Visible Light Response Range Research Articles

Preparation of g-C3N4/{001}-AR-TiO2 composite photocatalyst and its degradation of tetracycline hydrochloride in sunlight

In this study, a {001}-AR-TiO2 catalyst (001-ART) was prepared by the sol–gel method, where g-C3N4 (CN) was combined with 001-ART to form g-C3N4{001}-AR-TiO2 (CN/001-ART). The crystal shape, morphology, optical properties, photoelectron-hole recombination, and specific surface area of the prepared materials were studied. Tetracycline hydrochloride (TTCH) was used as the target pollutant to investigate the catalytic properties, and the results showed that the specific surface area, visible light response range, band gap, photo-generated carrier separation ability, and average life span of 001-ART after CN composite integration increased. Furthermore, the degradation rate of TTCH within 120 min was 92.48%, and the reaction constant was 0.0215. After 5 repeated use cycles, the degradation rate of TTCH was 85.21%. We also found that OH and O2− were produced in CN/001-ART after exposure to light, and the electrons of 001-ART were excited to the conduction band and combined with the holes in the valence band of CN, thus, forming a Z-type heterostructure. This resulted in the higher activity of CN/001-ART.

Hydrothermal synthesis of Bi2WO6/Bi2O4 heterojunction with WO3 and NaBiO3·2 H2O powders as precursors to improve visible light photocatalytic degradation performance

The limited visible light response range and fast recombination rate of photoinduced carriers restrict the photocatalytic performance of Bi2WO6. Herein, a novel low temperature hydrothermal approach was developed to construct the Bi2WO6/Bi2O4 heterojunction with WO3 and NaBiO3•2 H2O powders as precursors and the latter as the only bismuth source. During the hydrothermal reaction, WO3 first reacts with NaBiO3·2 H2O to generate Bi2WO6 and then the residual NaBiO3·2 H2O converts into Bi2O4, in-situ forming the Bi2WO6/Bi2O4 heterojunction with the co-shared Bi atoms. The content of Bi2WO6 in the heterostructure can be facilely modulated by changing the amount of WO3 added. The construction of Bi2WO6/Bi2O4 heterojunction could not only extend the spectral response range but also improve the separation efficiency of photoinduced charges. Consequently, the photocatalytic degradation performance to tetracycline (phenol) for the optimal Bi2WO6/Bi2O4 heterostructure is 5.19 and 1.77 times (4.75 and 1.66 times) higher than that of single Bi2WO6 and Bi2O4 under visible light, respectively. The capture experiments of active species and electron spin resonance spectra demonstrate that radicals (·O2-) and holes (h+) are the first and second important active species, respectively, during the catalytic degradation. Our work provides a new idea for the fabrication of high-performance Bi2WO6-based junction photocatalysts.

Efficient degradation of ciprofloxacin by a flower-spherical Bi2MoO6/BiOCl Z-type heterojunction photocatalyst enriched with oxygen vacancies

Ciprofloxacin (CIP) is difficult to degrade naturally, for example by microorganisms, and will persist in water bodies for a long period of time, seriously jeopardizing the ecological environment and human health. Photocatalysis has high practical application value as a green and efficient technology. However, the photogenerated electrons and holes of the photocatalysts are prone to complexation, which limits the degradation efficiency of photocatalysis. Therefore, in this work, spherical Bi2MoO6/BiOCl (OVs-BMO/BOC) Z-type heterojunction photocatalysts enriched with oxygen vacancies (OVs) were successfully synthesized by a hydrothermal-calcination method. A series of characterizations showed that the OVs-BMO/BOC photocatalysts could perform Z-type charge transfer, which increased the visible light response range and improved the separation efficiency of photogenerated electrons and holes, thus improving the degradation efficiency of CIP. Under visible light, the removal efficiency of OVs-BMO/BOC composites for CIP could reach 97.40% at 120 min. It has a quasi-primary rate constant of 0.03008, which is 4.1, 3.48, and 2.19 times higher than that of monomeric BOC, BMO, and BMO/BOC, respectively. Meanwhile, the good stability of OVs-BMO/BOC was verified, and its degradation efficiency could still reach 87.80% after four cycles. Finally, electron spin resonance analysis and trapping experiments were carried out, which demonstrated that a large number of OVs were produced by the BMO/BOC composite photocatalyst generated by calcination, and also identified that the OVs-BMO/BOC produced active substances (•OH, h+, and •O2−), which revealed the mechanism of degradation of CIP by the OVs-BMO/BOC. Our study provides a new way of thinking to achieve efficient elimination of antibiotics from wastewater.

