Van der Waals(VDW)heterojunctions in a 2D/2D contact provide the highest area for the separation and transfer of charge carriers.In this work,a top-down strategy with a gas erosion process was employed to fabricate a ...Van der Waals(VDW)heterojunctions in a 2D/2D contact provide the highest area for the separation and transfer of charge carriers.In this work,a top-down strategy with a gas erosion process was employed to fabricate a 2D/2D carbon nitride VDW heterojunction in carbon nitride(g-C_(3)N_(4))with carbon-rich carbon nitride.The created 2D semiconducting channel in the VDW structure exhibits enhanced electric field exposure and radiation absorption,which facilitates the separation of the charge carriers and their mobility.Consequently,compared with bulk g-C_(3)N_(4)and its nanosheets,the photocatalytic performance of the fabricated carbon nitride VDW heterojunction in the water splitting reaction to hydrogen is improved by 8.6 and 3.3 times,respectively,while maintaining satisfactory photo-stability.Mechanistically,the finite element method(FEM)was employed to evaluate and clarify the contributions of the formation of VDW heterojunction to enhanced photocatalysis,in agreement quantitatively with experimental ones.This study provides a new and effective strategy for the modification and more insights to performance improvement on polymeric semiconductors in photocatalysis and energy conversion.展开更多
Previous results revealed that the defect and/or interface had a great impact on the electromagnetic pa-rameters of materials.In order to understand the main physical mechanisms and effectively utilize these strategie...Previous results revealed that the defect and/or interface had a great impact on the electromagnetic pa-rameters of materials.In order to understand the main physical mechanisms and effectively utilize these strategies,in this study,M Fe_(2)O_(4)and flower-like core@shell M Fe_(2)O_(4)@MoS_(2)(M=Mn,Ni,and Zn)sam-ples with different categories were elaborately designed and selectively produced in large scale through a simple two-step hydrothermal reaction.We conducted the systematical investigation on their microstruc-tures,electromagnetic parameters and microwave absorption performances(MAPs).The obtained results revealed that the large radius of M^(2+)cation could effectively boost the concentration of oxygen vacancy in the M Fe_(2)O_(4)and M Fe_(2)O_(4)@MoS_(2)samples,which resulted in the improvement of dielectric loss capabil-ities and MAPs.Furthermore,the introduction of MoS_(2)nanosheets greatly improved the interfacial effect and enhanced the polarization loss capabilities,which also boosted the MAPs.By taking full advantage of the defect and interface,the designed M Fe_(2)O_(4)@MoS_(2)samples displayed tunable and excellent com-prehensive MAPs including strong absorption capability,wide absorption bandwidth and thin matching thicknesses.Therefore,the clear understanding of defect and interface engineering made these strategies well elaborately designed and applicable to improving MAPs.展开更多
Defect and interface engineering are efficient approaches to adjust the physical and chemical properties of nanomaterials.In order to effectively utilize these strategies for the improvement of microwave absorption pr...Defect and interface engineering are efficient approaches to adjust the physical and chemical properties of nanomaterials.In order to effectively utilize these strategies for the improvement of microwave absorption properties(MAPs),in this study,we reported the synthesis of hollow carbon shells and hollow carbon@MoS_(2)nanocomposites by the template-etching and templateetching-hydrothermal methods,respectively.The obtained results indicated that the degree of defect for hollow carbon shells and hollow carbon@MoS_(2)could be modulated by the thickness of hollow carbon shell,which effectively fulfilled the optimization of electromagnetic parameters and improvement of MAPs.Furthermore,the microstructure investigations revealed that the precursor of hollow carbon shells was encapsulated by the sheet-like MoS_(2)in high efficiency.And the introduction of MoS_(2)nanosheets acting as the shell effectively improved the interfacial effects and boosted the polarization loss capabilities,which resulted in the improvement of comprehensive MAPs.The elaborately designed hollow carbon@MoS_(2)samples displayed very outstanding MAPs including strong absorption capabilities,broad absorption bandwidth,and thin matching thicknesses.Therefore,this work provided a viable strategy to improve the MAPs of microwave absorbers by taking full advantage of their defect and interface engineering.展开更多
基金the National Natural Science Foundation of China(51676096)supported by the Australian Research Council(DP170104264 and DP190103548).
