Field Of Photocatalysis Research Articles

Tuning (Photo)Electronic Properties of an Electron Deficient Porous Polymer via n-Doping with Tetrathiafulvalene.

Charge-transfer complex formation within the pores of porous polymers is an efficient way to tune their electronical properties. Introduction of electron accepting guests to the electron donating hosts to conduct their p-doping is intensively studied in this context. However, the vice versa scenario, n-doping by treating the electron deficient (i.e., n-type) porous polymers with electron donating dopants, is rare. In this work, synthesis of an n-type phenazine based conjugated microporous polymer and its exposure to strong electron donating tetrathiafulvalene (TTF) dopants are presented. The fundamental physical characterizations (e.g., elemental analysis, gas sorption) showed that the vacuum impregnation technique is a good approach to load the guest molecules inside the pores. Moreover, the formation of charge-transfer complexes between the phenazine building blocks of the polymeric network and TTF dopants are confirmed via spectral techniques such Fourier transform infra-red, UV-vis, steady-state/time-resolved photoluminescence, and transient absorbance spectroscopies. Effect of the doping to the electronical properties is monitored by employing photoelectrochemical measurements, which showed lower charge-transfer resistivity and nearly doubled photocurrents after the doping. The study is, therefore, an important advancement for the applicability of (n-type) porous polymeric materials in the field of photo(electro)catalysis and organic electronics.

Modulation of π-Electron Density in Ultrathin 2D Layers of Graphite Carbon Nitride for Efficient Photocatalytic Hydrogen Production.

The rational design and synthesis of novel semiconductor nano-/quantum materials have been ambitiously pursued in the field of photocatalysis as the technology is promising and critical for attaining future energy and environmental sustainability. Herein, the integrity of aromatic carbon into graphitic carbon nitride (CN) at the same molecular plane with a few 2D layers is achieved by using modulated precursors of CN, forming carbon regulated ultrathin CN (CUCN) with improved charge transfer kinetics and photocatalytic hydrogen production. The grafted graphite rings adjacent to carbon nitride frameworks induce a significant rearrangement and relocalization of the overall framework, and form conjugated sp2 hybridized interfaces and internal electric fields that drive the separation and directional transfer of photogenerated electrons from CN sheets towards intralayer graphite regions, where the photocatalytic hydrogen evolution reaction occurs extensively, yielding largely increased HER rate of 2231.8 µmol g-1 h-1 by 8.2 times relative to CN, as well as a remarkable apparent quantum yield of 2.93% under monochromatic light at 420 nm. The high physicochemical stability and low synthesis cost of CUCN make it a potential benchmark photocatalyst that can be readily modified via element doping, heterojunction introduction, defect engineering, and so on, to further enhance its HER performance.

Construction of scheelite CaWO4 with natural diatomite for boosted photocatalytic degradation of tetracycline and doxycycline antibiotics under natural conditions

Fabrication of efficient and recyclable catalysts with natural supporting materials is still a challenge in the field of photocatalysis. In the present work, scheelite type calcium tungstate was successfully constructed with natural diatomite via in-situ co-precipitation method for effective photocatalytic degradation of tetracycline (TC) and doxycycline (DC) antibiotics. The as-synthesized photocatalysts were characterized by SEM-EDX, TEM, BET, XRD, XRF, XPS, FTIR, UV–vis DRS, PL and EIS techniques. The morphological and physiochemical analyses confirmed the successful hybridization of CaWO4 with natural diatomite. The optical, photoluminescence and electrochemical tests confirmed that the composite material displayed narrower band gap energy, lower recombination rate and facilitated separation of photogenerated carriers. After construction of CaWO4 with the diatomite structure, the TC and DC decomposition efficiencies were found 4.70 and 2.54 times higher than that of the pristine sample, respectively. Furthermore, the composite catalyst showed superior degradation performances (91.8 % for TC and 90.7 % for DC) in the presence of hydrogen peroxide as a Fenton-agent. The enhanced photocatalytic performance was assigned to the increased specific surface area and pore volume, decreased band gap energy, limited recombination rate of photoinduced carriers, decreased charge transfer resistance as well as the abundant of hydroxyl radicals. The degradation reaction was found to be mainly driven by photogenerated holes and superoxide radicals. The CWO@DT/Vis/Fenton catalytic system exhibited good performance at near-neutral pH, also the composite catalyst was sufficiently utilized in the presence of co-existing anions. Furthermore, the photocatalytic efficiency was also tested under natural sunlight irradiation and the TC degradation remained 71.4 % after four cycles, indicating the outstanding feature of the composite catalyst in outdoor process conditions. Under these circumstances, the present work demonstrated the utilization potential of natural diatomite for effective photocatalytic remediation of antibiotic molecules under natural sunlight irradiation.

