The Haber-Bosch process for industrial NH_(3) production is energy-intensive with heavy CO_(2) emissions.Electrochemical N_(2) reduction reaction(NRR)is an attractive carbon-neutral alternative for NH_(3) synthesis,wh...The Haber-Bosch process for industrial NH_(3) production is energy-intensive with heavy CO_(2) emissions.Electrochemical N_(2) reduction reaction(NRR)is an attractive carbon-neutral alternative for NH_(3) synthesis,while the challenge associated with N_(2) activation highlights the demand for efficient electrocatalysts.Herein,we demonstrate that PdCu nanoparticles with different Pd/Cu ratios anchored on boron nanosheet(PdCu/B)behave as efficient NRR electrocatalysts toward NH_(3) synthesis.Theoretical and experimental results confirm that the highly efficient NH_(3) synthesis can be achieved by regulating the charge transfer between interfaces and forming a symmetry-breaking site,which not only alleviates the hydrogen evolution but also changes the adsorption configuration of N_(2) and thus optimizes the reaction pathway of NRR over the separated Pd sites.Compared with monometallic Pd/B and Cu/B,the PdCu/B with the optimized Pd/Cu ratio of 1 exhibits superior activity and selectivity for NH_(3) synthesis.This study provides new insight into developing efficient catalysts for small energy molecule catalytic conversion via regulating the charge transfer between interfaces and constructing symmetry-breaking sites.展开更多
Catalytic oxidation of benzene with N_(2)O to phenol over the hierarchical and microporous Fe/ZSM-5-based catalysts in a continuous fixedbed reactor was investigated.The spent catalyst was in-situ regenerated by an ox...Catalytic oxidation of benzene with N_(2)O to phenol over the hierarchical and microporous Fe/ZSM-5-based catalysts in a continuous fixedbed reactor was investigated.The spent catalyst was in-situ regenerated by an oxidative treatment using N_(2)O and in total 10 reaction-regeneration cycles were performed.A 100% N_(2)O conversion,93.3% phenol selectivity,and high initial phenol formation rate of 16.49±0.06mmol_(phenol gcatalyst)^(-1)h^(-1)at time on stream(TOS) of 5 min,and a good phenol productivity of 147.06 mmol_(phenol gcatalyst)^(-1)during catalyst lifetime of 1800 min were obtained on a fresh hierarchical Fe/ZSM-5-Hi2.8 catalyst.With the reaction-regeneration cycle,N_(2)O conversion is fully recovered within TOS of 3 h,moreover,the phenol productivity was decreased ca.2.2±0.8% after each cycle,leading to a total phenol productivity of ca.0.44 ton_(pheol kg_(catalyst)^(-1)estimated for 300 cycles.Catalyst characterizations imply that the coke is rapidly deposited on catalyst surface in the initial TOS of 3 h(0.28 mgc_(gcatalyst)^(-1)min^(-1)) and gradually becomes graphitic during the TOS of 30 h with a slow formation rate of 0.06 mgc g_(catalyst)^(-1)min^(-1).Among others(e.g.,the decrease of textural property and acidity),the nearly complete coverage of the active Fe-O-Al sites by coke accounts for the main catalyst deactivation.Besides these reversible deactivation characteristics related to coking,the irreversible catalyst deactivation is also observed with the reaction-regeneration cycle.The latter is reflected by a further decreased amount of the active Fe-O-Al sites,which agglomerate on catalyst surface with the cycle,likely associated with the hard coke residue that is not completely removed by the regeneration.展开更多
g-C_(3)N_(4) coupled with high specific area TiO_(2)(HSA-TiO_(2))composite was prepared by a simple solvothermal method,which was easy to operate with low energy consumption.Degradation of methyl orange test results s...g-C_(3)N_(4) coupled with high specific area TiO_(2)(HSA-TiO_(2))composite was prepared by a simple solvothermal method,which was easy to operate with low energy consumption.Degradation of methyl orange test results showed that HSA-TiO_(2) effectively improved the photocatalytic activity effectively.Photoelectrochemical test results indicated that the separation of photo-generated carriers and the charge carrier migration speed of TiO_(2) were improved after combination with g-C_(3)N_(4).g-C3N4/HSA-TiO_(2) showed strong photocatalytic ability.The degree of degradation of methyl orange by 6%-g-C_(3)N_(4)/HSA-TiO_(2) could reach up to 92.44%.Furthermore,it revealed good cycle performance.The photocatalytic mechanism of g-C_(3)N_(4)/HSA-TiO_(2) was proposed.展开更多
