WO_(3),an abundant transition metal semiconductor,is one of the most discussed materials to be used as a photoanode in photoelectrochemical water-splitting devices.The photoelectrochemical properties,such as photoacti...WO_(3),an abundant transition metal semiconductor,is one of the most discussed materials to be used as a photoanode in photoelectrochemical water-splitting devices.The photoelectrochemical properties,such as photoactivity and selectivity of WO_(3) in different electrolytes,are already well understood.However,the understanding of stability,one of the most important properties for utilization in a commercial device,is still in the early stages.In this work,a photoelectrochemical scanning flow cell coupled to an inductively coupled plasma mass spectrometer is applied to determine the influence of co-catalyst overlayers on photoanode stability.Spray-coatedWO_(3) photoanodes are used as a model system.Iridium is applied to the electrodes by atomic layer deposition in controlled layer thickness,as determined by ellipsometry and x-ray photoelectron spectroscopy.Photoactivity of the iridium-modified WO_(3) photoanodes decreases with increasing iridium layer thickness.Partial blocking of the WO_(3) surface by iridium is proposed as the main cause of the decreased photoelectrochemical performance.On the other hand,the stability of WO_(3) is notably increased even in the presence of the thinnest investigated iridium overlayer.Based on our findings,we provide a set of strategies to synthesize nanocomposite photoelectrodes simultaneously possessing high photoelectrochemical activity and photostability.展开更多
The synthesis of high-quality ultrathin overlayers is critically dependent on the surface structure of substrates,especially involving the overlayer–substrate interaction.By using in situ surface measurements,we demo...The synthesis of high-quality ultrathin overlayers is critically dependent on the surface structure of substrates,especially involving the overlayer–substrate interaction.By using in situ surface measurements,we demonstrate that the overlayer–substrate interaction can be tuned by doping near-surface Ar nanobubbles.The interfacial coupling strength significantly decreases with near-surface Ar nanobubbles,accompanying by an“anisotropic to isotropic”growth transformation.On the substrate containing near-surface Ar,the growth front crosses entire surface atomic steps in both uphill and downhill directions with no difference,and thus,the morphology of the two-dimensional(2D)overlayer exhibits a round-shape.Especially,the round-shaped 2D overlayers coalesce seamlessly with a growth acceleration in the approaching direction,which is barely observed in the synthesis of 2D materials.This can be attributed to the immigration lifetime and diffusion rate of growth species,which depends on the overlayer–substrate interaction and the surface catalysis.Furthermore,the“round to hexagon”morphological transition is achieved by etching-regrowth,revealing the inherent growth kinetics under quasi-freestanding conditions.These findings provide a novel promising way to modulate the growth,coalescence,and etching dynamics of 2D materials on solid surfaces by adjusting the strength of overlayer–substrate interaction,which contributes to optimization of large-scale production of 2D material crystals.展开更多
This study aims to assess landslide susceptibility in Hulu Selangor,Selangor,Malaysia,an area that is exposed to rapid industrial and infrastructural growth.Six conditioning factors,such as slope,land use,lithology,ro...This study aims to assess landslide susceptibility in Hulu Selangor,Selangor,Malaysia,an area that is exposed to rapid industrial and infrastructural growth.Six conditioning factors,such as slope,land use,lithology,road proximity,and river proximity,were integrated through the Analytic Hierarchy Process(AHP)in a GIS environment.Theweights distribution analysis revealed slope(40.50%)and lithology(23.12%)as themost important factors,followed by river proximity(15.09%)and road proximity(13.76%).The developed susceptibility map was divided into five zones:very low(12.4%),low(18.7%),medium(35.6%),high(22.1%),and very high(11.2%).Model validation was performed using past landslide events,in which it was found that all the reported events in the study area were found in medium to very high susceptibility zones,with 100%accuracy.Notwithstanding this,the validation is limited by the low number of historical landslide locations,which tends to overestimate model performance.The outcome indicates that medium to high susceptibility zones dominate the district,particularly in large road and river networks,identifying the interaction between hydrological processes and human interference in influencing landslide instability.Aside from the scientific understanding of landslide hazard,the results also provide actionable recommendations for land use planning,infrastructure security,and site-specific mitigation strategies in Hulu Selangor.展开更多