Research Progress in Preparation and Modification Strategies of Graphitic Carbon Nitride for Efficient Photocatalysis: A Mini Review

With the acceleration of industrialization, energy shortage and environmental pollution are becoming more and more serious. It is urgent to develop green and sustainable new energy. Photocatalytic technology, especially the use of solar energy to convert chemical energy, has attracted much attention due to its environmental friendliness and sustainability. As an excellent photocatalyst, graphitic carbon nitride (g-C3 N4 ) has emerged rapidly in the field of photocatalysis due to its low cost, simple preparation and nontoxicity. However, g-C3 N4 has some limitations in practical applications, such as small specific surface area, weak photogenerated carrier transport capacity and narrow visible light response range. To overcome these challenges, researchers have modified g-C3 N4 through various strategies to improve its photocatalytic performance. In this paper, the synthesis methods and modification strategies of g-C3 N4 are summarized from the structural characteristics of g-C3 N4 , and its research focus and application prospect in the field of photocatalysis are prospected.

Construction of Ternary Ce Metal-Organic Framework/Bi/BiOCl Heterojunction towards Optimized Photocatalytic Performance.

Photocatalysis is the most promising green approach to solve antibiotic pollution in water, but the actual treatment effect is limited by photocatalytic activity. Herein, Bi and BiOCl were loaded onto the surface of Ce-MOF (metal-organic framework) using an electrostatic adsorption method, and a special ternary heterojunction of Ce/Bi/BiOCl was successfully prepared as a photocatalyst for the degradation of tetracycline (TC). FTIR demonstrated that the obtained photocatalyst contains functional groups such as -COOH belonging to Ce-MOF and characteristic crystal planes of Bi and BiOCl, indicating the successful construction of a ternary photocatalyst. The results of UV-vis absorption spectra confirm that the band gap of Ce/Bi/BiOCl heterojunction is reduced from 3.35 eV to 2.7 eV, resulting in an enhanced light absorption capability in the visible light region. The special ternary heterojunction constructed by Ce-MOF, Bi, and BiOCl could achieve a narrow band gap and reasonable band structure, thereby enhancing the separation of photogenerated charges. Consequently, the photocatalytic performance of the Ce/Bi/BiOCl ternary heterojunction was significantly enhanced compared to Ce-MOF, Bi, and BiOCl. Therefore, Ce/Bi/BiOCl can achieve a photocatalytic degradation rate of 97.7% within 20 min, which is much better than Bi (14.8%) and BiOCl (67.9%). This work successfully constructed MOF-based ternary photocatalysts and revealed the relationship between ternary heterojunctions and photocatalytic activity. This provides inspiration for constructing other heterogeneous catalysts for use in the field of photocatalysis.

Recent progress of NH2-MIL-125(Ti)-based photocatalytic system in energy production and environmental purification

With the increasing prominence of metal–organic frameworks (MOFs) in photocatalysis, NH2-MIL-125(Ti) has attracted much attention due to its typical structural and remarkable optical properties. This review furnishes a comprehensive outline of the development of NH2-MIL-125(Ti)-based nanomaterials in the field of photocatalysis. First, various conditions involved in the synthesis methods of NH2-MIL-125(Ti) and the corresponding impact on the final morphology are analyzed and discussed. Additionally, we highlight the advantages of NH2-MIL-125(Ti)-based catalysts within the photocatalytic reaction systems, further exploring and summarizing the merits and characteristics of different modification strategies for NH2-MIL-125(Ti)-based catalysts. Moreover, the review discusses the performance and benefits of NH2-MIL-125(Ti)-based photocatalysts in energy conversion, sustainable chemistry, and environmental purification. Finally, the promising prospects and current challenges facing NH2-MIL-125(Ti)-based materials have been emphasized, aiming to inspire future advancements in photocatalytic applications.