Visible-light-assisted PMS activation by heterojunction photocatalyst MgIn2S4/Bi2O3 for tetracycline degradation

Composite MgIn2S4/Bi2O3 was prepared and applied to the photocatalytic degradation of tetracycline (TC) under visible light. Results showed that formation of type-II heterojunction extended the visible light response range of the composite to 628 nm, effectively limiting the rapid recombination of photogenerated carriers. Further, the degradation experiment showed that TC was effectively decomposed by the composite. The main active substances for degrading TC were SO4·−, ·OH, h+ and 1O2. Cycling experiments showed that the TC removal rate by MgIn2S4/Bi2O3 photocatalytic material was still as high as 75% after 4 cycles without any obvious changes in the crystalline phase structure.

Metalloporphyrin based MOF-545 coupled with solid solution ZnxCd1-xS for efficient photocatalytic hydrogen production

The growing concern over the rapid consumption of fossil fuels has spurred scientists to seek environment-friendly and sustainable energy alternatives. The utilization of photocatalytic water splitting shows great potential in generating environmentally friendly hydrogen energy. Zirconium-based porphyrin MOF-545 has drawn extensive attention in photocatalysis since it has strong light absorption and fast electron transfer capability. A series of Zr-based metalloporphyrins containing different metals, MOF-545M (M = Co, Ni, Cu, Zn), were synthesized and assembled with solid solution ZnxCd1-xS (ZCS) nanoparticle to develop the corresponding of hybrid photocatalysts, ZCS/MOF-545M. Various characterizations show that introducing the porphyrin MOF-545Co not only improve the visible light response range of Zn0.5Cd0.5S (ZCS-0.5) but also enhance the carrier separation efficiency of ZCS-0.5. The carrier transfer direction during the reaction was confirmed by surface photovoltage spectroscopy and shows the formation of S-scheme. Under visible light irradiation, the hybrid photocatalyst ZCS-0.5/MOF-545Co exhibits a high H2 evolution rate of 148 μmol h−1, with increases of 52.8, 22.9 and 6.5 times than those of bare ZnS, CdS and ZCS-0.5, respectively. The present work gives a strategy for erecting S-scheme heterojunction to inhibit the photocorrosion of metal sulfides and enhancement the carrier separation efficiency.

Fabrication of Z-scheme ZnO/g-C3N4 heterojunction modified by silver nanoparticles for photocatalytic removal of Norfloxacin and Rhodamine B

A novel ternary photocatalyst with a Z-scheme heterojunction was successfully synthesized through the deposition of Ag nanoparticles onto the surface of a ZnO/g-C3N4 composite. The prepared photocatalysts were characterized by XRD, FT-IR, XPS, HRSEM, TEM, DRS, PL, EIS, TPC, and M-S. The photocatalytic performance of the as-synthesized photocatalysts was systematically investigated through the photodegradation of norfloxacin (NOR) and rhodamine B (RhB) under visible light irradiation. The photodegradation efficiency of 5% Ag/ZnO/g-C3N4 (5AZCN) composite photocatalyst reached 86.7% (480 min) and 98.0% (60 min) for NOR and RhB, respectively. Moreover, the apparent rate constants of the 5AZCN composite photocatalysts for NOR and RhB were found to be 3.4 and 22.2 times higher than that of the ZCN composite photocatalysts, respectively. The significantly enhanced photocatalytic performance was ascribed to the widened range of visible light response and the efficient separation and migration of carriers facilitated by the introduction of Ag nanoparticles that functioned as electron transfer mediators. Based on the free radicals quenching experiment and electron spin resonance (ESR) spectroscopy characterization, superoxide radicals (·O2−) were the main reactive species in the photodegradation process. Furthermore, the charge transfer process was proved to be a Z-scheme transfer mechanism. This work provides a promising approach to simply constructing novel efficient Z-scheme photocatalysts for the elimination of environmental pollutants.

