Recently, Prof. Jinlong Zhang and Associate Prof. Mingyang Xing from Key Laboratory for Advanced Materials and Institute of Fine Chemicals has made significant progress in the “Z-scheme Typed CdS/Co9S8 Hollow Cube with Efficient Solar-light-harvesting Towards Synergetic Photocatalytic Water Splitting”. This work was published on “Angewandte Chemie International Edition” (Angew. Chem. Int. Ed., 2017, 56, 2684–2688), which was finished by the group members of Prof. Jinlong Zhang, Dr. Mingyang Xing, Dr. Bocheng Qiu and Qiaohong Zhu.
To date, the solar-light-driven catalytic water splitting into H2 and O2 in the presence of a semiconductor powder is still a promising approach for storing solar energy as chemical energy. As an efficient photocatalytic water splitting system, Z-scheme has attracted a wide attention in recent years, which involves two-step photo-excitation using two different semiconductor powders and a reversible donor/acceptor pair (shuttle redox mediator). However, the suppressing backward reactions involving shuttle redox mediators has always been one of the biggest challenges in the development of efficient Z-scheme water splitting systems. In this regard, redox-mediator-free Z-scheme systems are the ultimate solution, although the back electron transfer between two different semiconductors is thermodynamically downhill. In addition, the poor solar light harvesting of nanoparticles is another obstacle to enhance the solar utilization over the traditional Z-scheme typed heterojunction. There is thereby an urgent need but it is still a significant challenge to develop efficient redox-mediator-free Z-scheme systems with a weak back electron transfer that can operate under a solar light.
Here, we develop a novel strategy for the design and synthesis of Co9S8 hollow cubes decorated by CdS QDs hybrid Z-scheme system, which is obtained through a simple hydrothermal method containing dimethyl sulfoxide (DMSO) as solvent, and hollow Co(OH)2 cube as a cubic template. The solvent of DMSO is not only served as sulfur source to react with Cd2+ to produce CdS QDs, but also used as the anion exchange reagent to react with easy-prepared Co(OH)2 cubes. The as-prepared CdS/Co9S8 hollow cubes exhibit efficient solar-light-harvesting, as well as impressively enhanced hydrogen evolution reaction (HER) activity and stability under the solar light irradiation. The hydrogen evolution rate over hollow CdS/Co9S8 is 134 and 9.1 times higher than that of pure Co9S8 and CdS QDs under solar light, respectively. An efficient Z-scheme building and the multiple reflections of solar light into the cavity of hollow cubes are responsible for the substantially enhanced HER activity and stability. It is important to highlight that this is the first report on building hollow Co9S8 based Z-scheme system for photocatalytic water splitting, which gives full play to the advantages of solar-light-harvesting and charges separation. We believe that the research provides a promising concept of combining the advantages of multiple light-reflection and Z-scheme charge transfer to fabricate new materials with improved photocatalytic activity for wearable optoelectronic device, large solar installation and other applications.
This work has been supported by the State Key Research Development Program of China (2016YFA0204200), the National Nature Science Foundation of China (21577036, 21377038, 21237003) and sponsored by “Chenguang Program” supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission (14CG30, 16JC1401400) and the Fundamental Research Funds for the Central Universities (22A201514021).