The photocatalytic activity of catalysts depends on the energy-harvesting ability and the separation or transport of photogenerated carriers.The light absorption capacity of graphitic carbon nitride(g-C_(3)N_(4))-base...The photocatalytic activity of catalysts depends on the energy-harvesting ability and the separation or transport of photogenerated carriers.The light absorption capacity of graphitic carbon nitride(g-C_(3)N_(4))-based composites can be enhanced by adjusting the surface plasmon resonance(SPR)of noble metal nanoparticles(e.g.,Cu,Au,and Pd)in the entire visible region.Adjustments can be carried out by varying the nanocomponents of the materials.The SPR of noble metals can enhance the local electromagnetic field and improve interband transition,and resonant energy transfer occurs from plasmonic dipoles to electron-hole pairs via near-field electromagnetic interactions.Thus,noble metals have emerged as relevant nanocomponents for g-C_(3)N_(4) used in CO_(2) photoreduction and water splitting.Herein,recent key advances in noble metals(either in single atom,cluster,or nanoparticle forms)and composite photocatalysts based on inorganic or organic nanocomponent-incorporated g-C_(3)N_(4) nanosheets are systematically discussed,including the applications of these photocatalysts,which exhibit improved photoinduced charge mobility in CO_(2) photoconversion and H2 production.Issues related to the different types of multi-nanocomponent heterostructures(involving Schottky junctions,Z-/S-scheme heterostructures,noble metals,and additional semiconductor nanocomponents)and the adjustment of dimensionality of heterostructures(by incorporating noble metal nanoplates on g-C_(3)N_(4) forming 2D/2D heterostructures)are explored.The current prospects and possible challenges of g-C_(3)N_(4) composite photocatalysts incorporated with noble metals(e.g.,Au,Pt,Pd,and Cu),particularly in water splitting,CO_(2) reduction,pollution degradation,and chemical conversion applications,are summarized.展开更多
In this work,La-doped Mg-Ni multiphase alloys were prepared by resistance melting furnace(RMF)and then modified by high-energy ball milling(HEBM).The hydrolysis H_(2) generation kinetics/thermodynamics of prepared all...In this work,La-doped Mg-Ni multiphase alloys were prepared by resistance melting furnace(RMF)and then modified by high-energy ball milling(HEBM).The hydrolysis H_(2) generation kinetics/thermodynamics of prepared alloys in Na Cl solutions have been investigated with the help of nonlinear and linear fitting by Avrami-Erofeev and Arrhenius equations.Combining the microstructure information before and after hydrolysis and thermodynamics fitting results,the hydrolysis H_(2) generation mechanism based on nucleation&growth has been elaborated.The final H_(2) generation capacities of 0La,5La,10La and 15 La alloys are 677,653,641 and 770 m L·g^(-1)H_(2) in 240 min at291 K,respectively.While,the final H_(2) generation capacities of HEBM 0La,5La,10La and 15 La alloys are 632,824,611 and 653 m L·g^(-1)H_(2) in 20 min at 291 K,respectively.The as-cast 15La alloy and HEMB 5La alloy present the best H_(2) production rates and final H_(2) production capacities,especially the HEBM 5La can rapidly achieve high H_(2) generation capacity(670 and 824 m L·g^(-1)H_(2) )at low temperature(291 K)within short time(5 and 20 min).The difference between the H_(2) generation capacities is mainly originated from the initial nucleation rate of Mg(OH)_(2) and the subsequent processes affected by the microstructures and phase compositions of the hydrolysis alloys.Relative low initial nucleation rate and fully growth of Mg(OH)_(2) nucleus are the premise of high H_(2) generation capacity due to the hydrolysis H_(2) generation process consisted by the nucleation,growth and contacting of Mg(OH)_(2) nucleus.To utilization H_(2) by designing solid state H_(2) generators using optimized Mg-based alloys is expected to be a feasible H_(2) generation strategy at the moment.展开更多
基金National Key R&D Program of China,Grant/Award Number:2020YFA0710000National Natural Science Foundation of China,Grant/Award Numbers:22008170,21978200,22161142002,22121004。
