Backfill is often employed in mining operations for ground support,with its positive impact on ground stability acknowledged in many underground mines.However,existing studies have predominantly focused only on the st...Backfill is often employed in mining operations for ground support,with its positive impact on ground stability acknowledged in many underground mines.However,existing studies have predominantly focused only on the stress development within the backfill material,leaving the influence of stope backfilling on stress distribution in surrounding rock mass and ground stability largely unexplored.Therefore,this paper presents numerical models in FLAC3D to investigate,for the first time,the time-dependent stress redistribution around a vertical backfilled stope and its implications on ground stability,considering the creep of surrounding rock mass.Using the Soft Soil constitutive model,the compressibility of backfill under large pressure was captured.It is found that the creep deformation of rock mass exercises compression on backfill and results in a less void ratio and increased modulus for fill material.The compacted backfill conversely influenced the stress distribution and ground stability of rock mass which was a combined effect of wall creep and compressibility of backfill.With the increase of time or/and creep deformation,the minimum principal stress in the rocks surrounding the backfilled stope increased towards the pre-mining stress state,while the deviatoric stress reduces leading to an increased factor of safety and improved ground stability.This improvement effect of backfill on ground stability increased with the increase of mine depth and stope height,while it is also more pronounced for the narrow stope,the backfill with a smaller compression index,and the soft rocks with a smaller viscosity coefficient.Furthermore,the results emphasize the importance of minimizing empty time and backfilling extracted stope as soon as possible for ground control.Reduction of filling gap height enhances the local stability around the roof of stope.展开更多
The pursuit of Ag-based alloys with both high strength and toughness has posed a longstanding chal-lenge.In this study,we investigated the cluster strengthening and grain refinement toughening mecha-nisms in fully oxi...The pursuit of Ag-based alloys with both high strength and toughness has posed a longstanding chal-lenge.In this study,we investigated the cluster strengthening and grain refinement toughening mecha-nisms in fully oxidized AgMgNi alloys,which were internally oxidized at 800℃ for 8 h under an oxy-gen atmosphere.We found that Mg-O clusters contributed to the hardening(138 HV)and strengthening(376.9 MPa)of the AgMg alloy through solid solution strengthening effects,albeit at the expense of duc-tility.To address this limitation,we introduced Ni nanoparticles into the AgMg alloy,resulting in signifi-cant grain refinement within its microstructure.Specifically,the grain size decreased from 67.2μm in the oxidized AgMg alloy to below 6.0μm in the oxidized AgMgNi alloy containing 0.3 wt%Ni.Consequently,the toughness increased significantly,rising from toughness value of 2177.9 MJ m^(-3) in the oxidized AgMg alloy to 6186.1 MJ m^(-3) in the oxidized AgMgNi alloy,representing a remarkable 2.8-fold enhancement.Furthermore,the internally oxidized AgMgNi alloy attained a strength of up to 387.6 MPa,comparable to that of the internally oxidized AgMg alloy,thereby demonstrating the successful realization of concurrent strengthening and toughening.These results collectively offer a novel approach for the design of high-performance alloys through the synergistic combination of cluster strengthening and grain refinement toughening.展开更多
BACKGROUND In recent years,the global prevalence of gastric cancer(GC)has witnessed a progressive decrease,accompanied by a step-growth in the incidence of gastric signet ring cell carcinoma(GSRCC).As precision medici...BACKGROUND In recent years,the global prevalence of gastric cancer(GC)has witnessed a progressive decrease,accompanied by a step-growth in the incidence of gastric signet ring cell carcinoma(GSRCC).As precision medicine concepts progress,GSRCC,a distinct sub-type of GC,has drawn considerable attention from researchers.However,there still persist some controversies regarding the associated research findings.AIM To summarize the current obstacles and potential future directions for research on GSRCC.METHODS To begin with,all literature related to GSRCC published from January 1,2004 to December 31,2023 was subjected to bibliometric