Visible Light Photocatalytic Activity Research Articles

Enhancing the Visible Light Photocatalytic Activity of TiO2-Based Coatings by the Addition of Exfoliated g-C3N4

In the last few years, increasing interest from researchers and companies has been shown in the development of photocatalytic coatings for air purification and self-cleaning applications. In order to maintain the photocatalyst’s concentration as low as possible, highly active materials and/or combinations of them are required. In this work, novel photocatalytic formulations containing g-C3N4/TiO2 composites were prepared and deposited in the form of coatings on a-block substrates. The obtained photocatalytic surfaces were tested for NOx and acetaldehyde removal from model air. It was found that the addition of only 0.5 wt% g-C3N4 towards TiO2 content results in over 50% increase in the photocatalytic activity under visible light irradiation in comparison to pure TiO2 coating, while the activity under UV light was not affected. The result was related to the creation of a g-C3N4/TiO2 heterojunction that improves the light absorption and the separation of photogenerated electron-hole pairs, as well as to the inhibition of TiO2 particles’ agglomeration due to the presence of g-C3N4 sheets.

Phytosynthesis and characterization of tin-oxide nanoparticles (SnO2-NPs) from Croton macrostachyus leaf extract and its application under visible light photocatalytic activities

Nanotechnology is rapidly becoming more and more important in today's technological world as the need for industry increases with human well-being. In this study, we synthesized SnO2 nanoparticles (NPs) using an environmentally friendly method or green method from Croton macrostachyus leaf extract, leading to the transformation of UV absorbance to visible absorbance by reducing the band gap energy. The products underwent UV, FTIR, XRD, SEM, EDX, XPS, BET, and DLS for characterization. Characterization via UV–Vis spectroscopy confirmed the shift in absorbance towards the visible spectrum, indicating the potential for enhanced photocatalytic activity under visible light irradiation. The energy band gap for as-synthesized nanoparticles was 3.03 eV, 2.71 eV, 2.61 eV, and 2.41 eV for the 1:1, 1:2, 1:3, and 1:4 sample ratios, respectively. The average crystal size of 32.18 nm and very fine flakes with tiny agglomerate structures of nanoparticles was obtained. The photocatalytic activity of the green-synthesized SnO2 nanoparticles was explored under visible light irradiation for the degradation of rhodamine B (RhB) and methylene blue (MB), which were widespread fabric pollutants. It was finally confirmed that the prepared NPs were actively used for photocatalytic degradation. Our results suggest the promising application of these green-synthesized SnO2 NPs as efficient photocatalysts for environmental remediation with low energy consumption compared to other light-driven processes. The radical scavenging experiment proved that hydroxyl radicals (_OH) are the predominant species in the reaction kinetics of both pollutant dyes under visible light degradation.

Nitrogen-doped carbon quantum dot as electron acceptor anchored on graphitic carbon nitride nanosheet for improving rhodamine B degradation

Carbon quantum dots (CQDs) hold significant promise for wastewater treatment because of their remarkable attributes, including robust stability, outstanding biocompatibility, minimal toxicity, superior water dispersibility, cost-effective production, and exceptional photo-stability.In this study, CQDs were synthesized using microplasma and tested for the degradation of rhodamine B (RhB) (5 mg/L) under different conditions, with a Solar simulator and UVA illumination. Specifically, graphitic carbon nitride nanosheets (NCN) in conjugation with carbon quantum dots (NCN@CQD) were prepared with different amounts of CQD. The synthesized CQD, NCN, and NCN@CQD underwent characterization using various compositional and structural analytical techniques. The results show that nitrogen species were effectively incorporated into the CQDs framework and CQDs are anchored on NCN forming NCN@CQD successfully. Subsequently, all samples were then investigated in degrading Rhodamin B, RhB, to assess the photocatalytic activity. The results reveal that the presence of CQDs substantially improved the photocatalytic efficiency of NCN. Specifically, the CQDs anchored on NCN exhibited a substantial enhancement in the photoactivity for RhB decomposition under a solar light simulator, surpassing that of pure NCN. The amount of CQD in the NCN@CQD sample exerted a strong influence on the photocatalytic activity. All NCN@CQD samples exhibited remarkable enhancements in both adsorption and photocatalytic performance compared to pure CQD and NCN samples. In an optimization study, a best NCN@CQ photocatalyst was identified, showing a 40 % enhancement of photocatalytic efficiency compared to the use of NCN alone. A visible light photocatalytic activity of 91 % can be attained within 150 min, exhibiting a reaction rate constant of 0.0135 min−1 toward RhB decomposition, which was double as for the individual NCN (0.0067 min−1). The boosted photocatalytic activity resulting from the synergistic effect between NCNs and CQDs can be attributed to the efficient function of CQD as an electron acceptor. The proposed mechanism of photocatalytic degradation of RhB is illustrated in detail.