文摘The Haber-Bosch process for industrial NH_(3) production is energy-intensive with heavy CO_(2) emissions.Electrochemical N_(2) reduction reaction(NRR)is an attractive carbon-neutral alternative for NH_(3) synthesis,while the challenge associated with N_(2) activation highlights the demand for efficient electrocatalysts.Herein,we demonstrate that PdCu nanoparticles with different Pd/Cu ratios anchored on boron nanosheet(PdCu/B)behave as efficient NRR electrocatalysts toward NH_(3) synthesis.Theoretical and experimental results confirm that the highly efficient NH_(3) synthesis can be achieved by regulating the charge transfer between interfaces and forming a symmetry-breaking site,which not only alleviates the hydrogen evolution but also changes the adsorption configuration of N_(2) and thus optimizes the reaction pathway of NRR over the separated Pd sites.Compared with monometallic Pd/B and Cu/B,the PdCu/B with the optimized Pd/Cu ratio of 1 exhibits superior activity and selectivity for NH_(3) synthesis.This study provides new insight into developing efficient catalysts for small energy molecule catalytic conversion via regulating the charge transfer between interfaces and constructing symmetry-breaking sites.
基金Financial support by the Specialized Research Fund for Doctoral Program of Higher Education,China (No.20120010110003)。
文摘Catalytic oxidation of benzene with N_(2)O to phenol over the hierarchical and microporous Fe/ZSM-5-based catalysts in a continuous fixedbed reactor was investigated.The spent catalyst was in-situ regenerated by an oxidative treatment using N_(2)O and in total 10 reaction-regeneration cycles were performed.A 100% N_(2)O conversion,93.3% phenol selectivity,and high initial phenol formation rate of 16.49±0.06mmol_(phenol gcatalyst)^(-1)h^(-1)at time on stream(TOS) of 5 min,and a good phenol productivity of 147.06 mmol_(phenol gcatalyst)^(-1)during catalyst lifetime of 1800 min were obtained on a fresh hierarchical Fe/ZSM-5-Hi2.8 catalyst.With the reaction-regeneration cycle,N_(2)O conversion is fully recovered within TOS of 3 h,moreover,the phenol productivity was decreased ca.2.2±0.8% after each cycle,leading to a total phenol productivity of ca.0.44 ton_(pheol kg_(catalyst)^(-1)estimated for 300 cycles.Catalyst characterizations imply that the coke is rapidly deposited on catalyst surface in the initial TOS of 3 h(0.28 mgc_(gcatalyst)^(-1)min^(-1)) and gradually becomes graphitic during the TOS of 30 h with a slow formation rate of 0.06 mgc g_(catalyst)^(-1)min^(-1).Among others(e.g.,the decrease of textural property and acidity),the nearly complete coverage of the active Fe-O-Al sites by coke accounts for the main catalyst deactivation.Besides these reversible deactivation characteristics related to coking,the irreversible catalyst deactivation is also observed with the reaction-regeneration cycle.The latter is reflected by a further decreased amount of the active Fe-O-Al sites,which agglomerate on catalyst surface with the cycle,likely associated with the hard coke residue that is not completely removed by the regeneration.
基金supported by the National Natural Science Foundation of China(No.61308095,No.21801092,and No.11904128)the Program for the Development of Science and Technology of Jilin province(No.20180520002JH)+1 种基金the Graduate Innovation Project of Jilin Normal University(No.201941)the Key Research Programs in Universities of Henan Province(20A150031).
文摘g-C_(3)N_(4) coupled with high specific area TiO_(2)(HSA-TiO_(2))composite was prepared by a simple solvothermal method,which was easy to operate with low energy consumption.Degradation of methyl orange test results showed that HSA-TiO_(2) effectively improved the photocatalytic activity effectively.Photoelectrochemical test results indicated that the separation of photo-generated carriers and the charge carrier migration speed of TiO_(2) were improved after combination with g-C_(3)N_(4).g-C3N4/HSA-TiO_(2) showed strong photocatalytic ability.The degree of degradation of methyl orange by 6%-g-C_(3)N_(4)/HSA-TiO_(2) could reach up to 92.44%.Furthermore,it revealed good cycle performance.The photocatalytic mechanism of g-C_(3)N_(4)/HSA-TiO_(2) was proposed.
