Enhancing multifunctional photocatalysis with acetate-assisted cesium doping and unlocking the potential of Z-scheme solar water splitting

Graphitic carbon nitride(g-C_(3)N_(4))has been extensively doped with alkali metals to enlarge photocatalytic output,in which cesium(Cs)doping is predicted to be the most efficient.Nevertheless,the sluggish diffusion and doping kinetics of precursors with high melting points,along with imprecise regulation,have raised the debate on whether Cs doping could make sense.For this matter,we attempt to confirm the positive effects of Cs doping on multifunctional photocatalysis by first using cesium acetate with the character of easy manipulation.The optimized Csdoped g-C_(3)N_(4)(CCN)shows a 41.6-fold increase in visible-light-driven hydrogen evolution reaction(HER)compared to pure g-C_(3)N_(4) and impressive degradation capability,especially with 77%refractory tetracycline and almost 100%rhodamine B degradedwithin an hour.The penetration ofCs+is demonstrated to be a mode of interlayer doping,and Cs–N bonds(especially with sp^(2) pyridine N in C═N–C),along with robust chemical interaction and electron exchange,are fabricated.This atomic configuration triggers the broadened spectral response,the improved charge migration,and the activated photocatalytic capacity.Furthermore,we evaluate the CCN/cadmium sulfide hybrid as a Z-scheme configuration,promoting the visible HER yield to 9.02 mmol g^(−1) h^(−1),which is the highest ever reported among all CCN systems.This work adds to the rapidly expanding field of manipulation strategies and supports further development of mediating served for photocatalysis.

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.

Enhanced visible-light photocatalytic activity of Z-scheme graphitic carbon nitride/oxygen vacancy-rich zinc oxide hybrid photocatalysts

With the objectives of enhancing the stability,optical properties and visible-light photocatalytic activity of photocatalysts,we modified oxygen vacancy-rich zinc oxide（Vo-ZnO） with graphitic carbon nitride（g-C3N4）. The resulting g-C3N4/Vo-ZnO hybrid photocatalysts showed higher visible-light photocatalytic activity than pure Vo-ZnO and g-C3N4. The hybrid photocatalyst with a g-C3N4 content of 1 wt% exhibited the highest photocatalytic degradation activity under visible-light irradiation（λ≥ 400 nm）. In addition,the g-C3N4/Vo-ZnO photocatalyst was not deactivated after five cycles of methyl orange degradation,indicating that it is stable under light irradiation. Finally,a Z-scheme mechanism for the enhanced photocatalytic activity and stability of the g-C3N4/Vo-ZnO hybrid photocatalyst was proposed. The fast charge separation and transport within the g-C3N4/Vo-ZnO hybrid photocatalyst were attributed as the origins of its enhanced photocatalytic performance.

Enhanced visible light photocatalytic H_2 production over Z-scheme g-C_3N_4 nansheets/WO_3 nanorods nanocomposites loaded with Ni(OH)_x cocatalysts

Novel WO3/g-C3N4/Ni（OH）x hybrids have been successfully synthesized by a two-step strategy of high temperature calcination and in situ photodeposition.Their photocatalytic performance was investigated using TEOA as a hole scavenger under visible light irradiation.The loading of WO3 and Ni（OH）x cocatalysts boosted the photocatalytic H2 evolution efficiency of g-C3N4.WO3/g-C3N4/Ni（OH）x with 20 wt%defective WO3 and 4.8 wt%Ni（OH）x showed the highest hydrogen production rate of 576 μmol/（g·h）,which was 5.7,10.8 and 230 times higher than those of g-C3N4/4.8 wt%Ni（OH）x,20 wt%WO3/C3N4 and g-C3N4 photocatalysts,respectively.The remarkably enhanced H2 evolution performance was ascribed to the combination effects of the Z-scheme heterojunction（WO3/g-C3N4） and loaded cocatalysts（Ni（OH）x）,which effectively inhibited the recombination of the photoexcited electron-hole pairs of g-C3N4 and improved both H2 evolution and TEOA oxidation kinetics.The electron spin resonance spectra of ·O2^- and ·OH radicals provided evidence for the Z-scheme charge separation mechanism.The loading of easily available Ni（OH）x cocatalysts on the Z-scheme WO3/g-C3N4 nanocomposites provided insights into constructing a robust multiple-heterojunction material for photocatalytic applications.