Insight into mechanism of excellent visible-light photocatalytic activity of CuO/MgO/ZnO nanocomposite for advanced solution of environmental remediation

Environmental remediation has sought several innovative ways for the treatment of wastewater and captivated researchers around the globe towards it. Through this study, we aim to proceed with the efforts to foster sustainable and feasible ways for the treatment of wastewater. In this work, we report the sol-gel synthesis of CuO/MgO/ZnO nanocomposite and carry out their systematic characterization with the help of state-of-the-art analytical techniques, such as FTIR, SEM, TEM, PL, XRD, Raman, and AFM. The SEM along with TEM and AFM provided useful insights into the surface morphology of the synthesized nanocomposite on both 2D and 3D surfaces and concluded the well-dispersed behavior of the nanocomposite. The characteristic functional groups responsible for carrying out the reaction of Cu–O, Mg–O, and Zn–O were identified by FTIR spectroscopy. On the other hand, crystal size, dislocation density, and microstrain of the nanocomposite were calculated by XRD. For optical studies, photoluminescence spectroscopy was performed. Once the characterization of the nanocomposite was done, they were eventually treated against the toxic organic dye, methylene blue. The calculated rate constant values of k for CuO was 2.48 × 10−3 min−1, for CuO/MgO (2.04 × 10−3 min−1), for CuO/ZnO (1.82 × 10−3 min−1) and CuO/MgO/ZnO was found to be 2.00 × 10−3 min−1. It has become increasingly evident that nanotechnology can be used in various facets of modern life, and its implementation in wastewater treatment has recently received much attention.

Conical porous hollow g-C3N4 charge separation with high efficiency for enhancing visible-light photocatalytic activity

The performance of the photocatalysts is influenced by factors such as electron generation ability, charge separation rate, and active sites distribution. In this study, needle-shaped precursors were prepared through low-temperature supramolecular self-assembly, and conical porous hollow carbon nitride (PHCN) was obtained after high-temperature pyrolysis. The PHCN not only possesses a thin-walled porous structure but also contains nitrogen defects embedded in its structure, which synergistically enhance the efficiency of photogenerated charge separation and provide more reactive sites. The DFT calculations showed that nitrogen defects and Pt-loading synergistically optimize the intermediate reaction process of graphitic carbon nitride (g-C3N4). PHCN had excellent photocatalytic degradation of tetracycline hydrochloride (TCH) and Rhodamine B (Rh B). The photocatalytic hydrogen evolution rate of PHCN was 20.0 times higher than that of bulk g-C3N4 (BCN). This study elucidated the relationship between crystallization rate and precursor morphology, as well as the influence of their physicochemical properties on photocatalytic performance. It also lays the foundation for constructing materials with nitrogen defects and special morphology through supramolecular self-assembly.

