Enhanced photocatalytic properties of TiO2 nanosheets@2D layered black phosphorus composite with high stability under hydro-oxygen environment

Recent Progress on Synthesis and Properties of Black Phosphorus and Phosphorene As New-Age Nanomaterials for Water Decontamination

Concerted efforts have been made in recent years to find solutions to water and wastewater treatment challenges and eliminate the difficulties associated with treatment methods. Various techniques are used to ensure the recycling and reuse of water resources. Owing to their excellent chemical, physical, and biological properties, nanomaterials play an important role when integrated into water/wastewater treatment technologies. Black phosphorus (BP) is a potential nanomaterial candidate for water and wastewater treatment, especially its monolayer 2D derivative called phosphorene. Phosphorene offers relative adjustability in its direct bandgap, high charge carrier mobility, and improved in-plane anisotropy compared to the most extensively studied 2D nanomaterials. In this study, we examined the physical and chemical characteristics and synthetic processes of BP and phosphorene. We provide an overview of the latest advancements in the main applications of BP and phosphorene in water/wastewater treatment, which are categorized as photocatalytic, adsorption, and membrane filtration processes. Additionally, we explore the existing difficulties in the integration of BP and phosphorene into water/wastewater treatment technologies and prospects for future research in this field. In summary, this review highlights the ongoing necessity for significant research efforts on the integration of BP and phosphorene in water and wastewater applications.

Photocatalytic water splitting for hydrogen production with high efficiency monolayer In2Te5: a theoretical study

Employing density functional theory (DFT) calculations, we explore the excellent performance of two-dimensional (2D) semiconductor In2Te5 in photocatalytic water splitting at the theoretical level. The calculated results illustrate that 2D In2Te5 is a direct band gap semiconductor with a moderate band gap value and an ultrahigh optical absorption coefficient in the visible light region. It was found that its conduction band edge is higher than the reduction potential of water (-4.44 eV), which proves that it can split water to produce hydrogen. Furthermore, its excellent hydrogen evolution activity can be tuned under an appropriate biaxial strain. In addition, 2D In2Te5 shows a remarkable photo-generated current, suggesting that electrons and holes can be separated efficiently. Our results offer a superior candidate material for realizing photocatalytic water splitting for hydrogen evolution.

Oxygen-deficient titanium dioxide-loaded black phosphorus nanosheets for synergistic photothermal and sonodynamic cancer therapy

Malignant tumors, particularly those located in deep tissues, have always been a grievous threat to human health. Sonodynamic therapy (SDT) has recently attracted great attention due to deep tissue penetration. However, the lack of effective sonosensitizers and the poor therapeutic efficacy severely limit their wider use. Herein, dual-functionalized black phosphorus nanosheets (BP@PEI-PEG, i.e., PPBP) integrating black oxygen-deficient titanium dioxide particles (B-TiO₂) were successfully constructed (PPBP-B-TiO₂) for synergistic photothermal (PTT)/sonodynamic therapy. In these nanocomposites, black titanium dioxide can enhance the separation of electrons (e^-) and holes (h⁺) due to the oxygen-deficient structure and significantly improves the production of reactive oxygen species (ROS) for SDT, while the BP nanosheets endow the nanocomposites with a higher photothermal conversion capability for photothermal therapy (η = 44.1%) which can prolong the blood circulation and improve the O₂ supply. In vivo experiments prove that PPBP-B-TiO₂ nanocomposites exhibited outstanding tumor inhibition efficacy and excellent biocompatibility. This work provides a prospective platform for combined photothermal/sonodynamic cancer therapy.

