Jiansheng Zhang

This review analyses the key factors that govern the state-of-the-art catalytic pyrolysis of polystyrene, providing useful design rules for making catalysts aimed at specific value-added products.

Optimizing the separation efficiency of photo-generated electron-hole pairs is an essential concern in the subject matter of photocatalytic hydrogen generation. Zn0.5Cd0.5S@NiO/Ni-GC (ZCS@NG) as a photocatalyst is synthetized to increase the photogenerated carriers’ separation efficiency and tailor the photocatalytic H2 evolution. The ZCS@NG-10 exhibits superior photocatalytic performance with highest H2 yield of 25.1 mmol·g-1·h-1, which is 6.1 times greater than that of ZCS (4.1 mmol·g-1·h-1). The heterojunction significantly increases the photocatalytic production capacity of hydrogen and also the separation and transfer efficiency of photo-generated carriers, as demonstrated via transient photocurrent, electrochemical impedance spectroscopy, and photoluminescence tests. The insight from this work will offer a new strategy for creating inexpensive photocatalysts that have excellent catalytic activity.

Photocatalytic hydrogen production is considered to be a green method to obtain green energy hydrogen. However, the low efficiency of photocatalyst and the instability of recycling limit its use. Rod-shaped CdS was effectively fabricated via a hydrothermal technique, and the NCP/CdS catalyst was subsequently created using an in-situ growth process. Under visible light irradiation, the NCP/CdS catalyst exhibits excellent hydrogen production performance. The absorbance and carrier dissociation efficiency of NCP/CdS were investigated using UV-Vis, photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS) techniques, and a hypothesis for the photocatalytic mechanism was suggested. Under visible light (λ ≥ 420 nm), the photocatalytic hydrogen production rate can reach up to 5.503 mmol/g/h, which is 12.91 times that of pure CdS (0.4263 mmol/g/h). The benefits are primarily seen in the following: enhanced visible light absorption, increased surface area, and effective transfer of photogenerated electrons from CdS to NCP at the interface. These factors together promote the significant improvement of hydrogen production rate. The NCP/CdS hybrids synthesized through this cost-effective and efficient process demonstrate significant promise for use in photocatalytic hydrogen evolution.

The S-vacancy-rich Vs-Zn0.5Cd0.5S/NiOOH (Vs-ZCS/NiOOH) heterojunction composite was synthesized by simple solvent thermal and in situ growth methods. Under the synergistic effect of sulfur vacancies and heterostructures, Vs-ZCS/NiOOH-5 exhibited the best photocatalytic hydrogen evolution performance of 53.2 mmol·g-1·h-1, which was 10.4 times higher than that of ZCS monomer, and also superior to that of Vs-ZCS (13.0 mmol·g-1·h-1) and ZCS/NiOOH-5 (16.3 mmol·g-1·h-1). In addition, a series of experimental results showed that the synergistic effect of the two can effectively inhibit the complexation of photogenerated carriers and promote charge separation and transfer, thus improving the photocatalytic hydrogen production performance of the materials. This strategy also provides a different perspective for the improvement of ZCS-based catalysts.