The pursuit of an efficient photocatalytic pathway for hydrogen peroxide(H2O2)synthesis from pure water without adding additional sacrifice agents poses a formidable research endeavor and remains a pivotal chall...The pursuit of an efficient photocatalytic pathway for hydrogen peroxide(H2O2)synthesis from pure water without adding additional sacrifice agents poses a formidable research endeavor and remains a pivotal challenge.Herein,we demonstrate that incorporating hexaketocyclohexane-derived carbon dots(H-CDs)and S vacancies into ZnIn2S4 weakens the exciton effect,leading to the dissociation into free carriers that participate in the dual pathways of oxygen reduction reaction and water oxidation reaction,thereby achieving efficient photocatalytic H2O2 production with a high H2O2 yield of 17.8 mM/g/h under visible light in pure water.Experimental results combined with theoretical calculations clearly illustrate that the presence of H-CDs and S vacancies modulates the local charge density of ZnIn2S4,markedly diminishing the exciton binding energy and facilitating the occurrence of exciton dissociation.Moreover,S vacancies and H-CDs effectively capture free electrons and extract free holes,respectively,significantly inhibiting the recombination of photogenerated electron-hole pairs.By optimizing the electronic structure and optical properties of ZnIn2S4,they thermodynamically satisfy the conditions for oxygen reduction and water oxidation reactions.Additionally,the synergy between H-CDs and S vacancies in ZnIn2S4 enhances the adsorption of oxygen and intermediate products,increasing their participation in the reaction and facilitating the conversion to H2O2.This work offers novel insights into catalyst design from the perspective of excitons dissociation,and underscores the distinct roles that free charge carriers play in various pathways for photocatalytic H2O2 production.展开更多
The synergistic coupling of photocatalytic hydrogen peroxide(H2O2)production and green organic synthesis not only optimizes utilization of photogenerated electron-hole pairs but also circumvents kinetically slug...The synergistic coupling of photocatalytic hydrogen peroxide(H2O2)production and green organic synthesis not only optimizes utilization of photogenerated electron-hole pairs but also circumvents kinetically sluggish water oxidation reaction.In this study,an efficient composite photocatalyst was developed through in-situ growth of irregular TpPa-Cl blocks on the surface of boron-doped TiO2,which boasts a large specific surface area.Boron doping enhances light absorption range and inhibits recombination of charge carriers.Additionally,deep integration of porous TiO2 with TpPa-Cl improves the contact between the reactants and the photocatalyst,extends the carrier lifetime,and provides more active sites.In the absence of a co-catalyst,the yield of H2O2 reached 2082.6μmol g-1 h-1,with a furfuryl alcohol conversion rate of 94%.In-situ XPS and density functional theory calculations confirmed S-scheme charge transfer mechanism,which enhances carrier separation and transfer efficiency while retaining photogenerated electrons and holes with strong redox properties.Quenching experiments,electron paramagnetic resonance,and in-situ diffuse reflectance infrared Fourier transformed spectroscopy demonstrated that H2O2 was primarily generated via a 2-electron oxygen reduction reaction with·O2-and OOH*as intermediates.Furthermore,furfuryl alcohol was oxidized to the radical·C5H5O2 by h+and subsequently converted to furfural or furoic acid through reactions with h+or·OH.This work presents a novel strategy for designing efficient composite photocatalysts for H2O2 production and green organic synthesis.展开更多
