The adsorption behavior and mechanism of Bi（Ⅲ） ions on the rutile-water interface were investigated through micro-flotation, Zeta potential measurement, adsorption amount measurement and X-ray photoelectron spectro...The adsorption behavior and mechanism of Bi（Ⅲ） ions on the rutile-water interface were investigated through micro-flotation, Zeta potential measurement, adsorption amount measurement and X-ray photoelectron spectroscopy（XPS）. According to the results of micro-flotation, Bi（Ⅲ） ions could largely improve the rutile flotation recovery（from 62% to 91%）, and they could increase the activating sites and reduce the competitive adsorption between nonyl hydroxamic acid negative ions and OH-ions, which determined that Bi（Ⅲ） ions were capable of activating rutile flotation. The adsorption of Bi（Ⅲ） ions onto the rutile surface led to the shift of Zeta potential into the positive direction, which was good for the adsorption of nonyl hydroxamic acid anions. In addition, the results of XPS indicated that the chemical environment around Ti atom had not changed before and after the adsorption of Bi（Ⅲ） ions. Based on the adsorption mechanism of Bi（Ⅲ） ions, it was deduced that firstly Bi（Ⅲ） ions occupied the vacancies of the original Ca^2＋, Mg^2＋ and Fe^2＋ ions on the rutile surface; secondly Bi（Ⅲ） ions covered on the rutile surface in the form of hydroxides.展开更多
Silver‐modified semiconductor photocatalysts typically exhibit enhanced photocatalytic activitytoward the degradation of organic substances.In comparison,their hydrogen‐evolution rates arerelatively low owing to poo...Silver‐modified semiconductor photocatalysts typically exhibit enhanced photocatalytic activitytoward the degradation of organic substances.In comparison,their hydrogen‐evolution rates arerelatively low owing to poor interfacial catalytic reactions to producing hydrogen.In the presentstudy,thiocyanate anions(SCN–)as interfacial catalytic active sites were selectively adsorbed ontothe Ag surface of g‐C3N4/Ag photocatalyst to promote interfacial H2‐evolution reactions.The thiocyanate‐modified g‐C3N4/Ag(g‐C3N4/Ag‐SCN)photocatalysts were synthesized via photodepositionof metallic Ag on g‐C3N4and subsequent selective adsorption of SCN– ions on the Ag surface by animpregnation method.The resulting g‐C3N4/Ag‐SCN photocatalysts exhibited considerably higherphotocatalytic H2‐evolution activity than the g‐C3N4,g‐C3N4/Ag,and g‐C3N4/SCN photocatalysts.Furthermore,the g‐C3N4/Ag‐SCN photocatalyst displayed the highest H2‐evolution rate(3.9μmolh?1)when the concentration of the SCN– ions was adjusted to0.3mmol L?1.The H2‐evolution rateobtained was higher than those of g‐C3N4(0.15μmol h?1)and g‐C3N4/Ag(0.71μmol h?1).Consideringthe enhanced performance of g‐C3N4/Ag upon minimal addition of SCN– ions,a synergistic effectof metallic Ag and SCN– ions is proposed―the Ag nanoparticles act as an effective electron‐transfermediator for the steady capture and rapid transportation of photogenerated electrons,while theadsorbed SCN– ions serve as an interfacial active site to effectively absorb protons from solution andpromote rapid interfacial H2‐evolution reactions.Considering the present facile synthesis and itshigh efficacy,the present work may provide new insights into preparing high‐performance photocatalytic materials展开更多
Dynamic defects on halide perovskite materials,caused by ion dissociation and migration under light illumination,typically result in undesirable energy dissipation and limited energy conversion efficiency.However,in t...Dynamic defects on halide perovskite materials,caused by ion dissociation and migration under light illumination,typically result in undesirable energy dissipation and limited energy conversion efficiency.However,in this work,we demonstrated that dynamic halogen defects generated by the same process in bismuth oxyhalide(Bi_(5)O_(7)Cl)materials can act as active sites to promote charge separation and photocatalytic efficiency.Mechanistic studies and density functional theory calculations revealed that dynamic Cl defects affected the electronic structure of Bi_(5)O_(7)Cl and photocatalytic CO_(2)reduction process.As active sites,these defects promoted charge transfer,leading to the activation of adsorbed CO_(2)molecules and reduction of the energy barrier of the rate-determining step.Thus,CO_(2)was spontaneously converted into COOH−intermediate and finally reduced to CO with a high efficiency of 108.60μmol g^(−1) and selectivity of 100%after 4-h of CO_(2)photoreduction.This work is highly instructive and valuable to the exploration of dynamic defects on halide-containing materials applied in solar energy conversion.展开更多
