Multicomponent Photocatalysts Research Articles

Pore walls as high-way for efficient bulk charge transfer in porous SrTiO3 single crystals boosting photocatalytic overall water splitting

Suppressing carrier recombination in bulk and facilitating carrier transfer to surface via rational structure design is of great significance to improve solar-to-H2 conversion efficiency. We demonstrate a facile hydrothermal method to synthesize porous SrTiO3 single crystals (SrTiO3-P) with exposed (001) facets by introducing carbon spheres as templates. The obviously increased surface photovoltage and photocurrent response indicate that the interconnected pore walls act as enormous charge transfer “highways”, accelerating carrier transport from bulk to surface. Furthermore, the absence of grain boundaries and high crystallinity could also lower the carrier recombination rate. Thus, the SrTiO3-P photocatalyst loaded with Rh/Cr2O3 as cocatalyst exhibits 1.5 times higher overall water splitting activity than that of solid SrTiO3, with gas evolution rate of 19.99 μmol h−1 50 mg−1 for H2 and 11.37 μmol h−1 50 mg−1 for O2. Additionally, SrTiO3-P also shows superior stability without any decay during cycling testing. This work provides a new insight into designing efficient multicomponent photocatalysts with a single-crystal porous structure.

Controlled synthesis of Cadmium doped CuBi2O4 nanorods with rapid and synergistic visible light photocatalytic performance

The rise of nanotechnology has significantly influenced the synthesis of advanced photo materials and their various potential applications. In this study, newly advanced multicomponent photocatalyst was designed by a simple hydrothermal method i.e., CuBi2O4, Cd0.05Cu0.95Bi2O4, Cd0.1Cu0.90Bi2O4, and Cd0.15Cu0.85Bi2O4. These nanostructures were characterized using various spectroscopic techniques. The synthesized nanostructure material was tested for decontaminating water polluted with Congo red, using visible light irradiation. Within 60 min of irradiation, Cd0.1Cu0.90Bi2O4 exhibited 91 % degradation of Congo red, while Cd0.05Cu0.95Bi2O4 and Cd0.15Cu0.85Bi2O4 showed degradation rates of 80 % and 86 % respectively. In contrast, the pure CuBi2O4 had a lower photo degradation rate of 70 % over 70 min of visible light irradiation. Among the synthesized materials, Cd0.1Cu0.90Bi2O4 demonstrated the highest efficiency, require the shortest time to achieve significant degradation. Additionally, the impact of various parameters such as dosage, initial concentration, hydrogen peroxide, and salts on the photo-catalytic degradation of the dye has been studied. Consequently, it can be concluded that the use of hierarchical porous Cd0.1Cu0.90Bi2O4 photocatalyst holds promising potential in wastewater remediation.

Synthesis, Characterization, and Photocatalytic Performance of ZnFe2O4-g-C3N4 Composites for Tetracycline Removal from Contaminated Water

The presence of emerging contaminants in wastewater like tetracycline poses a significant challenge in water reuse worldwide. The implementation of a p-n heterojunction and dye-sensitized techniques in the enhancement of graphite carbon nitride provides a promising alternative for visible light-driven degradation of emerging contaminants present in wastewater. The present study investigated dye-sensitized and plain composites in degrading tetracycline using natural sunlight in a parabolic trough reactor. The study synthesized four composites of ZnFe2O4-g-C3N4 at 5, 15, and 25 wt% loading of the ferrite by direct annealing of melamine, followed by thermal and ultrasonic exfoliation of bulk graphite carbon nitride and in situ precipitation with zinc ferrites to yield a composite photocatalyst. The photocatalysts were characterized using X-ray diffraction (XRD) analyses which confirmed that all the spinel ferrite phases of ZnFe2O4 were well bonded with g-C3N4 nanosheets to form a composite. The crystallite sizes were calculated by the Debye–Scherrer equation indicating crystal sizes of between 4.63 and 8.61 nm confirming the nanostructures. The scanning electron microscope-energy dispersive spectroscopy (SEM-EDX) tests verified that the spherical globules of ZnFe2O4 were well attached to the mesoporous layers of g-C3N4 and absence of contaminant phases. The UV-Vis analysis for 25% ZF-GCN revealed a band gap reduction from 2.67 eV to 2.03 eV. The PL intensity for all the composites decreased at excitation of 266 nm and 550 nm which was evidence for suppressed charge recombination. A 25% ferrite loading resulted in the best photocatalytic performance with tetracycline degradation of 93.64% and total organic carbon (TOC) removal of 51.89%. The sensitization of the 25% ZF-GCN composite with Eosin Y further improved its performance for degradation of tetracycline to 94.62% and TOC removal to 68.29%. Therefore, dye sensitization is an efficient way of improving the photocatalytic activity of a multicomponent photocatalyst for the removal of emerging pollutants.

