Mn-N-P doped carbon spheres as an efficient oxygen reduction catalyst for high performance Zn-Air batteries

Low-cost and efficient oxygen reduction reaction(ORR)electrocatalysts are the key to developing Zn-air batteries for renewable energy storage.Herein,the Mn-N-P doped carbon sphere was prepared through polymerization of hexachlorotripolyphosphazene(HCCP)and phloroglucinol,and then followed the calcination at 900°C.Theory calculations demonstrated the introduction of Mn in N-P doped carbon could lower the dissociation barrier of O2into O*and promote the ORR through a 4e-pathway.The asprepared catalysts exhibited a half-wave potential of 0.82 V vs.RHE and limiting current density of 5.2 m A/cm^(2)toward ORR,which was comparable to those of the commercial Pt/C catalysts.In addition,Zn-air batteries with 0.05 Mn-N-P-C catalysts showed a high specific capacity of 830 m Ah/gZnand excellent cycle stability.This facile approach demonstrated herein could be a solution to develop optimum non-precious metal catalysts for the application in cathodes of proton exchange membrane fuel cells.This study also provides new insight to design the catalysts of multi-heteroatom coordinated metal in the carbon matrix for both fundamental researches and practical applications.

Environmentally regulated intrinsic oxygen-ion transport for oxideion conductors

Oxide-ion conductors have been widely used as catalytic,conductive,detecting and other materials under oxidizing,reducing,inert,mixed environments and the like.However,so far the evaluation of their oxygen-ion transport(such as oxide-ion conductivity and oxygen permeability)either is extrinsic or is limited only in oxidizing or inert environment.Herein,the evaluation of intrinsic oxygen-ion transport for oxide-ion conductors in all environments seems especially important.In this work,a new test system was designed to enable the oxide-ion conductors placing in single oxidizing,reducing,inert or mixed environment separately,which also realized all the oxygen-vacancy concentrations of oxide-ion conductors are in equilibrium in all environments.The intrinsic oxide-ion conductivity and oxygen permeability were evaluated in all environments,and the influencing factors regulated by environments also were analyzed to correlate the variation of oxygen-ion transport.

Factors influencing Li^(+)migration in garnet-type ceramic electrolytes

Garnet-type ceramic electrolyte with exceptionally high Li^(+) conductivity has attracted wide interests for the development of safe electrochemical devices.However,the factors affecting the ionic migration still deserve more attentions.In this study,five garnet-types ceramic electrolyte were chosen to investigate the factors.The thermal behavior of garnet-type electrolyte during sintering was studied to achieve high conductivity.The electrochemical properties are correlated with crystal structure,migrating route and lattice parameters.Nine influening factors were discussed to analyze the ionic migration in garnet-type ceramic electrolyte.

Robust Joule-heating ceramic reactors for catalytic CO oxidation

Joule-heating reactors have the higher energy efficiency and product selectivity compared with the reactors based on radiative heating.Current Joule-heating reactors are constructed with electrically-conductive metals or carbon materials,and therefore suffer from stability issue due to the presence of corrosive or oxidizing gases during high-temperature reactions.In this study,chemicallystable and electrically-conductive(La_(0.80)Sr_(0.20))_(0.95)FeO_(3)(LSF)/Gd_(0.1)Ce_(0.9)O_(2)(GDC)ceramics have been used to construct Joule-heating reactors for the first time.Taking the advantage of the resistance decrease of the ceramic reactors with temperature increase,the ceramic reactors heated under current control mode achieved the automatic adjustment of heating to stabilize reactor temperatures.In addition,the electrical resistance of LSF/GDC reactors can be tuned by the content of the highconductive LSF in composite ceramics and ceramic density via sintering temperature,which offers flexibility to control reactor temperatures.The ceramic reactors with dendritic channels(less than 100μm in diameter)showed the catalytic activity for CO oxidation,which was further improved by coating efficient MnO_(2)nanocatalyst on reactor channel wall.The Joule-heating ceramic reactors achieved complete CO oxidation at a low temperature of 165℃.Therefore,robust ceramic reactors have successfully demonstrated effective Joule heating for CO oxidation,which are potentially applied in other high-temperature catalytic reactions.

Enhanced cross-flow filtration with flat-sheet ceramic membranes by titanium-based coagulation for membrane fouling control

Application of ceramic membrane(CM)with outstanding characteristics,such as high flux and chemical-resistance,is inevitably restricted by membrane fouling.Coagulation was an economical and effective technology for membrane fouling control.This study investigated the filtration performance of ceramic membrane enhanced by the emerging titanium-based coagulant(polytitanium chloride,PTC).Particular attention was paid to the simulation of ceramic membrane fouling using four widely used mathematical models.Results show that filtration of the PTC-coagulated effluent using flat-sheet ceramic membrane achieved the removal of organic matter up to 78.0%.Permeate flux of ceramic membrane filtration reached 600 L/(m2$h),which was 10-fold higher than that observed with conventional polyaluminum chloride(PAC)case.For PTC,fouling of the ceramic membrane was attributed to the formation of cake layer,whereas for PAC,standard filtration/intermediate filtration(blocking of membrane pores)was also a key fouling mechanism.To sum up,cross-flow filtration with flat-sheet ceramic membranes could be significantly enhanced by titanium-based coagulation to produce both high-quality filtrate and high-permeation flux.