analysis in this article.Additionally,this paper analyzed the research data using CiteSpace,GraphPad Prism v8.0.2,and VOSviewer,which was obtained from the Web of Science Core Collection database.The analysis results were visually represented.RESULTS This study provided a comprehensive overview of the statistical characteristics of the 995 English articles related to GSRCC,including cited references,authors,journals,countries,institutions,and keywords.The popular keywords and clusters contain"prognosis","survival","expression","histology",and"chemotherapy".CONCLUSION The prognosis,precise definition and classification,as well as chemoresistance of GSRCC,continue to be crucial areas of ongoing research,whose directions are closely tied to advancements in molecular biology research on GSRCC.展开更多
Hydrogen evolution reaction (HER) from water electrolysis is an ideal alternative solution to address the energy crisis and develop clean energy. However, the construction of an efficient electrocatalyst with multiple...Hydrogen evolution reaction (HER) from water electrolysis is an ideal alternative solution to address the energy crisis and develop clean energy. However, the construction of an efficient electrocatalyst with multiple active sites that can ensure high metal utilization and promote reaction kinetics simultaneously still leaves a major challenge. Herein, we present a facile strategy to synthesize a HER catalyst comprising Pt single atoms (PtSA) anchored in Fe vacancies and Pt quantum dots (Pt_(QD)) on the surface of NiFe LDH. Benefitting from the hierarchical and ultrathin nanosheet arrays and strong electronic interaction between PtSA/Pt_(QD) and NiFe LDH matrix, the optimized sample (Pt_(SA/QD)-NiFe_(V9) LDH) exhibits outstanding HER performance in 1 M KOH with ultra-low overpotentials of 20 and 67 mV at 10 and 100 mA cm^(−2), respectively, outperforming the benchmark Pt/C electrocatalyst. In addition, the electrolyzer using Pt_(SA/QD)-NiFe_(V9) LDH as a cathode requires voltages of only 1.48 and 1.73 V to yield current densities of 10 and 1000 mA cm^(−2), respectively. The combination of in situ tests and density functional theory (DFT) calculations reveal that the synergy of PtSA and Pt_(QD) can optimize the kinetics of water dissociation and hydrogen desorption, thus the Volmer-Tafel pathway prevailing the HER process. This work provides a promising surface engineering strategy to develop catalysts for efficient and robust hydrogen evolution.展开更多
BACKGROUND Immunotherapy has surfaced as a promising therapeutic modality for gastric cancer(GC).A comprehensive review of advancements,current status,and research trends in GC immunotherapy is essential to inform fut...BACKGROUND Immunotherapy has surfaced as a promising therapeutic modality for gastric cancer(GC).A comprehensive review of advancements,current status,and research trends in GC immunotherapy is essential to inform future investigative efforts.AIM To delineate the trends,advancements,and focal points in immunotherapy for GC.METHODS We performed a bibliometric analysis of 2906 articles in English concerning GC immunotherapy published from 2000 to December 20,2023,indexed in the Web of Science Core Collection.Data analysis and visualization were facilitated by CiteSpace(6.1.6R),VOSviewer v.1.6.17,and GraphPad Prism v8.0.2.RESULTS There has been an increase in the annual publication rate of GC immunotherapy research.China leads in publication volume,while the United States demonstrates the highest citation impact.Fudan University is notable for its citation frequency and publication output.Co-citation analysis and keyword frequency revealed and highlighted a focus on GC prognosis,the tumor microenvironment(TME),and integrative immunotherapy with targeted therapy.Emerging research areas include gastroesophageal junction cancer,adoptive immunotherapy,and the role of Treg cell in immunotherapy.CONCLUSION GC immunotherapy research is an expanding field attracting considerable scientific interest.With the clinical adoption of immunotherapy in GC,the primary goals are to enhance treatment efficacy and patient outcomes.Unlike hematological malignancies,GC's solid TME presents distinct immunological challenges that may attenuate the cytotoxic effects of immune cells on cancer cells.For instance,although CAR-T therapy is effective in hematological malignancies,it has underperformed in GC settings.Current research is centered on overcoming immunosuppression within the TME,with a focus on combinations of targeted therapy,adoptive immunotherapy,Treg cell dynamics,and precise prognosis prediction in immunotherapy.Additionally,immunotherapy's role in treating gastroesophageal junction cancer has become a novel research focus.展开更多
