One-step synthesis of three-dimensional mesoporous Co_(3)O_(4)@Al_(2)O_(3)nanocomposites with deep eutectic solvent:An efficient and stable peroxymonosulfate activator for organic pollutant degradations

The effective,stable,and secure catalysts are essential for sulfate radical(SO_(4)·−)-based advanced oxidation processes(SR-AOPs)to the degradation of organic contaminants in water.Heterogeneous supported cobalt-based catalysts are commonly used to activate peroxymonosulfate(PMS)to achieve the degradation.In this work,we synthesized Co_(3)O_(4)@Al_(2)O_(3)three-dimensional(3D)mesoporous nanocomposite(denoted as Co_(3)O_(4)@Al_(2)O_(33)DPNC)in just one step by calcining cheap and green deep eutectic solvent(DES)solution containing Co salt.Co_(3)O_(4)@Al_(2)O_(33)DPNC with the high specific surface area(93.246 m^(2)/g),uniform pore distribution(3.829 nm)and rich porosity(0.255 cm^(3)/g)were attained in a beautiful hierarchical structure which exhibited the open 3D propeller-like microstructure,two-dimensional lamellar substructure with rich folds,as well as the decoration of highly dispersed Co_(3)O_(4)nanoparticles on mesoporous amorphous Al_(2)O_(3).The excellent chemical and thermal stability of Al_(2)O_(3)ensures the high stability of the catalyst,and the formation of the complex hierarchical structure makes the active Co_(3)O_(4)be homogenously dispersed for effective catalysis.The catalyst demonstrated outstanding performance for catalytic degradations of organic pollutants(acetaminophen,oxytetracycline,5-sulfosalicylic acid,orange G and Rhodamine B)by generated SO_(4)·−,·OH and^(1)O_(2).With a very low cobalt content(equal to 28.2 mg/L of Co),the catalyst exhibited very high stability and excellent reusability in the recycling usages,while the leaching of the cobalt element(<0.145 mg/L)was also at a low level.Our catalyst achieved effective degradations of acetaminophen in cycles without losing its stable hierarchical nanostructure.

Design of metal-organic frameworks(MOFs)-based photocatalyst for solar fuel production and photo-degradation of pollutants

Metal organic frameworks(MOFs)is a research hotspot in the solar fuel production and photo-degradation of pollutants field due to high surface area,rich metal/organic species,large pore volume,and adjustability of structures and compositions.Therefore,in this review,we first summarized the design factors of photocatalytic materials based on MOF from the perspective of"star"MOF.The modification strategies of MOFs-based photocatalysts were discussed to improve its photocatalytic activity and specific applications were summarized as well,including photocatalytic CO_(2)reduction,photocatalytic water splitting and photo-degradation of pollutants.Finally,the advantages and disadvantages of MOFs-based photocatalysts were discussed,the current challenges were highlighted,and suggestions for future research directions were proposed.

One-step preparation of Fe_xO_y/N-GN/CNTs heterojunctions as a peroxymonosulfate activator for relatively highly-efficient methylene blue degradation

Persulfate decontamination technologies utilizing radical‐driven processes are powerful tools for the treatment of a broad range of impurities.However,the design of high‐performance catalytic activators with multi‐functionality remains a great challenge.Therefore,in this study,three‐dimensional multifunctional FexOy/N‐GN/CNTs(N‐GN:nitrogen‐doped graphene,CNTs:carbon nanotubes)heterojunctions,which can be employed as microwave absorbers and catalysts,were synthesized via a solvothermal method and applied to activate peroxymonosulfate for the degradation of methylene blue(MB).X‐ray diffraction(XRD),Fourier transform infrared spectrometer(FTIR),scanning electron microscope(SEM),and X‐ray photoelectron microscopy(XPS)analyses revealed that the FexOy were anchored in‐situ onto the N‐GN network.Using MB as the model organic dye,various factors,such as degradation systems,PMS loading,initial organic pollutant concentration,and catalyst dosage were optimized.The results revealed that the remarkable efficiency was attributable to the synergistic effects of carbon,nitrogen,and iron‐based species.The oxidation system corresponded to the pseudo‐first‐order kinetic with a k value of^0.33 min^-1.It was demonstrated that both SO4^-and OH^-were the predominant reactive species through quenching experiments.Because these heterojunctions were employed as microwave absorbers and have a semiconductor‐like texture,the Fe/N co‐rich hierarchical porous carbon skeleton favored electron transport and storage.These heterojunctions increase the options for transitional metal catalysts and highlights the importance of designing other heterojunctions for specific applications,such as supercapacitors,energy storage,CO2 capture,and oxygen reduction electrocatalysts.

