Promoting Photodegradation Efficiency via a Heterojunction Photocatalyst Combining with Oxygen Direct and Fast Diffusion from the Gas Phase to Active Catalytic Sites

Abstract

The low solubility of oxygen in solution is the main obstacle for the biodegradation of organic pollutants in wastewater. To address this problem, inspired by the degradation mechanism of aerobic bacteria toward organic pollutants, a novel photodegradation system was presented and operated by a heterojunction photocatalyst combining with a hydrophobic triphase interface, allowing oxygen to directly diffuse from the gas phase to active catalytic sites submersed in polluted solutions. Especially, the heterojunction photocatalyst was fabricated by graphitic carbon nitride nanosheets (C 3 N 4 NS) sensitized with 5,10,15,20-tetrakis(4-carboxylphenyl)porphyrin (TCPP). The resulting photocatalyst was coated on a certain part of the commercial superhydrophobic carbon paper (CP) and submersed in the polluted wastewater, while the other part of hydrophobic CP (without coating with C 3 N 4 -TCPP nanocomposite) was exposed to air to form a gas−liquid−solid tri-phase photodegradation system. With this system, the photodegradation rate was 10-fold higher than that of a conventional liquid/solid diphase system in oxygen-saturated solutions. This was, on one hand, due to the abundant oxygen on the surface of a photocatalyst coming from the fast and direct diffusion from the gas phase through the superhydrophobic nanoporous part of CP. On the other hand, the hybrid C 3 N 4 -TCPP nanocomposite enhanced the light absorption efficiency under simulated sunlight irradiation and restrained the recombination of photogenerated electron−hole. Moreover, the triphase photodegradation system was stable in aqueous solutions for a long time and can be reused almost without attenuation for five cycles, which provided a great potential to be utilized for practical wastewater treatment.

Cooperative Coupling of H2O2 Production and Organic Synthesis over a Floatable Polystyrene‐Sphere‐Supported TiO2/Bi2O3 S‐Scheme Photocatalyst

“…They can float on the solution surface, which increases light utilization and enables intimate contact with reactants. [18,19] Besides, floatable photocatalysts are easy to be separated and recycled. Thus, floatable photocatalysts are the optimal choice for photocatalytic H 2 O 2 production coupled with organic synthesis.…”

Superhydrophobic Materials: Versatility and Translational Applications

“…[ 39j,234 ] For example, the construction of superhydrophobic nanopores in carbon paper can promote the rapid and direct diffusion of oxygen from the gas phase to the active catalytic sites, which can greatly improve the efficiency of photodegradation of polluted wastewater. [ 235 ] By using a superhydrophobic pillar‐structured electrode, a solid‐liquid‐gas three‐phase interface can be formed between the electrolyte and the electrode, which enables different electrochemical behaviors. [ 236 ] Inspired by desert beetles, superwettable patterned surfaces have been fabricated and used for water harvesting.…”

Sensitive fluorescence biosensor for SARS-CoV-2 nucleocapsid protein detection in cold-chain food products based on DNA circuit and g-CNQDs@Zn-MOF

“…Among them, graphitic carbon nitrides quantum dots (g-CNQDs) are the carbon material rich in nitrogen with the graphitized structure ( Vashisht et al, 2020 ). The applieed research on g-CNQDs have been a research hotspot owing to good optical properties, water solubility, low toxicity and good biocompatibility ( Kong et al, 2020 ; Shao et al, 2019 ). An important technology for the fabrication of such QD-based fluorescence biosensors is the development of matrices to exist between the particles, which need to ensure the stable fluorescence performance and adequately optical characteristics of each QD.…”