基于竞争反应抑制策略构筑高效Z机制光催化全分解水体系

Particulate-based photocatalytic overall water splitting (OWS) for hydrogen production is one of the ideal ways to convert and store solar energy into chemical energy (hydrogen). The Z-scheme OWS system has attracted a lot of attention because it can utilize the wide wavelength range of visible light. Currently, most researches on Z-scheme were focused on the development of new materials and redox mediator, whereas very few attention has been paid to suppress the competing reactions caused by the introduction of the redox mediator. Due to the competing reactions, the efficient and oriented utilization of charge is impossible, which leads to the fact that most developed/novel photocatalysts can only be used in hydrogen or oxygen evolving half reaction and cannot be used to construct Z-scheme system. Hence, understanding and regulating the oriented utilization of charge are of great importance for extending new Z-scheme and improving available Z-scheme systems. This project plans to use [Fe(CN)6]3-/4- as the redox mediator with advantages of mild solution condition and easy to be activated, achieve the selective adsorption of [Fe(CN)6]3- or [Fe(CN)6]4- ions through morphological regulation and surface modification strategies, which then helps to suppress the competing reactions. Based on this, the project plans to select cocatalyst with selective catalyzing performance, in order to achieve high efficient oriented charge transfer and utilization. Through this strategy, we have successfully constructed a Z-scheme OWS system with IO3-/I- as redox mediator, which was impossible for the original catalysts. And we also have proven this strategy was also feasible using [Fe(CN)6]3-/4- as redox mediator. We hope we can construct a Z-scheme OWS system with an apparent quantum efficiency over 15% under visible light excitation, and promote the research and development in the field of solar energy to hydrogen energy.

利用粉末光催化剂实现全分解水制氢是太阳能转化储存的理想途径之一。Z机制全分解水因其可利用长波长范围的可见光而受到广泛关注。针对Z机制，现有研究多集中于材料和电对的开发，对因电对的引入而引发的竞争反应关注较少。由于不能抑制竞争反应，大量新型材料仅可用于产氢/产氧半反应，而无法构筑Z体系。因此，认识和调控竞争反应的抑制机理，实现电荷定向利用，对于拓展和提升Z体系具有十分重要的意义。本项目拟以条件温和且易活化的[Fe(CN)6]3-/4-为氧化还原电对，通过形貌调控、表面修饰策略实现光催化剂表面对电对离子的选择性吸附；在此基础上，筛选具有选择性催化功能的助催化剂，实现竞争反应的抑制。通过这一策略，项目组已实现基于IO3-/I-电对的新型Z机制构筑，且初步证明对于[Fe(CN)6]3-/4-的可行性。项目期望最终指导构筑可见光激发下表观量子效率超过15%的Z体系，促进太阳能至氢能领域的研究发展。

利用粉末光催化剂实现全分解水制氢是太阳能转化储存的理想途径之一。Z机制全分解水因其可利用长波长范围的可见光而受到广泛关注。针对Z机制，现有研究多集中于材料和电对的开发，对因电对的引入而引发的竞争反应关注较少。由于不能抑制竞争反应，大量新型材料仅可用于产氢/产氧半反应，而无法构筑Z体系。因此，认识和调控竞争反应的抑制机理，实现电荷定向利用，对于拓展和提升Z体系具有十分重要的意义。本项目的研究重点以条件温和且易活化的[Fe(CN)6]3-/4-为氧化还原电对，通过表界面修饰策略实现竞争反应的抑制。项目实施以来取得了如下成果：1）基于Ir/FeCoOx双助催化剂的开发抑制竞争反应构筑高效Z机制全分解水制氢体系，420 nm单色光下的表观量子效率达12.3%；2）基于金属-载体强相互作用实现半导体与助催化剂间致密的界面接触，通过原位光诱导实现Ir/IrO2双助催化剂的选择性转化以及高效电荷分离，并基于此构筑量子效率为16.9% （420 nm单色光）的全分解水制氢体系；3）开发烧绿石结构氮氧化物（Nd2Ta2O5N2）实现Z机制全分解水制氢。其中可见光催化全分解水制氢量子效率（16.9% at 420 nm）达到国际同类领先。项目执行期间共发表SCI论文10篇，申请专利1项。研究结果具有原创性并为实现太阳能到氢能的高效转化存储奠定了基础。