Facile synthesis of plasmonic Ag/AgCl/polydopamine-TiO 2 fibers for efficient visible photocatalysis

Recent Advances in Plasmonic Photocatalysis Based on TiO2 and Noble Metal Nanoparticles for Energy Conversion, Environmental Remediation, and Organic Synthesis

Plasmonic photocatalysis has emerged as a prominent and growing field. It enables the efficient use of sunlight as an abundant and renewable energy source to drive a myriad of chemical reactions. For instance, plasmonic photocatalysis in materials comprising TiO₂ and plasmonic nanoparticles (NPs) enables effective charge carrier separation and the tuning of optical response to longer wavelength regions (visible and near infrared). In fact, TiO₂ -based materials and plasmonic effects are at the forefront of heterogeneous photocatalysis, having applications in energy conversion, production of liquid fuels, wastewater treatment, nitrogen fixation, and organic synthesis. This review aims to comprehensively summarize the fundamentals and to provide the guidelines for future work in the field of TiO₂ -based plasmonic photocatalysis comprising the above-mentioned applications. The concepts and state-of-the-art description of important parameters including the formation of Schottky junctions, hot electron generation and transfer, near field electromagnetic enhancement, plasmon resonance energy transfer, scattering, and photothermal heating effects have been covered in this review. Synthetic approaches and the effect of various physicochemical parameters in plasmon-mediated TiO₂ -based materials on performances are discussed. It is envisioned that this review may inspire and provide insights into the rational development of the next generation of TiO₂ -based plasmonic photocatalysts with target performances and enhanced selectivities.

Mitochondria-Targeting MoS2-Based Nanoagents for Enhanced NIR-II Photothermal-Chemodynamic Synergistic Oncotherapy

The synergy of chemodynamic therapy (CDT) and photothermal therapy (PTT) can improve anticancer efficacy, while the limited diffusion distance and the short lifetime of ^•OH still greatly restrict the therapeutic efficacy of PTT-CDT. Herein, MoS₂@PDA-Fe@PEG/TPP (MPFPT) nanosheets (NSs) with mitochondria-targeting ability were reported for enhanced PTT-CDT synergistic oncotherapy. MPFPT NSs were prepared by covalent modification of poly(ethylene glycol) (PEG) and triphenylphosphonium (TPP) on polydopamine (PDA)-Fe³⁺coated MoS₂ NSs. Co-localization experiments showed that MPFPT NSs can efficiently target mitochondria via the direction of TPP. Moreover, MPFPT NSs have good photothermal performance in the second near-infrared (NIR-II) region and can greatly accelerate the Fenton reaction from H₂O₂ to generate more hydroxyl radicals (^•OH). In vitro experimental results showed that MPFPT NSs have improved therapeutic efficacy to cancer cells than similar MoS₂-based nanoagents without mitochondria-targeting units, which can be attributed to the short distance between mitochondria and MPFPT NSs and the efficient damage of mitochondria by in situ generated ^•OH. In the 4T1 tumor-bearing mice model, MPFPT NSs demonstrated significantly enhanced therapeutic efficacy by PTT-CDT, suggesting the superiority of the mitochondria-targeting strategy. This study reveals that mitochondria-targeting MPFPT NSs are promising nanoagents for oncotherapy.

Silver nanoparticle-decorated titanium dioxide nanowire systems via bioinspired poly(L-DOPA) thin film as a surface-enhanced Raman spectroscopy (SERS) platform, and photocatalyst

