g-C3N4/carbon dot-based nanocomposites serve as efficacious photocatalysts for environmental purification and energy generation: A review

As an "up-and-coming" two-dimensional (2D) material, black phosphorus (BP) has attracted much attention due to its abundant metal-free properties and broad application prospects in photocatalysis. This study introduces a promising sunlight-driven metal-free photocatalyst for oxytetracycline hydrochloride degradation and hexavalent chromium reduction in water and wastewater. The roles of BP quantum dots (BPQDs) in the distribution of electrons and photocatalytic performances were well identified by experimental and density functional theory (DFT) calculations. As expected, the specially designed 0D/1D structure shows unusual photocatalytic efficiency toward the degradation of oxytetracycline hydrochloride (0.0276 min−1) and reduction of hexavalent chromium (0.0404 min−1). Reactive species, namely, O2− and h+ comprised the primary photocatalytic mechanisms for oxytetracycline hydrochloride degradation. This work highlights that the combination of tubular g-C3N4 (TCN) with BPQDs facilitates the charge spatial separation in the photocatalytic process, and provides alternative strategy for design of highly active and metal-free nanomaterials toward environmental remediation and sustainable solar-to-chemical energy conversion.

1D porous tubular g-C3N4 capture black phosphorus quantum dots as 1D/0D metal-free photocatalysts for oxytetracycline hydrochloride degradation and hexavalent chromium reduction

Degradation and mineralization of ibuprofen (IBU) were investigated using Ultraviolet (UV) Light Emitting Diodes (LEDs) in TiO 2 photocatalysis. Samples of ultrapure water (UP) and a secondary treated effluent of a municipal wastewater treatment plant (WWTP), both spiked with IBU, as well as a highly concentrated IBU (230 mg L −1 ) pharmaceutical industry wastewater (PIWW), were tested in the TiO 2 /UV-LED system. Three operating parameters, namely, pH, catalyst load and number of LEDs were optimized. The process efficiency was evaluated in terms of IBU removal using high performance liquid chromatography (HPLC) and ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). Additionally, the mineralization was investigated by determining the dissolved organic carbon (DOC) content. The chemical structures of transformation products were proposed based on the data obtained using liquid chromatography with a high resolution mass spectrometer ion trap/time-of-flight (LC-MS-IT-TOF). A possible pathway of IBU degradation was accordingly suggested. Bioassays were performed using the marine bacterium Vibrio fischeri to evaluate the potential acute toxicity of original and treated wastewaters. TiO 2 heterogeneous photocatalysis was efficient to remove IBU from UP and from PIWW, and less efficient in treating the wastewater from the municipal WWTP. The acute toxicity decreased by ca. 40% after treatment, regardless of the studied matrix.

Heterogeneous Photocatalytic Degradation of Ibuprofen in Ultrapure Water, Municipal and Pharmaceutical Industry Wastewaters Using a TiO2/UV-LED System

Boosting photocatalytic degradation of tetracycline under visible light over hierarchical carbon nitride microrods with carbon vacancies.

Recently, heterogeneous photocatalysts have achieved much interest on account of their great potential applications in resolving many tough energy and environmental troubles around the world through an ecologically sustainable way. Heterogeneous nanocomposites composed of graphitic carbon nitride (g-C3 N4 ) and carbon dots (CDs) possess broad spectrum absorption, appropriate electronic band structures, rapid carrier mobility, abundant reserves, excellent chemical stability, and facile synthesis methods, which make them promising composite photocatalysts for suitable applications such as photocatalytic solar fuels production and contaminant decomposition. With the rapid development in photocatalysis by hybridization of g-C3 N4 and CDs, a systematic summary and prospection of performance improvement are urgent and meaningful. This review first focuses on various kinds of effectively synthetic methods of composites. Following, the strategies available for enhanced performance, including morphology optimization, spectral absorption improvement, ternary or quaternary composition hybrid, lateral or vertical heterostructures construction, heteroatom doping, and so forth, are fully discussed. Then, the applications mainly in efficient photocatalytic hydrogen generation, photocatalytic carbon dioxide reduction, and organic pollutants degradation are systematically demonstrated. Finally, the remaining issues and prospect of further development are proposed as some kind of guidance for powerful combination of g-C3 N4 and CDs with high efficiency to photocatalysis.

Efficient Combination of G-C 3 N 4 and CDs for Enhanced Photocatalytic Performance: A Review of Synthesis, Strategies, and Applications

Wavelength-dependent effects of carbon quantum dots on the photocatalytic activity of g-C3N4 enabled by LEDs

https://ira.lib.polyu.edu.hk/bitstream/10397/78287/1/Cai_Room_Corneal_Illuminance.pdf

The impact of room surface reflectance on corneal illuminance and rule-of-thumb equations for circadian lighting design

Spatial and spectral illumination design for energy-efficient circadian lighting

Cuttle proposed mean room surface exitance as a new interior lighting design methodology, which focuses on lit appearance rather than visual performance. A few challenges exist, among which, an eas...

Calculation and measurement of mean room surface exitance: The accuracy evaluation:

Policymakers and standardization bodies have started to make recommendations about the use of lighting products at night, with the goal of reducing negative impacts on human health. We report a ser...

https://tandfonline.com/doi/pdf/10.1080/15502724.2018.1523013

Yingying Huang

Papers

Wavelength-dependent effects of carbon quantum dots on the photocatalytic activity of g-C3N4 enabled by LEDs

The impact of room surface reflectance on corneal illuminance and rule-of-thumb equations for circadian lighting design

Spatial and spectral illumination design for energy-efficient circadian lighting

Calculation and measurement of mean room surface exitance: The accuracy evaluation:

Estimation of Possible Suppression of Melatonin Production Caused by Exterior Lighting in Commercial Business Districts in Metropolises