Synthesizing highly efficient,low-toxicity catalysts for the remediation of polycyclic aromatic hydrocarbons(PAHs)contaminated soils is crucial.Nanoscale zero-valent iron(n-ZVI)is widely used in the treatment of pollut...Synthesizing highly efficient,low-toxicity catalysts for the remediation of polycyclic aromatic hydrocarbons(PAHs)contaminated soils is crucial.Nanoscale zero-valent iron(n-ZVI)is widely used in the treatment of pollutants due to its high catalytic activity.However,n-ZVI is prone to aggregation and passivation.Therefore,to design an environmentally friendly,efficient,and practical catalyst material,this study designed a nanoscale zero-valent iron-loaded biochar(BC)polyacrylic acid(PAA)composite materials.Biochar and polyacrylic acid can prevent the ag-gregation of zero-valent iron and provide a large number of functional groups.The iron on the carrier is uniformly distributed,exposing active sites and activating persulfate to remove anthracene(ANT)pollutants from the soil.The BC/PAA/Fe0 system can achieve an anthracene degradation efficiency of 93.7%in soil,and the degradation efficiency of anthracene remains around 90%under both acidic and alkaline con-$$ditions.Free radical capture experiments indicate that the degradation of anthracene proceeds through the radical pathways SO4,$OH,O2 and the non-radical pathway 1O2.In addition,possible degradation pathways for anthracene have been proposed.Plant planting experiments have shown that the catalyst designed in this study has low toxicity and has excellent application prospects in thefield of soil remediation.展开更多
Single-atom catalysts are promising for H_(2)O_(2) photosynthesis from O_(2) and H_(2)O,but their efficiency is still limited by the ill-defined electronic structure.In this study,Co single-atoms with unique four plan...Single-atom catalysts are promising for H_(2)O_(2) photosynthesis from O_(2) and H_(2)O,but their efficiency is still limited by the ill-defined electronic structure.In this study,Co single-atoms with unique four planar N-coordination and one axial P-coordination(Co-N_(4)P_(1))are decorated on the lateral edges of nanorod-like crystalline g-C_(3)N_(4)(CCN)photocatalysts.Significantly,the electronic structures of central Co as active sites for O_(2) reduction reaction(ORR)and planar N-coordinator as active sites for H_(2)O oxidation reaction(WOR)in Co-N_(4)P_(1) can be well regulated by the synergetic effects of introducing axial P-coordinator,in contrast to the decorated Co single-atoms with only four planar N-coordination(Co-N_(4)).Specifically,directional photoelectron accumulation at central Co active sites,induced by an introduced midgap level in Co-N_(4)P_(1),mediates the ORR active sites from 4e–-ORR-selective terminal–NH_(2) sites to 2e–-ORR-selective Co sites,moreover,an elevated d-band center of Co 3d orbital strengthens ORR intermediate*OOH adsorption,thus jointly facilitating a highly selective and active 2e^(–)-ORR pathway to H_(2)O_(2) photosynthesis.Simultaneously,a downshifted p-band center of N_(2)p orbital in Co-N_(4)P_(1) weakens WOR intermediate*OH adsorption,thus enabling a preferable 2e^(–)-WOR pathway toward H_(2)O_(2) photosynthesis.Subsequently,Co-N_(4)P_(1) exhibits exceptional H_(2)O_(2) photosynthesis efficiency,reaching 295.6μmol g^(-1) h^(-1) with a remarkable solar-to-chemical conversion efficiency of 0.32%,which is 15 times that of Co-N_(4)(19.2μmol g^(-1) h^(-1))and 10 times higher than CCN(27.6μmol g^(-1) h^(-1)).This electronic structure modulation on single-atom catalysts offers a promising strategy for boosting the activity and selectivity of H_(2)O_(2) photosynthesis.展开更多
Recently,Li[16]introduced three kinds of single-hidden layer feed-forward neural networks with optimized piecewise linear activation functions and fixed weights,and obtained the upper and lower bound estimations on th...Recently,Li[16]introduced three kinds of single-hidden layer feed-forward neural networks with optimized piecewise linear activation functions and fixed weights,and obtained the upper and lower bound estimations on the approximation accuracy of the FNNs,for continuous function defined on bounded intervals.In the present paper,we point out that there are some errors both in the definitions of the FNNs and in the proof of the upper estimations in[16].By using new methods,we also give right approximation rate estimations of the approximation by Li’s neural networks.展开更多