Dry reforming of methane(DRM)over Ni-based catalysts is an economically reasonable technology for large-scale CO_(2)utilization.However,prolonged Ni sintering and carbon deposition reduce the durability and efficiency...Dry reforming of methane(DRM)over Ni-based catalysts is an economically reasonable technology for large-scale CO_(2)utilization.However,prolonged Ni sintering and carbon deposition reduce the durability and efficiency of DRM,hindering its engineering application.Herein,we propose a facile approach by combining continuous microscale coprecipitation with solid-state reactions to construct a BaAl_(2)O_(4)-overlayer-confined Ni catalyst.The 5-wt%-Ni@BaAl_(2)O_(4)catalyst exhibited advanced CO_(2)and CH_(4)conversions of 96% and 86% at 800℃ and a GHSV of 144 L g_(cat)^(-1).h^(-1).Moreover,the k_(d)-CO_(2)and k_(d)-CH_(4)of Ni@BaAl_(2)O_(4)were 0.0063 and 0.0029 h^(-1);which are approximately half and one-thirds of those of Ni/BaAl_(2)O_(4)and slightly better than those of Ni@MgAl_(2)O_(4),underscoring the versatility of the proposed synthesis protocol for constructing core-shell structures.XAS,HAADF-STEM-EDS,and CO transmission-IR characterizations confirmed the SMSI of~2-nm amorphous BaAl_(2)O_(4)-overlaid~10 nm Ni with an overall mesoporous structure.After a long-term test,the sintering and coking inhibition effects of Ni@BaAl_(2)O_(4)(10→11 nm,0.55 mgCg_(cat)^(-1).h^(-1))outperformed Ni/BaAl_(2)O_(4)(13→22 nm,1.90 mgCg_(cat)^(-1).h^(-1))and Ni@MgAl_(2)O_(4).In situ time-resolved CH4→CO_(2)transient response,DRIFTS experiments,and DFT calculations suggested that Ni@BaAl_(2)O_(4)and Ni/BaAl_(2)O_(4)followed the Mars-van Krevelen and Langmuir-Hinshelwood redox mechanisms,respectively.The functional interfacial lattice oxygen promoted the removal of C_(ads)^(*)on Ni and core-shell structure induced fast CO_(2)adsorption and CO desorption.The present study provides a facile approach for constructing a stable and active Ni-based core-shell catalyst.Furthermore,it offers novel insights into the functionalities of non-reducible spinel overlayers in the DRM process.展开更多
This research presents a numerical simulation methodology for optimizing circular composite overlays’dimensions and pressure characteristics with orthotropic mechanical properties,specifically,for metal conduits with...This research presents a numerical simulation methodology for optimizing circular composite overlays’dimensions and pressure characteristics with orthotropic mechanical properties,specifically,for metal conduits with temperature-dependent elastoplastic behavior.The primary objective of the proposed method is to prevent crack propagation during pressure surges from operational to critical levels.This study examines the“Beineu-Bozoy-Shymkent”steel gas conduit,examining its performance across a temperature range of−40 to+50℃.This work builds on prior research on extended avalanche destruction in steel gas conduits and crack propagation prevention techniques.Theanalysis was conducted using a dynamic finite-element approach with the ANSYS-19.2/ExplicitDynamics software.Simulations of unprotected conduits revealed that increasing gas-dynamic pressure can convert a partial-depth crack into a through-crack,extending longitudinally to approximately seven times its initial length.Notably,at T=+50℃,the developed crack length was 1.2%longer than that at T=−40℃,highlighting the temperature sensitivity of crack progression.The modeling results indicate that crack propagation can be effectively controlled using a circular composite overlay with a thickness between 37.5%and 50%of the crack depth and a length approximately five times that of the initial crack,centered symmetrically over the crack.In addition,preliminary stress analysis indicated that limiting the overlay-induced pressure to 5%of the operational pressure effectively arrested crack growth without generating significant stress concentrations near the overlay boundaries,thereby preventing conduit integrity.展开更多
This research extends ongoing efforts to develop methods for reinforcing damaged main gas pipelines to prevent catastrophic failure.This study establishes the use of scaled-down experimental models for assessing the d...This research extends ongoing efforts to develop methods for reinforcing damaged main gas pipelines to prevent catastrophic failure.This study establishes the use of scaled-down experimental models for assessing the dynamic strength of damaged pipeline sections reinforced with wire wrapping or composite sleeves.A generalized dynamic model is introduced for numerical simulation to evaluate the effectiveness of reinforcement techniques.The model incorporates the elastoplastic behavior of pipe and wire materials,the influence of temperature on mechanical properties,the contact interaction between the pipe and the reinforcement components(including pretensioning),and local material failure under transient internal pressure.Based on these parameters,a finite element model was developed using ANSYS 19.2 to enable parametric studies.The accuracy of the proposed model was verified by comparing the simulation results with the experimental findings.Pipeline section samples containing non-penetrating longitudinal crackswere subjected to comparative analyses and transient pressure until critical failure.The unreinforced and steel wire-wrapped sections were investigated.The results confirm the feasibility of applying the computational model to study the dynamic strength of reinforced damaged pipe sections.Furthermore,pipelines with longitudinal cracks reinforced using circular composite overlays with orthotropic mechanical properties were examined,and recommendations are provided for selecting the geometric parameters of such overlays.展开更多