When discharge faults occur in dry air switchgear,the air decomposes to produce diverse gases,with NO_(2) reaching the highest levels.Detecting the NO_(2) level can reflect the operation status of the equipment.This p...When discharge faults occur in dry air switchgear,the air decomposes to produce diverse gases,with NO_(2) reaching the highest levels.Detecting the NO_(2) level can reflect the operation status of the equipment.This paper proposes to combine ZnO cluster with MoS_(2) to improve the gassensitive properties of the monolayer.Based on the Density Functional Theory(DFT),the effect of(ZnO)n size on the behavior of MoS_(2 )is considered.Key parameters such as adsorption energy and band gap of(ZnO)n-MoS_(2)/NO_(2) system were calculated.The ZnO-MoS_(2) heterojunction was successfully synthesized by a hydrothermal method.The gas sensor exhibits a remarkable response and a fast response-recovery time to 100 ppm NO_(2).In addition,it demonstrates excellent selectivity,long-term stability and a low detection limit.This work confirms the potential of the ZnO-MoS_(2) composite structure as a highly effective gas sensor for NO_(2) detection,which provides valuable theoretical and experimental insights for fault detection in dry air switchgear.展开更多
Metal-support interaction(MSI)is regarded as an indispensable manner to stabilize active metals and modulate catalytic activity,which shows great potentials in developing of efficient hydrogen evolution reaction(HER)e...Metal-support interaction(MSI)is regarded as an indispensable manner to stabilize active metals and modulate catalytic activity,which shows great potentials in developing of efficient hydrogen evolution reaction(HER)electrode with high activity and strong robustness.Herein,this work presents a novel heterostructure with ultrafine platinum quantum dots(Pt QDs)on defective catalytic supports derived from metal-organic frameworks(MOFs).It is indicated substantial oxygen vacancies can be generated and Pt–Pt bonds can be optimized through topological transformation.The resulting Pt/T-NiFe-BDC(BDC:C8H6O4)exhibits competitive HER activity in alkaline seawater,attaining ultralow overpotentials of 158 and 266 mV at 500 and 1000 mA cm^(-2)with fast kinetics and outstanding stability.An asymmetric water electrolyzer using Pt/T-NiFe-BDC as a cathode only requires a voltage of 1.89 V to generate an industrial density of 1000 mA cm^(-2)and shows no attenuation in 500-h continuous test at 500 mA cm^(-2).Theoretical calculations and in-situ spectroscopic analysis reveal the reversible hydrogen spillover mechanism,in which oxygen vacancies facilitate the sluggish water dissociation and Pt QDs promote the H^(*)combination.This study provides a new paradigm to engineer metal-supported catalysts for efficient and robust seawater splitting.展开更多
The Yellow River(YR),China’s second-longest river,remains understudied regarding its greenhouse gases(GHGs)emissions,particularly the impacts of urban drainage ditches and wastewater treatment facilities on regional ...The Yellow River(YR),China’s second-longest river,remains understudied regarding its greenhouse gases(GHGs)emissions,particularly the impacts of urban drainage ditches and wastewater treatment facilities on regional GHGs dynamics.This study investigated methane(CH_(4))and carbon dioxide(CO_(2))concentrations,fluxes and stable carbon isotopes(δ^(13)C-CH_(4)and δ^(13)C-CO_(2))across six main stream,three ditches,and one wastewater treatment site along the upper Lanzhou section of the YR,spanning from the urban entrance(36.176°N,103.449°E)to the exit of Lanzhou city(36.056°N,104.020°E).Measured CH_(4)diffusion fluxes in mainstem sites ranged from 0.01 to 2.58 mmol·m^(−2)·d^(−1)(mean:0.36 mmol·m^(−2)·d^(−1)),while ebullitive fluxes(gas bubbles)ranged from 0.01 to 18.89 mmol·m^(−2)·d^(−1)(mean:0.90 mmol·m^(−2)·d^(−1)).CO_(2)diffusion fluxes varied between 9.16–92.80 mmol·m^(−2)·d^(−1)(averaged:39.11 mmol·m^(−2)·d^(−1))at these locations.Ebullition(bubble)fluxes accounted for 53.1%±22.4%(range:9.0%to 98.4%)to total CH_(4)emissions(diffusion plus ebullition),with peak fluxes occurring during summer,indicating its significance as a CH_(4)transport mechanism.Notably,both diffusion CH_(4)and CO_(2)fluxes and ebullitive CH_(4)rates at ditch sites substantially exceeded those in mainstream reaches.The lowest CH_(4)and highest CO_(2)concentrations were observed at a wastewater treatment