Silver-decorated black phosphorus: a synergistic antibacterial strategy

Black phosphorus (BP) exhibits great potential as antibacterial materials due to its unique photocatalytic activity. However, the unsatisfactory optical absorption and quick recombination of photoinduced electron-hole pairs restrain its photocatalytic antibacterial performance. In this work, silver nanoparticles (AgNPs) were decorated on BP to construct BP@AgNPs nanohybrids and then introduced into poly-l-lactic acid scaffold. Combining the tunable bandgap of BP and the LSPR effect of AgNPs, BP@AgNPs nanohybrids displayed the broaden visible light absorption. Furthermore, AgNPs acted as electron acceptors could accelerate charge transfer and suppress electron-hole recombination. Therefore, BP@AgNPs nanohybrids achieved synergistically enhanced photocatalytic antibacterial activity under visible light irradiation. Fluorescence probe experiment verified that BP@AgNPs promoted the generation of reactive oxygen species, which could disrupt bacteria membrane, damage DNA and oxide proteins, and finally lead to bacteria apoptosis. As a result, the scaffold possessed strong antibacterial efficiency with a bactericidal rate of 97% under light irradiation. Moreover, the scaffold also exhibited good cytocompatibility. This work highlighted a new strategy to develop photocatalytic antibacterial scaffold for bone implant application.

Preparation of LDO@TiO2 core-shell nanosheets for enhanced photocatalytic degradation of organic pollution

TiO₂-based nanosheet materials with a core-shell structure are expected to be one of the promising photocatalysts for the degradation of organic pollution. It is a challenge to synthesize TiO₂ by the desired nucleation and growth process, so most reported TiO₂ core-shell photocatalysts are prepared using TiO₂ as a core material. Layered double hydroxides (LDHs) are considered ideal platforms to grow TiO₂in situ and further serve as additional components to improve the separation of photogenerated charge carriers. In this work, we report the design and fabrication of anatase TiO₂-coated ZnAl-layered double oxide (LDO@TiO₂) nanosheets, which involve the in situ growth of TiO₂ on ZnAl-LDH followed by subsequent calcination treatment. The resulting LDO@TiO₂ photocatalyst yields typical core-shell nanosheet morphology with a mesoporous structure, exhibiting excellent photodegradation and mineralization efficiency for organic pollution.

2D phosphorene nanosheets, quantum dots, nanoribbons: synthesis and biomedical applications

Phosphorene, also known as black phosphorus (BP), is a two-dimensional (2D) material that has gained significant attention in several areas of current research. Its unique properties such as outstanding surface activity, an adjustable bandgap width, favorable on/off current ratios, infrared-light responsiveness, good biocompatibility, and fast biodegradation differentiate this material from other two-dimensional materials. The application of BP in the biomedical field has been rapidly emerging over the past few years. This article aimed to provide a comprehensive review of the recent progress on the unique properties and extensive medical applications for BP in bone, nerve, skin, kidney, cancer, and biosensing related treatment. The details of applications of BP in these fields were summarized and discussed.

Silver-Decorated TiO2 Inverse Opal Structure for Visible Light-Induced Photocatalytic Degradation of Organic Pollutants and Hydrogen Evolution

TiO₂ inverse opal (TIO) structures were prepared by the conventional wet chemical method, resulting in well-formed structures for photocatalytic activity. The obtained structures were functionalized with liquid flame spray-deposited silver nanoparticles (AgNPs). The nanocomposites of TIO and AgNPs were extensively characterized by various spectroscopies such as UV, Raman, X-ray diffraction, energy-dispersive spectroscopy, and X-ray photoelectron spectroscopy combined with microscopic methods such as scanning electron microscopy, transmission electron microscopy (TEM), and high-resolution TEM. The characterization confirmed that high-quality heterostructures had been fabricated with evenly and uniformly distributed AgNPs. Fabrication of anatase TiO₂ was confirmed, and formation of AgNPs was verified with surface plasmon resonant properties. The photocatalytic activity results measured in the gas phase showed that deposition of AgNPs increases photocatalytic activity both under UVA and visible light excitation; moreover, enhanced hydrogen evolution was demonstrated under visible light.

High-performance TiO2 photocatalyst produced by the versatile functions of the tiny bimetallic MOF-derived NiCoS-porous carbon cocatalyst

Bimetallic zeolitic imidazolate framework (NiCo-ZIF)-templated NiCoS-porous carbon (PC) at only 0.2 at% exhibited versatile effects on the morphology as well as the photocatalytic hydrogen performance of TiO₂ nanocrystals.

An elemental S/P photocatalyst for hydrogen evolution from water under visible to near-infrared light irradiation

An elemental S/P photocatalyst exhibits enhanced photocatalytic activity for hydrogen evolution from water due to the co-catalyst effect of S.