Highly selective aerobic oxidation of cyclohexane by flower-like MoO3-x microspheres-nitrogen-doped carbon dots heterojunction

Due to the higher susceptibility of alcohols and ketones to oxidation compared to alkanes, converting inert C-H bonds in alkanes into high value-added product KA oil with high selectivity is still a significant obstacle. In this study, flower-like microspheres of MoO3-x, featuring aligned nanosheets and oxygen vacancies, were combined with nitrogen doped carbon dots (NCDs) to fabricate S-scheme heterojunctions of MoO3-x-NCDs for boosting the photocatalytic efficiency in oxidizing cyclohexane. Because of the oxygen vacancies-triggered localized surface plasmon resonance (LSPR) and the S-scheme charge transfer mechanism, there was a significant improvement in the absorption of visible light and an enhancement in the efficiency of charge separation. The MoO3-x-NCDs composites exhibited a notably improved catalytic performance in cyclohexane oxidation. The MoO3-x-NCDs composite exhibited remarkable selectivity of KA oil in catalyzing cyclohexane oxidation under light exposure, attributed to the substantial increase in cyclohexane adsorption capacity. The highest cyclohexane transformation rate of 9.98 % was achieved by MoO3-x-NCDs-2 composites with a MoO3-x/NCDs ratio of 50:1, outperforming bare MoO3-x by 1.81 times, while exhibiting a KA oil selectivity reaching 93.75 %. The mechanism of selective photocatalytic oxidation was explored using photoelectric examination, analysis of energy bands, and evaluation of active radicals. In this research, green photocatalysts were fabricated through the utilization of NCDs, enabling efficient conversion and selective oxidation of cyclohexane in gentle environments. This innovative approach holds great potential for advancing the field of photocatalysis.

A novel hydrogen-bonded organic framework/g-C3N4 heterojunction for improved sulfadiazine photodegradation via effective electron transfer

As one of the most widely used antibiotics, sulfamethoxazole (SDZ) poses significant health risks to the ecological environment by causing harm to aquatic organisms and accelerating evolution of antibiotic resistant bacteria. Metalloporphyrin hydrogen-bonded organic framework (PFC-72) demonstrates promising prospect in the field of photocatalysis owing to its high specific surface area, wide light harvesting range, stable physical and chemical properties, and semiconductor properties. Herein, we constructed an efficient photocatalyst PFC-72/g-C3N4 by one-step solvent thermal method for photocatalytic degradation of SDZ. When doping content of PFC-72 is 10 %, photocatalytic degradation efficiency of SDZ can reach 96.82 % after 120 min of visible light irradiation, and PFC-72/g-C3N4 exhibits excellent structural stability. The photocatalytic efficiency of SDZ is improved by increasing specific surface area, enhancing absorption range of visible light, and inhibiting recombination of photogenerated electron-hole pairs. In addition, photodegradation pathways of SDZ in PFC-72/g-C3N4 was determined by UPLC-MS/MS analysis. Finally, dominant reactive species (·O2−, hVB+, and ·OH) in the system were detected through free radical masking experiments, and photocatalytic mechanism was clarified. This work investigates a novel and efficient porphyrin-HOF based photocatalyst, which has great potential for degradation of SDZ.