水系锌离子电池中,VOPO4·2H2O正极材料在充放电循环过程中易受电解液中自由水的侵蚀而发生溶解,导致严重的电压衰减和容量损失。高浓度双三氟甲磺酰亚胺锂(LiTFSI)虽可通过其丰富的磺酰基氧原子作为氢键受体有效降低自由水含...水系锌离子电池中,VOPO4·2H2O正极材料在充放电循环过程中易受电解液中自由水的侵蚀而发生溶解,导致严重的电压衰减和容量损失。高浓度双三氟甲磺酰亚胺锂(LiTFSI)虽可通过其丰富的磺酰基氧原子作为氢键受体有效降低自由水含量,从而抑制正极材料溶解,但其成本高昂且黏度过大,限制了实际应用。针对该问题,本研究提出一种三氟甲磺酸锌(Zn(OTf)2)电解液协同替代策略,采用低成本果糖(Fru)部分替代高浓度LiTFSI,在保持氢键受体总数相近的前提下,显著降低电解液黏度和成本,同时优化Zn2+传输动力学,成功构建了4.5 m Zn(OTf)2+11 m Fru+8.5 m LiTFSI(m表示mol/kg水)优化电解液体系,并将其与4 m Zn(OTf)2及1 m Zn(OTf)2+18 m LiTFSI电解液进行系统对比。XRD、SEM-EDS、TEM表征结果表明,VOPO4·2H2O粉末结晶性良好,呈明显片层堆积结构。浸泡实验显示,VOPO4·2H2O粉末在4 m Zn(OTf)2电解液中仅10 min即发生明显溶解,而在含LiTFSI的两种电解液中浸泡10 d后仍未发生显著溶解。电化学测试结果表明,优化电解液显著提升了VOPO4·2H2O正极的循环稳定性和倍率性能,在1 C倍率下循环150次后容量保持率达95%,优于对比体系。动力学分析进一步揭示,优化电解液有效降低了电荷转移电阻,并显著提升了Zn2+扩散系数。拉曼光谱分析证实,优化电解液中,果糖分子凭借其五个羟基的灵活构型,与LiTFSI上丰富的氢键位点协同作用,与水分子形成致密氢键网络,显著降低自由水含量,从而抑制了VOPO4·2H2O的溶解及不可逆相变。本研究通过低成本、环境友好的电解液设计策略,解决了高浓度LiTFSI电解液体系的高黏度与高成本难题,为水系锌离子电池中VOPO4·2H2O正极材料的结构稳定化提供了有效途径,展现出良好的应用潜力。展开更多
This study develops a two-dimensional fluid model for atmospheric pressure non-equilibrium CO2-H2O plasma needle-plate configuration,incorporating a comprehensive set of plasma chemical reactions and photoioniza...This study develops a two-dimensional fluid model for atmospheric pressure non-equilibrium CO2-H2O plasma needle-plate configuration,incorporating a comprehensive set of plasma chemical reactions and photoionization effects.It focuses on investigating the influence of the CO2/H2O concentration ratio and quenching pressure on plasma streamer initiation and propagation dynamics.Numerical simulations show that increasing initial water vapor content significantly reduces electron energy and density,causing the discharge channel to contract when the reduced electric field is below 200 Td,due to strong dissociative adsorption reactions between electrons and water molecules.At higher reduced electric fields(above 200 Td),variations in water vapor content have minimal impact on primary electron transport parameters,likely because dissociative and ionizing collisions between electrons and CO2/H2O molecules become dominant.Increasing the quenching pressure enhances photoionization,but plasma discharge remains primarily sustained by direct electron-impact ionization.Low initial water vapor content and elevated quenching pressure both accelerate streamer propagation,with the concentration ratio exerting a more significant effect.Finally,the primary reaction pathways for key products(CO,OH,and electrons)are analyzed.These findings contribute to a better understanding of how the reactant concentration ratio and quenching pressure regulate the discharge reaction mechanism in atmospheric pressure non-equilibrium CO2-H2O plasma.展开更多
Electrocatalytic CO2reduction reaction(CO2RR)has been developed as a promising and attractive strategy to close the anthropogenic carbon cycle.Among various reduction products,multi-carbon(C2+)oxygenate and h...Electrocatalytic CO2reduction reaction(CO2RR)has been developed as a promising and attractive strategy to close the anthropogenic carbon cycle.Among various reduction products,multi-carbon(C2+)oxygenate and hydrocarbon compounds are desirable value-added fuels or chemicals.Extensive researches have revealed the crucial role of local CO2and H2O concentrations(or the adsorption of *CO and *H)close to the electrode/catalyst surface in manipulating multi-carbon generation pathways.In this mini reviews,we mainly summarized the recent progress of this field over the past five years.The modulating strategies for the hydrogen and carbon species ratio can be divided into three categories,i.e.,catalyst morphology,electrolyte composition and mass transfer.The effectiveness of the aforementioned strategies in promoting multi-carbon product selectivity was discussed in detail from the perspectives of tuning the local CO2and H2O concentrations and the subsequent thermodynamic-and kinetic-controlled *CO and *H ratios.Finally,the critical challenges remaining in balancing the ratio of CO2and H2O as well as potential upgrading directions for future research are addressed.展开更多
