Visible light-responsive photocatalytic technology holds great potential in water treatment to enhance purification efficiency, as well as to augment water supply through the safe usage of unconventional water sources. This review summarizes the recent progress in the design and fabrication of visible light-responsive photocatalysts via various synthetic strategies, including the modification of traditional photocatalysts by doping, dye sensitization, or by forming a heterostructure, coupled with π-conjugated architecture, as well as the great efforts made within the exploration of novel visible light-responsive photocatalysts. Background information on the fundamentals of heterogeneous photocatalysis, the pathways of visible light-responsive photocatalysis, and the unique features of visible light-responsive photocatalysts are presented. The photocatalytic properties of the resulting visible light-responsive photocatalysts are also covered in relation to the water treatment, i.e., regarding the photocatalytic degradation of organic compounds and inorganic pollutants, as well as photocatalytic disinfection. Finally, this review concludes with a summary and perspectives on the current challenges faced and new directions in this emerging area of research.

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Recent developments in heterogeneous photocatalytic water treatment using visible light-responsive photocatalysts: a review

Fenton-like degradation of 2,4-dichlorophenol (2,4-DCP) in aqueous solution was investigated over Fe3O4 magnetic nanoparticles (MNPs) as catalyst. The obtained samples were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption–desorption isotherms, and physical property measurement system (PPMS). The catalytic results showed that Fe3O4 MNPs presented good properties for the degradation and mineralization of 2,4-DCP, achieving complete decomposition of 2,4-DCP and 51% of TOC removal after 180 min at reaction conditions of H2O2 12 mM, Fe3O4 MNPs 1.0 g/L, 2,4-DCP 100 mg/L, pH 3.0 and T 30 °C. The effect of different reaction parameters such as initial pH, H2O2 dosage, Fe3O4 MNPs addition, initial concentration of 2,4-DCP and temperature on two-stage first-order kinetics of 2,4-DCP degradation was studied. A high utilization efficiency of H2O2 calculated as 73% was observed. According to the analyses of iron leaching, reactive oxidizing species and degradation intermediates, a possible mechanistic steps of 2,4-DCP degradation dominated by OH reactions (especially by free OH in the bulk solution) were proposed. Besides, stability and reusability of Fe3O4 MNPs were tested.

Fenton-like degradation of 2,4-dichlorophenol using Fe3O4 magnetic nanoparticles

Degradation of azo dye Orange G in aqueous solutions by persulfate with ferrous ion

Critical review of advanced oxidation processes in organic wastewater treatment.

Despite its growing promise in cancer treatment, ferrotherapy has low therapeutic efficacy due to compromised Fenton catalytic efficiency in tumor milieu. We herein report a hybrid semiconducting nanozyme (HSN) with high photothermal conversion efficiency for photoacoustic (PA) imaging-guided second near-infrared photothermal ferrotherapy. HSN comprises an amphiphilic semiconducting polymer as photothermal converter, PA emitter and iron-chelating Fenton catalyst. Upon photoirradiation, HSN generates heat not only to induce cytotoxicity but also to enhance Fenton reaction. The increased ·OH generation promotes both ferroptosis and apoptosis, oxidizes HSN (42 nm) and transforms it into tiny segments (1.7 nm) with elevated intratumoral permeability. The non-invasive seamless synergism leads to amplified therapeutic effects including a deep ablation depth (9 mm), reduced expression of metastasis-related proteins and inhibition of metastasis from primary tumor to distant organs. Thereby, our study provides a generalized nanozyme strategy to compensate both ferrotherapy and phototherapeutics for complete tumor regression.

https://dr.ntu.edu.sg/bitstream/10356/146532/2/Transformable%20hybrid%20semiconducting%20polymer%20nanozyme%20for%20second%20near-infrared%20photothermal%20ferrotherapy.pdf

Transformable hybrid semiconducting polymer nanozyme for second near-infrared photothermal ferrotherapy.

