An Efficient p–n Heterojunction Photocatalyst Constructed from a Coordination Polymer Nanoplate and a Partically Reduced Graphene Oxide for Visible‐Light Hydrogen Production

A new p–n heterojunction photocatalyst has been synthesized successfully through chemical‐bond‐mediated combination of coordination polymer nanoplates (CPNPs) and partially reduced graphene oxide (PRGO) with a simple colloidal blending process. Photocatalytic H₂ production by the p–n heterojunction photocatalyst PRGO / CPNP was investigated under visible‐light irradiation, which illustrates that PRGO / CPNP exhibits a much higher photocatalytic H₂ production rate than neat the CPNPs. The improvement of this photocatalytic property can be attributed to the inner electrical field formed in the p–n heterojunction, which impedes recombination of photogenerated electrons and holes. In PRGO / CPNP, the existence of the p–n heterojunction has been confirmed by electrochemical methods clearly. For PRGO / CPNP, the reductive degree of the PRGO has a great influence on the H₂ production rate and an ideal condition to get a PRGO / CPNP photocatalyst with higher performance has been obtained.     

Ag3PO4/Ag2CO3 p-n异质结复合光催化剂的制备及增强的可见光催化性能

半导体光催化氧化技术作为一种“绿色技术”,被广泛应用于环境污染物治理和太阳能转化领域.高效、稳定、可回收利用的催化剂的开发是光催化技术发展的一个重要方向. Ag系半导体光催化剂因在可见光分解水制氢及降解有机污染物等方面表现出优异的催化性能而广受关注.然而,该催化剂失活快制约了其应用.因此,提高Ag系半导体材料的光催化稳定性成为近年来研究的一个热点.研究发现,在半导体的表面或者界面形成p–n异质结是提高催化剂光催化性能和稳定性的有效途径.理论上讲,当p型半导体和n型半导体形成p–n结以后,在两种半导体接触边缘的附近处存在着正、负空间电荷分列两边的偶极层,产生了从n型半导体指向p型半导体的内建电场.内建电场的存在使得p型半导体与n型半导体之间产生了电位差,即内建电势差.这种电势差能够有效促进电子和空穴的分离,达到光生电子和空穴对分离、转移和传递的目的,从而抑制电子和空穴的复合,提高光催化效率. Ag2CO3是p型半导体,其导带为0.21 eV,价带为2.83 eV; Ag3PO4是n型半导体,其导带为0.43 eV,价带为2.86 eV.两者能带结构匹配,能形成p–n异质结.因此,本文采用简单的共沉淀法,制备了不同比例的Ag3PO4/Ag2CO3复合光催化剂,并通过X射线衍射、透射电镜、X射线光电子能谱、紫外-可见漫反射光谱以及瞬态光电压谱等对其进行了表征.透射电镜照片显示,粒径较小的Ag3PO4颗粒均匀的分布在粒径较大的Ag2CO3周围. P元素和C元素的摩尔比接近于投料比. Ag3PO4/Ag2CO3复合催化剂的吸收光谱体现出两种催化剂的混合特征,在可见光区的吸收强度增加.瞬态光电压表征不仅证实了Ag2CO3是p型半导体, Ag3PO4是n型半导体,更说明了40%-Ag3PO4/Ag2CO3复合光催化剂的载流子寿命较长.罗丹明B(RhB)的降解实验证实40%-Ag3PO4/Ag2CO3(Ag3PO4与Ag2CO3的摩尔比为40%：60%)复合催化剂的光催化效率最高,500 W氙灯(附加420 nm截止波长的滤光片)照射15 min后, RhB就能被完全降解,而纯的Ag3PO4和Ag2CO3对RhB的降解率只有40%和10%.循环实验发现,前两次循环中由于单质银的生成导致催化剂活性下降,但从第三次循环开始其催化活性趋于稳定.此外,还通过添加草酸钠(空穴的清除剂)、异丙醇(羟基自由基的清除剂)和对苯醌(超氧自由基的淬灭剂)等来判断光催化过程中起主要作用的活性自由基.实验证实空穴是Ag3PO4/Ag2CO3光催化剂在降解RhB过程中产生的主要活性自由基物种. Ag3PO4/Ag2CO3光催化剂相对于单纯的Ag3PO4和Ag2CO3有更高的空穴产生能力.当可见光照射到复合催化剂表面时, Ag2CO3导带上的激发电子能够快速转移到Ag3PO4的导带上,同时Ag3PO4价带上的光生空穴能够快速转移到Ag2CO3的价带上. p–n结的形成提高了光生电子和空穴的分离效率,抑制了电子和空穴的再结合,因此,复合光催化剂光催化降解效率提高.综上所述, Ag3PO4/Ag2CO3之间能形成有效p–n结,40%-Ag3PO4/Ag2CO3复合光催化剂表现出最佳的光催化性能.     

