Wide Light Absorption Range Research Articles

Enhanced visible-light-driven photocatalytic degradation via in-situ AIS/ZIS high-low junctions

The I-III-VI QDs Ag-In-S (AIS) exhibits excellent properties in photocatalysis because of the adjustable band gap, wide light absorption range, and multiple active sites. Introducing homologous or heterogeneous ions not only derives the composition into quaternary/ quinary quantum dots but also generates new sulfide QDs to form composites, which is an effective strategy to promote photoactivity. In this work, we in-situ synthesized the AIS/ZIS (AgIn5S8/Zn4In2S7) composite photocatalyst by introducing Zn2+ and changing the reaction temperature. We found that the composite photocatalyst could efficiently photodegrade larger concentrations of RhB than that of the previous reports. The superior photocatalytic activity was due to the formation of the type I high-low junction, which could effectively separate carriers. The photoelectrons on the CB of AIS reacted with dissolved oxygen to produce strongly oxidative O2–, which degraded RhB into intermediates and eventually into CO2 and H2O. This work not only reports an excellent photocatalyst but also offers new ideas on the design and manufacture of highly efficient high-low junction photocatalysts.

Ultrasensitive miRNA-let-7a detection based on AgInS2 quantum dots co-sensitization and CRISPR/Cas12a induced strand displacement reaction for signal amplification

The evolution of breast cancer is usually accompanied by abnormal expression of miRNA-let-7a. Sensitive gauging of miRNA-let-7a is crucial for breast cancer monitoring and prognosis. Herein, a novel photoelectrochemical (PEC) biosensor was served as miRNA-let-7a detection on the basis of the coupling of co-sensitization and CRISPR/Cas12a-mediated strand displacement amplification (SDA). In short, AgInS2 quantum dots (QDs), characterized by a wide visible light absorption range and a stable photocurrent response, have an obvious sensitizing effect on TiO2/Bi2MoO6. Under the condition of without miRNA-let-7a, the AgInS2 fixed DNA probe was located near the surface of the TiO2/Bi2MoO6 electrode, forming a co-sensitive structure. During the detection process, hairpin DNA2 (HP2) specifically recognized miRNA-let-7a through base complementary pairing, triggering the SDA reaction to convert massive double-stranded DNA (dsDNA). The dsDNA product then triggered CRISPR/Cas12a lateral cleavage activity, causing AgInS2-sensitized DNA to leave the electrode surface and the co-sensitization effect to disappear, further reducing the photocurrent. Using a dual effect for signal amplification, the biosensor platform had linear detection capability within the scope of 0.01–10 nM, and the detection limit was 3.35 pM. The biosensor which was fabricated effectively provided an excellent platform for the effective monitoring of various tumor biomarkers in clinical detection.

Tuning the Structural and Electronic Properties of Zn-Cr LDH/GCN Heterostructure for Enhanced Photodegradation of Estrone in UV and Visible Light.

Estrone is an emerging contaminant found in waters and soils all over the world. Conventional water treatment methods are not suitable for estrone removal due to its nonpolarity and low bioavailability. Heterogeneous photocatalysis is a promising approach; however, pristine semiconductors need optimization for efficient estrone photodegradation. Herein, we compared Zn-Cr LDH/GCN heterostructures obtained by three different synthesis methods. The influence of the GCN content in the heterostructure on photoactivity was also tested. The morphology, structure, and electronic properties of the materials were analyzed and compared. The photocatalytic kinetic tests were conducted with 1 ppm of estrone in both UV and visible light, separately. The HLDH-G50 material, obtained by the hydrothermal route and containing 50 wt % of GCN exhibited the highest photocatalytic efficiency. After 1 h, 99.5% of the estrone was degraded in visible light. In UV light, the pollutant concentration was below the detection limit after 0.5 h. The superior effectiveness was caused by numerous factors such as high homogeneity of the formed heterostructure, lower band gap energy of hydrothermal LDH, and increased photocurrent. These characteristics led to prolonged lifetimes of charge carriers, a wider light absorption range, and uniformity of the material for predictable performance. This study highlights the importance of a proper heterostructure engineering strategy for acquiring highly effective photocatalysts designed for water purification. In particular, this work provides innovative insight into comparing different synthesis methods and their influence on materials' properties.

