纯相光催化材料的产氢性能主要受限于较低的电荷分离效率和缓慢的界面催化反应速率.表面负载助催化剂因其能够实现快速转移光生电子和提供界面催化活性中心被认为是促进电荷分离和提升界面催化反应的有效手段.贵金属类材料,尤其是金属铂...纯相光催化材料的产氢性能主要受限于较低的电荷分离效率和缓慢的界面催化反应速率.表面负载助催化剂因其能够实现快速转移光生电子和提供界面催化活性中心被认为是促进电荷分离和提升界面催化反应的有效手段.贵金属类材料,尤其是金属铂(Pt),被认为是光催化产氢领域的理想助剂,但储量低和价格昂贵严重制约了其大规模实际应用.因此,发展低成本的产氢助剂对未来光催化产氢技术的发展至关重要.金属银(Ag)是一种优异的导电金属材料,其高电导率(6.3×10^(7) S m^(–1))能够在光催化产氢反应中快速转移光生电子,从而极大地抑制光生电子-空穴对的复合.与金属Pt相比,Ag作为助剂在光催化体系中的析氢活性并不理想,这主要归因于Ag表面缺乏有效的产氢活性位点,使得界面催化产氢反应速率受到极大限制,最终表现出较低的光催化产氢活性.因此,优化Ag表面性质并提供丰富的界面产氢活性位点对于提升Ag助剂的光催化产氢活性具有重要意义.本文采用原位表面/界面工程策略对金属Ag助剂进行改性,以设计高效的Ag修饰光催化材料.首先通过一步光沉积方法制备了Ag纳米粒子修饰的TiO_(2)光催化材料,然后,将金属Ag纳米粒子表面部分原位硒化为非晶态AgSe_(x),成功制备了新型核壳结构Ag@AgSe_(x)助剂修饰的TiO_(2)光催化剂(TiO_(2)/Ag@AgSe_(x)).X射线衍射、高分辨透射电镜、X射线光电子能谱等表征结果表明,所得结构为Ag@AgSe_(x)助剂的核壳结构.光催化结果表明,TiO_(2)/Ag@AgSe_(x)光催化剂具有比TiO_(2)和TiO_(2)/Ag更高的光催化产氢速率,其中TiO_(2)/Ag@AgSe_(x)(20μL)表现出最高的光催化产氢速率,是TiO_(2)/Ag样品的2.4倍.结合原位X射线光电子能谱和密度泛函理论计算结果认为,TiO_(2)/Ag@AgSe_(x)光催化剂的高效产氢活性可以归因于金属Ag核和非晶AgSe_(x)壳的协同机制,即具有优良导电性的金属Ag核可以有效且快速地转移光生电子,而非晶态AgSe_(x)壳可以提供大量的产氢活性中心,最终实现高效的电荷分离效率和快速的界面催化反应,显著提升TiO_(2)的光催化产氢活性.综上,本文为构建高效的Ag改性光催化剂以及开发经济高效的太阳能转换助催化剂提供了新的思路.展开更多
Conventional hexagonal dimolybdenum carbide(Mo2 C) as a good cocatalyst has been widely applied for the enhanced photocatalytic hydrogen production of various photocatalysts. Compared with the hexagonal Mo2 C, however...Conventional hexagonal dimolybdenum carbide(Mo2 C) as a good cocatalyst has been widely applied for the enhanced photocatalytic hydrogen production of various photocatalysts. Compared with the hexagonal Mo2 C, however, the investigation about cubic molybdenum carbide(Mo C) is still very limited in photocatalytic field. In this study, carbon-coated cubic molybdenum carbide(MoC@C) nanoparticle was synthesized and used as an effective cocatalyst to improve the H2-evolution efficiency of Ti O2. The cubic MoC@C can be obtained by adjusting the mass ratio of C3 N3(NH2)3 to(NH4)6 Mo7 O(24)(2:1) and controlling the calcination temperature to 800 °C. When the above cubic MoC@C nanoparticles were evenly loaded on the Ti O2 via a sonication-assisted deposition, a homogeneous composite of TiO2/MoC@C was formed due to the strong coupling interface between TiO2 and cubic MoC nanoparticles. More importantly, the highest H2-production rate of Ti O-12/MoC@C reached 504 μmol hg^(-1)(AQE=1.43%), which was 50 times as high as that of the pure TiO2. The enhanced performance of TiO2/MoC@C can be attributed to the synergistic effect of carbon layer as an electron mediator and the cubic MoC as interfacial H2-evolution active sites. This work provides a feasible guideline to develop high-efficiency Mo-based cocatalysts for potential applications in the H2-evolution field.展开更多
