基于超薄单晶半导体电荷自发空间分离特性构筑双助催化剂负载的复合光催化材料及其太阳能驱动光解水产氢性能研究

Hydrogen is a well-known clean energy to sustain the future development of our planet. Among various hydrogen production techniques, solar-driven hydrogen production from water-splitting is fascinating because it is an environmentally benign process using abundant resources, water and sunlight. However, the industrialized application of this green technique is substantially limited by the low photocatalytic efficiency. Based on our previous work, it is proposed a new method to design highly efficient solar-driven photocatalysts composites loaded with spatial dual-cocatalysts in this proposal. The central idea is utilization of the excellent properties of spatial dual-cocatalysts loaded by the spontaneously separated charge carriers in ultrathin single crystalline semiconductor for effectively promoting both of the photo-induced carriers separation and surface catalytic transfer, and combining with regulation of energy level structure by bandgap engineering to improve the utilization of visible light. Based on density functional theory calculations, the ultrathin single-crystalline semiconductor matrix, which have the advantage of both shortening volume diffusion path of photo-generated charge to the surface-reactive sites and the spontaneously isolated carriers, will be fabricated by hydrothermal method or solvothermal method. On this basis, the novel photocatalysts composites with separated dual-cocatalysts will be designed and prepared via selectively photo-deposition, and combining with semiconductor combination. The as-prepared photocatalysts will be detailedly characterized by various analysis techniques. The solar-driven water-splitting activities of these novel photocatalysts composites with separated dual-cocatalysts and the relationship between the solar-driven performance and the structure of photocatalysts composites, as well as the mechanism of solar-driven water-splitting reaction will be investigated and elucidated. In addition, this project will yield several highly efficient photocatalysts for hydrogen from solar-driven water splitting. We anticipate the studies in this proposal will advance our fundamental understanding of charge separation in a desired and efficient manner, and provide some new theoretical and technical basis for the designing and preparation of high-performance solar-driven photocatalytic materials.

光解水效率低是制约这一绿色制氢技术实际应用的瓶颈。针对这一难题，本项目拟基于 “利用超薄单晶半导体电荷自发分离特性负载双助催化剂，协同促进光生电荷空间分离和表面催化转移”的理念，开展高效太阳能驱动制氢复合光催化材料的设计和制备研究。拟设计及制备具有光生电荷自发空间分离特性的超薄单晶半导体，探讨电荷自发空间分离性能与超薄单晶半导体的结构、组成之间的联系；在此基础上，通过选择性光沉积，负载空间分离的双助催化剂，结合半导体复合方法，协同强化可见光吸收利用，从而构筑新型双助催化剂负载的复合光催化材料。系统分析所制复合光催化材料的组成、结构和性质，考察其太阳能驱动光解水产氢性能，解析光催化材料的结构、性质与性能之间的关系，并探究其光解水产氢电荷转移机制及催化机理。通过本项目的成功实施，不仅有望丰富对光生电荷分离的认识，而且可望研制出高效太阳能驱动制氢复合光催化材料，为开发新型光催化剂提供重要的参考。

氢能是公认的清洁能源，低成本的制备绿氢是氢能大规模应用的关键。本项目围绕高效太阳能驱动光解水制氢、新能源电解水制氢，开展了系列研究：.1.制备出接近100%暴露{010}高活性晶面的TiO2纳米带，利用其光生电荷自发分离特性，通过原位光沉积，制得了双助催化剂空间分离负载的暴露{010}高活性晶面的TiO2纳米带复合光催化材料，实现了锐钛矿TiO2全分解水；.2.制得了暴露（001）高能晶面的超薄CdS纳米带。负载廉价金属镍作为助催化剂时，可见光（λ＞400 nm）产氢速率高达417.5 mmol/ h/g；在碱性反应条件，负载廉价铜作助催化剂时，能够高选择性氧化乙醇C-C增长耦合高效析氢，为生物质的高效利用提供了新思路。制备出由暴露（001）晶面超薄纳米页构筑的CdS纳米花，并研究了其形成机理。.3.研制出4种廉价双金属析氢、析氧催化材料，制备出产氢量500 Nm3/h的工业碱性电解水制氢成套装置，单位制氢直流电耗约3.8 kWh/Nm3，处于碱性电解水行业领先水平；.4.设计出新型碱性电解槽结构，构建出面向风、光等新能源消纳应用的高压碱性电解水制氢示范样机，单位制氢直流电耗仅约3.7 kWh/Nm3，并实现了超低温超快速启动。. 本课题从绿氢的高效低成本制取入手，获得了3种具有良好光催化活性的光催化材料；系列廉价双金属析氢、析氧电极，并初步实现了工程化应用，有望突破制约碱性电解水制氢大规模应用的能耗高、响应慢等两大瓶颈，助力实现双碳战略。