site,likely resulting from the removal of high organic loads.Acetoclastic methanogenesis—the process converting acetate-derived methyl groups to CH_(4)—was identified as the dominant production pathway in both mainstream and ditch environments.CH_(4)and CO_(2)flux magnitudes in the upper YR(Lanzhou section)were comparable to those observed in subtropical Yangtze River tributaries.These results demonstrate that anthropogenic influences significantly enhance CO_(2)/CH_(4)emissions,and the lateral exports of dissolved carbon(DIC and DOC)in the main stream site was quantified.,which cannot be overlooked.The findings emphasize the critical need to account for pronounced spatiotemporal variations in arid-region GHG fluxes to improve basin-scale estimates for the YR.展开更多
The reasonable development and design of high-efficiency and low-cost electrocatalysts for hydrogen evolution reaction(HER)under industrial current densities are imperative for achieving carbon neutrality,while also p...The reasonable development and design of high-efficiency and low-cost electrocatalysts for hydrogen evolution reaction(HER)under industrial current densities are imperative for achieving carbon neutrality,while also posing challenges.In this study,an efficient electrocatalyst is successfully constructed through electrodeposition methods,which consists of monodispersed Pt loaded on amorphous/crystalline nickel–iron layered double hydroxide(Pt-SAs/ac-NiFe LDH).The Pt-SAs/ac-NiFe LDH demonstrates an elevated mass activity of 17.66 A mg_(Pt)^(−1)and a significant turnover frequency of 17.90 s^(−1)for HER in alkaline conditions under the overpotential of 100 mV.Meanwhile,for alkaline freshwater and seawater,Pt-SAs/ac-NiFe LDH exhibits ultra-low overpotentials of 141 and 138 mV to reach 1000 mA cm^(−2),respectively.Remarkably,it maintains stable operation for 100 h at 500 mA cm^(−2),showcasing its robustness and reliability.In situ Raman spectra reveal that Pt single atoms(Pt-SAs)accelerate interfacial water dissociation,thereby enhancing the HER kinetics in Pt-SAs/ac-NiFe LDH.Furthermore,theoretical calculation results show significant electronic interaction between the Pt-SAs and the ac-NiFe LDH support.The interaction significantly enhances water adsorption and dissociation,and balances the adsorption/desorption of hydrogen intermediates,ultimately improving HER performance.This research provides a viable method for designing efficient HER catalysts for water electrolysis in alkaline freshwater and seawater under industrial current densities.展开更多
基金the funding support from the National Natural Science Foundation of China(Grant Nos.52304101 and 52004206)the China Postdoctoral Science Foundation(Grant No.2023MD734215)。
文摘Backfill is often employed in mining operations for ground support,with its positive impact on ground stability acknowledged in many underground mines.However,existing studies have predominantly focused only on the stress development within the backfill material,leaving the influence of stope backfilling on stress distribution in surrounding rock mass and ground stability largely unexplored.Therefore,this paper presents numerical models in FLAC3D to investigate,for the first time,the time-dependent stress redistribution around a vertical backfilled stope and its implications on ground stability,considering the creep of surrounding rock mass.Using the Soft Soil constitutive model,the compressibility of backfill under large pressure was captured.It is found that the creep deformation of rock mass exercises compression on backfill and results in a less void ratio and increased modulus for fill material.The compacted backfill conversely influenced the stress distribution and ground stability of rock mass which was a combined effect of wall creep and compressibility of backfill.With the increase of time or/and creep deformation,the minimum principal stress in the rocks surrounding the backfilled stope increased towards the pre-mining stress state,while the deviatoric stress reduces leading to an increased factor of safety and improved ground stability.This improvement effect of backfill on ground stability increased with the increase of mine depth and stope height,while it is also more pronounced for the narrow stope,the backfill with a smaller compression index,and the soft rocks with a smaller viscosity coefficient.Furthermore,the results emphasize the importance of minimizing empty time and backfilling extracted stope as soon as possible for ground control.Reduction of filling gap height enhances the local stability around the roof of stope.