Novel in-situ Ag-decorated trithiocyanuric acid polymer with superior visible light photocatalytic activity

A novel Ag-decorated trithiocyanuric acid polymer (Ag-TTCA) was fabricated via a photocatalytic reduction method based on the strong affinity between Ag ion and trithiocyanic acid (TTCA). The as-prepared photocatalysts were characterized, and the paralleled experiments were conducted on the photocatalytic oxidation of bisphenol A (BPA) to evaluate the photocatalytic activity. Compared with TTCA, Ag-TTCA has a much higher photocatalytic activity. The 0.08Ag-TTCA catalyst can remove BPA (20 mg L−1) in 240 min with a degradation efficiency as high as 96.4 %. The improved photocatalytic performance of Ag-TTCA can be attributed to the dispersed nanoparticle morphology and unique electronic structure. The dispersed nanoparticle morphology of Ag-TTCA can provide more active sites for the adsorption and degradation of pollutants. After silver modification, the light absorption threshold of TTCA is redshifted from 466 nm to 522 nm, and the corresponding band gap is reduced from 2.74 eV to 2.54 eV, which broadens the light absorption range of the photocatalyst and significantly enhances the light absorption capacity. Moreover, metal silver can trap photogenerated electrons and generate surface plasmon resonance (SPR) when illuminated by sunlight, which can effectively promote the separation of electron-hole pairs. Trapping experiment indicates that photogenerated holes, singlet oxygen and superoxide free radicals are the main active species in photocatalytic system.

Fabricated layered g-C3N4 nanosheets for high efficiency photocatalytic degradation of atrazine：Insight into terminal-NHx in-situ activation of H2O2

It is well known that graphite-like carbon nitride (g-C3N4) is a good photocatalyst for in-situ the production of H2O2. However, how to activate H2O2 generating the strong oxidizing ·OH is the key factor to affect the degradation of pollutants. In this paper, the layered g-C3N4 nanosheets were prepared by using urea and H2O with different mass ratios and calcined in Muffle furnace by one-step synthesis method. The morphology, composition and structure of photocatalysts were analyzed, indicating that the as-prepared L-g-C3N4-7 had abundant edge regions in comparison with L-g-C3N4 made by solid urea. The photocatalytic performance of g-C3N4 nanosheets was investigated with atrazine (ATZ) as the target pollutant in water. The results revealed that the prepared L-g-C3N4-7 exhibited the best photocatalytic activity in visible light (λ ≥ 420 nm). The degradation of 1.0 mg/L ATZ reached over 96% after 3 hours and the photocatalytic degradation rate constant (k) was 6.8 times than that of L-g-C3N4 photocatalyst. In addition, under the same conditions, the H2O2 production of L-g-C3N4-7 was 4.5 times than that of L-g-C3N4 photocatalyst. Based on the capture experiments of free radicals, it was found that the contribution rate of ·OH in L-g-C3N4-7 photocatalytic increased to 17 % compared to 4 % of L-g-C3N4 photocatalyst during the degradation of ATZ. The ·OH quantitative experiment indicated that the L-g-C3N4-7 photocatalyst could obviously activate H2O2 to generate ·OH and the amount of ·OH was 2.5 times than that of the L-g-C3N4 photocatalyst. More importantly, a large amount of terminal-NHx (14.6 %) in L-g-C3N4-7 was measured by the XPS, FT-IR and zeta potential. The additive H2O2 adsorption experiment in the dark was used to confirm terminal-NHx sites of L-g-C3N4-7 photocatalyst, which was beneficial to adsorb and activate H2O2. The results illustrated that the L-g-C3N4-7 photocatalyst with rich edge regions and terminal-NHx had the characteristics of in-situ the activation of H2O2 to generate ·OH. The findings suggest that designing and developing efficient g-C3N4 photocatalysts pave a new avenue for activating in situ self-synthesizing H2O2 and the removal of atrazine in water.

