV）. Considering the absorption edge of the heterostructures in the visible region, the photocatalytic activities of photocatalysts containing different APO/LCO mass ratios were evaluated by the degradation of MB. GR-decorated composite with 20% LCO（APO/LCO20/GR） exhibited the highest photocatalytic activity for MB degradation, with a rate constant, k of 0.541 min. The photocatalytic activity of APO/LCO20/GR more greatly enhanced than those of the individual constituents（APO, LCO, APO/LCO20）. The enhanced photocatalytic activity of the heterostructure can be attributed to the co-catalytic effect of LCO as well as intriguing physicochemical properties of GR. To understand the enhanced photocatalytic activity of the heterostructures the photocatalytic reaction mechanism is proposed in detail. The recyclability of the APO/LCO/GR composite photocatalyst is further evaluated by reusing the catalyst in replicate photocatalytic experiments which shows consistent photocatalytic activity thereby confirms the stability and reusability of heterostructure photocatalyst.展开更多
Electrophysiological recording is a widely used method to investigate cardiovascular pathology,pharmacology and developmental biology.Microelectrode arrays record the electrical potential of cells in a minimally invas...Electrophysiological recording is a widely used method to investigate cardiovascular pathology,pharmacology and developmental biology.Microelectrode arrays record the electrical potential of cells in a minimally invasive and highthroughput way.However,commonly used microelectrode arays primarily employ planar microelectrodes and cannot work in applications that require a recording of the intracellular action potential of a single cell.In this study,we proposed a novel measuring method that is able to record the intracellular action potential of a single cardiomyocyte by using a nanowell patterned microelectrode array(NWMEA).The NWMEA consists of five nanoscale wells at the center of each circular planar microelectrode.Biphasic pulse electroporation was applied to the NWMEA to penetrate the cardiomyocyte membrane,and the intracellular action potential was continuously recorded.The intracellular potential recording of cardiomyocytes by the NWMEA measured a potential signal with a higher quality(213.76±25.85%),reduced noise root-mean-square(~33%),and higher signal-to-noise ratio(254.36±12.61%)when compared to those of the extracellular recording.Compared to previously reported nanopillar microelectrodes,the NWMEA could ensure single cell electroporation and acquire high-quality action potential of cardiomyocytes with reduced fabrication processes.This NWMEA-based biosensing system is a promising tool to record the intracellular action potential of a single cell to broaden the usage of microelectrode arrays in electrophysiological investigation.展开更多
Thermokinetics of the dismutation of superoxide anion(O_(2)^(.-))catalyzed by superoxide dismutase(SOD),in which the decomposition of hydrogen peroxide catalyzed by catalase is utilized as a source of oxygen and the a...Thermokinetics of the dismutation of superoxide anion(O_(2)^(.-))catalyzed by superoxide dismutase(SOD),in which the decomposition of hydrogen peroxide catalyzed by catalase is utilized as a source of oxygen and the autoxidation of pyrogallod as a source of the substrate(O_(2)^(.-)),has been studied by microcalorimetry.The molar reaction enthalpies of the SOD reaction and the pyrogallol autoxidation have been measured as-160.1 and-218 kJ·mol^(-1),respectively,at 298.15 K and pH 7.0.A novel method for the determination of SOD activity,the microcalorimetric assay for SOD,has been proposed.The experimental results showed that SOD had no effect on both kinetic parameters and the mechanism for the pyrogallol autoxidation.This autoxidation followed the second-order reaction kinetics in the presence of limited oxygen(the first order with respect to both pyrogallol and O2),and the second-order rate constants were hermined at 298.15 K and pH 8.0 to be 1.25 and 1.30 L·mol^(-1)·s^(-1 )in the absence and presence of SOD,respectively.A possible mechanism for the autoxidation of pyrogallol inhibited by SOD was also suggested.展开更多
基金supported by the National Natural Science Foundation of China (21872040)the Natural Science Foundation of Guangxi (2016GXNSFCB380002)+1 种基金the Hundred Talents Program of Guangxi Universitiesthe Excellence Scholars and Innovation Team of Guangxi Universities。
文摘Although Pt Ni catalyst possesses good oxygen reduction activity, its poor stability is the main obstacle for the commercialization of proton exchange membrane fuel cells(PEMFCs). In this work, we introduce the acid-resistant refractory Mo to enhance the structure stability and modify the electronic structure of Pt in the prepared PtNi catalyst, improving the catalytic activity for oxygen reduction reaction(ORR). In addition, near-surface Pt content in the nanoparticle is also optimized to balance the ORR activity and stability. The electrochemical results show that the alloy formed by Mo and Pt Ni is obviously more stable than the PtNi alloy alone, because the acid-resistant Mo and its oxides effectively prevent the dissolution of Pt. Especially, the Pt3 Ni3 MoN/C exhibits the optimal ORR catalytic performance in O2-saturated 0.1 mol L^(-1) HClO4 aqueous solutions, with mass activity(MA) of 900 m A mg^(-1) Pt at 0.90 V vs. RHE, which is 3.75 times enhancement compared with the commercial Pt/C(240 mA mg^(-1) Pt). After 30 k accelerated durability tests, its MA(690 m A mg^(-1) Pt) is still 2.88 times higher than the pristine Pt/C. This study thus provides a valuable method to design stable ORR catalysts with high efficiency and has great significance for the commercialization of PEMFCs.