Construction of Hierarchical Hollow Co9S8/ZnIn2S4 Tubular Heterostructures for Highly Efficient Solar Energy Conversion and Environmental Remediation

Visible‐light‐responsive hierarchical Co₉S₈/ZnIn₂S₄ tubular heterostructures are fabricated by growing 2D ZnIn₂S₄ nanosheets on 1D hollow Co₉S₈ nanotubes. This design combines two photoresponsive sulfide semiconductors in a stable heterojunction with a hierarchical hollow tubular structure, improving visible‐light absorption, yielding a large surface area, exposing sufficient catalytically active sites, and promoting the separation and migration of photogenerated charges. The hierarchical nanotubes exhibit excellent photocatalytic H₂ evolution and Cr^VI reduction efficiency. Under visible‐light illumination, the optimized Co₉S₈/ZnIn₂S₄ heterostructure provides a remarkable H₂ generation rate of 9039 μmol h^?1 g^?1 without the use of any co‐catalysts and Cr^VI is completely reduced in 45 min. The Co₉S₈/ZnIn₂S₄ heterostructure is stable after multiple photocatalytic cycles.     

Heterophase Photocatalysts from Water‐Soluble Conjugated Polyelectrolytes: An Example of Self‐Initiation under Visible Light

We herein report a new design route to stable, heterophase photocatalysts, which function as highly dispersible conjugated polymer nanoparticles and porous monoliths under visible light in aqueous medium. They were constructed by attachment of the ionic‐liquid species 1‐alkyl‐3‐vinylimidazolium bromide onto the side chains of a photoactive polymer. The structure configuration allows not only photocatalysis in aqueous environment but also a unique self‐initiation radical cross‐linking process to transform the water‐soluble photoactive polymer into a heterophase system, either as nanoparticles or a porous monolith. High photocatalytic activity and reusability of the heterophase system were demonstrated in the degradation of organic dyes and reduction of Cr^VI into Cr^III in water under visible‐light irradiation.     

An Efficient,Visible‐Light‐Driven,Hydrogen Evolution Catalyst NiS/ZnxCd1−xS Nanocrystal Derived from a Metal–Organic Framework

Photocatalytic water splitting for hydrogen production using sustainable sunlight is a promising alternative to industrial hydrogen production. However, the scarcity of highly active, recyclable, inexpensive photocatalysts impedes the development of photocatalytic hydrogen evolution reaction (HER) schemes. Herein, a metal–organic framework (MOF)‐template strategy was developed to prepare non‐noble metal co‐catalyst/solid solution heterojunction NiS/Zn_xCd_1−xS with superior photocatalytic HER activity. By adjusting the doping metal concentration in MOFs, the chemical compositions and band gaps of the heterojunctions can be fine‐tuned, and the light absorption capacity and photocatalytic activity were further optimized. NiS/Zn_0.5Cd_0.5S exhibits an optimal HER rate of 16.78 mmol g⁻¹ h⁻¹ and high stability and recyclability under visible‐light irradiation (λ>420 nm). Detailed characterizations and in‐depth DFT calculations reveal the relationship between the heterojunction and photocatalytic activity and confirm the importance of NiS in accelerating the water dissociation kinetics, which is a crucial factor for photocatalytic HER.     