TiO2 embedded in AC-COFs/SiO2 composites with core-shell structure for improved photocatalytic degradation performance of tetracycline

The excellent photocatalytic properties of covalent organic frameworks (COFs) and Titanium dioxide (TiO2) have been a hot research topic. However, the extensive application of the COFs and TiO2 in photocatalysis is restricted by their easy agglomeration and poor visible light usage, respectively. In this research, acyl chloride-covalent organic frameworks (AC-COFs) prepared by ultrasound assisted synthesis method was attached to the surface of silica oxides (SiO2) prepared by the modified Stöber method with high specific surface area and high porosity through amino groups to form a core-shell structure, which effectively solved the problem of easy agglomeration of the AC-COFs. Subsequently, TiO2 was loaded onto the surface of the AC-COFs@SiO2 composites to create high-performing TiO2/AC-COFs@SiO2 composites with a wide visible light absorption range (λ=409 nm), a narrow band gap (Eg=2.32 eV) and strong adsorption performance (Qm=314.47 mg/g). Compared with SiO2, the adsorption performance of this composite material was improved by 1.5 times. Meanwhile, the formed binary heterogeneous structure effectively reduces carrier recombination rate and releases more active substances like h+ and ·OH, so the catalyst has excellent self-cleaning and cyclic stability under the combined effect of adsorption and photocatalysis. It was found that tetracycline (TC) completely degrades after 50 min and the degradation rate decreasing by only 2.8 % after six cycles.

Construction of CoFe2O4/Fe2O3 S-type heterojunctions on biochar for activating peroxymonosulfate towards simultaneous removal of TC and Cr(VI)

The construction of S-type heterojunctions for restraining the rapid recombination of photogenerated charges is considered an efficient approach to boost redox capacity. Herein, the growth of CoFe2O4/Fe2O3 S-type heterojunctions on biochar (BC) was accomplished by thermal polymerization-hydrothermal. BC/CoFe2O4/Fe2O3 displayed a wide range of light absorption from 200 to 800 nm and enhanced photocurrent (0.41 μA cm−2). Furthermore, BC/CoFe2O4/Fe2O3 can remove tetracycline (TC) (98.84 %) and Cr(VI) (88.43 %) more efficiently compared to the CoFe2O4 (40.32 % of TC, 68.52 % of Cr(VI)) and Fe2O3 (29.81 % of TC, 53.67 % of Cr(VI)) single counterparts upon 45 min visible light irradiation in the presence of peroxymonosulfate (PMS). Free radical capture experiments revealed that •OH, •O2−, and SO4−• are the primary activated species for the removal of TC and e− is the major activated species for the removal of Cr(VI). Meanwhile, the degradation pathway of TC was monitored via LC-MS and Fukui index calculations. Combining density functional calculations (DFT) with UPS and radical capture tests, the possible mechanism of photocatalytic degradation was proposed. The findings demonstrated the remarkable photocatalytic activity and stability of the photocatalyst, evidencing the potential of BC/CoFe2O4/Fe2O3 for practical wastewater treatment.

High photocatalytic activity of g-C3N4/CdZnS/MoS2 heterojunction for hydrogen production

In an effort to improve the light absorption efficiency of the photocatalyst, g-C3N4 nanosheets with visible light response have been prepared by roasting method, and the g-C3N4/CdZnS composite catalyst with 2D/0D architecture has been prepared by hydrothermal method after ultrasonic thinning. The g-C3N4/CdZnS/MoS2 composite catalyst with 2D/0D architecture has been synthesized by secondary hydrothermal method. TEM analysis proves that a close heterogeneous interface has been formed between g-C3N4 and CdZnS, and between CdZnS and MoS2. The ultraviolet diffuse reflectance spectrum shows that MoS2 has a wide light absorption range, which effectively enhances the light utilization ratio of the composite catalyst. The energy band structure diagram and photoelectrochemical test results show that a continuous stepped type II ternary heterojunction is formed among g-C3N4, CdZnS and MoS2, which promotes its separation of photogenerated charges. When the loading mass fraction of g-C3N4 and MoS2 is 4%, the hydrogen evolution rate of g-C3N4/CdZnS/MoS2 composite catalyst is 57.02 mmol g−1 h−1 under visible light, which is exceeding 20% that of g-C3N4/CdZnS and 4.79 times and 44.9 times higher than that of CdZnS and g-C3N4, respectively. The two-dimensional structure of g-C3N4 and MoS2 significantly improves the stability of the composite catalyst. This work offers feasible ways for ternary heterogeneous photocatalyst construction.

Interface engineering of Ti3C2 MXene assisted anatase/rutile TiO2 with hetero-phase junction for enhancing the photocatalytic activity of tetracycline hydrochloride removal and H2 production

