Preparation of metal-free BP/CN photocatalyst with enhanced ability for photocatalytic tetracycline degradation

Accelerating the environmental applications of black phosphorus: A review

Since its rediscovery in 2014, layered black phosphorus (BP) has received extensive attention as a new two-dimensional semiconductor. BP is a promising material with properties of a large surface-to-volume ratio, wide light absorption range, tunable band gap, and high charge carrier mobility. These unique characteristics of BP make it a promising contender for various applications, particularly in the realm of environmental applications. This literature review provides a comprehensive discussion and overview of the latest developments in utilizing BP for environmental purposes. The review starts with the applications of BP in photocatalysis including photodegradation of refractory pollutants, H2 evolution reaction (HER), and reduction of CO2 and N2. In the following section, Environmental electrocatalysis of HER and N2 reduction reaction (NRR) is discussed. In addition, BP-based environmental sensing (detection of heavy metal ions, antibiotics, mycotoxins, NOx) and eco-friendly halogen-free flame retardant are summarized as well. Finally, a thorough comprehension of the current state and potential future trends of BP-based nanomaterials for various environmental applications are presented.

Recent Advances in Black Phosphorous-Based Photocatalysts for Degradation of Emerging Contaminants

The recalcitrant nature of emerging contaminants (ECs) in aquatic environments necessitates the development of effective strategies for their remediation, given the considerable impacts they pose on both human health and the delicate balance of the ecosystem. Semiconductor-based photocatalytic technology is recognized for its dual benefits in effectively addressing both ECs and energy-related challenges simultaneously. Among the plethora of photocatalysts, black phosphorus (BP) stands as a promising nonmetallic candidate, offering a host of advantages including its tunable direct band gap, broad-spectrum light absorption capabilities, and exceptional charge mobility. Nevertheless, pristine BP frequently underperforms, primarily due to issues related to its limited ambient stability and the rapid recombination of photogenerated electron-hole pairs. To overcome these challenges, substantial research efforts have been devoted to the creation of BP-based photocatalysts in recent years. However, there is a noticeable absence of reviews regarding the advancement of BP-based materials for the degradation of ECs in aqueous solutions. Therefore, to fill this gap, a comprehensive review is undertaken. In this review, we first present an in-depth examination of the fabrication processes for bulk BP and BP nanosheets (BPNS). The review conducts a thorough analysis and comparison of the merits and limitations inherent in each method, thereby delineating the most auspicious avenues for future research. Then, in line with the pathways followed by photogenerated electron-hole pairs at the interface, BP-based photocatalysts are systematically categorized into heterojunctions (Type I, Type II, Z-scheme, and S-scheme) and hybrids, and their photocatalytic performances against various ECs and the corresponding degradation mechanisms are comprehensively summarized. Finally, this review presents personal insights into the prospective avenues for advancing the field of BP-based photocatalysts for ECs remediation.

Progress on simultaneous photocatalytic degradation of pollutants and production of clean energy: A review

In the current era of severe energy and environmental crises, the need for efficient and sustainable methods to control pollution and promote resource recycling has become increasingly important. Photocatalytic degradation of pollutants and simultaneous production of clean energy is one such approach that has garnered significant attention in recent years. The principle of photocatalysis involves the development of efficient photocatalysts and the efficient utilization of solar energy. The use of organic contaminants can enhance the photocatalytic reactions, leading to the sustainable generation of clean energy. Herein, we provide a comprehensive review of the latest advances in the application of photocatalytic synergized clean energy production in the environmental field. This review highlights the latest developments and achievements in this field, highlighting the potential for this approach to revolutionize the way we approach environmental pollution control and resource recycling. The review focuses on (1) the mechanism of photocatalytic degradation and synergistic energy production, (2) photocatalysts and synthesis strategies, (3) photocatalytic carbon dioxide reduction, (4) pollutant degradation, and (5) hydrogen and electricity production. In addition, perspectives on key challenges and opportunities in photocatalysis and clean energy for future developments are proposed. This review provides a roadmap for future research directions and innovations of photocatalysis that could contribute to the development of more sustainable and cleaner energy solutions.

TiO2/BP/g-C3N4 heterojunction photocatalyst for the enhanced photocatalytic degradation of RhB

The efficiency of graphite carbon nitride (g-C3N4, CN) as a photocatalyst is limited due to its quick recombination of photogenerated carriers and layer re-stacking. To enhance its photocatalytic activity, a multi-heterojunction photocatalyst was developed using TiO2 and black phosphorus (BP) coupled with CN through a liquid-phase ultrasonic method. The composite, TiO2/BP/CN, demonstrated a wider range of light response and higher photo-induced carrier separation efficiency. The presence of TiO2 nanoparticles on CN nanolayers reduced interlayer stacking and increased specific surface area, thereby providing more reactive sites. As a result, the optimized TiO2/BP/CN composite demonstrated enhanced photocatalytic efficiency for the degradation of Rhodamine B (RhB), with a first-order kinetic constant of 2.8, 4.3, and 6.4 times that of CN, TiO2, and BP, respectively. Active substance capture experiments confirmed that superoxide radical (·O2) was the primary reactive species. This study highlights the potential of the developed TiO2/BP/CN composite as a promising photocatalyst for environmental remediation applications.