Energy band engineering over phosphorus-doped CdS/graphdiyne S-scheme heterojunction for enhance photocatalytic hydrogen production

The high recombination rate of photoelectron-hole pairs and the limited REDOX capacity of a single photocatalyst restrict the broader application of photocatalytic water splitting for hydrogen generation. This necessitates the design of an efficient multicomponent photocatalyst. In this work, phosphate-doped cadmium sulfide (CP) was designed by energy band engineering to have a wider band gap and reduce the recombination rate of photogenerated electrons and holes. Graphdiyne, prepared through a straightforward ball milling method, exhibits high conductivity and specific surface area. It pairs well with CP morphologically, effectively reducing CP aggregation and exposing more active sites. Compared with the original CdS (CS), the changes in the conduction and valence band positions of CP can form S-scheme heterojunction with graphdiyne, which effectively improves the interfacial charge migration effect, improves the photogenerated carrier separation efficiency, and maintains a high reduction capacity. Additionally, the mechanism of photocatalytic hydrogen evolution was verified by in-situ XPS. This work provides a feasible scheme for the design and construction of graphdiyne in heterojunction photocatalyst.

Detailed Insight into Photocatalytic Inactivation of Pathogenic Bacteria in the Presence of Visible-Light-Active Multicomponent Photocatalysts.

The use of heterogeneous photocatalysis in biologically contaminated water purification processes still requires the development of materials active in visible light, preferably in the form of thin films. Herein, we report nanotube structures made of TiO2/Ag2O/Au0, TiO2/Ag2O/PtOx, TiO2/Cu2O/Au0, and TiO2/Cu2O/PtOx obtained via one-step anodic oxidation of the titanium-based alloys (Ti94Ag5Au1, Ti94Cu5Pt1, Ti94Cu5Au1, and Ti94Ag5Pt1) possessing high visible light activity in the inactivation process of methicillin-susceptible S. aureus and other pathogenic bacteria-E. coli, Clostridium sp., and K. oxytoca. In the samples made from Ti-based alloys, metal/metal oxide nanoparticles were formed, which were located on the surface and inside the walls of the NTs. The obtained results showed that oxygen species produced at the surface of irradiated photocatalysts and the presence of copper and silver species in the photoactive layers both contributed to the inactivation of bacteria. Photocatalytic inactivation of E. coli, S. aureus, and Clostridium sp. was confirmed via TEM imaging of bacterium cell destruction and the detection of CO2 as a result of bacteria cell mineralization for the most active sample. These results suggest that the membrane ruptures as a result of the attack of active oxygen species, and then, both the membrane and the contents are mineralized to CO2.

Boosting Hydrogen Production of a MOF-based Multicomponent Photocatalyst with Clean Interface via Facile One-pot Electrosynthesis.