Enhanced degradation of tetracycline hydrochloride by activated peroxymonosulfate through Ni-doped LaFeO3

To achieve efficient degradation of tetracycline hydrochloride (TC), we employed a straightforward hydrothermal method to enhance the physicochemical properties of the initial lanthanum ferrite by substituting different ratios of Ni for Fe. Ni doping significantly reduced the energy band band gap of LFNO-5 from 1.93 eV to 1.76 eV, enhanced the visible light response range and photocurrent response, reduced the impedance, and generated more oxygen vacancies. The photocatalytic activity of the target materials was investigated using tetracycline hydrochloride as a model pollutant under the activation of a minute amount of potassium persulfate (PMS) and visible light. After 60 min of exposure to light, LFNO-5/PMS achieved a 90% degradation of TC (k = 0.03374 min−1), surpassing PMS (k = 0.00710 min−1) by a factor of 4.75 and LFO/PMS (k = 0.01781 min−1) by a factor of 1.89. The redox cycling of FeIII/FeII and NiIII/NiII in LFNO-5 facilitated an effective synergistic photocatalytic process. Vacancies (h+) and sulphate radicals (SO4−) played a crucial role in pollutant degradation within the LFNO/PMS system. Furthermore, the LFNO-5/PMS system exhibited excellent resistance to various inorganic ions and humic acids, while delivering noteworthy performance even in the presence of environmental disturbances. The degradation efficiency of the catalyst did not decrease significantly after several cycles, and the metal leaching rate was low, with good stability and reusability. Furthermore, Ni-doped LFO not only improved the activation efficiency for PMS, but also demonstrated the superiority of the LFNO-5 catalyst as a promising activator for PMS effluent remediation.

Constructing BiOBr1-xIx-y with Abundant Surface Br Vacancies for Excellent Visible-Light Photodegradation Capability of High-Concentration Refractory Contaminants.

Bismuth oxybromide (BiOBr) is a promising photocatalytic semiconductor material due to its unique hierarchical structure and band structure. However, its photocatalytic applications are restricted due to its narrow visible-light absorption range and poor photooxidation capability. In this study, BiOBr1-xIx-y with rich surface Br vacancies (BrVs-rich BiOBr1-xIx-y) was created via a facile indirect substitution strategy. Benefiting from the broadened visible-light response range and reduced recombination rate of photogenerated carriers, BiOBr1-xIx-y shows excellent visible-light photodegradation ability for high-concentration refractory contaminants, such as phenol, tetracycline, bisphenol A, rhodamine B, methyl orange, and even real wastewater. At the same time, the Br vacancies can regulate the band structure of BiOBr1-xIx-y and serve as trap states to promote charge separation, thus facilitating surface photoredox reactions. An in-depth investigation of the Br vacancy effect and photodegradation mechanism was conducted. This novel study revealed the significance of Br vacancies in enhancing the photocatalytic performance of BiOBr under visible light, providing a promising strategy for improving the utilization efficiency of sunlight in wastewater treatment.

Novel in-situ composites of chlorine-doped CQDs and g-C3N4 with improved interfacial connectivity and accelerated charge transfer to enhance photocatalytic degradation of tetracycline and hydrogen evolution