An Efficient,Visible‐Light‐Driven,Hydrogen Evolution Catalyst NiS/ZnxCd1−xS Nanocrystal Derived from a Metal–Organic Framework

Photocatalytic water splitting for hydrogen production using sustainable sunlight is a promising alternative to industrial hydrogen production. However, the scarcity of highly active, recyclable, inexpensive photocatalysts impedes the development of photocatalytic hydrogen evolution reaction (HER) schemes. Herein, a metal–organic framework (MOF)‐template strategy was developed to prepare non‐noble metal co‐catalyst/solid solution heterojunction NiS/Zn_xCd_1?xS with superior photocatalytic HER activity. By adjusting the doping metal concentration in MOFs, the chemical compositions and band gaps of the heterojunctions can be fine‐tuned, and the light absorption capacity and photocatalytic activity were further optimized. NiS/Zn_0.5Cd_0.5S exhibits an optimal HER rate of 16.78 mmol g^?1 h^?1 and high stability and recyclability under visible‐light irradiation (λ>420 nm). Detailed characterizations and in‐depth DFT calculations reveal the relationship between the heterojunction and photocatalytic activity and confirm the importance of NiS in accelerating the water dissociation kinetics, which is a crucial factor for photocatalytic HER.     

Fullerol–Titania Charge‐Transfer‐Mediated Photocatalysis Working under Visible Light

The development of visible‐light‐active photocatalysts is being investigated through various approaches. In this study, C₆₀‐based sensitized photocatalysis that works through the charge transfer (CT) mechanism is proposed and tested as a new approach. By employing the water‐soluble fullerol (C₆₀(OH)_x) instead of C₆₀, we demonstrate that the adsorbed fullerol activates TiO₂ under visible‐light irradiation through the “surface–complex CT” mechanism, which is largely absent in the C₆₀/TiO₂ system. Although fullerene and its derivatives have often been utilized in TiO₂‐based photochemical conversion systems as an electron transfer relay, their successful photocatalytic application as a visible‐light sensitizer of TiO₂ is not well established. Fullerol/TiO₂ exhibits marked visible photocatalytic activity not only for the redox conversion of 4‐chlorophenol, I^?, and Cr^VI, but also for H₂ production. The photoelectrode of fullerol/TiO₂ also generates an enhanced anodic photocurrent under visible light as compared with the electrodes of bare TiO₂ and C₆₀/TiO₂, which confirms that the visible‐light‐induced electron transfer from fullerol to TiO₂ is particularly enhanced. The surface complexation of fullerol/TiO₂ induced a visible absorption band around 400–500 nm, which was extinguished when the adsorption of fullerol was inhibited by fluorination of the surface of TiO₂. The transient absorption spectroscopic measurement gave an absorption spectrum ascribed to fullerol radical cations (fullerol^.+) the generation of which should be accompanied by the proposed CT. The theoretical calculation regarding the absorption spectra for the (TiO₂ cluster+fullerol) model also confirmed the proposed CT, which involves excitation from HOMO (fullerol) to LUMO (TiO₂ cluster) as the origin of the visible‐light absorption.     

Preparation of high‐activity AgBr/Ag3PO4 photocatalyst based on hexadecyltrimethylammonium bromide and mechanism of photocatalytic enhancement

A high‐activity AgBr/Ag₃PO₄ heterojunction photocatalyst was synthesized based on hexadecyltrimethylammonium bromide. Its microspheres were characterized using X‐ray diffractometry, transmission electron microscopy and ultraviolet–visible diffuse reflectance spectroscopy. The new photocatalyst with high photocatalytic activity exceptionally outperforms pure Ag₃PO₄ and AgBr in methyl orange degradation. The enhancement of photocatalytic activity is attributed to the efficient separation of electron–hole pairs. In this photocatalytic reaction, h⁺ and ^?O^2? are the main reactive species that induce visible‐light‐driven degradation.     