Hydrogen production from photocatalysis via the usage of multicomponent photocatalysts represents a promising pathway for carbon peaking and carbon neutrality, owing to their structural advantages in dealing with the three crucial processes in photocatalysis, namely, light harvesting, charge transfer, and surface redox reactions. We demonstrate the fabrication of a MOF-based multicomponent photocatalyst, denoted as semiconductor/MOF/cocatalyst, by a one-pot electrochemical synthetic route. The as-fabricated multicomponent photocatalyst has a clean interface among the components, leading to close connections that contribute to high-quality heterojunction and facilitate photogenerated charge transfer and separation, thereby the efficient hydrogen evolution. The hydrogen production rate of the resultant ZrO2 /Zr-MOF/Pt is 1327 μmol ⋅ g-1 ⋅ h-1 , which is much higher than that of ZrO2 /Zr-MOF (15 μmol ⋅ g-1 ⋅ h-1 ) and pure Zr-MOF (10.1 μmol ⋅ g-1 ⋅ h-1 ), as well as the photodeposited-Pt products ZrO2 /Zr-MOF/PtPD (287 μmol ⋅ g-1 ⋅ h-1 ) and Zr-MOF/PtPD (192 μmol ⋅ g-1 ⋅ h-1 ) obtained by the step-wise synthetic approach. The work gives a good inspiration for the rational design and construction of MOF-based multicomponent photocatalysts through the one-pot electrosynthesis.

In-situ generation of Au–carbon–TiO2 Ohmic junction from Ti3C2 MXene for efficient photocatalytic H2 evolution

Photogenerated charge separation is a challenging step in semiconductor-based photosynthesis. Though numerous efforts have been devoted to developing multi-component photocatalyst heterostructures for improving charge separation efficiency, the short distance between electrons and holes-aggregated regions still leads to undesirable charge recombination. Herein, a facile and commercial in-situ synthesis method was designed to directly prepare a three-component Au–carbon–TiO2 photocatalyst from Ti3C2 MXene, air, CO2, and HAuCl4, in which the carbon layer bridged Au and TiO2 nanoparticles for stable and efficient photocatalytic hydrogen production. Kelvin probe measurements and density functional theory (DFT) calculations demonstrated that a multi-interfacial charge transmission network was successfully constructed to achieve a directional and long-distance spatial charge separation/transfer channel between TiO2 and Au through carbon layer, desirably inhibiting the recombination of photogenerated charge carriers. The hydrogen production rate of the formed three-component Au/C–TiO2 (CTA) photocatalyst was demonstrated to be 27 times higher than that of Au–TiO2, which also surpassed many reported Ti3C2 MXene-derived carbon–TiO2 photocatalysts. This work sheds light on the ingenious use of 2D MXene to form a well-behaved TiO2-based photocatalytic system and helps to propose future design principles in accelerating charge transfer.

Highly efficient ZnFe2O4 decorated g-C3N4/GO with biomedical and photocatalytic activities

In this work, a novel magnetic composite was synthesized using graphene oxide (GO), graphitic carbon nitride(g-C3N4), and zinc ferrite (ZnFe2O4) for photocatalytic and biomedical functions. The synthesized nanocomposite (g-C3N4/GO/ZnFe2O4) was characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray (EDX), UV–Vis diffuse reflectance spectra (DRS), vibrating sample magnetometer (VSM), Brunner-Emmett-Teller theory (BET), and photoluminescence (PL) techniques. Decorating g-C3N4 and GO by ZnFe2O4 as a multi-component photocatalyst with a simple and cost-effective method in our work shows high efficiency, antibacterial, and anticancer activity. The outcome of using the nanocomposite as a novel heterojunction structure, in comparison to other individual photocatalysts, has shown great activity in degrading methylene blue (MB) due to the formation of electron-hole pairs. GO improved the photocatalyst adsorption capacity and life of charge carriers, facilitating the transfer of electrons. Also, ZnFe2O4 increased the separate charges and reusability process by making heterojunction structures. The dye degradation process attained 98 % promising efficiency in only 60 min and just 3.7 % degradation after 30 min in dark conditions. The Plausible mechanism shows the Z-scheme route. Also, practical factors such as pH, concentration, dosage, and scavenger were obtained, and the optimal values were 10, 20 mg/L, 0.3 g/L, and EDTA (Ethylenediamine tetraacetic acid), respectively. The reusability of nanocomposite was also analyzed in 6 cycles. Finally, the nanocomposite made the area of inhibition on Pseudomonas aeruginosa (Gram-negative bacteria) and Bacillus cereus (Gram-positive bacteria) about 18 ± 0.5 mm and 14 ± 0.2 mm, respectively. Also, the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium assay was examined. The MTT assay for breast cancer cell lines showed the survival percentage of cells is between 99.2 % and 61.4 %, so it can be applied as a carrier.