Promising graphdiyne-based nanomaterials for environmental pollutant control

ABSTRACT Environmental pollutants,including gas phase pollutants,liquid organic pollutants,heavy metal ions,and pathogenic bacteria,pose a serious threat to our ecological environment and human health.Effectively addressing these pollutants has become one of the most urgent issues.Graphdiyne(GDY),as an emerging carbon material for environmental remediation,has unique acetylene bonds and abundant pore structures.The unique carbon atomic structure of sp/sp2 hybrid endows it with tunable electronic structure and outstanding physical and chemical properties.This review summarizes the practical applications of GDY-based nanomaterials in the context of environmental pollution control,including carbon monoxide(CO)oxidation,ozone(O_(3))decomposition,heavy metal ion detection and adsorption,organic pollutant degradation,and bacterial inactivation.Furthermore,the structure-performance relationship of GDYbased nanomaterials is analyzed,and the issues and challenges in the field of environmental remediation of GDY-based materials are indicated.

Thermal catalysis under dark ambient conditions in environmental remediation:Fundamental principles, development, and challenges

Thermal catalytic degradation of organic pollutants conducted in the dark at room temperature under atmospheric pressure without the need of external chemicals and energy sources has attracted a lot of attention over the last two decades. It provides unparalleled advantages over other advanced oxidation processes (AOPs) in treating domestic and industrial contaminated wastewater from the viewpoint of energy/chemical conservation and ease of operation. Rich knowledge has been accumulated in terms of the synthesis and application of thermal catalysts though controversies remain regarding their underlying mechanisms. This review sheds light on the proposed thermo- catalysis mechanism for the first time and presents the development of thermal catalysts under dark ambient conditions with a focus on catalyst materials, catalytic activity, and mechanism. The present review aims to provide mechanistic insights into the rational design of novel and efficient catalysts, and their underlying mechanisms as well as the emerging challenges and perspectives in thermo-catalysis under dark ambient conditions used for the practical and efficient treatment of contaminated wastewater.

BiVO_4 Photoanode with Exposed(040) Facets for Enhanced Photoelectrochemical Performance

A BiVO_4 photoanode with exposed(040) facets was prepared to enhance its photoelectrochemical performance.The exposure of the(040) crystal planes of the BiVO_4 film was induced by adding NaCl to the precursor solution. The asprepared BiVO_4 photoanode exhibits higher solar-light absorption and charge-separation efficiency compared to those of an anode prepared without adding Na Cl. To our knowledge,the photocurrent density(1.26 m A cm^(-2) at 1.23 V vs. RHE) of as-prepared BiVO_4 photoanode is the highest according to the reports for bare BiVO_4 films under simulated AM1.5 G solar light, and the incident photon-to-current conversion efficiency is above 35% at 400 nm. The photoelectrochemical(PEC)water-splitting performance was also dramatically improvedwith a hydrogen evolution rate of 9.11 lmol cm^(-2) h^(-1), which is five times compared with the BiVO_4 photoanode prepared without NaCl(1.82 lmol cm^(-2) h^(-1)). Intensity-modulated photocurrent spectroscopy and transient photocurrent measurements show a higher charge-carrier-transfer rate for this photoanode. These results demonstrate a promising approach for the development of high-performance BiVO_4 photoanodes which can be used for efficient PEC water splitting and degradation of organic pollutants.

Bandgap engineering of tetragonal phase CuFeS_(2)quantum dots via mixed-valence single-atomic Ag decoration for synergistic Cr(VI)reduction and RhB degradation

Bandgap engineering through single-atom site binding on semiconducting photocatalyst can boost the intrinsic activity,selectivity,carrier separation,and electron transport.Here,we report a mixed-valence Ag(0)and Ag(I)single atoms co-decorated semiconducting chalcopyrite quantum dots(Ag/CuFeS_(2)QDs)photocatalyst.It demonstrates efficient photocatalytic performances for specific organic dye(rhodamine B,denoted as RhB)as well as inorganic dye(Cr(VI))removal in water under natural sunlight irradiation.The RhB degradation and Cr(VI)removal efficiencies by Ag/CuFeS_(2)QDs were 3.55 and 6.75 times higher than those of the naked CuFeS_(2)QDs at their optimal pH conditions,respectively.Besides,in a mixture of RhB and Cr(VI)solution under neutral condition,the removal ratio has been elevated from 30.2%to 79.4%for Cr(VI),and from 95.2%to 97.3%for RhB degradation by using Ag/CuFeS_(2)QDs after 2 h sunlight illumination.The intrinsic mechanism for the photocatalytic performance improvement is attributed to the narrow bandgap of the single-atomic Ag(I)anchored CuFeS_(2)QDs,which engineers the electronic structure as well as expands the optical light response range.Significantly,the highly active Ag(0)/CuFeS_(2)and Ag(I)/CuFeS_(2)effectively improve the separation efficiency of the carriers,thus enhancing the photocatalytic performances.This work presents a highly efficient single atom/QDs photocatalyst,constructed through bandgap engineering via mixed-valence single noble metal atoms binding on semiconducting QDs.It paves the way for developing high-efficiency single-atom photocatalysts for complex pollutions removal in dyeing wastewater environment.

