A simple strategy of Cu modification was proposed to broaden the operation temperature window for NbCe catalyst.The best catalyst Cu0.010/Nb1Ce3 presented over 90%NO conversion in a wide temperature range of 200-400℃...A simple strategy of Cu modification was proposed to broaden the operation temperature window for NbCe catalyst.The best catalyst Cu0.010/Nb1Ce3 presented over 90%NO conversion in a wide temperature range of 200-400℃and exhibited an excellent H_(2)O or/and SO_(2) resistance at 275℃.To understand the promotional mechanism of Cu modification,the correlation among the"activity-structure-property"were tried to establish systematically.Cu species highly dispersed on NbCe catalyst to serve as the active component.The strong interaction among Cu,Nb and Ce promoted the emergence of NbO4 and induced more Bronsted acid sites.And Cu modification obviously enhanced the redox behavior of the NbCe catalyst.Besides,EPR probed the Cu species exited in the form of monomeric and dimeric Cu^(2+),the isolated Cu^(2+)acted as catalytic active sites to promote the reaction:Cu^(2+)-NO_(3)^(-)+NO(g)→Cu^(2+)-NO_(2)^(-)+NO_(2)(g).Then the generated NO_(2) would accelerate the fast-SCR reaction process and thus facilitated the lowtemperature deNO_(x) efficiency.Moreover,surface nitrates became unstable and easy to decompose after Cu modification,thus providing additional adsorption and activation sites for NH3,and ensuring the improvement of catalytic activity at high temperature.Since the NH3-SCR reaction followed by E-R reaction pathway efficaciously over Cu_(0.010)/Nb_(1)Ce_(3) catalyst,the excellent H_(2)O and SO_(2) resistance was as expected.展开更多
Direct chemical vapor deposition(CVD)growth of graphene on dielectric/insulating materials promises transfer-free applications of graphene.However,growing graphene on non-catalytic substrates faces significant challen...Direct chemical vapor deposition(CVD)growth of graphene on dielectric/insulating materials promises transfer-free applications of graphene.However,growing graphene on non-catalytic substrates faces significant challenges,particularly due to its limited growth rate,restricting large-scale production and potential applications.Here,we develop graphene-skinned glass fiber fabric(GGFF)by growing graphene CVD on commercial glass fiber fabric(GFF).This study utilizes propane as a carbon source to prepare GGFF rapidly.The active carbon source(C2H)derived from propane plays a significant role in facilitating the rapid growth of graphene films.It accelerated growth rates(~50 times faster),and reduced growth temperature(~100℃ lower)compared to the conventional carbon source methane.Additionally,propane consistently maintains a higher graphene growth rate than methane at equivalent growth temperatures.The lightweight flexibility,excellent thermal radiation properties,and energy efficiency of GGFF make it an outstanding material for infrared radiation drying.展开更多
Direct growth of graphene on dielectric or insulating materials via chemical vapor deposition(CVD)offers a novel,transfer-free approach for various applications.However,challenges remain in growing graphene on non-cat...Direct growth of graphene on dielectric or insulating materials via chemical vapor deposition(CVD)offers a novel,transfer-free approach for various applications.However,challenges remain in growing graphene on non-catalytic substrates.In particular,the low growth rate of graphene remains a significant barrier to its large-scale production.In this study,propane(C_(3)H_(8))was used as the carbon source to prepare graphene on commercial alumina fiber fabric(AFF)via CVD,resulting in the synthesis of a novel material:graphene-skinned alumina fiber fabric(GAFF).Through comparative analysis of the graphene growth behaviors using C3H8 and traditional carbon sources(CH_(4)and C_(2)H_(4))on AFF,the growth mechanism of C_(3)H_(8)was elucidated.The pyrolysis of C_(3)H_(8) generates the unique carbon species C_(3)H,which exhibits distinct advantages in terms of migration,nucleation,and growth on AFF.Graphene nucleation density using C_(3)H_(8)was found to be 160 times higher than that of CH_(4)and 50 times higher than C_(2)H_(4).The resulting GAFF exhibits a wide tunable electrical conductivity range(1 to 7000Ω·sq^(−1)),high tensile strength(>170 MPa),lightweight properties,flexibility,and a hierarchical macrostructure.These characteristics make GAFF a promising candidate for various applications,including electromagnetic interference(EMI)shielding.展开更多
Direct synthesis of graphene on nonmetallic substrates via chemical vapor deposition (CVD) has become a frontier research realm targeting transfer-free applications of CVD graphene.However,the stable mass production o...Direct synthesis of graphene on nonmetallic substrates via chemical vapor deposition (CVD) has become a frontier research realm targeting transfer-free applications of CVD graphene.However,the stable mass production of graphene with a favorable growth rate and quality remains a grand challenge.Herein,graphene glass fiber fabric (GGFF) was successfully developed through the controllable growth of graphene on non-catalytic glass fiber fabric,employing a synergistic binary-precursor CVD strategy to alleviate the dilemma between growth rate and quality.The binary precursors consisted of acetylene and acetone,where acetylene with high decomposition efficiency fed rapid graphene growth while oxygencontaining acetone was adopted for improving the layer uniformity and quality.Notably,the bifurcating introducing-confluent premixing (BI-CP) system was self-built for the controllable introduction of gas and liquid precursors,enabling the stable production of GGFF.GGFF features solar absorption and infrared emission properties,based on which the self-adaptive dual-mode thermal management film was developed.This film can automatically switch between heating and cooling modes by spontaneously perceiving the temperature,achieving excellent thermal management performances with heating and cooling power of~501.2 and~108.6 W m-2,respectively.These findings unlock a new strategy for the large-scale batch production of graphene materials and inspire advanced possibilities for further applications.展开更多
