Shi Jinyan, Zhang Jie, Cui Zhiwei, Chu Siqi, Wang Ying, Zou Zhigang
School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, P. R. China.
Eco-materials and Renewable Energy Research Center (ERERC), National Laboratory of Solid State Microstructures, Kunshan Innovation Institute of Nanjing University, Jiangsu Key Laboratory for Nanotechnology, Nanjing, 210093, P. R. China.
Dalton Trans. 2022 Apr 12;51(15):5841-5858. doi: 10.1039/d1dt04188f.
In heterojunction photocatalytic materials, the size of the nanoparticles and electron-hole separation efficiency have a great influence on the photocatalytic hydrogen production activity. In this work, for the first time, a strategy of combining sulfur vacancy engineering and quantum size control for constructing CdS (MOF)/PI heterojunctions was reported. Sulfur-deficient CdS (MOF) nanoparticles with a size of 5-10 nm were derived from sulfurization of Cd-MOF precursors and highly dispersed on the surface of 2D polyimide (PI). The experimental and characterization results demonstrated that CdS (MOF)/PI heterojunctions possess broader and stronger light absorption towards the visible region than pristine PI. More importantly, a considerable amount of sulfur vacancies were introduced into CdS (MOF) nanoparticles. The presence of abundant surface and bulk sulfur vacancies created more unsaturated coordinated Cd 3c atoms, which increased the proportion of the (002) crystal planes that act as highly active crystal planes of CdS (MOF), providing more active reaction sites. The surface sulfur vacancy level located near the Fermi level serves as the photogenerated electron trap level, thereby increasing the efficiency of electron-hole separation and further prolonging the lifetime of photogenerated electrons. As a result, the 18%CdS(MOF)/PI heterojunction exhibited a higher hydrogen evolution rate of 8640 μmol g after 4 hours of illumination, which was 20 times higher than that of 18%CdS/PI under visible light irradiation. This work highlights the role of sulfur defects in the modification of the CdS (MOF)/PI heterojunction as a feasible strategy for improving charge separation and photocatalytic performance.
在异质结光催化材料中，纳米颗粒的尺寸和电子 - 空穴分离效率对光催化产氢活性有很大影响。在这项工作中，首次报道了一种结合硫空位工程和量子尺寸控制来构建CdS(MOF)/PI异质结的策略。尺寸为5 - 10 nm的缺硫CdS(MOF)纳米颗粒由Cd - MOF前驱体硫化得到，并高度分散在二维聚酰亚胺(PI)表面。实验和表征结果表明，CdS(MOF)/PI异质结对可见光区域具有比原始PI更宽、更强的光吸收。更重要的是，大量的硫空位被引入到CdS(MOF)纳米颗粒中。丰富的表面和体相硫空位的存在产生了更多不饱和配位的Cd 3c原子，这增加了作为CdS(MOF)高活性晶面的(002)晶面的比例，提供了更多的活性反应位点。位于费米能级附近的表面硫空位能级作为光生电子陷阱能级，从而提高了电子 - 空穴分离效率，并进一步延长了光生电子的寿命。结果，18%CdS(MOF)/PI异质结在光照4小时后表现出更高的析氢速率，为8640 μmol g，这比可见光照射下的18%CdS/PI高20倍。这项工作突出了硫缺陷在修饰CdS(MOF)/PI异质结中作为改善电荷分离和光催化性能的可行策略的作用。
