Cationic Ni-MOF-Assembled CdS/PFC-8 Catalyst for Photocatalytic Hydrogen Production with Selective Benzyl Alcohol Oxidation under Visible Light

Abstract

Visible-light-driven photocatalytic H2 evolution coupled with oxidative organic synthesis is attracting extensive attention owing to the environmental friendliness and sustainability of these processes, which can coproduce clean H2 fuel and high-value chemicals under mild conditions without requiring sacrificial agents. Semiconductor materials and metal-organic framework (MOF) materials have been widely used in photocatalys owing to their properties and advantages. In this work, we successfully synthesized a novel effective catalyst (named CdS/PFC-8) by electrostatic self-assembly. Among the components of the CdS/PFC-8 composite, PFC-8 was a nickel-based MOF. The CdS/PFC-8 composite, as a noble metal-free catalyst, enabled excellent photocatalytic H2 evolution and benzyl alcohol oxidation under visible light. A series of catalytic characterizations were performed with the CdS/PFC-8 composite. X-ray diffraction (XRD) and scanning electron microscopy (SEM) results demonstrated the successful synthesis of the CdS/PFC-8 composite. X-ray photoelectron spectroscopy (XPS) results demonstrated the existence of an interfacial interaction between CdS nanorods and PFC-8. The optoelectronic performance was characterized by ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), photoluminescence (PL) spectroscopy, and electrochemical tests, and the results demonstrated the visible-light response and photocatalytic feasibility of the CdS/PFC-8 composite. The photocatalytic results obtained with different catalysts were compared. Under visible light, the CdS/PFC-8 composite enabled the generation of H2 with the selective oxidation of benzyl alcohol in a single reaction. It exhibited a remarkable H2 production rate of 3376 μmol•g −1 •h −1 ; further, the benzaldehyde yield was 4120 μmol•g −1 •h −1 , which is higher than that of CdS alone. Photocatalytic cycling reactions were carried out to verify the activity and stability of the catalysts. The changes in the catalysts before and after the reaction were analyzed, and the results suggested that the nickel in PFC-8 could be used as a catalytically active site to improve the catalytic activity. In addition, the possible photocatalytic reaction mechanism was discussed. This work highlights the advantages of combining the functionalities of semiconductors and MOFs to enhance the photocatalytic activity.

Electrochemical semi-hydrogenation of adiponitrile over copper nanowires as a key step for the green synthesis of nylon-6

“…10 Some progress has been made in traditional hydrogenation of ADN, but current studies rely on Raney-type catalysts or noble-metal complexes with H 2 as the hydrogen source, operating at high-temperature and pressure, posing concerns about resource cost, safety, and feedstock/ product thermal degradation. 11 Since the photo-/ electrocatalytic technology offers a mild and sustainable alternative to organic synthesis, 12,13 in particular, the electrocatalyst utilizing water as a hydrogen/oxygen source can avoid the above disadvantages existing in ADN reduction. In addition, ADN can also be produced from the electrochemical hydrogenation of acrylonitrile (AN).…”

Boosted Charge Transfer via Coordinate Bond Construction in Porphyrin Metal–Organic Framework/ZnIn2S4 Core–Shell Heterostructures

“…Nowadays, the fossil energy crisis and environmental pollution have seriously restricted the development of human society. − Photocatalytic H 2 evolution as well as pollutant degradation has been considered the potential and cost-effective technology to satisfy the growing global energy demand. − Thus, developing high-efficiency photocatalysts with enhanced charge transfer rates is an effective strategy to design more efficient photocatalytic systems. It can be considered that most of the single-component photocatalysts were subjected to serious electron–hole recombination, insufficient active sites, or weak light capacity which led to low solar-energy conversion efficiency. − The construction of heterojunctions between two suitable semiconductors has been an effective way in improving the activity of the catalytic system. − Among all the heterojunctions, the organic–inorganic composite materials can share the optical and photoelectrical performance of inorganic species and the flexibility and tunability of organic components which lead to novel properties. , However, most of the heterojunctions combined together physically via electrostatic self-assembly led to the low charge and energy transfer efficiency due to the deficient interface contact. − Therefore, the design of chemical bonding at the molecular level is an effective strategy to overcome the high interfacial charge transfer barrier between inorganic materials and organic materials and afford satisfactory performance.…”