Optimizing photocatalytic hydrogen evolution performance by rationally constructing S-scheme heterojunction to modulate the D-band center

The research in the field of photocatalysis has progressed, with the development of heterojunctions being recognized as an effective method to improve carrier separation efficiency in light-induced processes. In this particular study, CuCo2S4 particles were attached to a new cubic CdS surface to create an S-scheme heterojunction, thus successfully addressing this issue. Specifically, owing to the higher conduction band and Fermi level of CuCo2S4 compared to CdS, they serve as the foundation and driving force for the formation of an S-scheme heterojunction. Through in-situ X-ray photoelectron spectroscopy and electron paramagnetic resonance analysis, the direction of charge transfer in the composite photocatalyst under light exposure was determined, confirming the charge transfer mechanism of the S-scheme heterojunction. By effectively constructing the S-scheme heterojunction, the d-band center of the composite photocatalyst was adjusted, reducing the energy needed for electron filling in the anti-bonding energy band, promoting the transfer of photogenerated carriers, and ultimately enhancing the photocatalytic hydrogen production. performance. After optimization, the hydrogen evolution activity of the composite photocatalyst CdS-C/CuCo2S4-3 reached 5818.9 μmol g−1h−1, which is 2.6 times higher than that of cubic CdS (2272.3 μmol g−1h−1) and 327.4 times higher than that of CuCo2S4 (17.8 μmol g−1h−1), showcasing exceptional photocatalytic activity. Electron paramagnetic resonance and in situ X-ray photoelectron spectroscopy have established a theoretical basis for designing and constructing S-scheme heterojunctions, offering a viable method for adjusting the D-band center to enhance the performance of photocatalytic hydrogen evolution.

Synthesis of uniform sized ZnS quantum dots using hydrodynamic cavitation and their characterization

As representative non-toxic cadmium-free quantum dots (QDs), ZnS QDs with high quantum efficiency, super stability and excellent biocompatibility had attracted wide attention in the fields of photocatalysis, solar cells and biomedicine. In this study, hydrodynamic cavitation (HC) technology was applied to the preparation of ZnS QDs. By adjusting HC device parameters, water soluble ZnS QDs with small particle size, narrow particle size distribution range, high absorbance, high luminous efficiency and high quantum yield were prepared. The morphology, size distribution, element composition and optical properties of ZnS QDs were studied by various characterization methods. ZnS QDs with average particle size of 1.48 nm, fluorescence quantum yield of 34.07% and Stokes shift of 112 nm were obtained. In addition, the mechanism of preparation of ZnS QDs by using HC method was also studied. It is hoped that this HC technology can provide a new idea for large-scale preparation of ZnS QDs with excellent properties.

MFe2O4 (M: Cu, Ni)/SnS2magnetic Core-Shell Heterostructure for Photocatalytic H2 Generation and Environmental Remediation

Overgrowing demand for sustainable energy sources and environmental remediation has driven extensive research in the field of photocatalysis. This study presents a hydrothermal synthesis of a novel MFe2O4 (M: Cu, Ni)/SnS2 magnetic core-shell heterostructure. The engineered heterostructure combines the unique properties of MFe2O4 (M: Cu, Ni) magnetic crystal as a core with SnS2 nanosheets as a shell, aiming to exploit type-2 heterojunction properties to improve effects for improved photocatalytic performance. The structural chemistry, phase formation, and crystal orientation of the prepared material are investigated using various analytical techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman, and FTIR Spectroscopy. FE-SEM analysis reveals a well-defined core-shell morphology with intimate interfaces between MFe2O4 (M: Cu, Ni) crystals and SnS2 nanosheets. Photocatalytic efficiency is assessed through the industrial dye degradation process. The influence of the heterostructure's structural features on the photocatalytic activity is explored through density function theory, emphasizing the role of the core-shell interface and the magnetic properties of MFe2O4 (M: Cu, Ni) cores. The chemistry between the magnetic core and the shell in the heterostructure is demonstrated to be crucial for optimizing charge carrier dynamics and promoting surface reactions. Photocatalytic H2 generation under artificial simulated sunlight irradiation in the presence of MFe2O4 (M: Cu, Ni)/SnS2 core-shell heterostructure is demonstrated. This study not only presents a novel MFe2O4 (M: Cu, Ni)/SnS2 heterostructure for photocatalytic H2 generation but also provides valuable insights into the intricate relationship between structural chemistry and photocatalytic efficiency. The engineered heterostructure shows promising potential for applications in sustainable energy production and environmental remediation, contributing to the ongoing efforts towards a cleaner and more sustainable future.