The photocatalytic performance of graphite-phase carbon nitrides (g-C3N4) composites is severely limited by poor interfacial connectivity and a narrow visible light response range. Although carbon quantum dots (CQDs) can enhance the visible light absorption of g-C3N4, it is difficult to produce effective interfacial connectivity due to their different properties. Herein, a novel “in-situ composite modified by chlorine-doped CQDs” strategy was proposed to further enhance the photocatalytic redox capability of g-C3N4. Specifically, chlorine-doped CQDs (Cl-CQDs) were prepared from mulberry branch powder and sulfoxide chloride directly, and the novel metal-free photocatalyst (Cl-CCN) was prepared by in-situ compounding the Cl-CQDs with g-C3N4. Cl-CCN shows superior photocatalytic tetracycline degradation rate (0.0269 min−1) and hydrogen production rate (1397.5 µmol g−1h−1), which are 14.9 and 2.75 times higher than those of g-C3N4, respectively. The characterization and DFT calculation results reveal that the C − Cl covalent bonds serve as fast electronic channels to bridge the hydrophilic Cl-CQDs and hydrophobic g-C3N4 and significantly enhance the interfacial coupling and charge transfer. On this basis, a possible mechanism for tetracycline degradation and hydrogen production photocatalyzed by Cl-CCN is proposed. This study provides a concise and economical method for modifying and enhancing the photocatalytic activity of composites CQDs/g-C3N4.

Oxygen-modified graphitic carbon nitride with nitrogen-defect for metal-free visible light photocatalytic H2O2 evolution

Photocatalytic oxygen reduction is regarded as the cleanest approach for the production of hydrogen peroxide (H2O2). Herein, oxygen-modified graphite carbon nitride (g-C3N4) with nitrogen-defect (namely g-C3N4-ND4-OM3) was synthesized by a feasible method. Owing to the existence of nitrogen vacancy and oxygen-containing functional group, the absorption bands derived from n → π* and π → π* electronic transitions were enhanced, thereby enlarging the visible light response range of catalysts. Interestingly, nitrogen-defect can capture electron and effectively suppress the recombination of photoinduced electrons and holes. More importantly, the introduction of oxygen-containing functional groups can improve the hydrophilicity of g-C3N4, which was beneficial for the adsorption of dissolved oxygen. The electrostatic potential distributions of g-C3N4-based photocatalyst structural unit were also changed after introducing nitrogen vacancy and oxygen-containing functional group, and the electron-donating ability of g-C3N4 was improved. As a result, the evolution rate of H2O2 catalyzed by g-C3N4-ND4-OM3 was as high as 146.96 μmol/g/L under visible light irradiation. The photocatalytic H2O2 generation was completed through the direct 2-e− oxygen reduction. In short, current work will share novel insights into photocatalytic H2O2 generation over g-C3N4-based catalyst.

Two-dimensional g-GeC/PtSe2 van der Waals heterostructure: a visible light-driven direct Z-scheme photocatalyst for overall water splitting

The vertical stacking of different two-dimensional materials to construct van der Waals heterostructures (vdWHs) opens up a promising platform for designing high-efficiency photocatalysts. Direct Z-scheme heterostructures for photocatalytic dissociation have received much attention in recent years, in which charge carriers migrate directly between two semiconductors without redox mediators. Here, the electronic and optical properties as well as the solar-to-hydrogen conversion efficiency of g-GeC/ PtSe2 vdWHs are systematically investigated, especially for their high-efficiency visible-light water splitting catalyst features. Calculations show that the g-GeC/ PtSe2 vdWH is a semiconductor with an indirect band gap of 1.356 eV, featuring a type-II band alignment. The built-in electric field E int and band bending at the interface lead to a direct Z-scheme photocatalytic structure, and photocatalytic water splitting can be realized in the pH range of 0–14. In particular, with biaxial tensile strain ϵ= 4% applied, the g-GeC/PtSe2 vdWH possesses a smaller band gap, wider visible light response range and very high STH conversion efficiency (η STH) up to 49.07%, entirely satisfying the optimal photocatalytic water splitting conditions. This work provides a new perspective for designing promising direct Z-scheme visible light water splitting catalysts with a high-efficiency solar energy conversion, beneficially to the development of clean energy.

Enhanced Photocatalytic Coupling of Benzylamine to N-Benzylidene Benzylamine over the Organic-Inorganic Composites F70-TiO2 Based on Fullerenes Derivatives and TiO2.