基金supported in part by the projects from the National Natural Science Foundation of China(No.51972145)Jinan Science&Technology Bureau,China(No.2021GXRC109)Science and Technology Program of the University of Jinan,China(No.XKY2118).
文摘The photocatalytic activity of catalysts depends on the energy-harvesting ability and the separation or transport of photogenerated carriers.The light absorption capacity of graphitic carbon nitride(g-C_(3)N_(4))-based composites can be enhanced by adjusting the surface plasmon resonance(SPR)of noble metal nanoparticles(e.g.,Cu,Au,and Pd)in the entire visible region.Adjustments can be carried out by varying the nanocomponents of the materials.The SPR of noble metals can enhance the local electromagnetic field and improve interband transition,and resonant energy transfer occurs from plasmonic dipoles to electron-hole pairs via near-field electromagnetic interactions.Thus,noble metals have emerged as relevant nanocomponents for g-C_(3)N_(4) used in CO_(2) photoreduction and water splitting.Herein,recent key advances in noble metals(either in single atom,cluster,or nanoparticle forms)and composite photocatalysts based on inorganic or organic nanocomponent-incorporated g-C_(3)N_(4) nanosheets are systematically discussed,including the applications of these photocatalysts,which exhibit improved photoinduced charge mobility in CO_(2) photoconversion and H2 production.Issues related to the different types of multi-nanocomponent heterostructures(involving Schottky junctions,Z-/S-scheme heterostructures,noble metals,and additional semiconductor nanocomponents)and the adjustment of dimensionality of heterostructures(by incorporating noble metal nanoplates on g-C_(3)N_(4) forming 2D/2D heterostructures)are explored.The current prospects and possible challenges of g-C_(3)N_(4) composite photocatalysts incorporated with noble metals(e.g.,Au,Pt,Pd,and Cu),particularly in water splitting,CO_(2) reduction,pollution degradation,and chemical conversion applications,are summarized.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51704188,51702199,61705125,51802181)the State Key Laboratory of Solidification Processing in NWPU(Grant No.SKLSP201809)+2 种基金Natural Science Foundation of Shaanxi Province(Grant No.2019JQ-099)Research Starting Foundation from Shaanxi University of Science and Technology(Grant No.2016GBJ-04)the financial support of China Scholarship Council(Grant No.201808610089)。
文摘In this work,La-doped Mg-Ni multiphase alloys were prepared by resistance melting furnace(RMF)and then modified by high-energy ball milling(HEBM).The hydrolysis H_(2) generation kinetics/thermodynamics of prepared alloys in Na Cl solutions have been investigated with the help of nonlinear and linear fitting by Avrami-Erofeev and Arrhenius equations.Combining the microstructure information before and after hydrolysis and thermodynamics fitting results,the hydrolysis H_(2) generation mechanism based on nucleation&growth has been elaborated.The final H_(2) generation capacities of 0La,5La,10La and 15 La alloys are 677,653,641 and 770 m L·g^(-1)H_(2) in 240 min at291 K,respectively.While,the final H_(2) generation capacities of HEBM 0La,5La,10La and 15 La alloys are 632,824,611 and 653 m L·g^(-1)H_(2) in 20 min at 291 K,respectively.The as-cast 15La alloy and HEMB 5La alloy present the best H_(2) production rates and final H_(2) production capacities,especially the HEBM 5La can rapidly achieve high H_(2) generation capacity(670 and 824 m L·g^(-1)H_(2) )at low temperature(291 K)within short time(5 and 20 min).The difference between the H_(2) generation capacities is mainly originated from the initial nucleation rate of Mg(OH)_(2) and the subsequent processes affected by the microstructures and phase compositions of the hydrolysis alloys.Relative low initial nucleation rate and fully growth of Mg(OH)_(2) nucleus are the premise of high H_(2) generation capacity due to the hydrolysis H_(2) generation process consisted by the nucleation,growth and contacting of Mg(OH)_(2) nucleus.To utilization H_(2) by designing solid state H_(2) generators using optimized Mg-based alloys is expected to be a feasible H_(2) generation strategy at the moment.
