Ni@NiOx/中空多孔主体光催化剂的矿物模板法设计合成及产氢性能研究

With semiconductor photocatalysts, photocatalytic H2 evolution from water is one of the best ways to solve the problems of energy shortage and environmental pollution. For the problems of low efficiency of light absorption and high cost of noble metal cocatalysts, this project is to synthesis the hollow, porous main photocatalyst based on the template of natural attapulgite for improving the light absorption, firstly. Then, the novel and non noble metal Ni@NiOx cocatalyst which is based on theory calculation and work function theory, will be loaded on the surface of main photocatalyst by solvent thermal method and calcination method. Ni core will improve the photogenerated charges separation efficiency by capturing photogenerated electrons. The defect state and effective adsorption to OH- of NiOx shell will effectively reduce H2 evolution potential. The photocatalytic H2 evolution efficiency from water splitting will be improved by synergistic effect of Ni@NiOx cocatalyst and the hollow and porous structure of photocatalyst. In order to make clear the effect of Ni@NiOx on main photocatalyst, the properties of photogenerated charges (the law of generation, separation and recombination of photogenerated charges) in Ni@NiOx/hollow porous main photocatalyst and H2 evolution potential will be thoroughly and systematically studied by surface photovoltage and photoelectric chemical measurements. The structure activity relationship of the Ni@NiOx/the hollow and porous main catalyst system (interface and surface structure, pore size and defect degree), the behavior of photogenerated charges and photocatalystic H2 evolution efficiency will be explored. Eventually, experimental and theoretical improvements of the photocatalystic system cocatalyst based on nickel/main catalyst model will be obtained to provide the basis for optimizing the structure and properties of photocatalystic system for H2 evolution.

利用半导体催化剂，光解水产氢是同时解决能源短缺和环境污染问题的理想途径之一。针对目前催化剂光利用率低，贵金属助催化剂高成本的问题，本项目拟首先以天然凹凸棒石为模板可控制备中空多孔的主体催化剂，提高光利用率。再根据理论计算及功函理论为筛选依据，采用溶剂热和煅烧的方法在主体催化剂的表面负载新颖的非贵金属核壳助催化剂Ni@NiOx，构筑Ni@NiOx助催化剂/中空多孔主体催化剂复合高效产氢体系。Ni核捕获光生电子，有效提高电荷分离效率；NiOx壳的缺陷态及对氢氧根的吸附，有效降低产氢过电势。采用表面光伏及光电化学测试技术深入系统的研究Ni@NiOx对主体催化剂光生电荷特性及产氢过电势的影响机制。探索复合体系的结构（界面与表面结构、晶粒、缺陷度等）、光生电荷特性、光解水产氢效率三者之间的构效关系。从实验和理论上完善镍基助催化剂/主体催化剂的模型，为优化光解水产氢催化剂的结构及性能提供科学依据。

利用半导体催化剂光解水产氢是同时解决能源短缺和环境污染问题的理想途径之一。针对目前催化剂光利用率低，贵金属助催化剂高成本的问题。本项目以天然凹凸棒石和二氧化硅为模板制备了中空多孔的主体催化剂，提高了光的利用率。再根据理论计算及功函理论为筛选依据，采用溶剂热和煅烧的方法在主体催化剂的表面负载非贵金属助催化剂Ni@NiO,构筑了Ni@NiO/C3N4，Ni@NiO/CdS, Ni@NiO/TiO2/ATP复合产氢光催化体系。研究了Ni及Ni@NiO对于主体催化剂产氢活性的影响。非贵金属Ni提高了主体催化剂光催化产氢的活性，NiO的负载使得主体催化剂的光催化活性进一步明显提高。通过表面表面光电压研究了Ni及Ni@NiO助催化剂对于主体催化剂光生电荷的影响。结果表明非贵金属Ni捕获光生电子，提高了主体催化剂光生电荷的分离效率，延长了光生电子的寿命，提高了主体催化剂光催化产氢活性。而NiO的负载对光生电荷分离效率的影响有限。NiO明显提高光催化产氢活性的原因并不是因为其提高了光生电荷的分离效率。本项目利用电化学测试技术研究了非贵金属助催化剂Ni及Ni@NiO对主体催化剂产氢过电势的影响。研究结果表明NiO(含有大量缺陷态)主要是弱化H-O键，吸附氢氧根，加速水的解离，从而降低表面产氢过电势的作用，产氢过电势的降低进一步明显改善主体催化剂光催化产氢的活性。本项目对于揭示Ni基助催化剂的作用规律，从实验和理论上完善镍基助催化剂/主体催化剂的模型，为优化光解水产氢催化剂的结构及性能具有一定意义。