Construction of Ag_3PO_4/Ag_2MoO_4 Z-scheme heterogeneous photocatalyst for the remediation of organic pollutants

Hole/electron separation and charge transfer are the key processes for enhancing the visible-light photocatalysis performance of heterogeneous photocatalytic systems.To better utilize and understand these effects,binary Ag3PO4/Ag2MoO4 hybrid materials were fabricated by a facile solution-phase reaction and characterized systematically by X-ray diffraction（XRD）,energy-dispersive spectroscopy,Fourier transform infrared spectroscopy,Raman spectroscopy,field-emission scanning electron microscopy and ultraviolet-visible diffuse-reflectance spectroscopy.Under visible-light illumination,a heterogeneous Ag3PO4/Ag/Ag2MoO4 photocatalyst was constructed and demonstrated enhanced photocatalytic activity and photostability compared with pristine Ag3PO4toward the remediation of the organic dye rhodamine B.The Ag3PO4/Ag2MoO4 hybrid catalyst with8%mole fraction of Ag2MoO4 exhibited the highest photocatalytic activity toward the removal of typical dye molecules,including methyl orange,methylene blue and phenol aqueous solution.Moreover,the mechanism of the photocatalytic enhancement was investigated via hole- and radical-trapping experiments,photocurrent measurements,electrochemical impedance spectroscopy and XRD measurements.The XRD analysis revealed that metallic Ag nanoparticles formed initially on the surface of the Ag3PO4/Ag2MoO4 composites under visible-light illumination,leading to the generation of a Ag3PO4/Ag/Ag2MoO4 Z-scheme tandem photocatalytic system.The enhanced photocatalytic activity and stability were attributed to the formation of the Ag3PO4/Ag/Ag2MoO4Z-scheme heterojunction and surface plasmon resonance of photo-reduced Ag nanoparticles on the surface.Finally,a plasmonic Z-scheme photocatalytic mechanism was proposed.This work may provide new insights into the design and preparation of advanced visible-light photocatalytic materials and facilitate their practical application in environmental issues.

石墨相氮化碳基Z-Scheme体系光催化分解水研究进展

石墨相氮化碳(g-C3N4)以独特的电子结构、稳定的化学结构和显著的可见光活性而备受瞩目,g-C3N4基Z-Scheme光催化体系能够有效地降低光生电子空穴的复合几率,提高光源吸收利用率。介绍了光催化分解水的反应机理,综述了g-C3N4基Z-Scheme体系在光催化水氧化、光催化水解制氢、光催化全分解水方面的应用,并对未来Z-Scheme的发展进行了展望。

Defect-assisted surface modification enhances the visible light photocatalytic performance of g-C_3N_4@C-TiO_2 direct Z-scheme heterojunctions

To increase the number of active sites and defects in TiO2 and promote rapid and efficient transfer of photogenerated charges, a g-C3N4@C-TiO2 composite photocatalyst was prepared via in situ deposition of g-C3N4 on a carbon-doped anatase TiO2 surface. The effects of carbon doping state and surface modification of g-C3N4 on the performance of g-C3N4@C-TiO2 composite photocatalysts were studied by X-ray diffraction, X-ray photoelectron spectroscopy, UV-visible diffuse-reflectance spectroscopy, transmission electron microscopy, electrochemical impedance spectroscopy, photoluminescence, and electron paramagnetic resonance. With increasing carbon doping content, the carbon doping state in TiO2 gradually changed from gap to substitution doping. Although the number of oxygen vacancies gradually increased, the degradation efficiency of g-C3N4@C-TiO2 for RhB (phenol) initially increased and subsequently decreased with increasing carbon content. The g-C3N4@10C-TiO2 sample exhibited the highest apparent reaction rate constant of 0.036 min儃1 (0.039 min儃1) for RhB (phenol) degradation, which was 150 (139), 6.4 (6.8), 2.3 (3), and 1.7 (2.1) times higher than that of pure TiO2, 10C-TiO2, g-C3N4, and g-C3N4@TiO2, respectively. g-C3N4 was grown in situ on the surface of C-TiO2 by surface carbon hybridization and bonding. The resultant novel g-C3N4@C-TiO2 photocatalyst exhibited direct Z-scheme heterojunctions with non-local impurity levels. The high photocatalytic activity can be attributed to the synergistic effects of the improved visible light response ability, higher photogenerated electron transfer efficiency, and redox ability arising from Z-type heterojunctions.