基金supported by the National Natural Science Foundation of China(Nos.51977027 and 51967008)the Scientific and Technological Project of Yunnan Precious Metals Lab-oratory(Nos.YPML-2023050250 and YPML-2022050206).
文摘The pursuit of Ag-based alloys with both high strength and toughness has posed a longstanding chal-lenge.In this study,we investigated the cluster strengthening and grain refinement toughening mecha-nisms in fully oxidized AgMgNi alloys,which were internally oxidized at 800℃ for 8 h under an oxy-gen atmosphere.We found that Mg-O clusters contributed to the hardening(138 HV)and strengthening(376.9 MPa)of the AgMg alloy through solid solution strengthening effects,albeit at the expense of duc-tility.To address this limitation,we introduced Ni nanoparticles into the AgMg alloy,resulting in signifi-cant grain refinement within its microstructure.Specifically,the grain size decreased from 67.2μm in the oxidized AgMg alloy to below 6.0μm in the oxidized AgMgNi alloy containing 0.3 wt%Ni.Consequently,the toughness increased significantly,rising from toughness value of 2177.9 MJ m^(-3) in the oxidized AgMg alloy to 6186.1 MJ m^(-3) in the oxidized AgMgNi alloy,representing a remarkable 2.8-fold enhancement.Furthermore,the internally oxidized AgMgNi alloy attained a strength of up to 387.6 MPa,comparable to that of the internally oxidized AgMg alloy,thereby demonstrating the successful realization of concurrent strengthening and toughening.These results collectively offer a novel approach for the design of high-performance alloys through the synergistic combination of cluster strengthening and grain refinement toughening.
基金Supported by National Natural Science Foundation of China,No.82073192,and No.82273231Beijing Science and Technology Program,No.Z221100007422125.
文摘BACKGROUND In recent years,the global prevalence of gastric cancer(GC)has witnessed a progressive decrease,accompanied by a step-growth in the incidence of gastric signet ring cell carcinoma(GSRCC).As precision medicine concepts progress,GSRCC,a distinct sub-type of GC,has drawn considerable attention from researchers.However,there still persist some controversies regarding the associated research findings.AIM To summarize the current obstacles and potential future directions for research on GSRCC.METHODS To begin with,all literature related to GSRCC published from January 1,2004 to December 31,2023 was subjected to bibliometric analysis in this article.Additionally,this paper analyzed the research data using CiteSpace,GraphPad Prism v8.0.2,and VOSviewer,which was obtained from the Web of Science Core Collection database.The analysis results were visually represented.RESULTS This study provided a comprehensive overview of the statistical characteristics of the 995 English articles related to GSRCC,including cited references,authors,journals,countries,institutions,and keywords.The popular keywords and clusters contain"prognosis","survival","expression","histology",and"chemotherapy".CONCLUSION The prognosis,precise definition and classification,as well as chemoresistance of GSRCC,continue to be crucial areas of ongoing research,whose directions are closely tied to advancements in molecular biology research on GSRCC.
