【摘要】 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(6.3×10⁷ Sm^–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TiO₂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TiO₂光催化剂（TiO₂/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, TiO₂/Ag@AgSe_x光催化剂具有比TiO₂和TiO₂/Ag更高的光催化产氢速率,其中TiO₂/Ag@AgSe_x （20μL）表现出最高的光催化产氢速率,是TiO₂/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, TiO₂/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TiO₂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.更多还原

【Abstract】 Effective charge separation and rapid interfacial H₂ production are imperative for the construction of efficient photocatalysts. Compared to Pt, the metallic Ag co-catalyst with its strong electron-trapping ability and excellent electronic conductivity typically exhibits an extremely limited photocatalytic H₂-evolution rate owing to its sluggish interfacial H₂-generation reaction. In this study, amorphous AgSe_x was incorporated in situ onto metallic Ag as a novel and excellent H₂-evolution active site to boost the interfacial H₂-generation rate of Ag nanoparticles in a TiO₂/Ag system. Core-shell Ag@AgSe_x nanoparticle-modified TiO₂ photocatalysts were prepared via a two-step pathway involving the photodeposition of metallic Ag and the selective surface selenization of metallic Ag to yield amorphous AgSe_x shells. The as-prepared TiO₂/Ag@AgSe_x（20 μL） photocatalyst exhibited an excellent H₂-production performance of 853.0 μmol h^-1 g^-1, prominently outperforming the TiO₂ and TiO₂/Ag samples by factors of 11.6 and 2.4, respectively. Experimental investigations and DFT calculations revealed that the enhanced H₂-generation activity of the TiO₂/Ag@AgSe_x photocatalyst could be accounted by synergistic interactions of the Ag@AgSe_x co-catalyst. Essentially, the metallic Ag core could quickly capture and transport the photoinduced electrons from TiO₂ to the amorphous AgSe_x shell, whereas the amorphous AgSe_x shell provided large active sites for boosting the interfacial H₂ evolution. This study offers a facile route for the construction of novel core-shell co-catalysts for sustainable H₂ evolution.更多还原