In situ proof construction of GDY/NiWO4/CdS double S-scheme heterojunction: Improving charge transfer and promoting photocatalytic activity

In the field of photocatalysis, the inherent properties of catalysts are a hard condition that affects catalytic performance, and constructing heterojunctions is a common method to improve catalyst defects and enhance catalyst performance. This article makes effective use of the outstanding stability and unique electronic structure of graphdiyne, along with its excellent semiconductor properties comparable to silicon. It uses these properties to attach rod-shaped CdS and microspherical NiWO4 onto sheet-like graphdiyne, creating an S-scheme heterojunction. With the construction of S-scheme heterojunctions and the special contact methods between the three, the physical potential barrier and the distance of electron transfer are reduced. Furthermore, the combined impact of NiWO4 and graphdiyne works to inhibit the photo corrosion of CdS, enhance its electron transfer capabilities, decrease electron-hole recombination efficiency, and boost hydrogen evolution sites. This maximizes the redox potential during catalysis, leading to exceptional stability and efficiency of the composite catalyst. This study opens up a new avenue for leveraging the superior properties of graphdiyne and advancing sustainable practices.

Design of a novel direct Z-scheme BiOIO3/Bi2WO6 heterojunction for enhanced photocatalytic degradation of norfloxacin under visible light

The unique electronic structure, appropriate bandgap energy, and excellent electron transfer capability make bismuth-based semiconductors hotspots in the field of photocatalysis. Novel BiOIO3/Bi2WO6 Z-scheme heterojunctions were fabricated via in-situ hydrothermal synthesis. The BIOBIW-3 heterojunctions (BiOIO3:Bi2WO6=0.25:0.8, mole ratio) exhibited excellent photocatalytic activity for norfloxacin (NOR), with a degradation efficiency of 90.41 % after 90 min of photoreaction and a reaction kinetic constant of 0.02132 min−1, which was 5.02 and 9.35 times higher than that of BIO and BIW, respectively. The superior photocatalytic performance can be attributed to the intimate interface between BiOIO3 and Bi2WO6, as well as the staggered energy band structure that facilitates the formation of a Z-type heterojunction. This not only widens the range of visible light absorption but also enhances the separation and transfer of photogenerated carriers while maintaining a high capacity for redox reactions. The dominant active species in the degradation process were photogenerated holes (h+) and superoxide (∙O2−) radicals, and an in-depth exploration of the possible mechanism was conducted. Furthermore, the effects of various parameters, including solution pH, catalyst dosage, and NOR concentration on the photocatalytic degradation of NOR were also investigated. The prepared BiOIO3/Bi2WO6 heterojunctions exhibited remarkable photocatalytic performance and chemical stability, presenting a novel research direction for employing layered bismuth-based materials in the degradation of fluoroquinolone antibiotic wastewater.

Application of multilevel immobilized carbon nanotube/sulfur doped carbon nitride composite photocatalytic coating for Cr6+(aq.) reduction

The difficulty in immobilizing carbon nitride (GCN), and the decrease in sorption capacity and photocatalytic performance after immobilization process have become two major bottlenecks limiting the practical application of carbon nitride in photocatalysis field. Herein, sulfur doped carbon nitride and carbon nanotube composite photocatalysts (CNT/SCN) with high sorption, light harvesting capacity, and reduction efficiency was synthesized by two-step solvothermal method. Furthermore, CNT/SCN composite photocatalytic coating with porous three-dimensional surface morphology was prepared using double liquid phase high speeding spray-deposition method. The coverage rate of CNT/SCN coating was calculated to be 55 %, which was 1.57 times higher than that of GCN coating. The introduction of carbon nanotube (CNT) significantly improved the sorption capacity of photocatalytic coating for hexavalent chromium (Cr6+(aq.)). The reduction efficiency of the composite coating towards Cr6+(aq.) under flowing water conditions was further investigated. The CNT/SCN coating exhibited a high removal efficiency of 84.7 % for Cr6+(aq.) (500 mL, 10 mgL−1) within 8 h, which was 29 times than that of GCN coating. The reduction efficiency of CNT/SCN photocatalytic coating remained above 75 % after three cycles of testing. This research provides theoretical basis and data support for the immobilization application of photocatalysts.