The organic-inorganic composites F70-TiO2, based on fullerene with carboxyl group derivatives and TiO2 semiconductor, have been designed and constructed to become an optical-functional photocatalyst via the facile sol-gel method. The composite photocatalyst obtained shows excellent photocatalytic activity for the high-efficiency conversion of benzylamine (BA) to N-benzylidene benzylamine (NBBA) with air pressure at a normal temperature under visible light irradiation. By optimizing the composition, the composites with the 1:15 mass ratio of F70 and TiO2, denoted as F70-TiO2(1:15), demonstrated the highest reaction efficiency for benzylamine (>98% conversion) to N-benzylidene benzylamine (>93% selectivity) in this study. However, pure TiO2 and fullerene derivatives (F70) exhibit decreased conversion (56.3% and 89.7%, respectively) and selectivity (83.8% and 86.0%, respectively). The UV-vis diffuse reflectance spectra (DRS) and Mott-Schottky experiment's results indicate that the introduction of fullerene derivatives into anatase TiO2 would greatly broaden the visible light response range and adjust the energy band positions of the composites, enhancing the sunlight utilization and promoting the photogenerated charge (e--h+) separation and transfer. Specifically, a series of results on the in situ EPR tests and the photo-electrophysical experiment indicate that the separated charges from the hybrid could effectively activate benzylamine and O2 to accelerate the formation of active intermediates, and then couple with free BA molecules to form the desired production of N-BBA. The effective combination, on a molecular scale, between fullerene and titanium dioxide has provided a profound understanding of the photocatalysis mechanism. This work elaborates and makes clear the relationship between the structure and the performance of functional photocatalysts.

Efficient reduction of hexavalent chromium by nubbly mesoporous NH2-MIL-125(Ti)/SnS2 Z-scheme heterostructures with enhanced visible photocatalytic activity

The Z-scheme heterostructures NH2-MIL-125(Ti)/SnS2(NTS) with mesoporous bulk characteristics were constructed by the introduction of amino group and supported by NH2-MIL-125(Ti). The prepared heterojunction photocatalysts exhibited good photocatalytic performance and cycle stability for hexavalent chromium reduction, and the NTS-2(the mass ratio of NH2-MIL-125(Ti): SnS2 = 1: 40) had the highest catalytic activity at pH = 3.5 and 0.5 g/L dosage, in which 98.45% Cr(VI) (10 mg/L) could be reduced within 30 min of irradiation time. The introduction of SnS2 nanosheets not only improves the visible light response range of NH2-MIL-125 (Ti), but also generates more photogenerated carriers. Meanwhile, the formation of Z-scheme heterostructures between the two monomers greatly promoted the charge separation. In conclusion, this study would provide a potential pathway for the construction of heterojunction photocatalysts of metal sulfides and metal-organic framework materials for the removal of heavy metals from wastewater.

Coupling ZnIn2S4 Nanosheets with MoS2 Hollow Nanospheres as Visible-Light-Active Bifunctional Photocatalysts for Enhancing H2 Evolution and RhB Degradation.

In this study, Mo-glycerate was used as a precursor to create MoS2 hollow nanospheres (HNS), which were then used for the first time to modify ZnIn2S4 nanosheets to create MoS2 HNS/ZnIn2S4 photocatalysts. The findings demonstrate that MoS2 HNS/ZnIn2S4 heterojunctions exhibited remarkably boosted photocatalytic properties and excellent reusability for both RhB degradation and H2 evolution without the use of Pt as a co-catalyst. Among the heterojunctions, the RhB degradation and H2 evolution efficiencies of the optimized MoS2 HNS/ZnIn2S4-3 wt % composite were almost 5 and 34 times higher than those of ZnIn2S4, respectively. The excellent performance of MoS2 HNS/ZnIn2S4-3 wt % might be attributed to the expansion of the visible-light response range and the accelerated separation efficiency of photo-induced carriers, according to the findings of the optical property tests. Based on the established band gap position and characterization results, a potential mechanism for appealing photocatalytic activity over MoS2 HNS/ZnIn2S4 heterojunctions was also postulated.