Advanced photocatalytic materials based degradation of micropollutants and their use in hydrogen production - a review.

The use of pharmaceuticals, dyes, and pesticides in modern healthcare and agriculture, along with expanding industrialization, heavily contaminates aquatic environments. This leads to severe carcinogenic implications and critical health issues in living organisms. The photocatalytic methods provide an eco-friendly solution to mitigate the energy crisis and environmental pollution. Sunlight-driven photocatalytic wastewater treatment contributes to hydrogen production and valuable product generation. The removal of contaminants from wastewater through photocatalysis is a highly efficient method for enhancing the ecosystem and plays a crucial role in the dual-functional photocatalysis process. In this review, a wide range of catalysts are discussed, including heterojunction photocatalysts and various hybrid semiconductor photocatalysts like metal oxides, semiconductor adsorbents, and dual semiconductor photocatalysts, which are crucial in this dual function of degradation and green fuel production. The effects of micropollutants in the ecosystem, degradation efficacy of multi-component photocatalysts such as single-component, two-component, three-component, and four-component photocatalysts were discussed. Dual-functional photocatalysis stands out as an energy-efficient and cost-effective method. We have explored the challenges and difficulties associated with dual-functional photocatalysts. Multicomponent photocatalysts demonstrate superior efficiency in degrading pollutants and producing hydrogen compared to their single-component counterparts. Dual-functional photocatalysts, incorporating TiO2, g-C3N4, CeO2, metal organic frameworks (MOFs), layered double hydroxides (LDHs), and carbon quantum dots (CQDs)-based composites, exhibit remarkable performance. The future of synergistic photocatalysis envisions large-scale production facilitate integrating advanced 2D and 3D semiconductor photocatalysts, presenting a promising avenue for sustainable and efficient pollutant degradation and hydrogen production from environmental remediation technologies.

Synergistic interface engineering in n-p-n type heterojunction Co3O4/MIL/Mn-STO with dual S-scheme multi-charge migration to enhance visible-light photocatalytic degradation of antibiotics

Constructing an effective multi-heterojunction photocatalyst with maximum charge carrier separation remains challenging. Herein, a high-efficient Co3O4/MIL-88A/Mn–SrTiO3 (Co3O4/MIL/Mn-STO) n-p-n heterojunction photocatalyst was successfully prepared by a simple hydrothermal method for the photodegradation of sulfamethoxazole (SMX). The combination of MIL and Co3O4/Mn-STO established an internal electric field and heterojunction, accelerating the separation of carriers, and thus improved photocatalytic performance. In the Co3O4/MIL/Mn-STO photocatalytic system, 95.5 % of SMX was degraded in 90 min. The photocatalytic kinetic removal rate of Co3O4/MIL/Mn-STO reached 0.0337 min−1, 8 times of Co3O4 (0.0041 min−1), 5.2 times of Mn-STO (0.0062 min−1), 4.6 times of MIL (0.0078 min−1), and 3.6 times of MIL/Mn-STO (0.0095 min−1). Remarkably, superoxide radicals (•O2−) and holes (h+) have been recognized as the main active species in the degradation process through reactive species elimination experiments and electron spin resonance (ESR) tests. The experimental and theoretical proved the in-built interfacial contact and synergistic effect between the photocatalyst accomplished with low bandgaps, high specific surface area, more reaction sites, high electron-hole pair separation, and maximum solar-light utilization. The molecular structure and possible degradation routes with intermediate products in the photocatalytic system were investigated using a liquid chromatography-mass spectrometer (LC-MS) and DFT calculations. This work provided new insight into the guidelines of rational design/growth of new multicomponent photocatalysts to remove antibiotics and other emerging contaminants in wastewater.

