Significant progress has been made in the development of non-precious metal electrocatalysts （NPMEs） during the past decade. Correspondingly, there is an urgent demand for an appropriate measurement method to be est...Significant progress has been made in the development of non-precious metal electrocatalysts （NPMEs） during the past decade. Correspondingly, there is an urgent demand for an appropriate measurement method to be established for the reliable evaluation of NPMEs. In this study, platinum and graphite counter electrodes were used to investigate the impact of counter electrode material on the accelerated durability testing （ADT） of NPMEs in acidic medium. Platinum used as the coun- ter electrode in a traditional three-electrode electrochemical cell was found to dissolve in acidic medium and re-deposit on NPME coated on the working electrode during ADT. Such re-deposition causes the oxygen reduction reaction （ORR） performance of NPMEs to remarkably improve, and thus will seriously mislead our judgment of NPMEs if we are unaware of it. The phenomenon can be avoided using a graphite counter electrode.展开更多
In this work,we have performed density functional theory(DFT)calculations to investigate the methanol electro‐oxidation reaction(MOR)catalyzed by the Pt,PtCu alloy and Cu.The complex reaction networks,including the i...In this work,we have performed density functional theory(DFT)calculations to investigate the methanol electro‐oxidation reaction(MOR)catalyzed by the Pt,PtCu alloy and Cu.The complex reaction networks,including the intermediate dehydrogenation,water dissociation and anti‐poison reaction steps,are systematically investigated to explore the mechanisms.At the standard condition of pH=0 and zero potential,for Cu,most dehydrogenation steps along the favorable pathway are endergonic,making it less active in MOR.For the Pt and PtCu alloy,their dehydrogenation steps are mainly exergonic,but the formed CO intermediate binds too tightly on Pt,that can accumulate on active sites to poison the electro‐catalyst.The CO can be consumed by the thermodynamic reaction with OH*,which comes from water dissociation.DFT calculation shows alloying the Pt with Cu could not only reduce the free energy barrier for binding between CO*and OH*,but also assist the water dissociation to produce more OH*for that anti‐poison reaction.That makes the PtCu alloy more active than the pure Pt electrode in experiment.The results reveal the importance of anti‐poison reaction and water dissociation in MOR,which could be applied to the rational design of more active alloy electro‐catalysts in future.展开更多
Sluggish kinetics of anodic hydrogen oxidation reaction(HOR)in alkaline media,which arises from the two orders of magnitude lower HOR activity in alkali than that in acid media for platinum group metals,hinders the co...Sluggish kinetics of anodic hydrogen oxidation reaction(HOR)in alkaline media,which arises from the two orders of magnitude lower HOR activity in alkali than that in acid media for platinum group metals,hinders the commercial implementation of anion exchange membrane fuel cells(AEMFCs).Consequently,the development of platinum-based catalysts combined with high efficiency and durability is urgently required.Herein,we report a facile route for the synthesis of ternary PtRuTe alloy nanofibers with Pt atomic ratio of only 11%via a simple galvanic replacement reaction.We optimize the adsorption strength of platinum and ruthenium towards hydrogen and hydroxyl species by regulating the electron donation from tellurium to platinum and ruthenium.Hence,the obtained trimetallic alloy catalyst exhibits an impressive kinetic current density of 30.6 mA cm^(−2)_(geo) at 50 mV and an exchange current density of 0.426 mA cm^(−2)_(metal),which shows 3.0-and 2.5-fold enhancement compared with the commercial Pt/C in alkaline electrolyte,respectively.Moreover,the catalyst also demonstrates excellent stability with merely 5%activity attenuation after 2000 potential cycles.This work offers new pathways to boost alkaline HOR by rationally designing multicomponent alloys.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(DUT15RC(3)001,DUT15ZD225)the Program for Liao-ning Excellent Talents in University(LR2015014)+1 种基金the Liaoning BaiQianWan Talents Program(201519)Dalian Excellent Young Scientific and Technological Talents(2015R006)
文摘Significant progress has been made in the development of non-precious metal electrocatalysts （NPMEs） during the past decade. Correspondingly, there is an urgent demand for an appropriate measurement method to be established for the reliable evaluation of NPMEs. In this study, platinum and graphite counter electrodes were used to investigate the impact of counter electrode material on the accelerated durability testing （ADT） of NPMEs in acidic medium. Platinum used as the coun- ter electrode in a traditional three-electrode electrochemical cell was found to dissolve in acidic medium and re-deposit on NPME coated on the working electrode during ADT. Such re-deposition causes the oxygen reduction reaction （ORR） performance of NPMEs to remarkably improve, and thus will seriously mislead our judgment of NPMEs if we are unaware of it. The phenomenon can be avoided using a graphite counter electrode.
文摘In this work,we have performed density functional theory(DFT)calculations to investigate the methanol electro‐oxidation reaction(MOR)catalyzed by the Pt,PtCu alloy and Cu.The complex reaction networks,including the intermediate dehydrogenation,water dissociation and anti‐poison reaction steps,are systematically investigated to explore the mechanisms.At the standard condition of pH=0 and zero potential,for Cu,most dehydrogenation steps along the favorable pathway are endergonic,making it less active in MOR.For the Pt and PtCu alloy,their dehydrogenation steps are mainly exergonic,but the formed CO intermediate binds too tightly on Pt,that can accumulate on active sites to poison the electro‐catalyst.The CO can be consumed by the thermodynamic reaction with OH*,which comes from water dissociation.DFT calculation shows alloying the Pt with Cu could not only reduce the free energy barrier for binding between CO*and OH*,but also assist the water dissociation to produce more OH*for that anti‐poison reaction.That makes the PtCu alloy more active than the pure Pt electrode in experiment.The results reveal the importance of anti‐poison reaction and water dissociation in MOR,which could be applied to the rational design of more active alloy electro‐catalysts in future.
基金the National Natural Science Foundation of China(21905178)Shenzhen Science and Technology Program(JCYJ20190808143007479 and JCYJ20170818144659020).
文摘Sluggish kinetics of anodic hydrogen oxidation reaction(HOR)in alkaline media,which arises from the two orders of magnitude lower HOR activity in alkali than that in acid media for platinum group metals,hinders the commercial implementation of anion exchange membrane fuel cells(AEMFCs).Consequently,the development of platinum-based catalysts combined with high efficiency and durability is urgently required.Herein,we report a facile route for the synthesis of ternary PtRuTe alloy nanofibers with Pt atomic ratio of only 11%via a simple galvanic replacement reaction.We optimize the adsorption strength of platinum and ruthenium towards hydrogen and hydroxyl species by regulating the electron donation from tellurium to platinum and ruthenium.Hence,the obtained trimetallic alloy catalyst exhibits an impressive kinetic current density of 30.6 mA cm^(−2)_(geo) at 50 mV and an exchange current density of 0.426 mA cm^(−2)_(metal),which shows 3.0-and 2.5-fold enhancement compared with the commercial Pt/C in alkaline electrolyte,respectively.Moreover,the catalyst also demonstrates excellent stability with merely 5%activity attenuation after 2000 potential cycles.This work offers new pathways to boost alkaline HOR by rationally designing multicomponent alloys.