Advances in Z-scheme semiconductor photocatalysts for the photoelectrochemical applications: A review

With continuous consumption of nonrenewable energy,solar energy has been predicted to play an essential role in meeting the energy demands and miti gating environmental issues in the future.Despite being green,clean and pollution-free energy,solar energy cannot be adopted directly as it cannot provide sufficiently high energy density to work in the absence of machinery.Thus,it is necessary to develop an effective strategy to convert and store solar energy into chemical energy to achieve social sustainable development using solar energy as the main power source.Photocatalysis,in which semi conductor photocatalysts play a key role,is one of the most promising can didates for realising the effective utilisation of sunlight in a green,low-cost and environmentally friendly method.The photocatalytic efficiency of photo catalysts is considerably influenced by their compositions.Among the various heterostructures,Z-scheme heterojunction is one of the most interesting ar chitecture due to its outstanding performance and excellent artificial imitation of photosynthesis.Z-scheme photocatalysts have attracted considerable at tention in the past few decades.Herein,we review contemporary Z-scheme systems,with a particular focus on mechanistic breakthroughs,and highlight current state-of-the-art systems.Z-type photocatalysts are classified as tradi tional,all-solid-state,direct Z-schemes and S-scheme photocatalysts.The morphology,characterisation and working mechanism of each type of Z-scheme are discussed in detail.Furthermore,the applications of Z-scheme in photoelectrochemical water splitting,nitrogen fixation,pollutant degrada tion and carbon dioxide reduction are illustrated.Finally,we outline the main challenges and potential advances in Z-scheme architectures,as well as their future development directions.

Direct electrospinning method for the construction of Z-scheme TiO_2/g-C_3N_4/RGO ternary heterojunction photocatalysts with remarkably ameliorated photocatalytic performance

A series of Z-scheme TiO2/g-C3N4/RGO ternary heterojunction photocatalysts are successfully constructed via a direct electrospinning technique coupled with an annealing process for the first time. They are investigated comprehensively in terms of crystal structure, morphology, composition, specific surface area, photoelectrochemical properties, photodegradation performance, etc. Compared with binary TiO2/g-C3N4 and single-component photocatalysts, ternary heterojunction photocatalysts show the best photodegradation performance for RhB under stimulated sunlight. This can be attributed to the enlarged specific surface area (111.41 m2/g), the formation of Z-scheme heterojunction, and the high separation migration efficiency of photoexcited charge carriers. A potential Z-scheme mechanism for ternary heterojunction photocatalysts is proposed to elucidate the remarkably ameliorated photocatalytic performance based on active species trapping experiments, PL detection test of hydroxyl radicals, and photoelectrochemical properties.

Z-scheme N-doped K4Nb6O17/g-C3N4 heterojunction with superior visible-light-driven photocatalytic activity for organic pollutant removal and hydrogen production

A simple calcination method was employed to prepare a Z-scheme N-doped K4Nb6O17/g-C3N4(KCN)heterojunction photocatalyst,in which the electronic structure of K4Nb6O17 was regulated by N-doping,and g-C3N4 was formed both on the surface and within the interlayer spaces of K4Nb6O17.The KCN composite showed profoundly improved photocatalytic activity for both H2 generation and RhB degradation compared to its counterparts.This improved performance was attributed to the synergistic effects of N-doping,which broadened its light harvesting ability,and heterojunction formation,which increased the charge separation rate.The relatively low BET specific surface area of the KCN composite had little effect on its photocatalytic activity.Based on ESR spectroscopy studies,•O2^−,•OH,and h^+are the main active species in the photocatalytic degradation of RhB.Thus,it is reasonable to propose a Z-scheme photocatalytic mechanism over the KCN composite,which exhibits the dual advantages of efficient charge separation and high redox ability.Our work provides a simple approach for constructing large-scale Z-scheme heterojunction photocatalysts with high photocatalytic performance.

Direct Z-scheme photochemical hybrid systems:Loading porphyrin-based metal-organic cages on graphitic-C_(3)N_(4) to dramatically enhance photocatalytic hydrogen evolution