A Z-scheme LaFeO_(3)-CuFe_(2)O4 composite for sulfate radical-based photocatalytic process:Synergistic effect and mechanism

The sulfate radical-based photocatalytic process is supposed to be the most promising way to degrade organic pollutants.However,the development of a suitable and efficient photocatalyst is very challenging.The 40LaFeO_(3)-CuFe_(2)O_(4)(40LFO-CFO)nanocomposite was constructed and its catalytic performance was studied using Rhodamine B(RhB)as the target pollutant.40LFO-CFO exhibited excellent RhB degradation by the persulfate(PS)-assisted photocatalytic process compared to the pristine LFO and CFO.The degradation rate constant for RhB by 40LFO-CFO in the Vis/PS system was 2.22h^(-1)which is 3.04 times and 5.05 times higher than the pristine LFO(0.73 h^(-1))and CFO(0.44h^(-1)),respectively.Furthermore,the trapping experiments and EPR spectra proved that h^(+) plays a leading role in the bleaching of RhB for the 40LFO-CFO/PS/Vis system.The enhanced photocatalytic oxidation activity of 40LFO-CFO could be attributed to the unique charge carriers flow in 40LFO-CFO due to the Z-scheme and the cooperation effect between photocatalysis and PS activation.The recycle tests confessed the stability of 40LFO-CFO.Additionally,the intermediates and products of RhB are detected by liquid chromatographymass spectrometry(LC-MS),and the photocatalytic degradation routes of RhB for the 40LFO-CFO/Vis/PS system were proposed.Moreover,the 40LFO-CFO nanocomposite has a superior catalytic performance for other organics,suggesting that it is a promising heterocatalyst because of its high catalytic activity and stability for the PS-assisted photocatalytic process.

Recent Progress on Visible Light Responsive Heterojunctions for Photocatalytic Applications

Photocatalysis has attracted much attention in recent years due to its potential in solving energy and environmental issues. Even though numerous achievements have been made, the photocatalytic systems developed to date are still far from practical applications due to the low efficiency and poor durability. Efficient light absorption and charge separation are two of the key factors for the exploration of high performance photocatalytic systems, which is generally difficult to be obtained in a single photocata- lyst. The combination of various materials to form heterojunctions provides an effective way to better harvest solar energy and to facilitate charge separation and transfer, thus enhancing the photocatalytic activity and stability. This review concisely summarizes the recent development of visible light respon- sive heterojunctions, including the preparation and performances of semiconductor/semiconductor junctions, semiconductor/cocatalyst junctions, semiconductor/metal junctions, semiconductor/non- metal junctions, and surface heterojunctions, and their mechanism for enhanced light harvesting and charge separation/transfer.

Fluorinated inverse opal carbon nitride combined with vanadium pentoxide as a Z-scheme photocatalyst with enhanced photocatalytic activity

In this work,Z-scheme V_(2)O_(5) loaded fluorinated inverse opal carbon nitride(IO F-CN/V_(2)O_(5)) was synthesized as a product of ternary collaborative modification with heterostructure construction,element doping and inverse opal structure.The catalyst presented the highest photocatalytic activity and rate constant for degradation of typical organic pollutants Rhodamine B(RhB)and was also used for the efficient removal of antibiotics,represented by norfloxacin(NOR),sulfadiazine(SD)and levofloxacin(LVX).Characterizations confirmed its increased specific surface area,narrowed bandgap,and enhanced visible light utilization capacity.Further mechanism study including band structure study and electron paramagnetic resonance(EPR)proved the successful construction of Z-scheme heterojunction,which improved photogenerated charge carrier migration and provide sufficient free radicals for the degradation process.The combination of different modifications contributed to the synergetic improvement of removal efficiency towards different organic pollutants.

Large-sized nano-TiO2/SiO2 mesoporous nanofilm-constructed macroporous photocatalysts with excellent photocatalytic performance

Novel large-sized mesoporous nanofilm-constructed macroporous SiO2(LMNCMS)with two sets of well-defined 3D continuous pass-through macropores(pore size of 0.5-1.0 um,wall thickness of 40-50 nm)was prepared through a dual-templating approach,and used as an advanced support for TiO2 nanocrystalline photocatalyst.The structural and optical properties of the as-prepared materials were investigated by various characterization techniques in order to explore the connections between catalysts'features and catalytic performance.The photocatalytic activities were evaluated by degradations of methylene blue(MB)and phenol under the simulated sunlight irradiation.To gain insight into the impact of preparation and operation conditions on photocatalytic degradation processes,experiments were conducted at wide ranges of the TiO2 loading content,calcination temperature,solution pH,and photocatalyst dosage.Nano-TiO2/LMNCMS exhibited high photocatalytic activity and stability.Rapid matter transport,good access ibility of pollutants to TiO2 and high light harvesting could mainly account for the superior photocatalytic performance.The trapping experiments were performed to identify the main reactive species in the catalytic reactions.