The effect of graphene oxide content on the photocatalytic activity of (ZnCdS/MnFe2O4/GO) nanocomposite

Novel ternary Zinc cadmium sulfate/Manganese ferrite/Graphene oxide (ZnCdS/MnFe2O4/GO) nanocomposites were synthesized via a hydrothermal process in this study, with a focus on optimizing the graphene oxide (GO) content. Characterization techniques such as X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), UV–visible spectroscopy, photoluminescence (PL) spectroscopy, and N2 physisorption were employed. The investigation revealed that nanocomposites with 3 wt% GO content exhibited superior adsorption capacity and visible-light photocatalytic activity for the removal of Methylene blue (MB) from wastewater. The ZnCdS/MnFe2O4/GO 3 % composite demonstrated exceptional stability and efficiency, achieving nearly 96 % MB removal within 220 min. Moreover, the ZnCdS/MnFe2O4/GO 3 % nanocomposites displayed promising reusability with sustained photocatalytic activity over multiple degradation-regeneration cycles. These findings highlight the potential of ternary GO/ZnCdS/MnFe2O4 nanocomposites as effective photocatalysts for the practical remediation of organic pollutants in wastewater systems.

Preparation and performance study of Mn-doped TiO2-loaded kapok-based activated carbon fibers

Due to its various advantages, such as a large specific surface area, high adsorption capacity, rapid adsorption rate, and moderate pore size, activated carbon fiber (ACF) has been extensively employed in wastewater treatment. In this study, the sol–gel-adsorption method was utilized to effectively synthesize Mn-doped TiO2-loaded kapok-based activated carbon fibers (Mn-TiO2/ACF). Several characterization techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and nitrogen adsorption-desorption were employed to investigate the Mn-TiO2/ACFs. The resulting Mn-TiO2/ACFs exhibited a combination of anatase and rutile forms in the produced TiO2. The introduction of Mn doping was found to hinder the crystal development, agglomeration, and crystallization of TiO2. The Mn-doped TiO2/ACFs demonstrated significant visible-light photocatalytic activity, attributed to the synergistic effects of two factors: the photocatalytic degradation of TiO2 films and the absorption capacity of ACF. The optimal molar ratio (Mn: Ti) for Mn-TiO2/ACFs in visible-light photocatalytic applications was determined to be 1:150. A pseudo-second-order kinetics model was employed to investigate the adsorption process of methyl bromide on Mn-TiO2/ACFs samples. The experimental results indicated that Mn-TiO2/ACF was reusable, with a removal efficiency exceeding 53% for all five cycles.

Artificial Photosynthases: Single-Chain Nanoparticles with Manifold Visible-Light Photocatalytic Activity for Challenging "in Water" Organic Reactions.

Photocatalyzed reactions of organic substances in aqueous media are challenging transformations, often because of scarce solubility of substrates and catalyst deactivation. Herein, we report single-chain nanoparticles, SCNPs, capable of efficiently catalyzing four different "in water" organic reactions by employing visible light as the only external energy source. Specifically, we decorated a high-molecular-weight copolymer, poly(OEGMA300-r-AEMA), with iridium(III) cyclometalated complex pendants at varying content amounts. The isolated functionalized copolymers demonstrated self-assembly into noncovalent, amphiphilic SCNPs in water, which enabled efficient visible-light photocatalysis of two reactions unprecedentedly reported in water, namely, [2 + 2] photocycloaddition of vinyl arenes and α-arylation of N-arylamines. Additionally, aerobic oxidation of 9-substituted anthracenes and β-sulfonylation of α-methylstyrene were successfully carried out in aqueous media. Hence, by merging metal-mediated photocatalysis and SCNPs for the fabrication of artificial photoenzyme-like nano-objects─i.e., artificial photosynthases (APS)─our work broadens the possibilities for performing challenging "in water" organic transformations via visible-light photocatalysis.