The rational design of photochemical molecular device(PMD)and its hybrid system has great potential in improving the activity of photocatalytic hydrogen production.A series of Pd6L3 type metal-organic cages,denoted as MOC-Py-M(M=H,Cu,and Zn),are designed for PMDs by combining metalloporphyrin-based ligands with catalytically active Pd^(2+)centers.These metal-organic cages(MOCs)are first successfully hybridized with graphitic carbon nitride(g-C_(3)N_(4))to form direct Z-scheme heterogeneous MOC-Py-M/g-C_(3)N_(4)(M=H,Cu,and Zn)photocatalysts via π-πinteractions.Benefiting from its better light absorption ability,the MOC-Py-Zn/g-C_(3)N_(4) catalyst exhibits high H_(2) production activity under visible light(10348μmol g^(-1) h^(-1)),far superior to MOC-Py-H/g-C_(3)N_(4) and MOC-Py-Cu/g-C_(3)N_(4).Moreover,the MOC-Py-Zn/g-C_(3)N_(4) system obtains an enhanced turn over number(TON)value of 32616 within 100 h,outperforming the homogenous MOC-Py-Zn(TON of 507 within 100 h),which is one of the highest photochemical hybrid systems based on MOC for visible-light-driven hydrogen generation.This confirms the direct Z-scheme heterostructure can promote effective charge transfer,expand the visible light absorption region,and protect the cages from decomposition in MOC-Py-Zn/g-C_(3)N_(4).This work presents a creative example that direct Z-scheme PMD-based systems for effective and persistent hydrogen generation from water under visible light are obtained by heterogenization approach using homogeneous porphyrin-based MOCs and g-C_(3)N_(4) semiconductors.

Preparation of Z-scheme WO_3(H_2O)_(0.333)/Ag_3PO_4 composites with enhanced photocatalytic activity and durability

Ag3PO4 is widely used in the field of photocatalysis because of its unique activity. However, photocorrosion limits its practical application. Therefore, it is very urgent to find a solution to improve the light corrosion resistance of Ag3PO4. Herein, the Z-scheme WO3(H2O)0.333/Ag3PO4 composites are successfully prepared through microwave hydrothermal and simple stirring. The WO3(H2O)0.333/Ag3PO4 composites are characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV-Vis spectroscopy. In the degradation of organic pollutants, WO3(H2O)0.333/Ag3PO4 composites exhibit excellent performance under visible light. This is mainly attributed to the synergy of WO3(H2O)0.333 and Ag3PO4. Especially, the photocatalytic activity of 15%WO3(H2O)0.333/Ag3PO4 is the highest, and the methylene blue can be completely degraded in 4 min. In addition, the stability of the composites is also greatly enhanced. After five cycles of testing, the photocatalytic activity of 15%WO3(H2O)0.333/Ag3PO4 is not obviously decreased. However, the degradation efficiency of Ag3PO4 was only 20.2%. This indicates that adding WO3(H2O)0.333 can significantly improve the photoetching resistance of Ag3PO4. Finally, Z-scheme photocatalytic mechanism is investigated.

Novel indirect Z-scheme g-C3N4/Bi2MoO6/Bi hollow microsphere heterojunctions with SPR-promoted visible absorption and highly enhanced photocatalytic performance

The surface plasmonic resonance(SPR)effect of Bi can effectively improve the light absorption abilities and photogenerated charge carrier separation rate.In this study,a novel ternary heterojunction of g-C3N4/Bi2MoO6/Bi(CN/BMO/Bi)hollow microsphere was successfully fabricated through solvothermal and in situ reduction methods.The results revealed that the optimal ternary 0.4 CN/BMO/9 Bi photocatalyst exhibited the highest photocatalytic efficiency toward rhodamine B(RhB)degradation with nine times that of pure BMO.The DRS and valence band of the X-ray photoelectron spectroscopy spectrum demonstrate that the band structure of 0.4 CN/BMO/9 Bi is a z-scheme structure.Quenching experiments also provided solid evidence that the·O^2-(at-0.33 eV)is the main species during dye degradation,and the conduction band of g-C3N4 is only the reaction site,demonstrating that the transfer of photogenerated charge carriers of g-C3N4/Bi2 MoO 6/Bi is through an indirect z-scheme structure.Thus,the enhanced photocatalytic performance was mainly ascribed to the synergetic effect of heterojunction structures between g-C3N4 and Bi2MoO6 and the SPR effect of Bi doping,resulting in better optical absorption ability and a lower combination rate of photogenerated charge carriers.The findings in this work provide insight into the synergism of heterostructures and the SPR absorption ability in wastewater treatment.

