Global energy crisis and environmental contamination have become hot topics in recent years. Hydrogen energy with the merits of high-value and environmental-friendly has attracted abundant attention. Photocatalytic hydrogen evolution over semiconductors is considered to be the most economic technology and shows great potential for large scale application. Therefore, it is critical to develop high-performance photocatalysts. However, single-component suffers from sluggish reaction kinetics due to the severe charge carriers recombination and high apparent activation energy of water splitting reaction. Construction semiconductor heterojunctions have shown great potential in developing high-performance photocatalysts. In particular, the decoration of noble metal cocatalysts obviously promotes the activity of photocatalysts. However, the high cost and scarcity restricted its further application. Therefore, it is imperative to explore noble metal free cocatalysts to substitute the noble metals. Co-based as the transition metal materials owing to low cost and excellent electrical conductivity have been intensively studied. Moreover, construction of hollow structured materials is another way to effectively promote the hydrogen activity. In our work, hollow Co9S8 polyhedron is developed by MOF-derived approaches, and Zn0.5Cd0.5S nanospheres are in-situ grown on the surface of Co9S8 co-catalyst, which effectively avoids the self-aggregation. The photocatalytic hydrogen performance of Zn0.5Cd0.5S is obviously improved after introducing Co9S8 species. The direction of built-in electronic field is orientated from Zn0.5Cd0.5S to Co9S8, which can be confirmed by the surface work function. The photoinduced electrons of Zn0.5Cd0.5S on valence band are transferred to the conduction band while the photoexcited holes are trapped by Co9S8 under the influence of built in electronic field, effectively expediting the photogenerated charge carriers separation and improving the photocatalytic hydrogen activity. Moreover, the photo-corrosion of Zn0.5Cd0.5S is largely prohibited. Furthermore, the mechanism is investigated by time-resolved fluorescence spectra, surface photovoltage spectroscopy and electron spin resonance techniques. This work aimed to present a new strategy on the design of photocatalysts with multilevel structure.

Hollow Co9S8 nanocages incorporating with Zn0.5Cd0.5S for photocatalytic hydrogen evolution

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.