Efficient antibiotic degradation catalyzed by oxygen vacancy and Cu-Doped Cu-MOF under visible light

The widespread use of antibiotics in contemporary healthcare has led to their accumulation in natural water systems, contributing to a growing resistance among bacteria and posing a significant challenge to the sustainable development of human society. Photocatalysis has emerged as an effective technique to mitigate antibiotic pollution in water. This study focuses on developing and synthesizing a visible light responsive metal–organic framework (MOF), Cu-NTC, which employs copper as the metal node instead of the usual choice of molybdenum, and the rigid 1,4,5,8-naphthalene tetracarboxylic acid (H4NTC) as the organic ligand. A pivotal step in the synthesis involved the partial reduction of Cu2+, leading to the formation of Cu0/Cu+ doping. This doping, together with oxygen vacancies (OVs), introduces a localized state that functions as a doped energy level, thus prolonging carrier lifetime and enhancing the visible light photocatalytic activity of Cu-NTC. Remarkably, Cu-NTC achieved photocatalytic degradation efficiencies of 84.5 % for tetracycline (TC) and 96.1 % for norfloxacin (NFX) after 30 min in darkness followed by 120 min under visible light exposure. Moreover, Cu-NTC exhibited effective removal capabilities for other antibiotics within the quinolone and tetracycline groups, underscoring their potential for broader applications in water purification.

Modulating of Bi2MoO6-based photocatalyst through manipulation of reactant ratios for enhanced visible light photocatalytic activity

In this work, a novel photocatalyst, comprising of Bi2MoO6 and Bi2O2(OH)(NO3), was successfully synthesized by the one-pot hydrothermal method, thereby illuminating an innovative avenue for structure modulation of Bi2MoO6. The characterizations proved the facile attainability of controllable modifications in the microstructure and morphology of Bi2MoO6. The comprehensive appraisal of the synergistic adsorption-photocatalytic performances of the composites in the context of ciprofloxacin (CIP) was carried out. The findings presented compelling evidence that the amalgamation of Bi2MoO6/Bi2O2(OH)(NO3) exhibited an extraordinary adsorption capacity and photocatalytic activity when compared with the pristine Bi2MoO6 and Bi2O2(OH)(NO3). By virtue of its high surface area and pore volume, the optimized BMO/BON manifested a CIP adsorption capacity that surpassed that of Bi2MoO6 and Bi2O2(OH)(NO3) by approximately 2.4 and 11.2 times, respectively. Furthermore, through the concerted effects of adsorption and photocatalytic degradation, BMO/BON demonstrated an impressive CIP removal efficiency of 99.2 % following a mere 30 min of visible light exposure. The reaction rate constant was found to be approximately 0.124 min−1 for BMO/BON, surpassing that of Bi2MoO6 and Bi2O2(OH)(NO3). The augmentation in the photocatalytic activity of BMO/BON can be ascribed to its diminutive crystalline dimensions, large specific surface area, and narrowed bandgap. Thus, this investigation introduces a practical and ingenious strategy for the tuning of the Bi2MoO6 structure by manipulation of reactant ratios, showcasing significant implications in the realm of catalysis.

Enhanced Visible Light Photocatalytic Activity of Exfoliated Boron‐TiO2 Composite for Degradation of Rhodamine B and Nitrogen Fixation

AbstractThe design of an efficient, recyclable, visible light photocatalytic system was examined as a viable new green way to address environmental challenges such as removal of pollutants from wastewater and N2 fixation. The exfoliated boron (Bexf)‐Titanium oxide (TiO2) composite visible light active photocatalysts were successfully constructed via a simple wet chemical method by utilizing acetone as a solvent. The composite was evaluated for the photodegradation of Rhodamine B (RhB) dye and reduction of N2, which exhibits improved photocatalytic activity for degradation of RhB as well as for reduction of N2. Experiments with different quenchers indicate that the photogenerated superoxide radical anion (O2⋅−) plays a significant role in the degradation of RhB as well as for N2 reduction reactions. The composite catalyst shows good photostability and there is no significant reduction of the catalyst activity for dye degradation up to 4 cycles of reaction. This work affords a significant view into the design of reusable TiO2 composite materials for photocatalytic RhB degradation and nitrogen fixation.