The coating of conducting copolymer on coordination polymer nanorod: A visible light active p-n heterojunction photocatalyst for H2 production

A visible light active p-n heterojunction photocatalyst was synthesized successfully through in-situ chemical oxidation copolymerization of aniline (ANI) and diphenylamine-4-sulfonate (DPAS) with the existence of coordination polymer nanorod (CPNR) under initiation of ammonium persulfate (APS). Compared with neat coordination polymer nanorod, the resulted p-n heterojunction photocatalyst exhibits higher H₂ generationrate under visible light irradiation. In this heterojunction photocatalyst, as a p-type semiconductor possessing suitable energy levels with coordination polymer nanorod, poly-(aniline-co-N-(4-sulfophenyl)-aniline) (PAPSA) forms p-n heterojunction with n-type coordination polymer nanorod, the inner electric field of p-n heterojunction accelerates the separation of electrons and holes, which enhances H₂ production performance. Furthermore, the influence of concentration ratio between DPAS and ANI on photocatalytic property of the p-n heterojunction photocatalyst was discussed and a reasonable condition to fabricate photocatalyst with high H₂ generationrate had been obtained. During photocatalytic water splitting H₂ generation, the p-n heterojunction photocatalyst exhibited outstanding stability.     

Synthesis of noble‐metal‐free ternary K7HNb6O19/Cd0.5Zn0.5S/g‐C3N4 tandem heterojunctions for efficient photocatalytic performance under visible light

Exploring noble‐metal‐free, highly active and durable catalysts is vital to get to grips with the energy and environmental issues. Herein, we first dexterously design and synthesize a class of ternary Nb₆/CZS/g‐CN photocatalysts for the removal of hexavalent chromium Cr (VI) and organic dye pollutant (MO) from wastewater under visible‐light irradiation. A heterojunction Nb₆–1/CZS/g‐CN loaded with 0.01 g K₇HNb₆O₁₉ showed excellent photocatalytic performance, with the MO photodegradation efficiency of 94% in 1 h and the Cr (VI) (150 mg/l) photoreduction efficiency as high as 91% in 2 hr. The main active species were deemed to be O₂^.‐. Additionally, the as‐prepared ternary heterojunction exhibits superior hydrogen evolution reaction (HER) rate. A heterojunction Nb₆–4/CZS/g‐CN loaded with 0.5 g K₇HNb₆O₁₉ exhibited the highest H₂ evolution rate as high as 1777.86 μmol h^?1 g^?1 under visible‐light illumination, which is increased to 5.7 and 2.7 times that of bare CZS and biphase heterojunction CZS/g‐CN_. These findings afford a new class of promising low‐cost photocatalyst bodying for its huge potential value in sustainable energy development and wastewater treatment.     

A New p‐Metal‐n Structure AgBr‐Ag‐BiOBr with Superior Visible‐Light‐Responsive Catalytic Performance

A novel visible‐light‐driven AgBr‐Ag‐BiOBr photocatalyst was synthesized by a facile hydrothermal method. Taking advantage of both p‐n heterojunctions and localized surface plasmon resonance, the p‐metal‐n structure exhibited a superior performance concerning degradation of methyl orange under visible‐light irradiation (λ>420 nm). A possible photodegradation mechanism in the presence of AgBr‐Ag‐BiOBr composites was proposed, and the radical species involved in the degradation reaction were investigated. HO₂^?/^?O₂^? played the same important role as ^?OH in the AgBr‐Ag‐BiOBr photocatalytic system, and both the electron and hole were fully used for degradation of organic pollutants. A dual role of metallic Ag in the photocatalysis was proposed, one being surface plasmon resonance and the other being an electron‐hole bridge. Due to the distinctive p‐metal‐n structure, the visible‐light absorption, the separation of photogenerated carriers and the photocatalysis efficiency were greatly enhanced.     

