形貌可控的二元合金纳米晶内核对核壳光催化材料性能的影响机制研究

In recent years, the novel core-shell nanomaterials with noble metal core@semiconductor shell structures have become the hot issue in the field of photocatalysis, due to their unique chemical structures and catalytic performance. In the previous exploring research, we have successfully synthesized the novel AuPd@TiO2 and PtCo@CdS core-shell photocatalytic materials with bimetallic cores, and found that the novel core-shell catalysts showed high hydrogen evolution activity via photocatalytic water splitting and catalytic stability. Based on the prior experimental results, the present proposal will investigate the water splitting performance and catalytic mechanisms of bimetallic alloy@semiconductor core-shell photocatalytic materials: first, we will synthesis bimetallic alloy nanocrystals with different structures via morphology control techniques, and investigate the surface structures and SPR effects of the bimetallic alloy cores, and reveal the “synergistic effect” micro mechanism of the metal elements. Next, we will analyze the physical chemistry properties of the "three-dimensional" interfaces between bimetallic alloy cores and photocatalysts, and achieve the efficient separation of photogenerated electrons and holes in the interfaces, and reveal the transfer mechanism and reacting path ways of photo-generated charge carriers. Thirdly, we will control the synthesis of core-shell photocatalytic materials with different component and structures based on the morphology of bimetallic alloy cores, and explore the effect mechanism of the bimetallic alloy cores morphology on the performance of core-shell materials. Finally, we will in-depth investigate and summary the experimental rules to reveal the influence mechanism of bimetallic alloy nanocrystal cores on the performance of core-shell photocatalytic materials, and provide the theoretical and experimental basis for the development of efficient photocatalytic systems.

近年来，贵金属内核@半导体外壳的核壳纳米材料，以独特的微观结构和催化特性，成为光催化领域的研究热点。在前期探索性研究中，申请人首次合成了二元合金内核的AuPd@TiO2、PtCo@CdS核壳光催化材料，发现其具有高的光解水产氢活性和催化稳定性。在此基础上，本项目拟深入研究二元合金@半导体核壳光催化材料的分解水活性及机理：首先，通过形貌调控合成不同结构的二元合金纳米晶，研究二元合金的表面结构、SPR效应等性质，揭示合金元素的“协同作用”微观机制；进一步研究二元合金与半导体“三维”界面的物理化学性质，实现光生载流子在界面处的高效分离，阐明载流子迁移机制和反应途径；再次，基于二元合金内核的形貌，控制合成多种结构的核壳材料，研究二元合金形貌对核壳材料光催化性能的影响规律；最终揭示二元合金纳米晶内核对核壳光催化材料性能的影响机制，通过对实验规律深入研究和总结，为高效光催化体系开发提供理论及实验依据。

随着氢能的研究热潮，太阳能光催化分解水产氢和降解污染物技术成为近年来的研究热点。本项目在设计合成高效复合光催化材料体系方面进行了以下创新性研究：首先合成了AuPd二元纳米合金，采用AuPd二元合金负载，设计AuPd/Cd0.5Zn0.5S复合光催化体系，进一步提高载流子的分离效率，产氢活性比纯硫化镉锌提高了12倍；通过原位化学还原法将二元合金AuPd纳米晶负载到g-C3N4纳米片中，光还原后具有较小的颗粒，进而加热还原处理与催化剂形成了紧密的接触界面，有效促进了载流子的分离；通过水热法合成了棒状Zn0.5Cd0.5S材料，采用原位沉积和热处理的手段，合成了棒状CoP/Zn0.5Cd0.5S复合光催化材料，光催化活性最高达到14.6mol·h-1·g-1，是Zn0.5Cd0.5S催化剂的19.7倍；使用原位化学沉积制备了新型PtPd/g-C3N4复合光催化剂，光催化产氢速率大幅度提高，其中负载量为0.2 wt.%的复合光催化剂的产氢速率最高，为1600.8 μmol g-1 h-1，是纯g-C3N4纳米片的800倍；通过原位水热的方法在CdS微米球上负载了Co2P 纳米颗粒，负载Co2P可以有效地提高光解水产氢效率。在Co2P 的负载量为1.2 mol%，催化剂以乳酸为牺牲试剂时，产氢速率为6.06 mmol·g-1·h-1 ，其数值是纯CdS的41倍 ；通过原位磷化及原位负载的方法构筑了NiCo-LDH/P-CdS光催化产氢体系，P 的掺杂策略使得 CdS 导带底形成了 mid-gap，促进了光生电荷的分离，并在一定程度上抑制了 CdS 的光腐蚀；采用硬模板法制备了具有空心结构的CdS (HCS) 纳米球，并且分别在其内外表面定向负载了Au和PdS， 构筑了具有多级结构的Au@HCS@PdS复合体系；当HCS负载Au 和PdS后产氢性能明显提高， 其中1wt.%Au@HCS@1wt. %PdS复合光催化剂的性能最好，高达16.35 mmol h-1 g-1，较纯CdS性能增长近112倍。本项目发表SCI、EI论文23篇，其中12篇JCR一区论文，10篇JCR二区论文。此外本项目发表的论文受到了广泛的关注和引用，被国内外多个单位的科研人员引用390余次，人才培养方面，培养硕士研究生14人，博士研究生5人。