Alkaline earth metal-doped monolayer AlN: A DFT study of photocatalytic and magnetic properties

The presence of the unintentional impurities C and O has been reported in the preparation of two-dimensional AlN using metal organic vapor phase epitaxy or molecular beam epitaxy under vacuum conditions, whereas the occurrence of VAl is inevitable. Thus, the photocatalytic and magnetic properties of monolayer AlN containing VAl, an unintentional impurity (C/O), and Be/Mg/Ca impurity are studied by using the GGA + U method based on density functional theory. Results indicate that the magnetic moment of Al34OiBeN36 is 2 μB, making it relatively suitable for spintronic devices. The Al34OiCaN36 system has the best visible-light absorption, relatively appropriate band-edge position, and relatively easy carrier separation and migration. Therefore, this system is suitable to be used as a photocatalyst for water decomposition. The results of this study will facilitate the preparation of AlN monolayers and provide insights into their potential applications in the field of spintronics and photocatalysis.

Novel furan-containing linear polymer with strong built-in electric field for H2O2 photosynthesis

Using oxygen and water as raw materials, the photocatalytic production of H2O2 is a promising pathway. However, the limited charge separation efficiency represents a significant challenge in the photocatalysis field, as it impedes the generation of H2O2. Herein, a novel highly crystalline linear polymer has been synthesized here by bridging the strongly electronegative furan group with a diphenyl group, in order to adjust its molecular dipole moment to construct an intrinsic electric field to optimize photocatalytic performance. The optimal sample exhibited the best H2O2 synthesis rate of 2686 μmol·g−1·h−1 under pure water conditions, which is the best-performing linear conjugated polymer reported to date for H2O2 photosynthesis system. Importantly, the large internal dipole moment within furan-diphenyl linear polymer, together with the ordered crystalline structure induced robust built-in electric field, can facilitate migration and separation of photogenerated charge carriers. Manipulating molecular dipoles to enhance the built-in electric field can significantly improve photocatalytic activity, providing a new perspective for the rational design of functional linear conjugated polymers in green chemistry and sustainable production.

Enhanced Photocatalytic Degradation by the Preparation of a Stable La-Doped FeTiO3 Photocatalyst: Experimental and DFT Study.

The rapid photocarrier recombination limits the photocatalytic activity of iron titanate (FeTiO3) to be further improved. Developing novel approaches to inhibit the rapid recombination rate of the FeTiO3 photocatalysts is crucial for efficiently degrading pollutants in wastewater. Rare earth ions, with unique electron dispositions and large ion radii, could effectively inhibit photocarrier recombination. Herein, novel lanthanum (La)-doped FeTiO3 photocatalysts were designed and successfully synthesized. The photocatalytic performance of the 12 mol % La/FeTiO3 photocatalyst was superior in degrading tetracycline hydrochloride (TCH), methylene blue (MB), and brilliant blue (BB). These degradation rate constants (k) were 0.12358, 0.01357, and 0.03064 L mg-1 min-1, respectively, which were 12.83, 1.61, and 7.78 times that of pure FeTiO3. The photoelectronic tests and density functional theory (DFT) calculations revealed that the La 4f orbital forms an impurity energy level in the conduction band of FeTiO3. This level narrows the bandgap and acts as an electron acceptor, capturing photoexcited electrons and inhibiting the rapid recombination of photoexcited electron-hole pairs in FeTiO3. This work enhances the potential of FeTiO3 in the photocatalysis field and provides important insights into the efficient degradation of organic pollutants in wastewater.

Ex Situ Covalent Functionalization of Germanene via 1,3-Dipolar Cycloaddition: A Promising Approach for the Bandgap Engineering of Group-14 Xenes.

