Synthesis of Bimetallic BiPO4/ZnO Nanocomposite: Enhanced Photocatalytic Dye Degradation and Antibacterial Applications

Multidrug-resistant strains (MDRs) are becoming a major concern in a variety of settings, including water treatment and the medical industry. Well-dispersed catalysts such as BiPO₄, ZnO nanoparticles (NPs), and different ratios of BiPO₄/ZnO nanocomposites (NCs) were synthesized through hydrothermal treatments. The morphological behavior of the prepared catalysts was characterized using XRD, Raman spectra, PL, UV-Vis diffuse reflectance spectroscopy (UV-DRS), SEM, EDX, and Fe-SEM. MDRs were isolated and identified by the 16s rDNA technique as belonging to B. flexus, B. filamentosus, P. stutzeri, and A. baumannii. The antibacterial activity against MDRs and the photocatalytic methylene blue (MB) dye degradation activity of the synthesized NPs and NCs were studied. The results demonstrate that the prepared BiPO₄/ZnO-NCs (B1Z4-75:300; NCs-4) caused a maximum growth inhibition of 20 mm against A. baumannii and a minimum growth inhibition of 12 mm against B. filamentosus at 80 μg mL^-1 concentrations of the NPs and NCs. Thus, NCs-4 might be a suitable alternative to further explore and develop as an antibacterial agent. The obtained results statistically justified the data (p ≤ 0.05) via one-way analysis of variance (ANOVA). According to the results of the antibacterial and photocatalytic study, we selected the best bimetallic NCs-4 for the photoexcited antibacterial effect of MDRs, including Gram ve⁺ and Gram ve^- strains, via UV light irradiation. The flower-like NCs-4 composites showed more effectiveness than those of BiPO₄, ZnO, and other ratios of NCs. The results encourage the development of flower-like NCs-4 to enhance the photocatalytic antibacterial technique for water purification.

Red Phosphorus: An Up-and-Coming Photocatalyst on the Horizon for Sustainable Energy Development and Environmental Remediation

Photocatalysis is a perennial solution that promises to resolve deep-rooted challenges related to environmental pollution and energy deficit through harvesting the inexhaustible and renewable solar energy. To date, a cornucopia of photocatalytic materials has been investigated with the research wave presently steered by the development of novel, affordable, and effective metal-free semiconductors with fascinating physicochemical and semiconducting characteristics. Coincidentally, the recently emerged red phosphorus (RP) semiconductor finds itself fitting perfectly into this category ascribed to its earth abundant, low-cost, and metal-free nature. More notably, the renowned red allotrope of the phosphorus family is spectacularly bestowed with strengthened optical absorption features, propitious electronic band configuration, and ease of functionalization and modification as well as high stability. Comprehensively detailing RP's roles and implications in photocatalysis, this review article will first include information on different RP allotropes and their chemical structures, followed by the meticulous scrutiny of their physicochemical and semiconducting properties such as electronic band structure, optical absorption features, and charge carrier dynamics. Besides that, state-of-the-art synthesis strategies for developing various RP allotropes and RP-based photocatalytic systems will also be outlined. In addition, modification or functionalization of RP with other semiconductors for promoting effective photocatalytic applications will be discussed to assess its versatility and feasibility as a high-performing photocatalytic system. Lastly, the challenges facing RP photocatalysts and future research directions will be included to propel the feasible development of RP-based systems with considerably augmented photocatalytic efficiency. This review article aspires to facilitate the rational development of multifunctional RP-based photocatalytic systems by widening the cognizance of rational engineering as well as to fine-tune the electronic, optical, and charge carrier properties of RP.

Bi2O2CO3/red phosphorus S-scheme heterojunction for H2 evolution and Cr(VI) reduction

Red phosphorus (RP) has a suitable energy band structure and excellent photocatalytic properties. However, there are some problems, such as low quantum efficiency and serious photogenerated electron-hole recombination. The S-scheme heterostructure shows great potential in facilitating the separation and transfer of photogenerated carriers and obtaining strong photo-redox ability. Herein, hydrothermally treated red phosphorus (HRP) was combined with Bi₂O₂CO₃ to construct Bi₂O₂CO₃/HRP S-scheme heterojunction composite. The Bi₂O₂CO₃ content was optimized, and the 5 %Bi₂O₂CO₃/HRP composite obtained at 5 %Bi₂O₂CO₃ mass fraction exhibited the strongest photoreduction ability. The Cr(VI) photoreduction and photolytic hydrogen production rates were as high as 0.22 min^-1 and 157.2 μmol •h^-1, which were 7.3 and 3.0 times higher than those of HRP, respectively. The promoted photocatalytic activity could be attributed to the formation of S-scheme heterojunctions, which accelerated the separation and transfer of useful photogenerated electron-hole pairs, while enhancing the recombination of relatively useless photogenerated electron-hole pairs, thereby resulting in the highest photocurrent density (17.3 μA/cm²) of the 5 %Bi₂O₂CO₃/HRP composite, which was 1.6 and 4.3 times higher than pure Bi₂O₂CO₃ (10.5 μA/cm²) and pure HRP (4.0 μA/cm²), respectively. This work would provide an advanced approach to enhance the photocatalytic activity of RP.

Preparation and photocatalytic application of a S, Nd double doped nano-TiO2 photocatalyst

Nowadays, water pollution is getting more and more severe in society, and recently the rational use of photocatalytic technology to treat sewage has become a hot spot for research. Because of the low-cost and environmental friendliness of nano-TiO₂, it has attracted widespread attention. In this paper, we dope sulfur and neodymium into nano-titanium dioxide via a sol–gel method. The synthesized S, Nd-codoped-TiO₂ was characterized via transmission electron microscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, EDS and N₂ adsorption–desorption isotherms. Then the real-life dye reactive red (X-3B) was used as the target degradant to compare the levels of practicality of single-doped and double-doped photocatalysts. The results showed that the photocatalytic activity of S, Nd-codoped-TiO₂ was significantly higher than that of Nd–TiO₂. The double-doped photocatalyst was transformed from anatase to rutile, and the bandgap was reduced considerably. The responding ability to visible light also increased, so S, Nd-codoped-TiO₂ has obvious advantages and has better degradation efficiency for the target degradation products. Under xenon lamp irradiation and pH = 4 conditions, the degradation of reactive red using the new catalyst reached 93.2%. The new catalyst has high practicality and also indicates a new direction for wastewater treatment.

Nowadays, water pollution is getting more and more severe in society, and recently the rational use of photocatalytic technology to treat sewage has become a hot spot for research.

Earth-abundant stable elemental semiconductor red phosphorus-based hybrids for environmental remediation and energy storage applications

The photocatalytic generation of hydrogen and the photodegradation of organic dyes in wastewater using solar light, preferably visible light, have attracted considerable interest because they are clean, low-cost, and environmentally friendly processes.