Steering the directional carrier migration across the interface is a central mission for efficient photocatalytic reactions.In this work,an atomic-shared heterointerface is constructed between the defect-rich ZnIn_(2)...Steering the directional carrier migration across the interface is a central mission for efficient photocatalytic reactions.In this work,an atomic-shared heterointerface is constructed between the defect-rich ZnIn_(2)S_(4)(HVs-ZIS)and CoIn_(2)S_(4)(CIS)via a defect-guided heteroepitaxial growth strategy.The strong interface coupling induces adequate carriers exchanging passageway between HVs-ZIS and CIS,enhancing the internal electric field(IEF)in the ZnIn_(2)S_(4)/CoIn_(2)S_(4)(HVs-ZIS/CIS)heterostructure.The defect structure in HVs-ZIS induces an additional defect level,improving the separation efficiency of photocarriers.Moreover,promoted by the IEF and intimate heterointerface,photogenerated electrons trapped by the defect level can migrate to the valence band of CIS,contributing to massive photogenerated electrons with intense reducibility in HVs-ZIS/CIS.Consequently,the HVs-ZIS/CIS heterostructure performs a boosted H_(2)evolution activity of 33.65 mmol g^(-1)h^(-1).This work highlights the synergistic effects of defect and strong interface coupling in regulating carrier transfer and paves a brave avenue for constructing efficient heterostructure photocatalysts.展开更多
NiS2 is a promising cocatalyst to improve the photocatalytic performance of g-C3N4 for the production of H2.However,the synthesis of the NiS2 cocatalyst usually requires harsh conditions,which risks destroying the mic...NiS2 is a promising cocatalyst to improve the photocatalytic performance of g-C3N4 for the production of H2.However,the synthesis of the NiS2 cocatalyst usually requires harsh conditions,which risks destroying the microstructures of the g-C3N4 photocatalysts.In this study,a facile and low-temperature（80 ℃） impregnation method was developed to prepare NiS2/g-C3N4 photocatalysts.First,the g-C3N4 powders were processed by the hydrothermal method in order to introduce oxygen-containing functional groups（such as-OH and-C0NH-） to the surface of g-C3N4.Then,the Ni^2＋ ions could be adsorbed near the g-C3N4 via strong electrostatic interaction between g-C3N4 and Ni^2＋ ions upon the addition of Ni（NO3）2 solution.Finally,NiS2 nanoparticles were formed on the surface of g-C3N4 upon the addition of TAA.It was found that the NiS2 nanoparticles were solidly and homogeneously grafted on the surface of g-C3N4,resulting in greatly improved photocatalytic H2production.When the amount of NiS2 was 3 wt%,the resultant NiS2/g-C3N4 photocatalyst showed the highest H2 evolution rate（116.343 μmol h^-1 g^-1）,which is significantly higher than that of the pure g-C3N4（3 μmol h^-1 g^-1）.Moreover,the results of a recycling test for the NiS2/g-C3N4（3 wt%）sample showed that this sample could maintain a stable and effective photocatalytic H2-evolution performance under visible-light irradiation.Based on the above results,a possible mechanism of the improved photocatalytic performance was proposed for the presented NiS2/g-C3N4 photocatalysts,in which the photogenerated electrons of g-C3N4 can be rapidly transferred to the NiS2 nanoparticles via the close and continuous contact between them;then,the photogenerated electrons rapidly react with H2O adsorbed on the surface of NiS2,which has a surficial metallic character and high catalytic activity,to produce H2.Considering the mild and facile synthesis method,the presented low-cost and highly efficient NiS2-modified g-C3N4 photocatalysts would have great potential for practical use in photocatalytic H2 production.展开更多
氢和氨作为清洁能源受到广泛关注,为深入探究氢-氨混燃的燃烧特性和影响因素,本文借助Chemkin仿真平台建立相关反应模型,以氢-氨混合气体为燃料,空气作为助燃剂,采用Otomo等人提出的一种氨氧化机理对其燃烧过程进行模拟计算,并模拟研究...氢和氨作为清洁能源受到广泛关注,为深入探究氢-氨混燃的燃烧特性和影响因素,本文借助Chemkin仿真平台建立相关反应模型,以氢-氨混合气体为燃料,空气作为助燃剂,采用Otomo等人提出的一种氨氧化机理对其燃烧过程进行模拟计算,并模拟研究了混合气体的点火延迟时间、层流燃烧速度、绝热燃烧温度、NO排放等燃烧特性随当量比、初始压力以及燃料中H_(2)比例的具体变化规律,对不同工况下的层流火焰结构、H和OH自由基的产率(rate of production,ROP)、NO生成的敏感度进行了化学动力学分析。结果表明:纯氨气体的点火延迟时间长、层流燃烧速度慢,掺氢后燃烧特性均有所改善,且提高了火焰的绝热燃烧温度,但掺氢比例越大,NO排放越多。NO摩尔分数随当量比变化的趋势先增后减,在当量比为0.8左右达到峰值。综合考虑氢-氨混燃的一系列燃烧特性以及掺氢、加压的成本和收益情况,推荐H_(2)占比15%、当量比φ=1.1、压力P=0.2 MPa为氢-氨混合燃烧的最优条件。展开更多