基金funded by the National Key Research and Development Program of China(No.2022YFB3803600)the National Natural Science Foundation of China(Nos.22368050,22378346)+4 种基金the Key Research and Development Program of Yunnan Province(No.202302AF080002)the Yunnan Basic Applied Research Project(Nos.202401AU070229,202401AT070460)the Scientific Research Fund Project of Yunnan Education Department(Nos.2024J0013,2024J0014)the Open Project of Yunnan Precious Metals Labo-ratory Co.,Ltd(Nos.YPML-2023050259,YPML-2023050260).Au-thors thank the Shiyanjia Lab(www.shiyanjia.com)the Electron Microscopy Center,the Advanced Computing Center,and the Ad-vanced Analysis and Measurement Center of Yunnan University for the sample testing and computational services.
文摘Hydrogen evolution reaction (HER) from water electrolysis is an ideal alternative solution to address the energy crisis and develop clean energy. However, the construction of an efficient electrocatalyst with multiple active sites that can ensure high metal utilization and promote reaction kinetics simultaneously still leaves a major challenge. Herein, we present a facile strategy to synthesize a HER catalyst comprising Pt single atoms (PtSA) anchored in Fe vacancies and Pt quantum dots (Pt_(QD)) on the surface of NiFe LDH. Benefitting from the hierarchical and ultrathin nanosheet arrays and strong electronic interaction between PtSA/Pt_(QD) and NiFe LDH matrix, the optimized sample (Pt_(SA/QD)-NiFe_(V9) LDH) exhibits outstanding HER performance in 1 M KOH with ultra-low overpotentials of 20 and 67 mV at 10 and 100 mA cm^(−2), respectively, outperforming the benchmark Pt/C electrocatalyst. In addition, the electrolyzer using Pt_(SA/QD)-NiFe_(V9) LDH as a cathode requires voltages of only 1.48 and 1.73 V to yield current densities of 10 and 1000 mA cm^(−2), respectively. The combination of in situ tests and density functional theory (DFT) calculations reveal that the synergy of PtSA and Pt_(QD) can optimize the kinetics of water dissociation and hydrogen desorption, thus the Volmer-Tafel pathway prevailing the HER process. This work provides a promising surface engineering strategy to develop catalysts for efficient and robust hydrogen evolution.
基金National Natural Science Foundation of China,No.82073192 and No.82273231Beijing Science and Technology Program,No.Z221100007422125The Chinese People's Liberation Army General Hospital Medical Engineering Laboratory Project,No.2022SYSZZKY16.
文摘BACKGROUND Immunotherapy has surfaced as a promising therapeutic modality for gastric cancer(GC).A comprehensive review of advancements,current status,and research trends in GC immunotherapy is essential to inform future investigative efforts.AIM To delineate the trends,advancements,and focal points in immunotherapy for GC.METHODS We performed a bibliometric analysis of 2906 articles in English concerning GC immunotherapy published from 2000 to December 20,2023,indexed in the Web of Science Core Collection.Data analysis and visualization were facilitated by CiteSpace(6.1.6R),VOSviewer v.1.6.17,and GraphPad Prism v8.0.2.RESULTS There has been an increase in the annual publication rate of GC immunotherapy research.China leads in publication volume,while the United States demonstrates the highest citation impact.Fudan University is notable for its citation frequency and publication output.Co-citation analysis and keyword frequency revealed and highlighted a focus on GC prognosis,the tumor microenvironment(TME),and integrative immunotherapy with targeted therapy.Emerging research areas include gastroesophageal junction cancer,adoptive immunotherapy,and the role of Treg cell in immunotherapy.CONCLUSION GC immunotherapy research is an expanding field attracting considerable scientific interest.With the clinical adoption of immunotherapy in GC,the primary goals are to enhance treatment efficacy and patient outcomes.Unlike hematological malignancies,GC's solid TME presents distinct immunological challenges that may attenuate the cytotoxic effects of immune cells on cancer cells.For instance,although CAR-T therapy is effective in hematological malignancies,it has underperformed in GC settings.Current research is centered on overcoming immunosuppression within the TME,with a focus on combinations of targeted therapy,adoptive immunotherapy,Treg cell dynamics,and precise prognosis prediction in immunotherapy.Additionally,immunotherapy's role in treating gastroesophageal junction cancer has become a novel research focus.