基金German Ministry of Education and Reseach(BMBF),Grant/Award Number:03SF0564ADeutsche Forschungsgemeinschaft(DFG),Grant/Award Number:429730598。
文摘WO_(3),an abundant transition metal semiconductor,is one of the most discussed materials to be used as a photoanode in photoelectrochemical water-splitting devices.The photoelectrochemical properties,such as photoactivity and selectivity of WO_(3) in different electrolytes,are already well understood.However,the understanding of stability,one of the most important properties for utilization in a commercial device,is still in the early stages.In this work,a photoelectrochemical scanning flow cell coupled to an inductively coupled plasma mass spectrometer is applied to determine the influence of co-catalyst overlayers on photoanode stability.Spray-coatedWO_(3) photoanodes are used as a model system.Iridium is applied to the electrodes by atomic layer deposition in controlled layer thickness,as determined by ellipsometry and x-ray photoelectron spectroscopy.Photoactivity of the iridium-modified WO_(3) photoanodes decreases with increasing iridium layer thickness.Partial blocking of the WO_(3) surface by iridium is proposed as the main cause of the decreased photoelectrochemical performance.On the other hand,the stability of WO_(3) is notably increased even in the presence of the thinnest investigated iridium overlayer.Based on our findings,we provide a set of strategies to synthesize nanocomposite photoelectrodes simultaneously possessing high photoelectrochemical activity and photostability.
基金the National Natural Science Foundation of China(Nos.21872169,91845109,21688102,and 21825203)the National Key R&D Program of China(No.2016YFA0200200)+2 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB17020000)China Postdoctoral Science Foundation(No.2019M651997)Natural Science Foundation of Jiangsu Province(No.BK20200257).
文摘The synthesis of high-quality ultrathin overlayers is critically dependent on the surface structure of substrates,especially involving the overlayer–substrate interaction.By using in situ surface measurements,we demonstrate that the overlayer–substrate interaction can be tuned by doping near-surface Ar nanobubbles.The interfacial coupling strength significantly decreases with near-surface Ar nanobubbles,accompanying by an“anisotropic to isotropic”growth transformation.On the substrate containing near-surface Ar,the growth front crosses entire surface atomic steps in both uphill and downhill directions with no difference,and thus,the morphology of the two-dimensional(2D)overlayer exhibits a round-shape.Especially,the round-shaped 2D overlayers coalesce seamlessly with a growth acceleration in the approaching direction,which is barely observed in the synthesis of 2D materials.This can be attributed to the immigration lifetime and diffusion rate of growth species,which depends on the overlayer–substrate interaction and the surface catalysis.Furthermore,the“round to hexagon”morphological transition is achieved by etching-regrowth,revealing the inherent growth kinetics under quasi-freestanding conditions.These findings provide a novel promising way to modulate the growth,coalescence,and etching dynamics of 2D materials on solid surfaces by adjusting the strength of overlayer–substrate interaction,which contributes to optimization of large-scale production of 2D material crystals.
文摘This study aims to assess landslide susceptibility in Hulu Selangor,Selangor,Malaysia,an area that is exposed to rapid industrial and infrastructural growth.Six conditioning factors,such as slope,land use,lithology,road proximity,and river proximity,were integrated through the Analytic Hierarchy Process(AHP)in a GIS environment.Theweights distribution analysis revealed slope(40.50%)and lithology(23.12%)as themost important factors,followed by river proximity(15.09%)and road proximity(13.76%).The developed susceptibility map was divided into five zones:very low(12.4%),low(18.7%),medium(35.6%),high(22.1%),and very high(11.2%).Model validation was performed using past landslide events,in which it was found that all the reported events in the study area were found in medium to very high susceptibility zones,with 100%accuracy.Notwithstanding this,the validation is limited by the low number of historical landslide locations,which tends to overestimate model performance.The outcome indicates that medium to high susceptibility zones dominate the district,particularly in large road and river networks,identifying the interaction between hydrological processes and human interference in influencing landslide instability.Aside from the scientific understanding of landslide hazard,the results also provide actionable recommendations for land use planning,infrastructure security,and site-specific mitigation strategies in Hulu Selangor.