Converting solar energy into chemical energy by artificial photosynthesis is promising in addressing the issues of the greenhouse effect and fossil fuel crisis.Herein,a novel photocatalyst,i.e.CdS/TiO_(2) hollow micro...Converting solar energy into chemical energy by artificial photosynthesis is promising in addressing the issues of the greenhouse effect and fossil fuel crisis.Herein,a novel photocatalyst,i.e.CdS/TiO_(2) hollow microspheres(HS),were dedicatedly designed to boost overall photocatalytic efficiency.TiO_(2) nanoparticles were in-situ decorated on the inside and outside the shell of Cd S HS,ensuring close contact between TiO_(2) and CdS.The CdS/TiO2 HS with abundant mesopores inside of the shell boost the light absorption via multiscattering effect as well as accessible to reactions in all directions.The heterojunction was scrutinized and the charge transfer across it was revealed by in-situ irradiated X-ray photoelectron spectroscopy(ISI-XPS).Ultimately,the charge transfer in this composite was determined to follow stepscheme mechanism,which not only facilitates the separation of charge carriers but also preserves strong redox ability.Benefited from the intimate linkage between Cd S and TiO_(2) and the favorable step-scheme heterojunction,enhanced photocatalytic CO_(2) reduction activity was accomplished.The CH4 yield rate of CdS/TiO_(2) reaches 27.85μmol g^(–1) h^(–1),which is 145.6 and 3.8 times higher than those of pristine CdS and TiO_(2),respectively.This work presents a novel insight into constructing step-scheme photocatalytic system with desirable performance.展开更多
基金supported by the National Natural Science Foundation of China(51672312,21373275,51808080,21571192)the Fundamental Research Funds for the Central Univsrsity,South-Central University for Nationalities(CZT19006)+2 种基金the Natural Science Foundation Project of CQ CSTC(cstc2018jcyjA 3794)China "post-doctoral innovative talent support program"(BX20180056)China Postdoctoral Science Foundation(2018M643788XB)~~
基金supported by the National Natural Science Foundation of China(51672312,21373275)the Fundamental Research Funds for the Central Universities,South-Central University for Nationalities(CZT19006)~~
文摘纯相光催化材料的产氢性能主要受限于较低的电荷分离效率和缓慢的界面催化反应速率.表面负载助催化剂因其能够实现快速转移光生电子和提供界面催化活性中心被认为是促进电荷分离和提升界面催化反应的有效手段.贵金属类材料,尤其是金属铂(Pt),被认为是光催化产氢领域的理想助剂,但储量低和价格昂贵严重制约了其大规模实际应用.因此,发展低成本的产氢助剂对未来光催化产氢技术的发展至关重要.金属银(Ag)是一种优异的导电金属材料,其高电导率(6.3×10^(7) S m^(–1))能够在光催化产氢反应中快速转移光生电子,从而极大地抑制光生电子-空穴对的复合.与金属Pt相比,Ag作为助剂在光催化体系中的析氢活性并不理想,这主要归因于Ag表面缺乏有效的产氢活性位点,使得界面催化产氢反应速率受到极大限制,最终表现出较低的光催化产氢活性.因此,优化Ag表面性质并提供丰富的界面产氢活性位点对于提升Ag助剂的光催化产氢活性具有重要意义.本文采用原位表面/界面工程策略对金属Ag助剂进行改性,以设计高效的Ag修饰光催化材料.首先通过一步光沉积方法制备了Ag纳米粒子修饰的TiO_(2)光催化材料,然后,将金属Ag纳米粒子表面部分原位硒化为非晶态AgSe_(x),成功制备了新型核壳结构Ag@AgSe_(x)助剂修饰的TiO_(2)光催化剂(TiO_(2)/Ag@AgSe_(x)).X射线衍射、高分辨透射电镜、X射线光电子能谱等表征结果表明,所得结构为Ag@AgSe_(x)助剂的核壳结构.光催化结果表明,TiO_(2)/Ag@AgSe_(x)光催化剂具有比TiO_(2)和TiO_(2)/Ag更高的光催化产氢速率,其中TiO_(2)/Ag@AgSe_(x)(20μL)表现出最高的光催化产氢速率,是TiO_(2)/Ag样品的2.4倍.结合原位X射线光电子能谱和密度泛函理论计算结果认为,TiO_(2)/Ag@AgSe_(x)光催化剂的高效产氢活性可以归因于金属Ag核和非晶AgSe_(x)壳的协同机制,即具有优良导电性的金属Ag核可以有效且快速地转移光生电子,而非晶态AgSe_(x)壳可以提供大量的产氢活性中心,最终实现高效的电荷分离效率和快速的界面催化反应,显著提升TiO_(2)的光催化产氢活性.综上,本文为构建高效的Ag改性光催化剂以及开发经济高效的太阳能转换助催化剂提供了新的思路.