Construction of BiVO_(4)/BiOCl@C Z-scheme heterojunction for enhanced photoelectrochemical performance

A Z-scheme heterostructure of Mo,W co-doped BiVO_(4)(Mo,W:BVO/BiOCl@C)was fabricated by a simple solid solution drying and calcination(SSDC)method.The heterostructure was characterized by X-ray diffraction(XRD),Fourier transform infrared(FTIR),X-ray photoelectron spectroscopy(XPS),etc.Under visible light irradiation,Mo,W:BVO/BiOCl@C heterostructure exhibits excellent photoelectrochemical capability compared with other as-prepared samples.The photocurrent density and the incident photon-to-electron conversion efficiency(IPCE)are about 5.4 and 9.0 times higher than those of pure BiVO_(4),respectively.The enhancement of the photoelectrochemical performance can be attributed to the construct of Z-scheme system,which is deduced from the radical trapping experiments.The Mo,W:BVO/BiOCl@C Z-scheme heterojunction enhances the visible-light absorption and reduces the recombination rate of charge carriers.This work provides an effective strategy to construct Z-scheme photoelectrodes for the application of photoelectrochemical water splitting.

Fabrication of Z-scheme MoO3/Bi2O4 heterojunction photocatalyst with enhanced photocatalytic performance under visible light irradiation

Constructing Z-scheme heterojunction to improve the separation efficiency of photogenerated carriers of photocatalysts has gained extensive attention.In this work,we fabricated a novel Z-scheme MoO3/Bi2O4 heterojunction photocatalyst by a hydrothermal method.XPS analysis results indicated that strong interaction between MoO3 and Bi2O4 is generated,which contributes to charge transfer and separation of the photogenerated carriers.This was confirmed by photoluminescence(PL)and electrochemical impedance spectroscopy(EIS)tests.The photocatalytic performance of the as-synthesized photocatalysts was evaluated by degrading rhodamine B(RhB)in aqueous solution under visible light irradiation,showing that 15%MoO3/Bi2O4(15-MB)composite exhibited the highest photocatalytic activity,which is 2 times higher than that of Bi2O4.Besides,the heterojunction photocatalyst can keep good photocatalytic activity and stability after five recycles.Trapping experiments demonstrated that the dominant active radicals in photocatalytic reactions are superoxide radical( O2-)and holes(h+),indicating that the 15-MB composite is a Z-scheme photocatalyst.Finally,the mechanism of the Z-scheme MoO3/Bi2O4 composite for photo-degrading RhB in aqueous solution is proposed.This work provides a promising strategy for designing Bi-based Z-scheme heterojunction photocatalysts for highly efficient removal of environmental pollutants.

Construction of a few-layer g-C_3N_4/α-MoO_3 nanoneedles all-solid-state Z-scheme photocatalytic system for photocatalytic degradation

The suppression of the recombination of electrons and holes(e–h) and the enhancement of the light absorption of semiconductors are two key points toward efficient photocatalytic degradation.Here,we report a few-layer g-C_3N_4/α-MoO_3 nanoneedles(flg-C_3N_4/α-MoO_3 NNs) all-solid-state Z-scheme mechanism photocatalyst synthesized via a typical hydrothermal method in a controlled manner.The recombination of the photo-induced e–h pairs could be effectively restrained by the Z-scheme passageway between the flg-C_3N_4 and α-MoO_3 NNs in the composite,which could also promise a high redox ability to degrade pollutants.And it became possible for the prepared photocatalyst to absorb light in a wide range of wavelengths.The detailed mechanism was studied by electron spin-resonance spectroscopy(ESR).The low-dimensional nanostructure of the two constituents(α-MoO_3 NNs with one-dimensional structure and flg-C_3N_4 with two-dimensional structure) endowed the composite with varieties of excellent physicochemical properties,which facilitated the transfer and diffusion of the photoelectrons and increased the specific surface area and the active sites.The 10 wt% flg-C_3N_4/α-MoO_3 NNs showed the best photocatalytic performance toward RhB degradation,the rate of which was 71.86%,～2.6 times higher than that ofα-MoO_3 NNs.

Experimental method to explore the adaptation degree of type-Ⅱand all-solid-state Z-scheme heterojunction structures in the same degradation system

TiO2 nanoparticles were prepared using the hydrothermal method and modified with CgN to syn-thesize a Type-Ⅱheterojunction semiconductor photocatalyst,TiO2-C;Na.In addition,a carbon layerwas coated onto the TiO2 nanoparticles and the obtained material was uniformly covered on thesurface of CaNa to form an all-solid-state Z-scheme semiconductor photocatalyst,TiO2-C-C3N4,Through characterization by XRD,XPS,SEM,TEM,BET,photoelectrochemical experiments,UV-visible diffuse reflection,and PL spectroscopy,the charge transfer mechanism and band gappositions for the composite photocatalysts were analyzed.The Type-Ⅱand all-solid-state Z-schemeheterojunction structures were compared.By combining microscopic internal mechanisms withmacroscopic experimental phenomena,the relationship between performance and structure wasverified.Experimental methods were used to explore the adaptation degree of different photocata-lytic mechanisms using the same degradation system.This study highlights effective photocatalystdesign to meet the requirements for specific degradation conditions.