基金financially supported by the National Natural Science Foundation of China(22378227)the National Research Foundation,Singapore,and A*STAR under its Low-Carbon Energy Research(LCER)Funding Initiative(FI)Project(U2102d2011,WBS:A-8000278-00-00)the Medium Energy X-ray Absorption Spectroscopy beamline at the Australian Synchrotron,part of ANSTO。
文摘Dry reforming of methane(DRM)over Ni-based catalysts is an economically reasonable technology for large-scale CO_(2)utilization.However,prolonged Ni sintering and carbon deposition reduce the durability and efficiency of DRM,hindering its engineering application.Herein,we propose a facile approach by combining continuous microscale coprecipitation with solid-state reactions to construct a BaAl_(2)O_(4)-overlayer-confined Ni catalyst.The 5-wt%-Ni@BaAl_(2)O_(4)catalyst exhibited advanced CO_(2)and CH_(4)conversions of 96% and 86% at 800℃ and a GHSV of 144 L g_(cat)^(-1).h^(-1).Moreover,the k_(d)-CO_(2)and k_(d)-CH_(4)of Ni@BaAl_(2)O_(4)were 0.0063 and 0.0029 h^(-1);which are approximately half and one-thirds of those of Ni/BaAl_(2)O_(4)and slightly better than those of Ni@MgAl_(2)O_(4),underscoring the versatility of the proposed synthesis protocol for constructing core-shell structures.XAS,HAADF-STEM-EDS,and CO transmission-IR characterizations confirmed the SMSI of~2-nm amorphous BaAl_(2)O_(4)-overlaid~10 nm Ni with an overall mesoporous structure.After a long-term test,the sintering and coking inhibition effects of Ni@BaAl_(2)O_(4)(10→11 nm,0.55 mgCg_(cat)^(-1).h^(-1))outperformed Ni/BaAl_(2)O_(4)(13→22 nm,1.90 mgCg_(cat)^(-1).h^(-1))and Ni@MgAl_(2)O_(4).In situ time-resolved CH4→CO_(2)transient response,DRIFTS experiments,and DFT calculations suggested that Ni@BaAl_(2)O_(4)and Ni/BaAl_(2)O_(4)followed the Mars-van Krevelen and Langmuir-Hinshelwood redox mechanisms,respectively.The functional interfacial lattice oxygen promoted the removal of C_(ads)^(*)on Ni and core-shell structure induced fast CO_(2)adsorption and CO desorption.The present study provides a facile approach for constructing a stable and active Ni-based core-shell catalyst.Furthermore,it offers novel insights into the functionalities of non-reducible spinel overlayers in the DRM process.
基金supported by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan(Grant No.AP19680589).
文摘This research presents a numerical simulation methodology for optimizing circular composite overlays’dimensions and pressure characteristics with orthotropic mechanical properties,specifically,for metal conduits with temperature-dependent elastoplastic behavior.The primary objective of the proposed method is to prevent crack propagation during pressure surges from operational to critical levels.This study examines the“Beineu-Bozoy-Shymkent”steel gas conduit,examining its performance across a temperature range of−40 to+50℃.This work builds on prior research on extended avalanche destruction in steel gas conduits and crack propagation prevention techniques.Theanalysis was conducted using a dynamic finite-element approach with the ANSYS-19.2/ExplicitDynamics software.Simulations of unprotected conduits revealed that increasing gas-dynamic pressure can convert a partial-depth crack into a through-crack,extending longitudinally to approximately seven times its initial length.Notably,at T=+50℃,the developed crack length was 1.2%longer than that at T=−40℃,highlighting the temperature sensitivity of crack progression.The modeling results indicate that crack propagation can be effectively controlled using a circular composite overlay with a thickness between 37.5%and 50%of the crack depth and a length approximately five times that of the initial crack,centered symmetrically over the crack.In addition,preliminary stress analysis indicated that limiting the overlay-induced pressure to 5%of the operational pressure effectively arrested crack growth without generating significant stress concentrations near the overlay boundaries,thereby preventing conduit integrity.
基金funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan(Grant No.AP19680589).
文摘This research extends ongoing efforts to develop methods for reinforcing damaged main gas pipelines to prevent catastrophic failure.This study establishes the use of scaled-down experimental models for assessing the dynamic strength of damaged pipeline sections reinforced with wire wrapping or composite sleeves.A generalized dynamic model is introduced for numerical simulation to evaluate the effectiveness of reinforcement techniques.The model incorporates the elastoplastic behavior of pipe and wire materials,the influence of temperature on mechanical properties,the contact interaction between the pipe and the reinforcement components(including pretensioning),and local material failure under transient internal pressure.Based on these parameters,a finite element model was developed using ANSYS 19.2 to enable parametric studies.The accuracy of the proposed model was verified by comparing the simulation results with the experimental findings.Pipeline section samples containing non-penetrating longitudinal crackswere subjected to comparative analyses and transient pressure until critical failure.The unreinforced and steel wire-wrapped sections were investigated.The results confirm the feasibility of applying the computational model to study the dynamic strength of reinforced damaged pipe sections.Furthermore,pipelines with longitudinal cracks reinforced using circular composite overlays with orthotropic mechanical properties were examined,and recommendations are provided for selecting the geometric parameters of such overlays.