Photocatalytic degradation of tetracycline by N-CQDs modified S-g-C3N4 nanotubes and its product toxicity evaluation

In this study, to improve the electron-hole pairs separation rate and enhance the antibiotic wastewater treatment efficiency, the sulfur doped g-C3N4 (SCN) nanotubes were modified with nitrogen-doped carbon quantum dots (N-CQDs) derived from pig manure by a simple solvothermal method, and SCN/N-CQDs composite photocatalyst was synthesized. SCN with hexagonal tubular structure has strong light scattering ability and abundant active sites. At the same time, the modification of N-CQDs extended the visible light response range, accelerated the separation of electron-hole pairs, and realized the efficient photocatalytic degradation of tetracycline (TC). The SCN/N-CQDs-1 showed the best photocatalytic performance, and degradation rate of TC could reach to 79.11% after 90 min of visible light irradiation, much higher than the degradation efficiency of pure SCN (58.33%). Among them, the generation of hole, hydroxyl radicals and superoxide radicals play an important role in the efficient degradation of TC. Furthermore, the intermediates produced during the degradation process were detected by ultra-performance liquid chromatography-mass spectrometry (HPLC − MS), and the possible TC degradation pathways were investigated. The repeatability and practicability of SCN/N-CQDs are proved by five cycle experiments. In addition, compared with the original toxicity, the inhibition rate of Escherichia coli (E. coli) colony growth was reduced by 91.315% after 90 min photodegradation. The results of biotoxicity analysis showed that SCN/N-CQDs leaching solution and its photodegradation wastewater did not produce biotoxicity to E. coli.

The Collision between g-C3 N4 and QDs in the Fields of Energy and Environment: Synergistic Effects for Efficient Photocatalysis.

Recently, graphitic carbon nitride (g-C3 N4 ) has attracted increasing interest due to its visible light absorption, suitable energy band structure, and excellent stability. However, low specific surface area, finite visible light response range (<460nm), and rapid photogenerated electron-hole (e- -h+ ) pairs recombination of the pristine g-C3 N4 limit its practical applications. The small size of quantum dots (QDs) endows the properties of abundant active sites, wide absorption spectrum, and adjustable bandgap, but inevitable aggregation. Studies have confirmed that the integration of g-C3 N4 and QDs not only overcomes these limitations of individual component, but also successfully inherits each advantage. Encouraged by these advantages, the synthetic strategies and the fundamental of QDs/g-C3 N4 composites are briefly elaborated in this review. Particularly, the synergistic effects of QDs/g-C3 N4 composites are analyzed comprehensively, including the enhancement of the photocatalytic performance and the avoidance of aggregation. Then, the photocatalytic applications of QDs/g-C3 N4 composites in the fields of environment and energy are described and further combined with DFT calculation to further reveal the reaction mechanisms. Moreover, the stability and reusability of QDs/g-C3 N4 composites are analyzed. Finally, the future development of these composites and the solution of existing problems are prospected.

Halogen doped g-C3N4/ZnAl-LDH hybrid as a Z-scheme photocatalyst for efficient degradation for tetracycline in seawater

The present research centered on the fabrication of halogen (F and Cl) doping g-C3N4 modified ZnAl-LDH (FCCN/LDH) nanohybrids and its application in the photodegradation of tetracycline (TC) in artificial seawater. Halogen doping g-C3N4 was prepared via hydrothermal and thermal polycondensation methods using melamine as the precursor. Heterostructural FCCN/LDH binary nanocomposites were synthesized by a facile co-precipitation process. The morphological analysis of binary heterojunction exhibited uniformed decoration of FCCN on the LDH nanosheet surface. FCCN/LDH hybrid displayed enhanced photocatalytic degradation efficiency in the artificial seawater compared with pure FCCN and LDH, which is attributed to appropriate band alignment and Z-scheme electron-hole pairs transfer mechanism to suppress the recombination of photogenerated charge carriers. Electrochemical properties and PL results confirmed the proposed mechanism for extended visible-light response range over FCCN/LDH nanocomposites. Finally, the degradation efficiency of other pollutants (MB, MO, CIP, Rh B, and Cr(VI)) and the photocatalytic stability over FCCN/LDH nanocomposites in the seawater system were also reconnoitered. The plausible Z-scheme mechanism signposted that h+ and O2– active species are foremost free radicals that play a pivotal role in photodegradation.