Facile synthesis of Ag2ZrO3 nanocrystals with highly enhanced visible-light photocatalytic activity

Abstract This paper describes the synthesis of Ag2ZrO3 nanocrystals using coprecipitation and microwave-assisted hydrothermal methods. These nanocrystals were characterized by means of X-ray diffraction, micro-Raman spectroscopy, Fourier transform infrared absorption spectroscopy, field emission scanning electron microscopy, and UV–Visible spectroscopy, and their photocatalytic performance for methylene blue degradation under visible-light irradiation has been tested. The X-ray diffraction, micro-Raman spectroscopy, Fourier transform infrared absorption spectroscopy analyses indicate that the Ag2ZrO3 nanocrystals have good crystallinity and no secondary phases. The UV–Visible spectroscopy results showed a variation in the optical band gap values (2.71–2.97 eV) with increasing temperature, which indicates the possible presence of defects in the crystal lattice at a medium range. Field emission scanning electron microscopy images revealed that the nanocrystals have uneven spherical shapes and average particle size around 50–70 nm. The good photocatalytic efficiency can be attributed to defects in the silver zirconate structure capable of forming the active adsorption sites. Finally, we discuss a photocatalytic mechanism to understand the photocatalytic process in cationic dye (methylene blue) degradation in aqueous solution.

Facile electrospinning synthesis of S-scheme heterojunction CoTiO3/g-C3N4 nanofiber with enhanced visible light photocatalytic activity

Facile electrospinning synthesis of S-scheme heterojunction CoTiO3/g-C3N4 nanofiber with enhanced visible light photocatalytic activity

Innovative ternary composite photocatalyst: BiOCl/Bi12O17Cl2/Bi2O3 for sustainable water remediation

The presence of pollutants in aquatic environments is causing severe health effects on both humans and animals. To address this issue, it has become crucial to develop more efficient and environmentally friendly photocatalysts for the removal of persistent pollutant mixtures from water. In this context, photocatalysts containing more than two bismuth-based materials have rarely been explored for water remediation. With this in mind, we propose an innovative ternary composite, BiOCl-1/Bi12O17Cl2/Bi2O3, as a potentially sustainable visible light-active photocatalyst. Firstly, bismuth oxychloride has been prepared in the presence of ionic liquid, leading to the formation of BiOCl-1 with highly reactive {110} facets. Subsequently, the construction of the ternary composite has been accomplished using a facile and soft hydrothermal approach. The as-prepared BiOCl-1/Bi12O17Cl2/Bi2O3 composite has been successfully used in degrading binary mixtures of contaminants (i.e. ciprofloxacin, methylparaben or methyl orange), achieving an improved visible-light photocatalytic activity compared to single BiOCl-1 and other previously reported bismuth-based photocatalysts. In addition, the photocatalytic mechanism and degradation pathways have been elucidated through scavenger and electrochemical experiments, as well as chromatography-mass spectrometry (LC-MS) analysis, respectively.

Heterostructured S-TiO2/g-C3N4 Photocatalysts with High Visible Light Photocatalytic Activity

Novel heterojunctions associating graphitic carbon nitride g-C3N4 and S-doped TiO2 nanoparticles were successfully designed and prepared via a hydrothermal method and used for photocatalytic degradations. The loading in S-TiO2 nanoparticles on g-C3N4 was varied (5, 10 and 20 wt%), and the photocatalysts were characterized by XRD, FT-IR, solid-state UV-visible diffuse reflectance, photoluminescence, XPS, TEM and SEM. The S-TiO2 (5%)/g-C3N4 catalyst exhibits the highest activity for the photocatalytic degradation of the methylene blue (MB) dye under visible light irradiation. The high photocatalytic performance originates from the enhanced separation and transfer of photogenerated charge carriers. The S-TiO2 (5%)/g-C3N4 photocatalyst is stable and can be reused five times without a sharp drop in activity, indicating its high potential for wastewater remediation.