文摘Van der Waals(VDW)heterojunctions in a 2D/2D contact provide the highest area for the separation and transfer of charge carriers.In this work,a top-down strategy with a gas erosion process was employed to fabricate a 2D/2D carbon nitride VDW heterojunction in carbon nitride(g-C_(3)N_(4))with carbon-rich carbon nitride.The created 2D semiconducting channel in the VDW structure exhibits enhanced electric field exposure and radiation absorption,which facilitates the separation of the charge carriers and their mobility.Consequently,compared with bulk g-C_(3)N_(4)and its nanosheets,the photocatalytic performance of the fabricated carbon nitride VDW heterojunction in the water splitting reaction to hydrogen is improved by 8.6 and 3.3 times,respectively,while maintaining satisfactory photo-stability.Mechanistically,the finite element method(FEM)was employed to evaluate and clarify the contributions of the formation of VDW heterojunction to enhanced photocatalysis,in agreement quantitatively with experimental ones.This study provides a new and effective strategy for the modification and more insights to performance improvement on polymeric semiconductors in photocatalysis and energy conversion.
基金This work was supported by the Fund of Fok Ying Tung Edu-cation Foundation,the Major Research Project of Innovative Group of Guizhou province(No.2018-013)Open Fund from Henan Uni-versity of Science and Technology,the National Science Foundation of China(Nos.11964006 and 11774156)the Foundation of the National Key Project for Basic Research(No.2012CB932304)for fi-nancial support。
文摘Previous results revealed that the defect and/or interface had a great impact on the electromagnetic pa-rameters of materials.In order to understand the main physical mechanisms and effectively utilize these strategies,in this study,M Fe_(2)O_(4)and flower-like core@shell M Fe_(2)O_(4)@MoS_(2)(M=Mn,Ni,and Zn)sam-ples with different categories were elaborately designed and selectively produced in large scale through a simple two-step hydrothermal reaction.We conducted the systematical investigation on their microstruc-tures,electromagnetic parameters and microwave absorption performances(MAPs).The obtained results revealed that the large radius of M^(2+)cation could effectively boost the concentration of oxygen vacancy in the M Fe_(2)O_(4)and M Fe_(2)O_(4)@MoS_(2)samples,which resulted in the improvement of dielectric loss capabil-ities and MAPs.Furthermore,the introduction of MoS_(2)nanosheets greatly improved the interfacial effect and enhanced the polarization loss capabilities,which also boosted the MAPs.By taking full advantage of the defect and interface,the designed M Fe_(2)O_(4)@MoS_(2)samples displayed tunable and excellent com-prehensive MAPs including strong absorption capability,wide absorption bandwidth and thin matching thicknesses.Therefore,the clear understanding of defect and interface engineering made these strategies well elaborately designed and applicable to improving MAPs.
基金the Fund of Fok Ying Tung Education Foundation,the Natural Science Foundation of Guizhou province(No.2017-1034)the Major Research Project of innovative Group of Guizhou province(No.2018-013)+1 种基金the Natural National Science Foundation of China(Nos.11604060,52101010,and 11964006)the Foundation of the National Key Project for Basic Research(No.2012CB932304)for financial support.
文摘Defect and interface engineering are efficient approaches to adjust the physical and chemical properties of nanomaterials.In order to effectively utilize these strategies for the improvement of microwave absorption properties(MAPs),in this study,we reported the synthesis of hollow carbon shells and hollow carbon@MoS_(2)nanocomposites by the template-etching and templateetching-hydrothermal methods,respectively.The obtained results indicated that the degree of defect for hollow carbon shells and hollow carbon@MoS_(2)could be modulated by the thickness of hollow carbon shell,which effectively fulfilled the optimization of electromagnetic parameters and improvement of MAPs.Furthermore,the microstructure investigations revealed that the precursor of hollow carbon shells was encapsulated by the sheet-like MoS_(2)in high efficiency.And the introduction of MoS_(2)nanosheets acting as the shell effectively improved the interfacial effects and boosted the polarization loss capabilities,which resulted in the improvement of comprehensive MAPs.The elaborately designed hollow carbon@MoS_(2)samples displayed very outstanding MAPs including strong absorption capabilities,broad absorption bandwidth,and thin matching thicknesses.Therefore,this work provided a viable strategy to improve the MAPs of microwave absorbers by taking full advantage of their defect and interface engineering.