基金supported by the National Natural Science Foundation of China (51872221 and 21771142)the Fundamental Research Funds for the Central Universities (WUT 2019IB002)。
文摘Conventional hexagonal dimolybdenum carbide(Mo2 C) as a good cocatalyst has been widely applied for the enhanced photocatalytic hydrogen production of various photocatalysts. Compared with the hexagonal Mo2 C, however, the investigation about cubic molybdenum carbide(Mo C) is still very limited in photocatalytic field. In this study, carbon-coated cubic molybdenum carbide(MoC@C) nanoparticle was synthesized and used as an effective cocatalyst to improve the H2-evolution efficiency of Ti O2. The cubic MoC@C can be obtained by adjusting the mass ratio of C3 N3(NH2)3 to(NH4)6 Mo7 O(24)(2:1) and controlling the calcination temperature to 800 °C. When the above cubic MoC@C nanoparticles were evenly loaded on the Ti O2 via a sonication-assisted deposition, a homogeneous composite of TiO2/MoC@C was formed due to the strong coupling interface between TiO2 and cubic MoC nanoparticles. More importantly, the highest H2-production rate of Ti O-12/MoC@C reached 504 μmol hg^(-1)(AQE=1.43%), which was 50 times as high as that of the pure TiO2. The enhanced performance of TiO2/MoC@C can be attributed to the synergistic effect of carbon layer as an electron mediator and the cubic MoC as interfacial H2-evolution active sites. This work provides a feasible guideline to develop high-efficiency Mo-based cocatalysts for potential applications in the H2-evolution field.
基金supported by the National Natural Science Foundation of China (51961135303, 51932007, 21871217 and U1705251)the National Key Research and Development Program of China (2018YFB1502001)Innovative Research Funds of SKLWUT (2017-ZD-4)
基金financially supported by the National Natural Science Foundation of China(NSFC)(Nos.51872220,51932007,51961135303,21871217,U1905215 and U1705251)the National Key Research and Development Program of China(No.2018YFB1502001)the Fundamental Research Funds for the Central Universities(No.WUT:2019IVB050)。
文摘Converting solar energy into chemical energy by artificial photosynthesis is promising in addressing the issues of the greenhouse effect and fossil fuel crisis.Herein,a novel photocatalyst,i.e.CdS/TiO_(2) hollow microspheres(HS),were dedicatedly designed to boost overall photocatalytic efficiency.TiO_(2) nanoparticles were in-situ decorated on the inside and outside the shell of Cd S HS,ensuring close contact between TiO_(2) and CdS.The CdS/TiO2 HS with abundant mesopores inside of the shell boost the light absorption via multiscattering effect as well as accessible to reactions in all directions.The heterojunction was scrutinized and the charge transfer across it was revealed by in-situ irradiated X-ray photoelectron spectroscopy(ISI-XPS).Ultimately,the charge transfer in this composite was determined to follow stepscheme mechanism,which not only facilitates the separation of charge carriers but also preserves strong redox ability.Benefited from the intimate linkage between Cd S and TiO_(2) and the favorable step-scheme heterojunction,enhanced photocatalytic CO_(2) reduction activity was accomplished.The CH4 yield rate of CdS/TiO_(2) reaches 27.85μmol g^(–1) h^(–1),which is 145.6 and 3.8 times higher than those of pristine CdS and TiO_(2),respectively.This work presents a novel insight into constructing step-scheme photocatalytic system with desirable performance.
基金supported by the National Natural Science Foundation of China(21771142 and 51672203)the Fun-damental Research Funds for the Central Universities(WUT 2019IB002)。