The expandable graphite(EG)modified TiO2 nanocomposites were prepared by the high shearmethod using the TiO2 nanoparticles(NPs)and EG as precursors,in which the amount of EG doped in TiO2 was 10 wt.%.Followed...The expandable graphite(EG)modified TiO2 nanocomposites were prepared by the high shearmethod using the TiO2 nanoparticles(NPs)and EG as precursors,in which the amount of EG doped in TiO2 was 10 wt.%.Followed by the impregnation method,adjusting the pH of the solution to 10,and using the electrostatic adsorption to achieve spatial confinement,the Pt elementswere mainly distributed on the exposed TiO2,thus generating the Pt/10EG-TiO2-10 catalyst.The best CO oxidation activity with the excellent resistance to H2O and SO2 was obtained over the Pt/10EG-TiO2-10 catalyst:CO conversion after 36 hr of the reaction was ca.85%under the harsh condition of 10 vol.%H2O and 100 ppm SO2 at a high gaseous hourly space velocity(GHSV)of 400,000 hr−1.Physicochemical properties of the catalystswere characterized by various techniques.The results showed that the electrostatic adsorption,which riveted the Pt elements mainly on the exposed TiO2 of the support surface,reduced the dispersion of Pt NPs on EG and achieved the effective dispersion of Pt NPs,hence significantly improving CO oxidation activity over the Pt/10EG-TiO2-10 catalyst.The 10 wt.%EG doped in TiO2 caused the TiO2 support to form a more hydrophobic surface,which reduced the adsorption of H2O and SO2 on the catalyst,greatly inhibited deposition of the TiOSO4 and formation of the PtSO4 species as well as suppressed the oxidation of SO2,thus resulting in an improvement in the resistance to H2O and SO2 of the Pt/10EG-TiO2-10 catalyst.展开更多
Herein,we established a Zn3(OH)2(V2O7)(H2O)2/V-Zn(O,S)Z-scheme heterojunction labeled ZnVO/V-Zn(O,S)with a heterovalent V4+/V5+states and oxygen vacancies in both phases via a one-step in-situ ...Herein,we established a Zn3(OH)2(V2O7)(H2O)2/V-Zn(O,S)Z-scheme heterojunction labeled ZnVO/V-Zn(O,S)with a heterovalent V4+/V5+states and oxygen vacancies in both phases via a one-step in-situ hydrolysis method.The NaBH4 regulated the ZnVO/V-Zn(O,S)-3 with rich Vo and suitable n(V4+)(V5+)ratio achieved an excellent photocatalytic nitrogen fixation activity of 301.7μmol/(g×h)and apparent quantum efficiency of 1.148%at 420 nm without any sacrificial agent,which is 11 times than that of V-Zn(O,S).The Vo acts as the active site to trap and activate N2 molecules and to trap and activate H2O to produce the H for N2 molecules photocatalytic reduction.The rich Vo defects can also reduce the competitive adsorption of H2O and N2 molecules on the surface active site of the catalyst.The heterovalent vanadium states act as the photogenerated electrons,quickly hopping between V4+and V5+to transfer for the photocatalytic N2 reduction reaction.Additionally,the Z-scheme heterojunction effectively minimizes photogenerated carrier recombination.These synergistic effects collectively boost the photocatalytic nitrogen fixation activity.This study provides a practical method for designing Z-scheme heterojunctions for efficient photocatalytic N2 fixation under mild conditions.展开更多
