基于纳米压印技术的Cu2ZnSnS4@CdS核壳纳米柱阵列光阴极制备及其太阳能制氢研究

Photoelectrochemical water splitting is one of the promising method for solving energy crisis. Development of efficient and low-cost photoelectrodes is essential for a practical application of photoelectrochemical water splitting. Cu2ZnSnS4(CZTS) has attracted considerable attention as a promising photocathode for solar water splitting due to its suitable conduction band position, abundance, and nontoxicity. However, the performance of CZTS photocathodes for water splitting is still low at present due to the serious carrier recombination. In this proposal, CZTS@CdS core-shell nanopillar array photocathodes will be prepared by nanoimprint lithography and the carrier separation efficiency of CZTS photocathodes will be improved by combining three-dimensional p-n junction with nanopillar structure. The effects of array size, CdS thickness and p-n junction interface on the carrier separation efficiency will be investigated and the separation, transmission and surface reaction mechanism of photogenerated carriers in the core-shell nanopillar array structure will also be revealed. The serious carrier recombination will be resolved by the optimal design of the core-shell structure and the interface charge transfer, and the efficiency of photoelectrochemical hydrogen production will be improved remarkably. These studies has a great significance to produce high performance CZTS photocathode and finally realize the application of photoelectrochemical water splitting.

太阳能光电化学分解水制氢是解决能源危机的理想方式之一，开发高效廉价的光电极是实现应用的关键。Cu2ZnSnS4(CZTS)具有导带位置合适，廉价无毒等优点，是一种非常有应用潜力的光阴极材料。然而，目前CZTS光阴极的光电化学产氢性能较差，主要原因在于光生载流子复合严重。本项目拟通过纳米压印技术制备CZTS@CdS核壳纳米柱阵列光阴极，借助三维结构p-n结与纳米柱结构有机结合提高光生载流子的分离效率。通过调控CZTS阵列尺寸、CdS壳层厚度以及p-n结界面性质，研究其对CZTS光阴极光生载流子分离效率的影响机制，揭示光生载流子在核壳纳米柱阵列结构中的分离、传输和表面反应机理。并通过核壳结构以及界面电荷传输进一步优化设计，显著改善CZTS光阴极光生载流子复合严重问题，从而大幅提高CZTS光阴极的光电化学产氢性能。本项目研究对于获得高性能CZTS光阴极并最终实现太阳能分解水应用具有重要意义。

光催化分解水制氢在解决能源问题方面具有应用潜力。要实现分解水制氢应用，关键在于开发出高效的半导体光催化材料。本项目以多元硫化物Cu2ZnSnS4和ZnIn2S4为研究对象，分别利用元素替位取代、异质结形貌调控以及负载单原子助催化剂等方法提升了其光催化产氢活性，并揭示了催化性能增强机理。具体内容如下：(1)利用Ag替位取代部分Cu使Cu2ZnSnS4光阴极光电化学分解水光电流提高到3.78 mA/cm2 (0 VRHE偏压)，开启电势提升至0.33 VRHE。结晶质量改善和CuZn反位缺陷减少是光电流能提升的两个原因。除上述两因素外，价带变正是开启电势增大的另一原因。(2)构建了AgIn5S8/ZnIn2S4 0D/2D以及CuInS2/ZnIn2S4 2D/2D异质结，利用异质结形貌优势提高了ZnIn2S4的光生载流子分离效率，同时使其可见光吸收范围拓展至800 nm左右。ZnIn2S4产氢速率最优达到3430.2 μmol•g-1•h-1，420 nm处产氢外量子效率为12.4%。(3)借助硫空位缺陷限域效应实现了Ni助催化剂在ZnIn2S4表面的单原子分散。单原子Ni助催化剂和硫空位缺陷协同提升了光生载流子分离效率并延长了载流子寿命，从而显著增强了ZnIn2S4产氢性能。产氢速率最优达到1786.9 μmol•g-1•h-1，420 nm处产氢外量子效率为9.6%。