Tracking Heterogeneous Interface Charge Reverse Separation in SrTiO3/NiO/NiS Nanofibers with In Situ Irradiation XPS

AbstractPhotocatalytic conversion of H2O and CO2 into solar fuels is considered to be a green and renewable technology while photocatalytic performance is hampered by the severe recombination of photogenerated electron–hole pairs. Drawing inspiration from the concepts of the electrons transfer layer (ETL) and the holes transfer layer (HTL) in perovskite solar cells, a multicomponent photocatalyst SrTiO3/NiO/NiS that incorporates p–n heterojunction and Schottky junction is constructed for converting solar energy into easily storable solar fuels. The NiS and NiO play the roles analogy to the ETL and the HTL which accomplishes the reverse migration of electrons and holes, accordingly, SrTiO3/NiO/NiS exhibits a noticeable enhancement in photocatalytic performance. However, the lack of direct observation of charge transfer pathways in complex multicomponent photocatalysts makes it challenging to thoroughly investigate their catalytic mechanisms. Herein, the in situ irradiation X‐ray photoelectron spectroscopy (ISI–XPS) is employed to track photogenerated charges migration pathways between microscopic heterogeneous interfaces, thereby providing a comprehensive elucidation of the catalytic mechanism and heterojunction formation process by integrating the photoelectrochemical tests. This study not only serves as compelling evidence for the capability of ISI–XPS in directly and accurately tracking charge transfer pathways but also as an intriguing highlight within the catalyst design strategy.

Revealing charge migration in a Multi-Multi photocatalyst by in situ irradiated X-ray photoelectron spectroscopy

Constructing efficient photocatalysts to produce solar fuels has been regarded as a potential way to alleviate energy crisis and environmental pollution. So far, simply modified single- and dual- component photocatalysts still suffer low efficiency due to their inherent weaknesses, making researchers turn their attention to multiple modified multi-component photocatalysts (“multi-multi” photocatalysts). However, the complex structure and composition of “multi-multi” photocatalysts will make it difficult for in-depth investigations on their working mechanisms, principally due to the lack of a method for direct observation of the migration route of charge carriers under the light irradiation in these systems. Herein, we report an in situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) method to show the transfer pathway of charge carriers through the shifts of binding energies using a triple-modified WS2/carbon nanofibers (CNFs)/ZnIn2S4 model system. With this method, we manage to reveal the role of each subcomponent and demonstrated that the synergy of multiple modifications significantly enhances the performance of the “multi-multi” photocatalyst. This novel method opens up a new avenue for studying the mechanisms of photocatalytic systems, facilitating the future development of highly efficient photocatalysts.

Calcium silicate hydrate decorated by Fe, Ti co-modified birnessite direct multi-component photocatalyst: Design, preparation and photocatalytic performance under visible light irradiation

Constructing a multi-component structure is an effective strategy to promote the formation of oxygen vacancies (OVs), which can enhance electron transition to improve the photocatalytic activity of materials. In this work, it was designed a series of novel photocatalysts supported on calcium silicate hydrates (C-S-H) via density functional theory calculation. These designed photocatalysts were then synthesized and marked as Bir@C-S-H, TiO2/Bir@C-S-H, and α-Fe2O3/TiO2/Bir@C-S-H, respectively. In comparison to other catalysts, α-Fe2O3/TiO2/Bir@C-S-H photocatalyst has a higher specific surface area, a lower band gap, more OVs, which can activate more dioxygen molecules, and more reactive radicals. The photocatalytic activity of as-synthesized photocatalysts was verified by using HCHO as the target pollutant. To the treatment of 80 ppm HCHO, the α-Fe2O3/TiO2/Bir@C-S-H exhibits 100% HCHO conversion corresponding gas hourly space velocity of 60 L/(g•h) with a relative humidity of 60% under visible light irradiation, while Bir@C-S-H and TiO2/Bir@C-S-H present 89.92% and 94.17% HCHO conversion, respectively at same conditions. This work demonstrates a more effective calcium silicate hydrate decorated by Fe, Ti co-modified birnessite heterostructures for HCHO oxidation, which can be directly used as decorative materials, providing a novel guidance for practical application.

