Transition metal M(M=Mn,Fe,Co,Ni,Cu,and Zn)doped mesoporous titania with a crystalline framework was employed as catalysts for the oxidation of p-bromotoluene(PBT)to p-bromobenzaldehyde(BBD)in acetic acid using aqueou...Transition metal M(M=Mn,Fe,Co,Ni,Cu,and Zn)doped mesoporous titania with a crystalline framework was employed as catalysts for the oxidation of p-bromotoluene(PBT)to p-bromobenzaldehyde(BBD)in acetic acid using aqueous hydrogen peroxide as oxidant.It was found that mesoporous TiO_(2) doped with those metals(Fe,Co and Ni)whose atomic radii are relatively smaller exhibited higher conversion rate of PBT.Among these catalysts,the Co/meso-TiO_(2) exhibited high substrate conversion and good product(p-bromobenzaldehyde)selectivity plus it can be reused once with almost the same activity.The effect of different Ti/Co(molar)ratio on the activities of Co/meso-TiO_(2) was also investigated.展开更多
Metal–phthalocyanines are a class of catalytically active materials promising in energy conversion and storage fields(e.g.,electrocatalysis).However,understanding and controlling the electrochemical properties in met...Metal–phthalocyanines are a class of catalytically active materials promising in energy conversion and storage fields(e.g.,electrocatalysis).However,understanding and controlling the electrochemical properties in metal-phthalocyanine systems is challenging.Herein,we elucidate the electrocatalytic origins of a series of cobalt-phthalocyanine molecular catalysts and finetune their electronic properties at the atomic level,both experimentally and computationally.The interactions between the cobalt center and the local coordination environment are regulated by introducing either electron-donating or electron-withdrawing groups on the phthalocyanine ligand,and the spin-orbit splitting of cobalt is increased by~0.15 eV compared with the nonsubstituted ligand.Specifically,the aminated cobalt phthalocyanine-based electrocatalysts exhibit low free energies in the ratedetermining steps of the oxygen reduction(-1.68 eV)and oxygen evolution reactions(0.37 eV).This contributes to the high electrocatalytic activity(e.g.,a halfwave potential of 0.84 V and an overpotential of 0.30 V at 10 mAcm^(-2)),featuring a high selectivity of a four-electron pathway(i.e.,a negligible by-product of hydrogen peroxide).These catalysts also exhibit exceptional kinetic current density(Tafel slope of 100 mV dec^(-1))in oxygen reduction reactions,in addition to a superior power density(158 mWcm^(-2))and a high cycling stability(>1,300 cycles)in Zn-air batteries,outperforming the commercial Pt/C and/or RuO2counterparts.展开更多
基金the National Natural Science Foundation of China(Grants Nos.20463003,20567004)Natural Science Foundation of Yunnan Province(Project 2007B018M)for financial support.
文摘Transition metal M(M=Mn,Fe,Co,Ni,Cu,and Zn)doped mesoporous titania with a crystalline framework was employed as catalysts for the oxidation of p-bromotoluene(PBT)to p-bromobenzaldehyde(BBD)in acetic acid using aqueous hydrogen peroxide as oxidant.It was found that mesoporous TiO_(2) doped with those metals(Fe,Co and Ni)whose atomic radii are relatively smaller exhibited higher conversion rate of PBT.Among these catalysts,the Co/meso-TiO_(2) exhibited high substrate conversion and good product(p-bromobenzaldehyde)selectivity plus it can be reused once with almost the same activity.The effect of different Ti/Co(molar)ratio on the activities of Co/meso-TiO_(2) was also investigated.
基金supported by the National Natural Science Foundation of China(S.P.,Project Nos.22378105 and 51703056X.X.,Project No.52172087)+5 种基金China Hunan Provincial Science and Technology Department(S.P.,Project No.2018JJ3028)China Fundamental Research Funds for the Central Universities(S.P.,Project Nos.021400541109030031)China Changsha Science and Technology Bureau(S.P.,Project No.kq2208015)China Petroleum&Chemical Corporation(W.X.,Project Nos.219012-3 and 420071-3)the National Supercomputing Center in Changsha(S.P.,Grant No.G2023016)the X-ray absorption spectroscopy and the small/wide angle X-ray scattering beamlines at the Australian Synchrotron,part of ANSTO(S.P.,Grant Nos.18766 and 20570)。
文摘Metal–phthalocyanines are a class of catalytically active materials promising in energy conversion and storage fields(e.g.,electrocatalysis).However,understanding and controlling the electrochemical properties in metal-phthalocyanine systems is challenging.Herein,we elucidate the electrocatalytic origins of a series of cobalt-phthalocyanine molecular catalysts and finetune their electronic properties at the atomic level,both experimentally and computationally.The interactions between the cobalt center and the local coordination environment are regulated by introducing either electron-donating or electron-withdrawing groups on the phthalocyanine ligand,and the spin-orbit splitting of cobalt is increased by~0.15 eV compared with the nonsubstituted ligand.Specifically,the aminated cobalt phthalocyanine-based electrocatalysts exhibit low free energies in the ratedetermining steps of the oxygen reduction(-1.68 eV)and oxygen evolution reactions(0.37 eV).This contributes to the high electrocatalytic activity(e.g.,a halfwave potential of 0.84 V and an overpotential of 0.30 V at 10 mAcm^(-2)),featuring a high selectivity of a four-electron pathway(i.e.,a negligible by-product of hydrogen peroxide).These catalysts also exhibit exceptional kinetic current density(Tafel slope of 100 mV dec^(-1))in oxygen reduction reactions,in addition to a superior power density(158 mWcm^(-2))and a high cycling stability(>1,300 cycles)in Zn-air batteries,outperforming the commercial Pt/C and/or RuO2counterparts.