基金supported by the National Natural Science Foundation of China(52072196,52002200,52102106,52202262,22379081,22379080)the Major Basic Research Program of Natural Science Foundation of Shandong Province(ZR2020ZD09)+1 种基金the Natural Science Foundation of Shandong Province(ZR2020QE063,ZR202108180009,ZR2023QE059)the Project funded by China Postdoctoral Science Foundation(2023M741871)。
文摘Steering the directional carrier migration across the interface is a central mission for efficient photocatalytic reactions.In this work,an atomic-shared heterointerface is constructed between the defect-rich ZnIn_(2)S_(4)(HVs-ZIS)and CoIn_(2)S_(4)(CIS)via a defect-guided heteroepitaxial growth strategy.The strong interface coupling induces adequate carriers exchanging passageway between HVs-ZIS and CIS,enhancing the internal electric field(IEF)in the ZnIn_(2)S_(4)/CoIn_(2)S_(4)(HVs-ZIS/CIS)heterostructure.The defect structure in HVs-ZIS induces an additional defect level,improving the separation efficiency of photocarriers.Moreover,promoted by the IEF and intimate heterointerface,photogenerated electrons trapped by the defect level can migrate to the valence band of CIS,contributing to massive photogenerated electrons with intense reducibility in HVs-ZIS/CIS.Consequently,the HVs-ZIS/CIS heterostructure performs a boosted H_(2)evolution activity of 33.65 mmol g^(-1)h^(-1).This work highlights the synergistic effects of defect and strong interface coupling in regulating carrier transfer and paves a brave avenue for constructing efficient heterostructure photocatalysts.
基金supported by the National Natural Science Foundation of China (21277107, 21477094, 51672203, 51472192)the Program for New Century Excellent Talents in University (NCET-13-0944)the Fundamental Research Funds for the Central Universities (WUT 2015IB002)~~
文摘NiS2 is a promising cocatalyst to improve the photocatalytic performance of g-C3N4 for the production of H2.However,the synthesis of the NiS2 cocatalyst usually requires harsh conditions,which risks destroying the microstructures of the g-C3N4 photocatalysts.In this study,a facile and low-temperature（80 ℃） impregnation method was developed to prepare NiS2/g-C3N4 photocatalysts.First,the g-C3N4 powders were processed by the hydrothermal method in order to introduce oxygen-containing functional groups（such as-OH and-C0NH-） to the surface of g-C3N4.Then,the Ni^2＋ ions could be adsorbed near the g-C3N4 via strong electrostatic interaction between g-C3N4 and Ni^2＋ ions upon the addition of Ni（NO3）2 solution.Finally,NiS2 nanoparticles were formed on the surface of g-C3N4 upon the addition of TAA.It was found that the NiS2 nanoparticles were solidly and homogeneously grafted on the surface of g-C3N4,resulting in greatly improved photocatalytic H2production.When the amount of NiS2 was 3 wt%,the resultant NiS2/g-C3N4 photocatalyst showed the highest H2 evolution rate（116.343 μmol h^-1 g^-1）,which is significantly higher than that of the pure g-C3N4（3 μmol h^-1 g^-1）.Moreover,the results of a recycling test for the NiS2/g-C3N4（3 wt%）sample showed that this sample could maintain a stable and effective photocatalytic H2-evolution performance under visible-light irradiation.Based on the above results,a possible mechanism of the improved photocatalytic performance was proposed for the presented NiS2/g-C3N4 photocatalysts,in which the photogenerated electrons of g-C3N4 can be rapidly transferred to the NiS2 nanoparticles via the close and continuous contact between them;then,the photogenerated electrons rapidly react with H2O adsorbed on the surface of NiS2,which has a surficial metallic character and high catalytic activity,to produce H2.Considering the mild and facile synthesis method,the presented low-cost and highly efficient NiS2-modified g-C3N4 photocatalysts would have great potential for practical use in photocatalytic H2 production.
文摘氢和氨作为清洁能源受到广泛关注,为深入探究氢-氨混燃的燃烧特性和影响因素,本文借助Chemkin仿真平台建立相关反应模型,以氢-氨混合气体为燃料,空气作为助燃剂,采用Otomo等人提出的一种氨氧化机理对其燃烧过程进行模拟计算,并模拟研究了混合气体的点火延迟时间、层流燃烧速度、绝热燃烧温度、NO排放等燃烧特性随当量比、初始压力以及燃料中H_(2)比例的具体变化规律,对不同工况下的层流火焰结构、H和OH自由基的产率(rate of production,ROP)、NO生成的敏感度进行了化学动力学分析。结果表明:纯氨气体的点火延迟时间长、层流燃烧速度慢,掺氢后燃烧特性均有所改善,且提高了火焰的绝热燃烧温度,但掺氢比例越大,NO排放越多。NO摩尔分数随当量比变化的趋势先增后减,在当量比为0.8左右达到峰值。综合考虑氢-氨混燃的一系列燃烧特性以及掺氢、加压的成本和收益情况,推荐H_(2)占比15%、当量比φ=1.1、压力P=0.2 MPa为氢-氨混合燃烧的最优条件。