基金support provided by the National Natural Science Foundation of China(22478267,22438009,U24A20535)Basic Research Program of Jiangsu province(BK20243002)+1 种基金Prospective Application Research Project of Suzhou(SYC2022042)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Synthesizing highly efficient,low-toxicity catalysts for the remediation of polycyclic aromatic hydrocarbons(PAHs)contaminated soils is crucial.Nanoscale zero-valent iron(n-ZVI)is widely used in the treatment of pollutants due to its high catalytic activity.However,n-ZVI is prone to aggregation and passivation.Therefore,to design an environmentally friendly,efficient,and practical catalyst material,this study designed a nanoscale zero-valent iron-loaded biochar(BC)polyacrylic acid(PAA)composite materials.Biochar and polyacrylic acid can prevent the ag-gregation of zero-valent iron and provide a large number of functional groups.The iron on the carrier is uniformly distributed,exposing active sites and activating persulfate to remove anthracene(ANT)pollutants from the soil.The BC/PAA/Fe0 system can achieve an anthracene degradation efficiency of 93.7%in soil,and the degradation efficiency of anthracene remains around 90%under both acidic and alkaline con-$$ditions.Free radical capture experiments indicate that the degradation of anthracene proceeds through the radical pathways SO4,$OH,O2 and the non-radical pathway 1O2.In addition,possible degradation pathways for anthracene have been proposed.Plant planting experiments have shown that the catalyst designed in this study has low toxicity and has excellent application prospects in thefield of soil remediation.
文摘Single-atom catalysts are promising for H_(2)O_(2) photosynthesis from O_(2) and H_(2)O,but their efficiency is still limited by the ill-defined electronic structure.In this study,Co single-atoms with unique four planar N-coordination and one axial P-coordination(Co-N_(4)P_(1))are decorated on the lateral edges of nanorod-like crystalline g-C_(3)N_(4)(CCN)photocatalysts.Significantly,the electronic structures of central Co as active sites for O_(2) reduction reaction(ORR)and planar N-coordinator as active sites for H_(2)O oxidation reaction(WOR)in Co-N_(4)P_(1) can be well regulated by the synergetic effects of introducing axial P-coordinator,in contrast to the decorated Co single-atoms with only four planar N-coordination(Co-N_(4)).Specifically,directional photoelectron accumulation at central Co active sites,induced by an introduced midgap level in Co-N_(4)P_(1),mediates the ORR active sites from 4e–-ORR-selective terminal–NH_(2) sites to 2e–-ORR-selective Co sites,moreover,an elevated d-band center of Co 3d orbital strengthens ORR intermediate*OOH adsorption,thus jointly facilitating a highly selective and active 2e^(–)-ORR pathway to H_(2)O_(2) photosynthesis.Simultaneously,a downshifted p-band center of N_(2)p orbital in Co-N_(4)P_(1) weakens WOR intermediate*OH adsorption,thus enabling a preferable 2e^(–)-WOR pathway toward H_(2)O_(2) photosynthesis.Subsequently,Co-N_(4)P_(1) exhibits exceptional H_(2)O_(2) photosynthesis efficiency,reaching 295.6μmol g^(-1) h^(-1) with a remarkable solar-to-chemical conversion efficiency of 0.32%,which is 15 times that of Co-N_(4)(19.2μmol g^(-1) h^(-1))and 10 times higher than CCN(27.6μmol g^(-1) h^(-1)).This electronic structure modulation on single-atom catalysts offers a promising strategy for boosting the activity and selectivity of H_(2)O_(2) photosynthesis.
文摘Recently,Li[16]introduced three kinds of single-hidden layer feed-forward neural networks with optimized piecewise linear activation functions and fixed weights,and obtained the upper and lower bound estimations on the approximation accuracy of the FNNs,for continuous function defined on bounded intervals.In the present paper,we point out that there are some errors both in the definitions of the FNNs and in the proof of the upper estimations in[16].By using new methods,we also give right approximation rate estimations of the approximation by Li’s neural networks.