Silver nanostructure decorated-titanium dioxide (TiO2) nanocomposite systems with their unique characteristics provide extraordinary performance in various applications including surface-enhanced Raman spectroscopy (SERS), and photocatalysis. Despite the recent progress, novel, simple, effective, low-cost, reducing and stabilizing agent-free, and easy-to-tune approaches are heavily demanded for the preparation of these nanocomposites. In this context, we propose the fabrication of silver nanostructure decorated TiO2 nanowires (TiO2 NWs) through a thin interphase layer of the polymer of 3,4-dihydroxyphenyl-l-alanine (PLDOPA). In the first step, TiO2 NWs were synthesized through the hydrothermal method and then a conformal thin film of PLDOPA was deposited onto the TiO2 NWs (TiO2@PLDOPA) by oxidative polymerization of l-DOPA. Having various functional groups including catechol and amine, the PLDOPA thin-film reduced the silver ions onto the TiO2 NWs and stabilized the resultant nanocomposites without the employment of any surfactant, reducing agent, and seed material. By simply tuning the amount of silver ions, we could manipulate the size, morphology, and interparticle distance of silver nanostructures decorated onto the TiO2@PLDOPA colloidal composite system (TiO2@PLDOPA@Ag NP). The TiO2@PLDOPA@Ag nanocomposite systems provided unique properties as an ideal SERS platform and photocatalyst. The optimized TiO2@PLDOPA@Ag nanosystem demonstrated a high SERS activity, reproducibility, and self-cleaning property with an enhancement factor of 5.1 × 105. As a photocatalyst, the TiO2@PLDOPA@Ag NP systems provided remarkable performance under visible light irradiation in the catalytic degradation of methylene blue.

Brilliant red X-3B uptake by a novel polycyclodextrin-modified magnetic cationic hydrogel: Performance, kinetics and mechanism

A novel polycyclodextrin-modified magnetic cationic hydrogel (PCD-MCH) was developed and its performance, kinetics and mechanism for the removal of reactive brilliant red X-3B (X-3B) were studied. The results showed that the zeta-potential of PCD-MCH was 32.8 to 16.7mV at pH3.0-10.5. The maximum X-3B adsorption capacity of PCD-MCH was 2792.3mg/g. The adsorption kinetics could be well-described by the Weber-Morris model and the homogeneous surface diffusion model (HSDM). Diffusion stages corresponding to surface or film diffusion, intra-particle or wide mesopore diffusion, and narrow mesopore/micropore diffusion occurred at 0-120, 120-480 and 480-1200min, respectively. The latter two diffusion stages were rate-controlling for X-3B adsorption kinetics. At the initial X-3B concentration of 600mg/L, the diffusion coefficient (D_s) and external mass transfer coefficient in the liquid phase (k_F) were 3×10^-11cm²/min and 4.68×10^-6cm/min, respectively. X-3B approaching the center of PCD-MCH particles could be observed at 360min. At the end of the third diffusion stage, the C_p at q/q_e=0 was 45.20mg/L, which was close to the homogeneous C_p value of 46mg/L along the radius of PCD-MCH particles. At pH3.0-10.0, PCD-MCH showed stable X-3B adsorption capacities. After five regeneration-reuse cycles, the residual adsorption capacity of regenerated PCD-MCH was higher than 892.7mg/g. The corresponding adsorption mechanism was identified as involving electrostatic interactions, cyclodextrin cavities and hydrogen bonds, of which cyclodextrin cavities showed prominent capture performance towards dye molecules through the formation of inclusion complexes.

Ternary semiconductor metal oxide blends grafted Ag@AgCl hybrid as dimensionally stable anode active layer for photoelectrochemical oxidation of organic compounds: Design strategies and photoelectric synergistic mechanism

The development of ultra-efficient, sustainable, and easily accessible anode with relative non-precious semiconducting metal oxides is highly significant for application in the practical treatment of organically polluted water. Herein, we report SnO₂, TiO₂, and Ag₂O ternary semiconductor metal oxide blend grafted Ag@AgCl hybrids, prepared with the one-step sol-gel method and applied as a dimensionally stable anode (DSA)-active layer on a SnO₂-Sb/Ti electrode. Factors affecting crystal formation, including the presence or absence of O₂ during calcination, the calcination temperature, and Ag@AgCl additive dosage were discussed. The micromorphology, phase composition, and photoelectrochemical activity of the newly designed anode were comprehensively characterized. The optimized preparation, which yielded a solid-solution structure with flat and smooth surface and well-crystallized lattice configuration, occurred in the absence of O₂ during calcination at 550 ℃ with an Ag@AgCl additive dosage of 0.2 g in the sol-gel precursor. The newly designed DSA displayed improved electrocatalysis (EC) and photoelectrical catalysis (PEC) capacity. The phenol and its TOC removal efficiency reached 90.65% and 58.17% for 10 mA/cm² current density with a metal halide lamp in 3 h. The lifespan was four times that of SnO₂-Sb/Ti electrode. This proposed DSA construction strategy may support improved EC and PEC reactivities toward the decomposition of organic pollutants.