Group-14 Xenes beyond graphene such as silicene, germanene, and stanene have recently gained a lot of attention for their peculiar electronic properties, which can be tuned by covalent functionalization. Up until now, reported methods for the top-down synthesis of covalently functionalized silicene and germanene typically yield multilayered flakes with a minimum thickness of 100nm. Herein, the ex situ covalent functionalization of germanene (fGe) is reported via 1,3-dipolar cycloaddition of the azomethine ylide generated by the decarboxylative condensation of 3,4-dihydroxybenzaldehyde and sarcosine. Amorphous few-layered sheets (average thickness of ≈6nm) of dipolarophile germanene (GeX) are produced by thermal dehydrogenation of its fully saturated parent precursor, germanane (GeH). Spectroscopic evidence confirmed the emergence of the dipolarophilic sp2 domains due to the dehydrogenation of germanane, and their sp3 hybridization due to the covalent functionalization of germanene. Elemental mapping of the functionalized germanene revealed flakes with a very high abundance of carbon uniformly covering the germanium backbone. The 500meV increase of the optical bandgap of germanene observed upon functionalization paves the way toward bandgap engineering of other group-14 Xenes, which could potentially be a major turning point in the fields of electronics, electrocatalysis, and photocatalysis.

The Role of Point Defects in Heterojunction Photocatalysts: Perspectives and Outlooks

AbstractThe development of efficient photocatalysts is a mainstay for the advancement of photocatalytic technology. Heterojunction photocatalysts can overcome the inherent limitations of single photocatalysts, integrating the advantages of each component, and achieving efficient separation of photogenerated charges, making them a research focus in the field of photocatalysis. The role of point defects in photocatalytic reactions is diverse and can significantly influence the performance of photocatalysts. This review comprehensively summarizes the latest advancements in point defect engineering for the modulation of heterojunction photocatalysts. First, the types of point defects and their impact on photocatalytic processes are introduced. Subsequently, the common types of heterojunction photocatalysts are presented. Then, in accordance with recent research progress, the regulatory mechanisms of point defects within heterojunction photocatalysts are outlined, with a particular focus on their functions on surface/interfacial properties and photogenerated charge transfer processes. Finally, the challenges faced by point defect engineering in optimizing heterojunction photocatalysts and promising solutions are proposed. This review provides an in‐depth understanding of the role of point defect engineering in heterojunction photocatalysts, with the expectation of offering insights into the development of highly active photocatalytic materials.

Ti-doped synergistic hollow thin-walled Bi2O3 nano-microspheres for efficient tetracycline hydrochloride photodegradation

Bismuth oxide (Bi2O3) has been extensively investigated in the fields of environmental photocatalysis, owing to its exceptional charge transport performance and remarkable resistance to photocorrosion. However, the limited absorption spectrum of light and rapid recombination of photogenerated charge results in a low quantum efficiency. Herein, an efficient photocatalytic system for tetracycline hydrochloride (TCH) photodegradation based on titanium (Ti)-doped hollow, thin-walled Bi2O3 with nano-microspheres is fabricated via a facile self-assembly strategy. It is shown that doping Ti in Bi2O3 can generate oxygen vacancies, in addition, the addition of Ti in the solvothermal process inhibits the conversion of Bi3+ to bismuth at high temperature, making the content of each component in the heterostructure controllable. The hybrid catalyst exhibits superior performance in visible-light-driven photocatalytic degradation of TCH (about 95.1 % degradation efficiency after 120 min) and excellent stability (up to 4 cycles) under visible light irradiation. The optimized catalyst exhibits excellent performance in visible light catalytic degradation, owing to the synergistic effect of high specific surface area, Bi plasma resonance effect and charge mobility. Moreover, the photocatalytic mechanism of Ti-Bi2O3 have been deeply analyzed through experimental investigation and DFT theoretical calculations. The findings contribute to the synthesis of efficient visible-light-driven Bi-based photocatalysts and to the understanding of photocatalytic degradation reactions.