低温等离子体(Low temperature plasma,LTP)可以将热力学稳定的CO2和H2O转化为高附加值产物,在CO2资源化利用和能源转化等领域有广阔前景,但是H2O的强猝灭效应使得LTP转化CO2/H2O的性能提升极具挑战。本文综述了LTP转...低温等离子体(Low temperature plasma,LTP)可以将热力学稳定的CO2和H2O转化为高附加值产物,在CO2资源化利用和能源转化等领域有广阔前景,但是H2O的强猝灭效应使得LTP转化CO2/H2O的性能提升极具挑战。本文综述了LTP转化CO2/H2O的研究进展,包括LTP转化CO2/H2O的反应动力学,以及不同LTP、催化剂、反应器对CO2/H2O转化性能的影响。通过对转化性能和反应机理分析,发现H2O对电子的强吸附效应、产物复合反应和H原子的低密度、副反应的竞争分别是抑制原料气转化率和高附加值产物选择性的关键。针对上述问题,本文从反应器优化、引入其他反应物、催化剂设计和串联催化四个方面,提出性能提升策略。最后,对LTP转化CO2/H2O的重点研究方向进行了展望。展开更多
摘要The pursuit of an efficient photocatalytic pathway for hydrogen peroxide(H2O2)synthesis from pure water without adding additional sacrifice agents poses a formidable research endeavor and remains a pivotal challenge.Herein,we demonstrate that incorporating hexaketocyclohexane-derived carbon dots(H-CDs)and S vacancies into ZnIn2S4 weakens the exciton effect,leading to the dissociation into free carriers that participate in the dual pathways of oxygen reduction reaction and water oxidation reaction,thereby achieving efficient photocatalytic H2O2 production with a high H2O2 yield of 17.8 mM/g/h under visible light in pure water.Experimental results combined with theoretical calculations clearly illustrate that the presence of H-CDs and S vacancies modulates the local charge density of ZnIn2S4,markedly diminishing the exciton binding energy and facilitating the occurrence of exciton dissociation.Moreover,S vacancies and H-CDs effectively capture free electrons and extract free holes,respectively,significantly inhibiting the recombination of photogenerated electron-hole pairs.By optimizing the electronic structure and optical properties of ZnIn2S4,they thermodynamically satisfy the conditions for oxygen reduction and water oxidation reactions.Additionally,the synergy between H-CDs and S vacancies in ZnIn2S4 enhances the adsorption of oxygen and intermediate products,increasing their participation in the reaction and facilitating the conversion to H2O2.This work offers novel insights into catalyst design from the perspective of excitons dissociation,and underscores the distinct roles that free charge carriers play in various pathways for photocatalytic H2O2 production.
摘要The synergistic coupling of photocatalytic hydrogen peroxide(H2O2)production and green organic synthesis not only optimizes utilization of photogenerated electron-hole pairs but also circumvents kinetically sluggish water oxidation reaction.In this study,an efficient composite photocatalyst was developed through in-situ growth of irregular TpPa-Cl blocks on the surface of boron-doped TiO2,which boasts a large specific surface area.Boron doping enhances light absorption range and inhibits recombination of charge carriers.Additionally,deep integration of porous TiO2 with TpPa-Cl improves the contact between the reactants and the photocatalyst,extends the carrier lifetime,and provides more active sites.In the absence of a co-catalyst,the yield of H2O2 reached 2082.6μmol g-1 h-1,with a furfuryl alcohol conversion rate of 94%.In-situ XPS and density functional theory calculations confirmed S-scheme charge transfer mechanism,which enhances carrier separation and transfer efficiency while retaining photogenerated electrons and holes with strong redox properties.Quenching experiments,electron paramagnetic resonance,and in-situ diffuse reflectance infrared Fourier transformed spectroscopy demonstrated that H2O2 was primarily generated via a 2-electron oxygen reduction reaction with·O2-and OOH*as intermediates.Furthermore,furfuryl alcohol was oxidized to the radical·C5H5O2 by h+and subsequently converted to furfural or furoic acid through reactions with h+or·OH.This work presents a novel strategy for designing efficient composite photocatalysts for H2O2 production and green organic synthesis.