With the continuous advancements in electronics towards downsizing and integration,efficient thermal dissipation from chips has emerged as a critical factor affecting their lifespan and operational efficiency.The fan-...With the continuous advancements in electronics towards downsizing and integration,efficient thermal dissipation from chips has emerged as a critical factor affecting their lifespan and operational efficiency.The fan-less chip cooling system has two critical interfaces for thermal transport,which are the contact interface between the base and the chip dominated by thermal conduction,and the surface of the fins dominated by thermal radiation.The different thermal transfer modes of these two critical interfaces pose different requirements for thermal management materials.In the study,a novel approach was proposed by developing graphene thermal transport functional material whose morphology could be intentionally designed via reformed plasmaenhanced chemical vapor deposition(PECVD)methods to meet the diverse requirements of heat transfer properties.Specifically,graphene with multilevel branching structure of vertical graphene(BVG)was fabricated through the hydrogenassisted PECVD(H_(2)-PECVD)strategy,which contributed a high emissivity of~0.98.BVG was deposited on the fins’surface and functioned as the radiation enhanced layer to facilitate the rapid radiation of heat from the heat sinks into the surrounding air.Meanwhile,the well-oriented vertical graphene(OVG)was successfully prepared through the vertical electric field-assisted PECVD process(EF-PECVD),which showed a high directional thermal conductivity of~53.5 W·m^(-1)·K^(-1).OVG was deposited on the contact interface and functioned as the thermal conduction enhanced layer,allowing for the quick transmission of heat from the chip to the heat sink.Utilizing this design concept,the two critical interfaces in the chip cooling system can be jointly enhanced,resulting in a remarkable cooling efficiency enhancement of~30.7%,demonstrating that this novel material possessed enormous potential for enhancing the performance of cooling systems.Therefore,this research not only provided new design concepts for the cooling system of electronic devices but also opened up new avenues for the application of graphene materials in thermal management.展开更多
基金Financial support from the National Natural Science Foundation of China,China(Nos.21972062,21976081,21976111)。
文摘A simple strategy of Cu modification was proposed to broaden the operation temperature window for NbCe catalyst.The best catalyst Cu0.010/Nb1Ce3 presented over 90%NO conversion in a wide temperature range of 200-400℃and exhibited an excellent H_(2)O or/and SO_(2) resistance at 275℃.To understand the promotional mechanism of Cu modification,the correlation among the"activity-structure-property"were tried to establish systematically.Cu species highly dispersed on NbCe catalyst to serve as the active component.The strong interaction among Cu,Nb and Ce promoted the emergence of NbO4 and induced more Bronsted acid sites.And Cu modification obviously enhanced the redox behavior of the NbCe catalyst.Besides,EPR probed the Cu species exited in the form of monomeric and dimeric Cu^(2+),the isolated Cu^(2+)acted as catalytic active sites to promote the reaction:Cu^(2+)-NO_(3)^(-)+NO(g)→Cu^(2+)-NO_(2)^(-)+NO_(2)(g).Then the generated NO_(2) would accelerate the fast-SCR reaction process and thus facilitated the lowtemperature deNO_(x) efficiency.Moreover,surface nitrates became unstable and easy to decompose after Cu modification,thus providing additional adsorption and activation sites for NH3,and ensuring the improvement of catalytic activity at high temperature.Since the NH3-SCR reaction followed by E-R reaction pathway efficaciously over Cu_(0.010)/Nb_(1)Ce_(3) catalyst,the excellent H_(2)O and SO_(2) resistance was as expected.
基金financially supported by the National Natural Science Foundation of China(Nos.T2188101,52272032,12302236,and 52021006).
文摘Direct chemical vapor deposition(CVD)growth of graphene on dielectric/insulating materials promises transfer-free applications of graphene.However,growing graphene on non-catalytic substrates faces significant challenges,particularly due to its limited growth rate,restricting large-scale production and potential applications.Here,we develop graphene-skinned glass fiber fabric(GGFF)by growing graphene CVD on commercial glass fiber fabric(GFF).This study utilizes propane as a carbon source to prepare GGFF rapidly.The active carbon source(C2H)derived from propane plays a significant role in facilitating the rapid growth of graphene films.It accelerated growth rates(~50 times faster),and reduced growth temperature(~100℃ lower)compared to the conventional carbon source methane.Additionally,propane consistently maintains a higher graphene growth rate than methane at equivalent growth temperatures.The lightweight flexibility,excellent thermal radiation properties,and energy efficiency of GGFF make it an outstanding material for infrared radiation drying.