The Side-chain design of rhodamine dye and the performance research of photocatalytic hydrogen production system by the first principles

It is very important to seek visible light photosensitizers with high catalytic activity and continuous reaction stability to promote the development of the homogeneous photocatalytic hydrogen production. The study shows that the hydrogen production activity of organic dyes is higher than that of noble metal complexes under the same experimental conditions, so the pure organic dyes can effectively reduce the hydrogen production reaction cost under the premise of ensuring the photocatalytic activity. In this work, we take rhodamine photosensitizers S150 to replace S in the xanthene ring as the prototype and modify its structure by extending side chain. We further comprehensively study the electronic and optical properties of newly designed photosensitizer molecules by density functional theory (DFT). The results indicate that both S156 and S162 molecules exhibit excellent light absorption properties, such as wide range of absorption spectrum and good visible light response. The molar extinction coefficient of S156 molecule is as high as2.65×104M-1·cm-1. And the molecules that are screened out have a larger photoinduced electron transfer drive and more negative reduction potential. The reduction potential of S162 (-0.76 V vs SCE) is 22.6 % higher than that of S150, which suggests that S162 has more outstanding photocatalytic performance of hydrogen production than S150. So the dyes extended by the 3-(methoxymethyl) Heptane side chain are very promising candidates for homogeneous photocatalytic hydrogen production photosensitizer systems.

Construction of Fe(III) doping modified AgI/NH2-MIL-68(In/Fe) Z-scheme heterojunction photocatalysts through unique internal and interfacial charge transmission and separation efficiency

The development of highly efficient strategy to facilitate comprehensive charge transmission and effective spatial charge separation is expected as a promising approach to improve photocatalytic performance. Herein, the Fe(III) doping modified AgI/NH2-MIL-68(In/Fe) Z-scheme heterojunction (ANM-x composite) with unique internal and interfacial charge transmission performance was fabricated by a facile ion exchange precipitation method. The optimized ANM-50 composite exhibits the maximum photocatalytic activity for the degradation of tetracycline, which is about 9.54, 2.61 and 1.86 times higher than that of pure NH2-MIL-68In, NH2-MIL-68(In/Fe) and AgI, respectively. The characterization results displayed that Ag nanoparticles (NPs) were generated during the photocatalytic procedure, which not only served as a charge transfer-highway, but also reduced the charge flow energy barrier, thereby accelerating charge transfer efficiency and consolidating the stability of the Z-scheme heterojunction. Mechanism exploration reflected that the superior photocatalytic performance was associated with synergetic effect among the introduced Fe(III), constructed ANM Z-scheme heterojunction and the generated Ag NPs, which significantly expands visible light response range and promotes more effective internal and interfacial charge separation. This research not only designs an efficient photocatalyst for decomposing tetracycline, but also opens a new perspective for rational developing Z-scheme heterojunction with unique internal and interfacial charge flow steering.

Z-scheme transfer pathway assisted photoelectrocatalyst Zn2SnO4/rGO/Ag/AgBr for organic pollutants treatment

Rational design of photoelectrode with high visible light utilization rate and separation efficiency of electron-hole pairs is the key step in photoelectrocatalytic technology. In this work, Z-Scheme photoelectrocatalyst (ZTO/rGO/Ag/AgBr) was synthesized by hydrothermal and photo-reduction process. Comparing with pure Zn2SnO4 (ZTO), adding reduced graphene oxide (rGO) effectively improved electrons transfer efficiency. Notably, the addition of Ag/AgBr not only broaden the visible light response range of ZTO, but also accelerated the separation of photo-generated electron-hole pairs, and constructed all-solid-state Z-Scheme heterojunction. Meanwhile, DFT calculation showed that Ag metal on rGO surface could act as active site for organic dyes degradation. Moreover, the addition of extra bias potential during photoelectrochemical process not only accelerate the migration of carriers, but also inhibit the recombination of photo-generated electron-hole pairs. Methylene blue (MB) could be effectively removed during photoelectrochemical reaction process, which was attributed to hydroxyl radical (•OH) and superoxide radical (•O2-). In this work, Z-Scheme transfer pathway, assisted photoelectrocatalytic technology, is a feasible strategy for improving catalytic performance.