3D flower-like mesoporous Bi_(4)O_(5)I_(2)/MoS_(2)Z-scheme heterojunction with optimized photothermal-photocatalytic performance

3D flower-like hierarchical mesoporous Bi_(4)O_(5)I_(2)/MoS_(2)Z-scheme layered heterojunction photocatalyst was fabricated by oil bath and hydrothermal methods.The heterojunction with narrow band gap of~1.95 eV extended the photoresponse to near-infrared region,which showed obvious photothermal effect due to the introduction of MoS_(2) with broad spectrum response.MoS_(2) nanosheets were anchored onto the surface of flower-like hierarchical mesoporous Bi_(4)O_(5)I_(2) nanosheets,thereby forming efficient layered heterojunctions,the solar-driven photocatalytic efficiency in degradation of highly toxic dichlorophenol and reduction of hexavalent chromium was improved to 98.5%and 99.2%,which was~4 and 7 times higher than that of the pristine Bi_(4)O_(5)I_(2),respectively.In addition,the photocatalytic hydrogen production rate reached 496.78 μmol h^(-1)g^(-1),which was~6 times higher than that of the pristine Bi_(4)O_(5)I_(2).The excellent photocatalytic performance can be ascribed to the promoted photothermal effect,as well as,the formation of compact Z-scheme layered heterojunctions.The 3D flower-like hierarchical mesoporous structure provided adequate surface active-sites,which was conducive to the mass transfer.Moreover,the high stability of the prepared photocatalyst further promoted its potential practical application.This strategy also provides new insights for fabricating layered Zscheme heterojunctions photocatalysts with highly photothermal-photocatalytic efficiency.

Construction of TiO_(2)-covalent organic framework Z-Scheme hybrid through coordination bond for photocatalytic CO_(2) conversion

In this work,a covalent organic framework(COF),which is constructed by the building blocks of[5,10,15,20-tetrakis(4-aminophenyl)porphinato]copper(Ⅱ)(CuTAPP)and p-benzaldehyde,is employed to integrate with TiO_(2) for the purpose of establishing a Z-scheme hybrid.Within the system,isonicotinic acid performs the role of a bridge that connects the two components through a coordination bond.Further photocatalytic application reveals the hybrid framework is able to catalyze CO_(2) conversion under simulated solar light,resulting in CO production rate of 50.5 μmol g^(-1)·h^(-1),about 9.9 and 24.5 times that of COF and pristine TiO_(2),respectively.The ameliorated catalytic performance owes much to the por-phyrin block acting as photosensitizer that augments the light absorbance,and the establishment of Z-scheme system between the inorganic and orga nic comp on ents that enhances the separati on of the carriers.In addition,the chemical bridge also ensures a steady usage and stable charge delivery in the catalysis.Our study sheds light on the development of versatile approaches to covalently in corporate COFs with inorga nic semic on ductors.

Highly efficient tandem Z-scheme heterojunctions for visible light-based photocatalytic oxygen evolution reaction

Oxygen is important in maintaining a clean and reliable water environment.Designing heterojunction photocatalysts that can evolve oxygen from water splitting through an artificial Z-scheme pathway is a promising strategy for solving environmental problems.In this study,flower-like MoS2 nanostructures were fabricated via a simple hydrothermal process,and the electrostatic-based assembly ion-exchange method was used to construct a tandem Ag3PO4/MoS2/g-C3N4(AMC)heterojunction.The as-synthesized photocatalyst exhibited significant improvements in harvesting visible light and transporting charge carriers.Moreover,the catalyst that was similar to the Z-scheme with intimate interface contact exhibited a strong oxygen evolution performance.The oxygen evolution activity of the optimal AMC-10 catalyst was approximately 11 times that of the pristine Ag3PO4.The results indicated that addition of a small amount of the flower-like MoS2 could significantly enhance the efficiency of oxygen evolution by the heterojunction.The findings in this study provide an alternative pathway for rationally designing efficient oxygen-evolving photocatalysts in order to improve the quality of water and rehabilitate the water environment.©2020 Hohai University.Production and hosting by Elsevier B.V.This is an open access article under the CC BY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/4.0/).