基金Project(51474254)supported by the National Natural Science Foundation of ChinaProject(2013M531813)supported by the China Postdoctoral Science Foundation+1 种基金Project(2016zzts111)supported by the Independent Exploration and Innovation Program of Central South University,ChinaProject(CSUZC201715)supported by Open-End Fund for the Valuable and Precision Instruments of Central South University,China
文摘The adsorption behavior and mechanism of Bi（Ⅲ） ions on the rutile-water interface were investigated through micro-flotation, Zeta potential measurement, adsorption amount measurement and X-ray photoelectron spectroscopy（XPS）. According to the results of micro-flotation, Bi（Ⅲ） ions could largely improve the rutile flotation recovery（from 62% to 91%）, and they could increase the activating sites and reduce the competitive adsorption between nonyl hydroxamic acid negative ions and OH-ions, which determined that Bi（Ⅲ） ions were capable of activating rutile flotation. The adsorption of Bi（Ⅲ） ions onto the rutile surface led to the shift of Zeta potential into the positive direction, which was good for the adsorption of nonyl hydroxamic acid anions. In addition, the results of XPS indicated that the chemical environment around Ti atom had not changed before and after the adsorption of Bi（Ⅲ） ions. Based on the adsorption mechanism of Bi（Ⅲ） ions, it was deduced that firstly Bi（Ⅲ） ions occupied the vacancies of the original Ca^2＋, Mg^2＋ and Fe^2＋ ions on the rutile surface; secondly Bi（Ⅲ） ions covered on the rutile surface in the form of hydroxides.
基金supported by the National Natural Science Foundation of China(51472192,21477094,21771142)the Fundamental Research Funds for the Central Universities(WUT 2017IB002)~~
文摘Silver‐modified semiconductor photocatalysts typically exhibit enhanced photocatalytic activitytoward the degradation of organic substances.In comparison,their hydrogen‐evolution rates arerelatively low owing to poor interfacial catalytic reactions to producing hydrogen.In the presentstudy,thiocyanate anions(SCN–)as interfacial catalytic active sites were selectively adsorbed ontothe Ag surface of g‐C3N4/Ag photocatalyst to promote interfacial H2‐evolution reactions.The thiocyanate‐modified g‐C3N4/Ag(g‐C3N4/Ag‐SCN)photocatalysts were synthesized via photodepositionof metallic Ag on g‐C3N4and subsequent selective adsorption of SCN– ions on the Ag surface by animpregnation method.The resulting g‐C3N4/Ag‐SCN photocatalysts exhibited considerably higherphotocatalytic H2‐evolution activity than the g‐C3N4,g‐C3N4/Ag,and g‐C3N4/SCN photocatalysts.Furthermore,the g‐C3N4/Ag‐SCN photocatalyst displayed the highest H2‐evolution rate(3.9μmolh?1)when the concentration of the SCN– ions was adjusted to0.3mmol L?1.The H2‐evolution rateobtained was higher than those of g‐C3N4(0.15μmol h?1)and g‐C3N4/Ag(0.71μmol h?1).Consideringthe enhanced performance of g‐C3N4/Ag upon minimal addition of SCN– ions,a synergistic effectof metallic Ag and SCN– ions is proposed―the Ag nanoparticles act as an effective electron‐transfermediator for the steady capture and rapid transportation of photogenerated electrons,while theadsorbed SCN– ions serve as an interfacial active site to effectively absorb protons from solution andpromote rapid interfacial H2‐evolution reactions.Considering the present facile synthesis and itshigh efficacy,the present work may provide new insights into preparing high‐performance photocatalytic materials
基金supported by the National Natural Science Foundation of China(21822601,22176029)Excellent Youth Foundation of Sichuan Scientific Committee(2021JDJQ0006)+1 种基金Fundamental Research Funds for the Central Universities(ZYGX2019Z021)111 Project(B20030)。
文摘Dynamic defects on halide perovskite materials,caused by ion dissociation and migration under light illumination,typically result in undesirable energy dissipation and limited energy conversion efficiency.However,in this work,we demonstrated that dynamic halogen defects generated by the same process in bismuth oxyhalide(Bi_(5)O_(7)Cl)materials can act as active sites to promote charge separation and photocatalytic efficiency.Mechanistic studies and density functional theory calculations revealed that dynamic Cl defects affected the electronic structure of Bi_(5)O_(7)Cl and photocatalytic CO_(2)reduction process.As active sites,these defects promoted charge transfer,leading to the activation of adsorbed CO_(2)molecules and reduction of the energy barrier of the rate-determining step.Thus,CO_(2)was spontaneously converted into COOH−intermediate and finally reduced to CO with a high efficiency of 108.60μmol g^(−1) and selectivity of 100%after 4-h of CO_(2)photoreduction.This work is highly instructive and valuable to the exploration of dynamic defects on halide-containing materials applied in solar energy conversion.