Decolorization of an azo dye Orange G in aqueous solution by Fenton oxidation process: effect of system parameters and kinetic study.

Incorporating biomolecules into metal‐organic frameworks (MOFs) as exoskeletons to form biomolecules‐MOFs biohybrids has attracted great attention as an emerging class of advanced materials. Organic devices have been shown as powerful platforms for next‐generation bioelectronics, such as wearable biosensors, tissue engineering constructs, and neural interfaces. Herein, biomolecules‐incorporated MOFs as innovative gating module is realized for the first time, which is exemplified by biocatalytic precipitation (BCP)‐oriented horseradish peroxidase (HRP)‐embedded zeolitic imidazolate framework‐90 (HRP@ZIF‐90)/CdIn2S4 gated organic photoelectrochemical transistor under light illumination. In connection to a sandwich immunocomplexing targeting the model analyte human IgG, the IgG‐dependent generation of H2O2 and the tandem HRP‐triggered BCP reaction can cause the in situ blocking of the pore network of ZIF‐90, leading to variant gating effect with corresponding responses of the device. This representative biodetection achieved good analytical performance with a wide linear range and a low detection limit of 100 fg mL−1. In the view of the plentiful biomolecule‐MOF complexes and their potential interactions with organic systems, this study provides a proof‐of‐concept study for the generic development of biomolecules‐MOFs‐gated electronics and beyond.

Biomolecules‐Incorporated Metal‐Organic Frameworks Gated Light‐Sensitive Organic Photoelectrochemical Transistor for Biodetection

Tyrosinase (TYR) level in the human serum has been generally regarded as a biomarker of metastatic melanoma and vitiligo. In this work, established upon a unique poly(amido amine) (PAMAM)/polymer dots...

Polymer Dots Synergized with NiO Hole Transporting Layer and Poly(amido amine) Dendrimer: Toward Sensitive Photocathodic Detection of Tyrosinase Level in Serum

Organic photoelectrochemical transistor (OPECT) bioanalysis has recently emerged as a promising avenue for biomolecular sensing, providing insight into the next-generation of photoelectrochemical biosensing and organic bioelectronics. Herein, this work validates the direct enzymatic biocatalytic precipitation (BCP) modulation on a flower-like Bi2S3 photosensitive gate for high-efficacy OPECT operation with high transconductance (gm), which is exemplified by a prostate-specific antigen (PSA)-dependent hybridization chain reaction (HCR) and subsequent alkaline phosphatase (ALP)-enabled BCP reaction toward PSA aptasensing. It has been shown that light illumination could ideally achieve the maximized gm at zero gate bias, and BCP could efficiently modulate the device's interfacial capacitance and charge-transfer resistance, resulting in a significantly changed channel current (IDS). The as-developed OPECT aptasensor realizes good analysis performance for PSA with a detection limit of 10 fg mL-1. This work features direct BCP modulation of organic transistors and is expected to stimulate further interest in exploring advanced BCP-interfaced bioelectronics with unknown possibilities.

Hybridization Chain Reaction-Enhanced Biocatalytic Precipitation on Flower-like Bi2S3: Toward Organic Photoelectrochemical Transistor Aptasensing with High Transconductance.

Cheng-Jie Li

Papers

Decolorization of an azo dye Orange G in aqueous solution by Fenton oxidation process: effect of system parameters and kinetic study.

Biomolecules‐Incorporated Metal‐Organic Frameworks Gated Light‐Sensitive Organic Photoelectrochemical Transistor for Biodetection

Polymer Dots Synergized with NiO Hole Transporting Layer and Poly(amido amine) Dendrimer: Toward Sensitive Photocathodic Detection of Tyrosinase Level in Serum

Hybridization Chain Reaction-Enhanced Biocatalytic Precipitation on Flower-like Bi2S3: Toward Organic Photoelectrochemical Transistor Aptasensing with High Transconductance.