Photocatalytic degradation of COVID-19 related drug arbidol hydrochloride by Ti3C2 MXene/supramolecular g-C3N4 Schottky junction photocatalyst

Because of the current COVID-19 outbreak all over the world, the problem of antiviral drugs entering water has become increasingly serious. Arbidol hydrochloride (ABLH) is one of the most widely used drugs against COVID-19, which has been detected in sewage treatment plant sediments after the COVID-19 outbreak. However, there has been no report on the degradation of ABLH. In order to remove ABLH we prepared a novel photocatalyst composed of Ti₃C₂ MXene and supramolecular g-C₃N₄ (TiC/SCN) via a simple method. The properties of the material were studied by a series of characterizations (SEM, TEM, EDS, XRD, FTIR, UV-vis, DRS, XPS, TPC, PL, EIS and UPS), indicating the successful preparation of TiC/SCN. Results show that 99% of ABLH was removed within 150 min under visible light illumination by the 0.5TiC/SCN (containing 0.5% of TiC). The performance of 0.5TiC/SCN was about 2.66 times that of SCN resulting from the formation of Schottky junction. Furthermore, under real sunlight illumination, 99.2% of ABLH could be removed by 0.5TiC/SCN within 120 min, which was better than that of commercial P25 TiO₂. The pH, anions (NO₃^- and SO₄^2-) and dissolved organic matter (fulvic acid) could significantly affect the ABLH degradation. Moreover, three possible degradation pathways of ABLH were proposed, and the toxicities of the corresponding by-products were less toxic than ABLH. Meanwhile, findings showed that the superoxide radicals played a major role in the photocatalytic degradation of ABLH by 0.5TiC/SCN. This study provides a well understanding of the mechanism of ABLH degradation and provides a valuable reference for the treatment of ABLH in water.

Solar light induced photocatalytic degradation of tetracycline in the presence of ZnO/NiFe2O4/Co3O4 as a new and highly efficient magnetically separable photocatalyst

In this study, a new solar light-driven magnetic heterogeneous photocatalyst, denoted as ZnO/NiFe₂O₄/Co₃O₄, is successfully prepared. FT-IR, XPS, XRD, VSM, DRS, FESEM, TEM, EDS, elemental mapping, and ICP analysis are accomplished for full characterization of this catalyst. FESEM and TEM analyses of the photocatalyt clearly affirm the formation of a hexagonal structure of ZnO (25–40 nm) and the cubic structure of NiFe₂O₄ and Co₃O₄ (10–25 nm). Furthermore, the HRTEM images of the photocatalyst verify some key lattice fringes related to the photocatalyt structure. These data are in very good agreement with XRD analysis results. According to the ICP analysis, the molar ratio of ZnO/NiFe₂O₄/Co₃O₄ composite is obtained to be 1:0.75:0.5. Moreover, magnetization measurements reveals that the ZnO/NiFe₂O₄/Co₃O₄ has a superparamagnetic behavior with saturation magnetization of 32.38 emu/g. UV-vis DRS analysis indicates that the photocatalyst has a boosted and strong light response. ZnO/NiFe₂O₄/Co₃O₄, with band gap energy of about 2.65 eV [estimated according to the Tauc plot of (αhν)²vs. hν], exhibits strong potential towards the efficacious degradation of tetracycline (TC) by natural solar light. It is supposed that the synergistic optical effects between ZnO, NiFe₂O₄, and Co₃O₄ species is responsible for the increased photocatalytic performance of this photocatalyst under the optimal conditions (photocatalyst dosage = 0.02 g L⁻¹, TC concentration = 30 mg L⁻¹, pH = 9, irradiation time = 20 min, and TC degradation efficiency = 98%). The kinetic study of this degradation process is evaluated and it is well-matched with the pseudo-first-order kinetics. Based on the radical quenching tests, it can be perceived that ^•O₂⁻ species and holes are the major contributors in such a process, whereas the ^•OH radicals identify to have no major participation. The application of this methodology is implemented in a facile and low-cost photocatalytic approach to easily degrade TC by using a very low amount of the photocatalyst under natural sunlight source in an air atmosphere. The convenient magnetic isolation and reuse of the photocatalyst, and almost complete mineralization of TC (based on TOC analysis), are surveyed too, which further highlights the operational application of the current method. Notably, this method has the preferred performance among the very few methods reported for the photocatalytic degradation of TC under natural sunlight. It is assumed that the achievements of this photocatalytic method have opened an avenue for sustainable environmental remediation of a broad range of contaminants.

Confining Metal-Organic Framework in the Pore of Covalent Organic Framework: A Microscale Z-Scheme System for Boosting Photocatalytic Performance

The search for building hierarchical porous materials with accelerated photo-induced electrons and charge-carrier separation is important because they hold great promise for applications in various fields. Here, a facile strategy of confining metal-organic framework (MOF) in the 1D channel of the 2D covalent organic framework (COF) to construct a novel COF@MOF micro/nanopore network is proposed. Specifically, a nitrogen-riched COF (TTA-BPDA-COF) is chosen as the platform for in-situ growth of a Co-based MOF (ZIF-L-Co) to form a TTA-BPDA-COF@ZIF-L-Co hybrid material. The hierarchical porous structure endows TTA-BPDA-COF@ZIF-L-Co with superior adsorption capacity. In addition, the integration of TTA-BPDA-COF and ZIF-L-Co forms a Z-scheme photocatalytic system, which significantly improved the redox properties and accelerated the separation of photogenerated charges and holes, achieving great improvement in photocatalytic activity. This confinement engineering strategy provides a new idea to construct a versatile molecular-material photocatalytic platform.