The electrochemical carbon dioxide reduction reaction(CO_(2)RR),which can produce value-added chemical feedstocks,is a proton-coupled-electron process with sluggish kinetics.Thus,highly efficient,cheap catalysts are u...The electrochemical carbon dioxide reduction reaction(CO_(2)RR),which can produce value-added chemical feedstocks,is a proton-coupled-electron process with sluggish kinetics.Thus,highly efficient,cheap catalysts are urgently required.Transition metal oxides such as CoO_(x),FeO_(x),and NiO_(x)are low-cost,low toxicity,and abundant materials for a wide range of electrochemical reactions,but are almost inert for CO_(2)RR.Here,we report for the first time that nitrogen doped carbon nanotubes(N-CNT)have a surprising activation effect on the activity and selectivity of transition metal-oxide(MO_(x)where M=Fe,Ni,and Co)nanoclusters for CO_(2)RR.MO_(x)supported on N-CNT,MO_(x)/N-CNT,achieves a CO yield of 2.6–2.8 mmol cm−2 min−1 at an overpotential of−0.55 V,which is two orders of magnitude higher than MO_(x)supported on acid treated CNTs(MO_(x)/O-CNT)and four times higher than pristine N-CNT.The faraday efficiency for electrochemical CO_(2)-to-CO conversion is as high as 90.3%at overpotential of 0.44 V.Both in-situ XAS measurements and DFT calculations disclose that MO_(x)nanoclusters can be hydrated in CO_(2)saturated KHCO_(3),and the N defects of N-CNT effectively stabilize these metal hydroxyl species under carbon dioxide reduction reaction conditions,which can split the water molecules and provide local protons to inhibit the poisoning of active sites under carbon dioxide reduction reaction conditions.展开更多
NiMnGaferromagnetic shape memory thin film was deposited onto Al foil using r.f.magnetron sputtering technique.The crystallization behavior of the film was investigated by XRD and DSC.The activation energy of crystall...NiMnGaferromagnetic shape memory thin film was deposited onto Al foil using r.f.magnetron sputtering technique.The crystallization behavior of the film was investigated by XRD and DSC.The activation energy of crystallization of the film was calculated by Kissinger’s method.The results show that the crystallization temperature of NiMnGafree-standing thin film in martensite state is 372 ℃,and the activation energy of crystallization is about 191.9 kJ·mol-1.展开更多
A diverse range of remarkable boron n itride (BN) nano structures subsumi ng nano-homs, nano-rods, nano-platelets, and clusters of hollow nano spheres (nano-onions, arguably of greatest applied and fun damental in ter...A diverse range of remarkable boron n itride (BN) nano structures subsumi ng nano-homs, nano-rods, nano-platelets, and clusters of hollow nano spheres (nano-onions, arguably of greatest applied and fun damental in terest) have bee n produced exclusively from crystalline BN precursor powder via lamp ablation. The procedure is safe, devoid of toxic reagents, simple, rapid and scalable—generating some genres of nan oparticles that had previously proved elusive. Product structure and composition were unambiguously assessed by high-resoluti on transmission electron microscopy, energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy.展开更多
基金Y.C.and J.C.are contributed equally to the paper.Project supported by the National Natural Science Foundation of China (U19A2017)the Fundamental Research Funds for the Central South University and the Australian Research Council (DP180100731 and DP180100568)。
文摘The electrochemical carbon dioxide reduction reaction(CO_(2)RR),which can produce value-added chemical feedstocks,is a proton-coupled-electron process with sluggish kinetics.Thus,highly efficient,cheap catalysts are urgently required.Transition metal oxides such as CoO_(x),FeO_(x),and NiO_(x)are low-cost,low toxicity,and abundant materials for a wide range of electrochemical reactions,but are almost inert for CO_(2)RR.Here,we report for the first time that nitrogen doped carbon nanotubes(N-CNT)have a surprising activation effect on the activity and selectivity of transition metal-oxide(MO_(x)where M=Fe,Ni,and Co)nanoclusters for CO_(2)RR.MO_(x)supported on N-CNT,MO_(x)/N-CNT,achieves a CO yield of 2.6–2.8 mmol cm−2 min−1 at an overpotential of−0.55 V,which is two orders of magnitude higher than MO_(x)supported on acid treated CNTs(MO_(x)/O-CNT)and four times higher than pristine N-CNT.The faraday efficiency for electrochemical CO_(2)-to-CO conversion is as high as 90.3%at overpotential of 0.44 V.Both in-situ XAS measurements and DFT calculations disclose that MO_(x)nanoclusters can be hydrated in CO_(2)saturated KHCO_(3),and the N defects of N-CNT effectively stabilize these metal hydroxyl species under carbon dioxide reduction reaction conditions,which can split the water molecules and provide local protons to inhibit the poisoning of active sites under carbon dioxide reduction reaction conditions.
基金This work is financially supported by the National Natural Science Foundation of China ( No 50531020)
文摘NiMnGaferromagnetic shape memory thin film was deposited onto Al foil using r.f.magnetron sputtering technique.The crystallization behavior of the film was investigated by XRD and DSC.The activation energy of crystallization of the film was calculated by Kissinger’s method.The results show that the crystallization temperature of NiMnGafree-standing thin film in martensite state is 372 ℃,and the activation energy of crystallization is about 191.9 kJ·mol-1.
文摘A diverse range of remarkable boron n itride (BN) nano structures subsumi ng nano-homs, nano-rods, nano-platelets, and clusters of hollow nano spheres (nano-onions, arguably of greatest applied and fun damental in terest) have bee n produced exclusively from crystalline BN precursor powder via lamp ablation. The procedure is safe, devoid of toxic reagents, simple, rapid and scalable—generating some genres of nan oparticles that had previously proved elusive. Product structure and composition were unambiguously assessed by high-resoluti on transmission electron microscopy, energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy.