基金Department of Electronics and Information Technology (Deit Y, New Delhi) for financial supportUGC-SAP, DST-FIST Department of Chemistry, Shivaji University Kolhapursupported by the Commercialization Promotion Agency for R&D Outcomes (COMPA) funded by the Ministry of Science, ICT and Future Planning (MISP) and NRF-2013R1A2A2A05005589
文摘We demonstrated a unique synthesis approach of graphene（GR）-wrapped AgPO/LaCOOH（APO/LCO）heterostructures by an in-situ wet chemical method. FESEM analysis reveals the formation of rhombic dodecahedrons of APO decorated with LCO and later wrapped with GR flakes. Optical studies shows two absorption edges corresponding to the band gap energies of APO（2.41 eV） and LCO（4.1 eV）. Considering the absorption edge of the heterostructures in the visible region, the photocatalytic activities of photocatalysts containing different APO/LCO mass ratios were evaluated by the degradation of MB. GR-decorated composite with 20% LCO（APO/LCO20/GR） exhibited the highest photocatalytic activity for MB degradation, with a rate constant, k of 0.541 min. The photocatalytic activity of APO/LCO20/GR more greatly enhanced than those of the individual constituents（APO, LCO, APO/LCO20）. The enhanced photocatalytic activity of the heterostructure can be attributed to the co-catalytic effect of LCO as well as intriguing physicochemical properties of GR. To understand the enhanced photocatalytic activity of the heterostructures the photocatalytic reaction mechanism is proposed in detail. The recyclability of the APO/LCO/GR composite photocatalyst is further evaluated by reusing the catalyst in replicate photocatalytic experiments which shows consistent photocatalytic activity thereby confirms the stability and reusability of heterostructure photocatalyst.
基金supported by the Center-initiated Research Project of Zheijiang Lab(Grant No.2021MHOALO1)the Startup Grant from Zhejang Lab(Grant No.113010-PI2108)。
文摘Electrophysiological recording is a widely used method to investigate cardiovascular pathology,pharmacology and developmental biology.Microelectrode arrays record the electrical potential of cells in a minimally invasive and highthroughput way.However,commonly used microelectrode arays primarily employ planar microelectrodes and cannot work in applications that require a recording of the intracellular action potential of a single cell.In this study,we proposed a novel measuring method that is able to record the intracellular action potential of a single cardiomyocyte by using a nanowell patterned microelectrode array(NWMEA).The NWMEA consists of five nanoscale wells at the center of each circular planar microelectrode.Biphasic pulse electroporation was applied to the NWMEA to penetrate the cardiomyocyte membrane,and the intracellular action potential was continuously recorded.The intracellular potential recording of cardiomyocytes by the NWMEA measured a potential signal with a higher quality(213.76±25.85%),reduced noise root-mean-square(~33%),and higher signal-to-noise ratio(254.36±12.61%)when compared to those of the extracellular recording.Compared to previously reported nanopillar microelectrodes,the NWMEA could ensure single cell electroporation and acquire high-quality action potential of cardiomyocytes with reduced fabrication processes.This NWMEA-based biosensing system is a promising tool to record the intracellular action potential of a single cell to broaden the usage of microelectrode arrays in electrophysiological investigation.
基金Project supported by the National Natural Science Foundation of China(Grant No.29273121)
文摘Thermokinetics of the dismutation of superoxide anion(O_(2)^(.-))catalyzed by superoxide dismutase(SOD),in which the decomposition of hydrogen peroxide catalyzed by catalase is utilized as a source of oxygen and the autoxidation of pyrogallod as a source of the substrate(O_(2)^(.-)),has been studied by microcalorimetry.The molar reaction enthalpies of the SOD reaction and the pyrogallol autoxidation have been measured as-160.1 and-218 kJ·mol^(-1),respectively,at 298.15 K and pH 7.0.A novel method for the determination of SOD activity,the microcalorimetric assay for SOD,has been proposed.The experimental results showed that SOD had no effect on both kinetic parameters and the mechanism for the pyrogallol autoxidation.This autoxidation followed the second-order reaction kinetics in the presence of limited oxygen(the first order with respect to both pyrogallol and O2),and the second-order rate constants were hermined at 298.15 K and pH 8.0 to be 1.25 and 1.30 L·mol^(-1)·s^(-1 )in the absence and presence of SOD,respectively.A possible mechanism for the autoxidation of pyrogallol inhibited by SOD was also suggested.