Highly Efficient Visible Light Plasmonic Photocatalyst Ag@Ag(Br,I)

The new plasmonic photocatalyst Ag@Ag(Br,I) was synthesized by the ion‐exchange process between the silver bromide and potassium iodide, then by reducing some Ag⁺ ions in the surface region of Ag(Br,I) particles to Ag⁰ species. Ag nanoparticles are formed from Ag(Br,I) by the light‐induced chemical reduction reaction. The Ag@Ag(Br,I) particles have irregular shapes with their sizes varying from 83 nm to 1 μm. The as‐grown plasmonic photocatalyst shows strong absorption in the visible light region because of the plasmon resonance of Ag nanoparticles. The ability of this compound to reduce Cr^VI under visible light was compared with those of other reference photocatalyst. The plasmonic photocatalyst is shown to be highly efficient under visible light. The stability of the photocatalyst was examined by X‐ray diffraction and X‐ray photoelectron spectroscopy. The XRD pattern and XPS spectra prove the stability of the plasmonic photocatalyst Ag@Ag(Br,I).     

Microwave‐Hydrothermal Preparation and Visible‐Light Photoactivity of Plasmonic Photocatalyst Ag‐TiO2 Nanocomposite Hollow Spheres

Visible‐light‐driven plasmonic photocatalyst Ag‐TiO₂ nanocomposite hollow spheres are prepared by a template‐free chemically‐induced self‐transformation strategy under microwave‐hydrothermal conditions, followed by a photochemical reduction process under xenon lamp irradiation. The prepared samples are characterized by using scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, N₂ adsorption‐desorption isotherms, X‐ray photoelectron spectroscopy, UV/Vis and Raman spectroscopy. Production of ?OH radicals on the surface of visible‐light illuminated TiO₂ was detected by using a photoluminescence method with terephthalic acid as the probe molecule. The photocatalytic activity of as‐prepared samples was evaluated by photocatalytic decolorization of Rhodamine B (RhB) aqueous solution at ambient temperature under visible‐light irradiation. The results show that the surface plasmon absorption band of the silver nanoparticles supported on the TiO₂ hollow spheres was red shifted, and a strong surface enhanced Raman scattering effect for the Ag‐TiO₂ nanocomposite sample was observed. The prepared nanocomposite hollow spheres exhibits a highly visible‐light photocatalytic activity for photocatalytic degradation of RhB in water, and their photocatalytic activity is higher than that of pure TiO₂ and commercial Degussa P25 (P25) powders. Especially, the as‐prepared Ag‐TiO₂ nanocomposite hollow spheres at the nominal atomic ratio of silver to titanium ( R ) of 2 showed the highest photocatalytic activity, which exceeds that of P25 by a factor of more than 2.     

Ultrasound‐assisted Synthesis of Ag‐ZnS/rGO and its Utilization in Photocatalytic Degradation of Tetracycline Under Visible Light Irradiation

Recent improvements based on heterojunction nanocomposites have opened new possibilities in photocatalysis. In this research, an ultrasound‐assisted coprecipitation method was used to fabricate silver, zinc sulfide and reduced graphene oxide (Ag‐ZnS/rGO) nanocomposite, and characterization results indicated that 3% Ag‐ZnS spherical nanoparticles are successfully embedded in rGO matrix. The potential of the Ag‐ZnS/rGO, as a visible light active photocatalyst, was assessed through optimizing degradation of Tetracycline (TC) by response surface methodology. It was found that the photocatalytic degradation of TC increased with an increase in the amount of nanocomposite and irradiation time, whereas it decreased with increasing the initial TC concentration. Under the optimal conditions (10 mg L^?1 of TC, 1.25 g L^?1 of Ag‐ZnS/rGO, at pH = 7, and irradiation duration 110 min), more than 90% of the TC was degraded. The study of the mechanism of the photocatalytic process disclosed that the synergistic role of surface plasmon resonance (SPR) induced by Ag nanoparticles and p‐type semiconductor feature of rGO leads to ZnS semiconductor stimulation in the visible light region. Eventually, a pseudo‐first order kinetics model was developed based on the proposed mechanism. The obtained results highlight the role of Ag‐ZnS/rGO nanophotocatalyst toward degradation of some antibiotics under visible light.     