基金supported by the National Natural Science Foundation of China(Nos.T2188101,52272032,12302236,and 52021006).
文摘Direct growth of graphene on dielectric or insulating materials via chemical vapor deposition(CVD)offers a novel,transfer-free approach for various applications.However,challenges remain in growing graphene on non-catalytic substrates.In particular,the low growth rate of graphene remains a significant barrier to its large-scale production.In this study,propane(C_(3)H_(8))was used as the carbon source to prepare graphene on commercial alumina fiber fabric(AFF)via CVD,resulting in the synthesis of a novel material:graphene-skinned alumina fiber fabric(GAFF).Through comparative analysis of the graphene growth behaviors using C3H8 and traditional carbon sources(CH_(4)and C_(2)H_(4))on AFF,the growth mechanism of C_(3)H_(8)was elucidated.The pyrolysis of C_(3)H_(8) generates the unique carbon species C_(3)H,which exhibits distinct advantages in terms of migration,nucleation,and growth on AFF.Graphene nucleation density using C_(3)H_(8)was found to be 160 times higher than that of CH_(4)and 50 times higher than C_(2)H_(4).The resulting GAFF exhibits a wide tunable electrical conductivity range(1 to 7000Ω·sq^(−1)),high tensile strength(>170 MPa),lightweight properties,flexibility,and a hierarchical macrostructure.These characteristics make GAFF a promising candidate for various applications,including electromagnetic interference(EMI)shielding.
基金National Natural Science Foundation of China (52272032, T2188101, and 52021006)Beijing Nova Program of Science and Technology (20220484079)。
文摘Direct synthesis of graphene on nonmetallic substrates via chemical vapor deposition (CVD) has become a frontier research realm targeting transfer-free applications of CVD graphene.However,the stable mass production of graphene with a favorable growth rate and quality remains a grand challenge.Herein,graphene glass fiber fabric (GGFF) was successfully developed through the controllable growth of graphene on non-catalytic glass fiber fabric,employing a synergistic binary-precursor CVD strategy to alleviate the dilemma between growth rate and quality.The binary precursors consisted of acetylene and acetone,where acetylene with high decomposition efficiency fed rapid graphene growth while oxygencontaining acetone was adopted for improving the layer uniformity and quality.Notably,the bifurcating introducing-confluent premixing (BI-CP) system was self-built for the controllable introduction of gas and liquid precursors,enabling the stable production of GGFF.GGFF features solar absorption and infrared emission properties,based on which the self-adaptive dual-mode thermal management film was developed.This film can automatically switch between heating and cooling modes by spontaneously perceiving the temperature,achieving excellent thermal management performances with heating and cooling power of~501.2 and~108.6 W m-2,respectively.These findings unlock a new strategy for the large-scale batch production of graphene materials and inspire advanced possibilities for further applications.
基金financially supported by the National Natural Science Foundation of China(Nos.52272032,T2188101,and 52021006)the Beijing Nova Program of Science and Technology(No.20220484079).
文摘With the continuous advancements in electronics towards downsizing and integration,efficient thermal dissipation from chips has emerged as a critical factor affecting their lifespan and operational efficiency.The fan-less chip cooling system has two critical interfaces for thermal transport,which are the contact interface between the base and the chip dominated by thermal conduction,and the surface of the fins dominated by thermal radiation.The different thermal transfer modes of these two critical interfaces pose different requirements for thermal management materials.In the study,a novel approach was proposed by developing graphene thermal transport functional material whose morphology could be intentionally designed via reformed plasmaenhanced chemical vapor deposition(PECVD)methods to meet the diverse requirements of heat transfer properties.Specifically,graphene with multilevel branching structure of vertical graphene(BVG)was fabricated through the hydrogenassisted PECVD(H_(2)-PECVD)strategy,which contributed a high emissivity of~0.98.BVG was deposited on the fins’surface and functioned as the radiation enhanced layer to facilitate the rapid radiation of heat from the heat sinks into the surrounding air.Meanwhile,the well-oriented vertical graphene(OVG)was successfully prepared through the vertical electric field-assisted PECVD process(EF-PECVD),which showed a high directional thermal conductivity of~53.5 W·m^(-1)·K^(-1).OVG was deposited on the contact interface and functioned as the thermal conduction enhanced layer,allowing for the quick transmission of heat from the chip to the heat sink.Utilizing this design concept,the two critical interfaces in the chip cooling system can be jointly enhanced,resulting in a remarkable cooling efficiency enhancement of~30.7%,demonstrating that this novel material possessed enormous potential for enhancing the performance of cooling systems.Therefore,this research not only provided new design concepts for the cooling system of electronic devices but also opened up new avenues for the application of graphene materials in thermal management.