摘要水系锌离子电池中,VOPO4·2H2O正极材料在充放电循环过程中易受电解液中自由水的侵蚀而发生溶解,导致严重的电压衰减和容量损失。高浓度双三氟甲磺酰亚胺锂(LiTFSI)虽可通过其丰富的磺酰基氧原子作为氢键受体有效降低自由水含量,从而抑制正极材料溶解,但其成本高昂且黏度过大,限制了实际应用。针对该问题,本研究提出一种三氟甲磺酸锌(Zn(OTf)2)电解液协同替代策略,采用低成本果糖(Fru)部分替代高浓度LiTFSI,在保持氢键受体总数相近的前提下,显著降低电解液黏度和成本,同时优化Zn2+传输动力学,成功构建了4.5 m Zn(OTf)2+11 m Fru+8.5 m LiTFSI(m表示mol/kg水)优化电解液体系,并将其与4 m Zn(OTf)2及1 m Zn(OTf)2+18 m LiTFSI电解液进行系统对比。XRD、SEM-EDS、TEM表征结果表明,VOPO4·2H2O粉末结晶性良好,呈明显片层堆积结构。浸泡实验显示,VOPO4·2H2O粉末在4 m Zn(OTf)2电解液中仅10 min即发生明显溶解,而在含LiTFSI的两种电解液中浸泡10 d后仍未发生显著溶解。电化学测试结果表明,优化电解液显著提升了VOPO4·2H2O正极的循环稳定性和倍率性能,在1 C倍率下循环150次后容量保持率达95%,优于对比体系。动力学分析进一步揭示,优化电解液有效降低了电荷转移电阻,并显著提升了Zn2+扩散系数。拉曼光谱分析证实,优化电解液中,果糖分子凭借其五个羟基的灵活构型,与LiTFSI上丰富的氢键位点协同作用,与水分子形成致密氢键网络,显著降低自由水含量,从而抑制了VOPO4·2H2O的溶解及不可逆相变。本研究通过低成本、环境友好的电解液设计策略,解决了高浓度LiTFSI电解液体系的高黏度与高成本难题,为水系锌离子电池中VOPO4·2H2O正极材料的结构稳定化提供了有效途径,展现出良好的应用潜力。
基金supported by the financial support provided by the National Natural Science Foundation of China(Grant Nos.12475261,12065019,and 12405296)the Qing Lan Project of Jiangsu Province,and the Yancheng Basic Research Fund Project of China(Grant No.YCBK2024003).
摘要This study develops a two-dimensional fluid model for atmospheric pressure non-equilibrium CO2-H2O plasma needle-plate configuration,incorporating a comprehensive set of plasma chemical reactions and photoionization effects.It focuses on investigating the influence of the CO2/H2O concentration ratio and quenching pressure on plasma streamer initiation and propagation dynamics.Numerical simulations show that increasing initial water vapor content significantly reduces electron energy and density,causing the discharge channel to contract when the reduced electric field is below 200 Td,due to strong dissociative adsorption reactions between electrons and water molecules.At higher reduced electric fields(above 200 Td),variations in water vapor content have minimal impact on primary electron transport parameters,likely because dissociative and ionizing collisions between electrons and CO2/H2O molecules become dominant.Increasing the quenching pressure enhances photoionization,but plasma discharge remains primarily sustained by direct electron-impact ionization.Low initial water vapor content and elevated quenching pressure both accelerate streamer propagation,with the concentration ratio exerting a more significant effect.Finally,the primary reaction pathways for key products(CO,OH,and electrons)are analyzed.These findings contribute to a better understanding of how the reactant concentration ratio and quenching pressure regulate the discharge reaction mechanism in atmospheric pressure non-equilibrium CO2-H2O plasma.
基金supported by the National Natural Science Foundation of China(No.52309132)Shandong Provincial Natural Science Foundation(No.ZR2023ME014).
摘要Electrocatalytic CO2reduction reaction(CO2RR)has been developed as a promising and attractive strategy to close the anthropogenic carbon cycle.Among various reduction products,multi-carbon(C2+)oxygenate and hydrocarbon compounds are desirable value-added fuels or chemicals.Extensive researches have revealed the crucial role of local CO2and H2O concentrations(or the adsorption of *CO and *H)close to the electrode/catalyst surface in manipulating multi-carbon generation pathways.In this mini reviews,we mainly summarized the recent progress of this field over the past five years.The modulating strategies for the hydrogen and carbon species ratio can be divided into three categories,i.e.,catalyst morphology,electrolyte composition and mass transfer.The effectiveness of the aforementioned strategies in promoting multi-carbon product selectivity was discussed in detail from the perspectives of tuning the local CO2and H2O concentrations and the subsequent thermodynamic-and kinetic-controlled *CO and *H ratios.Finally,the critical challenges remaining in balancing the ratio of CO2and H2O as well as potential upgrading directions for future research are addressed.