Potassium‐Ion‐Assisted Regeneration of Active Cyano Groups in Carbon Nitride Nanoribbons: Visible‐Light‐Driven Photocatalytic Nitrogen Reduction

As a metal‐free nitrogen reduction reaction (NRR) photocatalyst, g‐C₃N₄ is available from a scalable synthesis at low cost. Importantly, it can be readily functionalized to enhance photocatalytic activities. However, the use of g‐C₃N₄‐based photocatalysts for the NRR has been questioned because of the elusive mechanism and the involvement of N defects. This work reports the synthesis of a g‐C₃N₄ photocatalyst modified with cyano groups and intercalated K⁺ (mCNN), possessing extended visible‐light harvesting capacity and superior photocatalytic NRR activity (NH₃ yield: 3.42 mmol g^?1 h^?1). Experimental and theoretical studies suggest that the ‐C≡N in mCNN can be regenerated through a pathway analogous to Mars van Krevelen process with the aid of the intercalated K⁺. The results confirm that the regeneration of the cyano group not only enhances photocatalytic activity and sustains the catalytic cycle, but also stabilizes the photocatalyst.     

Acid‐treated g‐C3N4‐Cu2O composite catalyst with enhanced photocatalytic activity under visible‐light irradiation

Acid‐treated g‐C₃N₄‐Cu₂O was prepared by hydrothermal reduction followed by high temperature calcination and acid exfoliation. The structures and properties of as‐synthesized samples were characterized using a range of techniques, such as X‐ray photoelectron spectroscopy, scanning electron microscopy, Photoluminescence Spectroscopy and the Brunauer–Emmett–Teller (BET) theory. The photocatalytic activity was evaluated by measuring the photodegradation of methyl orange under visible‐light irradiation. Based on the results of TEM, XPS, EPR and other techniques, it was verified that a heterojunction was formed. The acid treatment process can increase the specific surface area to form abundant heterojunction interfaces as channels for photo‐generated carrier separation, thereby enhancing its light utilization and quantum efficiency. Results indicate that acid‐treated g‐C₃N₄‐Cu₂O possesses a large specific surface area, which provides plentiful activated sites for heterojunctions to form; in addition, it showed a high visible light effect and the minimum charge‐transfer resistance. Furthermore, the g‐C₃N₄‐Cu₂O material exhibits high levels of effectiveness and stability. Electron paramagnetic resonance and a series of radical trapping experiments demonstrate that the holes and ?O₂^? could be the main active species in methyl orange photodegradation. This work could provide new insights into the fabrication of composite materials as high‐performance photocatalysts, and facilitate their application in addressing environmental protection issues.     

Constructing Ordered Three‐Dimensional TiO2 Channels for Enhanced Visible‐Light Photocatalytic Performance in CO2 Conversion Induced by Au Nanoparticles

As a typical photocatalyst for CO₂ reduction, practical applications of TiO₂ still suffer from low photocatalytic efficiency and limited visible‐light absorption. Herein, a novel Au‐nanoparticle (NP)‐decorated ordered mesoporous TiO₂ (OMT) composite (OMT‐Au) was successfully fabricated, in which Au NPs were uniformly dispersed on the OMT. Due to the surface plasmon resonance (SPR) effect derived from the excited Au NPs, the TiO₂ shows high photocatalytic performance for CO₂ reduction under visible light. The ordered mesoporous TiO₂ exhibits superior material and structure, with a high surface area that offers more catalytically active sites. More importantly, the three‐dimensional transport channels ensure the smooth flow of gas molecules, highly efficient CO₂ adsorption, and the fast and steady transmission of hot electrons excited from the Au NPs, which lead to a further improvement in the photocatalytic performance. These results highlight the possibility of improving the photocatalysis for CO₂ reduction under visible light by constructing OMT‐based Au‐SPR‐induced photocatalysts.     