基金the financial support of National Natural Science Foundation of China(Nos.52207175 and 52407178)。
文摘When discharge faults occur in dry air switchgear,the air decomposes to produce diverse gases,with NO_(2) reaching the highest levels.Detecting the NO_(2) level can reflect the operation status of the equipment.This paper proposes to combine ZnO cluster with MoS_(2) to improve the gassensitive properties of the monolayer.Based on the Density Functional Theory(DFT),the effect of(ZnO)n size on the behavior of MoS_(2 )is considered.Key parameters such as adsorption energy and band gap of(ZnO)n-MoS_(2)/NO_(2) system were calculated.The ZnO-MoS_(2) heterojunction was successfully synthesized by a hydrothermal method.The gas sensor exhibits a remarkable response and a fast response-recovery time to 100 ppm NO_(2).In addition,it demonstrates excellent selectivity,long-term stability and a low detection limit.This work confirms the potential of the ZnO-MoS_(2) composite structure as a highly effective gas sensor for NO_(2) detection,which provides valuable theoretical and experimental insights for fault detection in dry air switchgear.
文摘Metal-support interaction(MSI)is regarded as an indispensable manner to stabilize active metals and modulate catalytic activity,which shows great potentials in developing of efficient hydrogen evolution reaction(HER)electrode with high activity and strong robustness.Herein,this work presents a novel heterostructure with ultrafine platinum quantum dots(Pt QDs)on defective catalytic supports derived from metal-organic frameworks(MOFs).It is indicated substantial oxygen vacancies can be generated and Pt–Pt bonds can be optimized through topological transformation.The resulting Pt/T-NiFe-BDC(BDC:C8H6O4)exhibits competitive HER activity in alkaline seawater,attaining ultralow overpotentials of 158 and 266 mV at 500 and 1000 mA cm^(-2)with fast kinetics and outstanding stability.An asymmetric water electrolyzer using Pt/T-NiFe-BDC as a cathode only requires a voltage of 1.89 V to generate an industrial density of 1000 mA cm^(-2)and shows no attenuation in 500-h continuous test at 500 mA cm^(-2).Theoretical calculations and in-situ spectroscopic analysis reveal the reversible hydrogen spillover mechanism,in which oxygen vacancies facilitate the sluggish water dissociation and Pt QDs promote the H^(*)combination.This study provides a new paradigm to engineer metal-supported catalysts for efficient and robust seawater splitting.
基金funded by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0950000)the NSFC(Grant No.42201155+2 种基金4240114742201137)the State Key Laboratory of Cryospheric Science and Frozen Soil Engineering(CSFSE-ZQ-2410).