基金supported by the National Key R&D Program of China (No.2017YFC0210303).
摘要The expandable graphite(EG)modified TiO2 nanocomposites were prepared by the high shearmethod using the TiO2 nanoparticles(NPs)and EG as precursors,in which the amount of EG doped in TiO2 was 10 wt.%.Followed by the impregnation method,adjusting the pH of the solution to 10,and using the electrostatic adsorption to achieve spatial confinement,the Pt elementswere mainly distributed on the exposed TiO2,thus generating the Pt/10EG-TiO2-10 catalyst.The best CO oxidation activity with the excellent resistance to H2O and SO2 was obtained over the Pt/10EG-TiO2-10 catalyst:CO conversion after 36 hr of the reaction was ca.85%under the harsh condition of 10 vol.%H2O and 100 ppm SO2 at a high gaseous hourly space velocity(GHSV)of 400,000 hr−1.Physicochemical properties of the catalystswere characterized by various techniques.The results showed that the electrostatic adsorption,which riveted the Pt elements mainly on the exposed TiO2 of the support surface,reduced the dispersion of Pt NPs on EG and achieved the effective dispersion of Pt NPs,hence significantly improving CO oxidation activity over the Pt/10EG-TiO2-10 catalyst.The 10 wt.%EG doped in TiO2 caused the TiO2 support to form a more hydrophobic surface,which reduced the adsorption of H2O and SO2 on the catalyst,greatly inhibited deposition of the TiOSO4 and formation of the PtSO4 species as well as suppressed the oxidation of SO2,thus resulting in an improvement in the resistance to H2O and SO2 of the Pt/10EG-TiO2-10 catalyst.
摘要Herein,we established a Zn3(OH)2(V2O7)(H2O)2/V-Zn(O,S)Z-scheme heterojunction labeled ZnVO/V-Zn(O,S)with a heterovalent V4+/V5+states and oxygen vacancies in both phases via a one-step in-situ hydrolysis method.The NaBH4 regulated the ZnVO/V-Zn(O,S)-3 with rich Vo and suitable n(V4+)(V5+)ratio achieved an excellent photocatalytic nitrogen fixation activity of 301.7μmol/(g×h)and apparent quantum efficiency of 1.148%at 420 nm without any sacrificial agent,which is 11 times than that of V-Zn(O,S).The Vo acts as the active site to trap and activate N2 molecules and to trap and activate H2O to produce the H for N2 molecules photocatalytic reduction.The rich Vo defects can also reduce the competitive adsorption of H2O and N2 molecules on the surface active site of the catalyst.The heterovalent vanadium states act as the photogenerated electrons,quickly hopping between V4+and V5+to transfer for the photocatalytic N2 reduction reaction.Additionally,the Z-scheme heterojunction effectively minimizes photogenerated carrier recombination.These synergistic effects collectively boost the photocatalytic nitrogen fixation activity.This study provides a practical method for designing Z-scheme heterojunctions for efficient photocatalytic N2 fixation under mild conditions.
摘要低温等离子体(Low temperature plasma,LTP)可以将热力学稳定的CO2和H2O转化为高附加值产物,在CO2资源化利用和能源转化等领域有广阔前景,但是H2O的强猝灭效应使得LTP转化CO2/H2O的性能提升极具挑战。本文综述了LTP转化CO2/H2O的研究进展,包括LTP转化CO2/H2O的反应动力学,以及不同LTP、催化剂、反应器对CO2/H2O转化性能的影响。通过对转化性能和反应机理分析,发现H2O对电子的强吸附效应、产物复合反应和H原子的低密度、副反应的竞争分别是抑制原料气转化率和高附加值产物选择性的关键。针对上述问题,本文从反应器优化、引入其他反应物、催化剂设计和串联催化四个方面,提出性能提升策略。最后,对LTP转化CO2/H2O的重点研究方向进行了展望。