Visible-light-driven benzyl alcohol oxidation over Pt/Mn-Bi4Ti3O12 nanosheets: Structure-function relationship of multicomponent photocatalysts

Herein, a series of Pt nanoparticles modificatory Mn doped Bi4Ti3O12 ultrathin nanosheets (Pt/MnNS) are constructed as a surface functionalized photocatalyst for the visible-light-driven selective benzyl alcohol (BA) oxidation. Especially, Pt/5MnNS shows the best performance with a benzaldehyde (BD) yield rate of 1180 μmol·g−1·h−1 and a selectivity of 99.9 %. More importantly, experimental results reveal that Mn doping not only extends the optical absorption range of the photocatalyst to the visible region, but also induces the formation of more surface Ti4+δ atoms. Those Ti4+δ atoms as stronger Lewis acid centers achieve more conspicuous adsorption and activation of BA via the CO⋯Ti coordination. It makes the deprotonation of BA by photogenerated holes be easier. Meanwhile, Pt nanoparticles significantly promote the separation and transfer of the photogenerated carriers for supporting the formation of superoxide and carbon-centered radicals. Thus, the photocatalytic BA oxidation efficiency is markedly improved by surface multicomponent synergistic effect.

One-pot synthesis of bismuth-containing multicomponent photocatalyst Ag-BWV-y towards efficient H2 generation

The bismuth-containing semiconductors have emerged as promising materials for the degradation of organic pollutants and reduction of CO2. However, their potential applications in photocatalytic H2 generation have not been explored clearly. Herein, bismuth-containing multicomponent photocatalyst Ag-BWV-y (where y represents the moles of Ag+ in the initial reaction system) has been synthesized by a simple one-pot chemical method for photocatalytic H2 generation. The element Ag is homogeneously distributed in as-prepared nanocomposite, and the band structure of Ag-BWV-y can be tuned by the dosage of Ag+ ions. The optimized photocatalyst Ag-BWV-y (y = 0.15) shows a maximum H2 evolution rate of 652 μmol h−1 g−1, which is about 5.6-fold that of undoped sample. The narrow band gap of Ag-BVW-0.15 favors the photocatalytic activity in promoting H2 production.

A Review on Carbon Quantum Dots Modified g-C3N4-Based Photocatalysts and Potential Application in Wastewater Treatment

Carbon quantum dots (CDs) are a fascinating class of carbon nanomaterials (less than 10 nm in size) with unique optical, electrical, and physicochemical properties. In addition to these properties, CQDs exhibit the desired advantages of aqueous stability, low toxicity, high surface area, economic feasibility, chemical inertness, and highly tunable photoluminescence behaviour. Recently, graphitic carbon nitride (g-C3N4) has appeared as one of the required stable carbon-based polymers due to its varied applications in several fields. In this regard, modification strategies have been made in the g-C3N4 semiconductor using CQDs to enhance the adsorptive and photocatalytic activity. In comparison to other semiconductor quantum dots, g-C3N4 shows strong fluorescent properties, such as wide excitation spectra, photostability, and tunable photo-luminescent emission spectra. The interaction inside this multicomponent photocatalyst further promotes the photocatalytic activity by improving charge transference, which plays a vital role in electrochemistry. Therefore, CQDs are auspicious nanomaterials in the field of photocatalysis, wastewater treatment and water adsorption treatment. This particular article featured the recent progression in the field of CDs/g-C3N4-based photocatalysts focusing on their luminescent mechanism and potential applications in wastewater treatment.