文摘The Yellow River(YR),China’s second-longest river,remains understudied regarding its greenhouse gases(GHGs)emissions,particularly the impacts of urban drainage ditches and wastewater treatment facilities on regional GHGs dynamics.This study investigated methane(CH_(4))and carbon dioxide(CO_(2))concentrations,fluxes and stable carbon isotopes(δ^(13)C-CH_(4)and δ^(13)C-CO_(2))across six main stream,three ditches,and one wastewater treatment site along the upper Lanzhou section of the YR,spanning from the urban entrance(36.176°N,103.449°E)to the exit of Lanzhou city(36.056°N,104.020°E).Measured CH_(4)diffusion fluxes in mainstem sites ranged from 0.01 to 2.58 mmol·m^(−2)·d^(−1)(mean:0.36 mmol·m^(−2)·d^(−1)),while ebullitive fluxes(gas bubbles)ranged from 0.01 to 18.89 mmol·m^(−2)·d^(−1)(mean:0.90 mmol·m^(−2)·d^(−1)).CO_(2)diffusion fluxes varied between 9.16–92.80 mmol·m^(−2)·d^(−1)(averaged:39.11 mmol·m^(−2)·d^(−1))at these locations.Ebullition(bubble)fluxes accounted for 53.1%±22.4%(range:9.0%to 98.4%)to total CH_(4)emissions(diffusion plus ebullition),with peak fluxes occurring during summer,indicating its significance as a CH_(4)transport mechanism.Notably,both diffusion CH_(4)and CO_(2)fluxes and ebullitive CH_(4)rates at ditch sites substantially exceeded those in mainstream reaches.The lowest CH_(4)and highest CO_(2)concentrations were observed at a wastewater treatment site,likely resulting from the removal of high organic loads.Acetoclastic methanogenesis—the process converting acetate-derived methyl groups to CH_(4)—was identified as the dominant production pathway in both mainstream and ditch environments.CH_(4)and CO_(2)flux magnitudes in the upper YR(Lanzhou section)were comparable to those observed in subtropical Yangtze River tributaries.These results demonstrate that anthropogenic influences significantly enhance CO_(2)/CH_(4)emissions,and the lateral exports of dissolved carbon(DIC and DOC)in the main stream site was quantified.,which cannot be overlooked.The findings emphasize the critical need to account for pronounced spatiotemporal variations in arid-region GHG fluxes to improve basin-scale estimates for the YR.
基金funded by the National Key Research and Development Program of China(2022YFB3803600)the National Natural Science Foundation of China(22368050,22378346)+4 种基金the Key Research and Development Program of Yunnan Province(202302AF080002)Yunnan Basic Applied Research Project(202401AT070460,202401AU070229)Xingdian Talent Support Program Project in Yunnan Province,the Scientific Research Fund Project of Yunnan Education Department(2024J0014,2024J0013)the Open Project of Yunnan Precious Metals Laboratory Co.,Ltd(YPML-2023050259,YPML-2023050260,YPML-20240502008)the Scientific Research and Innovation Project of Postgraduate Students in the Academic Degree of Yunnan University.
文摘The reasonable development and design of high-efficiency and low-cost electrocatalysts for hydrogen evolution reaction(HER)under industrial current densities are imperative for achieving carbon neutrality,while also posing challenges.In this study,an efficient electrocatalyst is successfully constructed through electrodeposition methods,which consists of monodispersed Pt loaded on amorphous/crystalline nickel–iron layered double hydroxide(Pt-SAs/ac-NiFe LDH).The Pt-SAs/ac-NiFe LDH demonstrates an elevated mass activity of 17.66 A mg_(Pt)^(−1)and a significant turnover frequency of 17.90 s^(−1)for HER in alkaline conditions under the overpotential of 100 mV.Meanwhile,for alkaline freshwater and seawater,Pt-SAs/ac-NiFe LDH exhibits ultra-low overpotentials of 141 and 138 mV to reach 1000 mA cm^(−2),respectively.Remarkably,it maintains stable operation for 100 h at 500 mA cm^(−2),showcasing its robustness and reliability.In situ Raman spectra reveal that Pt single atoms(Pt-SAs)accelerate interfacial water dissociation,thereby enhancing the HER kinetics in Pt-SAs/ac-NiFe LDH.Furthermore,theoretical calculation results show significant electronic interaction between the Pt-SAs and the ac-NiFe LDH support.The interaction significantly enhances water adsorption and dissociation,and balances the adsorption/desorption of hydrogen intermediates,ultimately improving HER performance.This research provides a viable method for designing efficient HER catalysts for water electrolysis in alkaline freshwater and seawater under industrial current densities.