Solvothermal Synthesis of Cs0.33WO3/LDHs Composite as a Novel Visible‐Light‐Driven Photocatalyst

A novel Cs_0.33WO₃/LDHs (CWLDH) composite was synthesized by simple two steps solvothermal method and first investigated as the photocatalyst for tetracycline (TC) and Congo red (CR) degradation under visible light irradiation. The CWLDH heterostructures catalysts were characterized by XRD, UV–Vis, SEM, XPS and BET. The composite CWLDH showed enhanced photocatalytic activity compared with pure Cs_0.33WO ₃ and NiAl‐LDH under identical experimental conditions. The enhanced photocatalytic activity was mainly attributed to the higher visible light‐absorbing ability, efficient electron–hole separation and prolonged lifetimes of photogenerated charges. The photocatalyst presented a high photocatalytic activity (92%) at the optimum of CWLDH ‐3 and initial TC concentration of 40 mg L⁻¹. Besides, the degradation efficiency of TC is higher than 75% for reused CWLDH after four cycles, demonstrating that it could be used as a potential catalyst with good photocatalytic activity, stability and reusability. According to the experimental results, a possible photocatalytic mechanism of CWLDH was discussed.     

Amino‐Assisted Anchoring of CsPbBr3 Perovskite Quantum Dots on Porous g‐C3N4 for Enhanced Photocatalytic CO2 Reduction

Halide perovskite quantum dots (QDs) have great potential in photocatalytic applications if their low charge transportation efficiency and chemical instability can be overcome. To circumvent these obstacles, we anchored CsPbBr₃ QDs (CPB) on NH_x‐rich porous g‐C₃N₄ nanosheets (PCN) to construct the composite photocatalysts via N?Br chemical bonding. The 20 CPB‐PCN (20 wt % of QDs) photocatalyst exhibits good stability and an outstanding yield of 149 μmol h^?1 g^?1 in acetonitrile/water for photocatalytic reduction of CO₂ to CO under visible light irradiation, which is around 15 times higher than that of CsPbBr₃ QDs. This study opens up new possibilities of using halide perovskite QDs for photocatalytic application.     

Ionic‐Liquid‐Assisted Synthesis of Uniform Fluorinated B/C‐Codoped TiO2 Nanocrystals and Their Enhanced Visible‐Light Photocatalytic Activity

Exploiting advanced photocatalysts under visible light is of primary significance for the development of environmentally relevant photocatalytic decontamination processes. In this study, the ionic liquid (IL), 1‐butyl‐3‐methylimidazolium tetrafluoroborate, was employed for the first time as both a structure‐directing agent and a dopant for the synthesis of novel fluorinated B/C‐codoped anatase TiO₂ nanocrystals (T_IL) through hydrothermal hydrolysis of tetrabutyl titanate. These T_IL nanocrystals feature uniform crystallite and pore sizes and are stable with respect to phase transitions, crystal ripening, and pore collapse upon calcination treatment. More significantly, these nanocrystals possess abundant localized states and strong visible‐light absorption in a wide range of wavelengths. Because of synergic interactions between titania and codopants, the calcined T_IL samples exhibited high visible‐light photocatalytic activity in the presence of oxidizing Rhodamine B (RhB). In particular, 300 °C‐calcined T_IL was most photocatalytically active; its activity was much higher than that of TiO_1.98N_0.02 and reference samples (T_W) obtained under identical conditions in the absence of ionic liquid. Furthermore, the possible photocatalytic oxidation mechanism and the active species involved in the RhB degradation photocatalyzed by the T_IL samples were primarily investigated experimentally by using different scavengers. It was found that both holes and electrons, as well as their derived active species, such as ^.OH, contributed to the RhB degradation occurring on the fluorinated B/C‐codoped TiO₂ photocatalyst, in terms of both the photocatalytic reaction dynamics and the reaction pathway. The synthesis of the aforementioned novel photocatalyst and the identification of specific active species involved in the photodegradation of dyes could shed new light on the design and synthesis of semiconductor materials with enhanced photocatalytic activity towards organic pollutants.