Novel Bi2O2Se/BiOCl with high visible light photocatalytic activity for environmental remediation: Effective layer to layer interfacial charge transfer based on heterojunction

The photocatalytic activity of promising layered structure BiOX (X = Cl, Br, I) is limited by the low carrier mobility and charge transfer based on heterojunction. Hereon, we reported that Bi2O2Se with the same layered structure, high carrier mobility and broad spectrum absorption was used to composited with BiOCl to obtain effective layer to layer interfacial charge transfer and high photocatalytic activity under visible light. Bi2O2Se/BiOCl were synthesized via ion exchange method in precursor of Bi2O2Se. 25-Bi2O2Se/BiOCl shows the optimal photocatalytic removal activity of methyl blue (MB) and Cr (VI), which was higher than that of pure BiOCl and Bi2O2Se. The analysis of morphology revealed the in-growth mechanism of Bi2O2Se/BiOCl. A strong interaction between the same layer structure Bi2O2Se and BiOCl was proved by detailed analysis of XPS and valence charge density. Transient photocurrent responses and energy-level indicated the sensitized electrons of Bi2O2Se can be injected into BiOCl effectively and produce H2O2. We believe layer structure Bi2O2Se can be candidate co-catalyst to expand photocatalytic activity of layer structure semiconductor catalysts in the visible and infrared regions, especially, for the same layered bismuth compounds.

Boosting Visible-Light Photocatalytic Activity of BiOCl Nanosheets via Synergetic Effect of Oxygen Vacancy Engineering and Graphene Quantum Dots-Sensitization.

In recent years, oxygen vacancy (VO) engineering has become a research hotspot in the field of photocatalysis. Herein, an efficient GQDs/BiOCl-VO heterojunction photocatalyst was fabricated by loading graphene quantum dots (GQDs) onto BiOCl nanosheets containing oxygen vacancies. ESR and XPS characterizations confirmed the formation of oxygen vacancy. Combining experimental analysis and DFT calculations, it was found that oxygen vacancy promoted the chemical adsorption of O2, while GQDs accelerated electron transfer. Benefiting from the synergistic effect of oxygen vacancy, GQDs, and dye sensitization, the as-prepared GQDs/BiOCl-VO sample exhibited improved efficiency for RhB degradation under visible-light irradiation. A 2 wt% GQDs/BiOCl-VO composite effectively degraded 98% of RhB within 20 min. The main active species were proven to be hole (h+) and superoxide radical (·O2-) via ESR analysis and radical trapping experiments. This study provided new insights into the effective removal of organic pollutants from water by combining defect engineering and quantum dot doping techniques in heterojunction catalysts.

Revealing the lattice engineering of Delafossite in core–shell CuRhO2@CuGaO2 heterostructure for efficient visible light photocatalytic activity

The establishment of heterojunctions at phase interfaces represents a pivotal strategy for enhancing photocatalytic performance. However, the inferior interfacial contact caused by the mismatch of crystal structure or lattice parameters seriously hampers the rapid and smooth migration of charge carriers in traditional heterojunctions. In this work, a tightly integrated Delafossite-based core–shell CuRhO2@CuGaO2 heterojunction was judiciously designed and constructed via a hydrothermal approach. Experimental and density-functional theory calculation results co-unravel that the built-in electric field is established in the lattice-matched heterogeneous interfaces, thereby providing smooth interface charge separation and transfer via the Z-scheme pathways. Benefitting from the heterojunction effect and unique core–shell coupling architecture, the strong visible light absorption and fast spatial charge transfer are realized in the CuRhO2@CuGaO2 heterostructure. The photocurrent density of the CuRhO2@CuGaO2 heterojunction is nearly 1.25 and 3.75 times those of pristine CuRhO2 and CuGaO2, respectively. As a result, the CuRhO2@CuGaO2 heterostructure reveals an excellent photocatalytic degradation rate of tetracycline hydrochloride, achieving a 3.02 and 2.38-fold improvement than those of the CuRhO2 and CuGaO2, respectively. This work is expected to pave the way for novel insights into the design of efficient heterojunction photocatalysts to steer the rapid photocarrier flows across the heterointerface.