Multicomponent photocatalysts for synergic removal of antibiotics in aqueous media: a review

Multicomponent photocatalysts for synergic removal of antibiotics in aqueous media: a review

Discovery of Two-Dimensional Multinary Component Photocatalysts Accelerated by Machine Learning.

Searching for novel and high-performance two-dimensional (2D) materials is an important task for photocatalytic applications. Although multinary compounds exhibit more diversity in structure and properties in comparison to binary 2D materials, they are comparatively under-studied. Herein, using a machine-learning (ML) technique and high-throughput screening, we develop an efficient approach to accurately predict 2D multicomponent photocatalysts. Over 4000 monolayers are examined, and 75 multinary compounds are identified for photocatalytic applications. Considering our predictions, we find that the ternary and quaternary compounds A2P2X6 and ABP2X6 with A = Cu/Zn/Ge/Ag/Cd, B = Ga/In/Bi, and X = S/Se exhibit superior properties, making them promising candidates for overall water splitting. Thus, our work provides an efficient way to explore novel photocatalysts, which could stimulate further theoretical and experimental investigations on 2D multinary compounds for application in photocatalytic water splitting.

Interfacial microenvironment-regulated cascade charge transport in Co6Mo6C2-MoO2-CoNC@ZnIn2S4 photocatalyst for efficient hydrogen evolution

High-quality interfacial coupling can effectively boost photogenerated charge separation/transfer efficiency. Herein, we develop a multicomponent photocatalyst, Co6Mo6C2-MoO2-CoNC@ZnIn2S4 (CMN@Z), featuring directional and swift carrier transfer ability through interfacial microenvironment modulation. The distinctive CMN@Z displays a ten-times enhanced photocatalytic H2-production performance of 4728 μmol·g−1·h−1 than pure ZIS, accompanied by optimized apparent quantum efficiency of 25.06 % at 420 nm. Typically, the well-tuned Schottky barrier readily balances its bifunctionality in rectifying effect and powerful photogenerated electron extraction impetus. Moreover, the gradient work function variation enables the interfacial potential as a robust driving force to expedite charge transfer. Therefore, the resulting cascade charge channel and intimate interfacial contact endow CMN@Z photocatalyst with optimized H2-production performance by virtue of high-efficiency carrier spatial separation and utilization. Our work deeply explores the role of multiple interfacial in coupling photocatalytic systems, which offers new insight into the rational design of cascade photocatalysts.

Review on Methylene Blue: Its Properties, Uses, Toxicity and Photodegradation

The unavailability of clean drinking water is one of the significant health issues in modern times. Industrial dyes are one of the dominant chemicals that make water unfit for drinking. Among these dyes, methylene blue (MB) is toxic, carcinogenic, and non-biodegradable and can cause a severe threat to human health and environmental safety. It is usually released in natural water sources, which becomes a health threat to human beings and living organisms. Hence, there is a need to develop an environmentally friendly, efficient technology for removing MB from wastewater. Photodegradation is an advanced oxidation process widely used for MB removal. It has the advantages of complete mineralization of dye into simple and nontoxic species with the potential to decrease the processing cost. This review provides a tutorial basis for the readers working in the dye degradation research area. We not only covered the basic principles of the process but also provided a wide range of previously published work on advanced photocatalytic systems (single-component and multi-component photocatalysts). Our study has focused on critical parameters that can affect the photodegradation rate of MB, such as photocatalyst type and loading, irradiation reaction time, pH of reaction media, initial concentration of dye, radical scavengers and oxidising agents. The photodegradation mechanism, reaction pathways, intermediate products, and final products of MB are also summarized. An overview of the future perspectives to utilize MB at an industrial scale is also provided. This paper identifies strategies for the development of effective MB photodegradation systems.