The conventional heterojunction formed by combining two different semiconductors is associated with issues of low compatibility, restricted intimate contact, and limited charge anti-recombination process. To address these issues, a simple strategy was adopted to fabricate a hetero-phase junction flanked with two dissimilar crystal phases of a single semiconducting material. This study employed TiB2 as the initial material to fabricate an anatase/rutile TiO2 hetero-phase junction material (AR-TiO2), followed by its combination with highly conductive monolayer Ti3C2 nanosheets to develop an AR-TiO2/Ti3C2 composite photocatalyst. The photocatalyst displayed a wide range of light absorption and a remarkable capability for separating photogenerated carriers. The closely interconnected hetero-phase junction surface, formed by the rutile and anatase phases of AR-TiO2, combined with the incorporation of highly conductive Ti3C2 nanosheets, synergistically increased the availability of multi-dimensional active sites and increased the efficacy of separating photogenerated electron pairs. The optimized AR-TiO2/Ti3C2 achieved a degradation efficiency of 91.49 % for tetracycline hydrochloride (TCH) within 2 h and produced 1005.81 μmol of hydrogen in 6 h. The impacts of initial pH, co-existing anions, initial TCH concentration, initial temperature, and various pollutant species on the catalytic efficiency were also investigated. pH was shown to have the greatest impact on the photocatalytic performance of AR-TiO2/Ti3C2 for TCH degradation. •O2−, and h+ were identified as the primary reactive species that enabled the photocatalytic performance of AR-TiO2/Ti3C2 through trapping experiments. This study presents a novel method to synthesize hetero-phase junction photocatalysts and suggests that Ti3C2 has potential prospects for use in photocatalysis.

Two-Dimensional GeC/MXY (M = Zr, Hf; X, Y = S, Se) Heterojunctions Used as Highly Efficient Overall Water-Splitting Photocatalysts.

Hydrogen generation by photocatalytic water-splitting holds great promise for addressing the serious global energy and environmental crises, and has recently received significant attention from researchers. In this work, a method of assembling GeC/MXY (M = Zr, Hf; X, Y = S, Se) heterojunctions (HJs) by combining GeC and MXY monolayers (MLs) to construct direct Z-scheme photocatalytic systems is proposed. Based on first-principles calculations, we found that all the GeC/MXY HJs are stable van der Waals (vdW) HJs with indirect bandgaps. These HJs possess small bandgaps and exhibit strong light-absorption ability across a wide range. Furthermore, the built-in electric field (BIEF) around the heterointerface can accelerate photoinduced carrier separation. More interestingly, the suitable band edges of GeC/MXY HJs ensure sufficient kinetic potential to spontaneously accomplish water redox reactions under light irradiation. Overall, the strong light-harvesting ability, wide light-absorption range, small bandgaps, large heterointerfacial BIEFs, suitable band alignments, and carrier migration paths render GeC/MXY HJs highly efficient photocatalysts for overall water decomposition.

Enhanced photocatalytic activities of FCNO nanoparticles on graphitic carbon nitride

Efficient charge separation and broadened light absorption are of crucial importance for photocatalytic environmental remediation, and graphitic carbon nitride (g-C3N4) is a very promising photocatalyst for this purpose. Herein, the synthesis of FCNO nanoparticles embedded within graphitic carbon nitride (g-C3N4) by hydrothermal route assisted with pyrolysis of urea was presented. The g-C3N4 was obtained from an abundantly available precursor urea and the synthesis process played double role. Urea reacted with metal salts to convert them into metallic oxides and yielded g-C3N4. The experimental results revealed the in-situ fabrication of FCNO nanoparticles and formation of g-C3N4. The band gap narrowing made it possible that the samples were able to show a wide range of visible light absorption which made them suitable for photocatalytic activity studies. Thus, the materials were utilized for the visible light-based photocatalytic degradation of methylene blue dye. Photocatalytic degradation efficiency with ~93 % was achieved by the composite FCNO/g-C3N4 (50:50). The present approach for the synthesis of materials was proved to be cost-effective and time saving which enabled their use as recyclable photocatalyst.

Multifunctional Supramolecular Hydrogel Modulated Heterojunction Interface Carrier Transport Engineering Facilitates Sensitive Photoelectrochemical Immunosensing.

Highly responsive interface of semiconductor nanophotoelectrochemical materials provides a broad development prospect for the identification of low-abundance cancer marker molecules. This work innovatively proposes an efficient blank WO3/SnIn4S8 heterojunction interface formed by self-assembly on the working electrode for interface regulation and photoregulation. Different from the traditional biomolecular layered interface, a hydrogel layer containing manganese dioxide with a wide light absorption range is formed at the interface after an accurate response to external immune recognition. The formation of the hydrogel layer hinders the effective contact between the heterojunction interface and the electrolyte solution, and manganese dioxide in the hydrogel layer forms a strong competition between the light source and the substrate photoelectric material. The process effectively improves the carrier recombination efficiency at the interface, reduces the interface reaction kinetics and photoelectric conversion efficiency, and thus provides strong support for target identification. Taking advantage of the process, the resulting biosensors are being explored for sensitive detection of human epidermal growth factor receptor 2, with a limit of detection as low as 0.037 pg/mL. Also, this study contributes to the advancement of photoelectrochemical biosensing technology and opens up new avenues for the development of sensitive and accurate analytical tools in the field of bioanalysis.

One-dimensional D-π-A conjugated polymers for photoenhanced gold recovery from e-waste

In principle, photocatalytic Au(III) reduction from e-waste using sunlight could provide a cleaner and more efficient alternative strategy to existing processes. Two-dimensional (2D) conjugated polymers are often employed for photocatalytic systems due to their structural diversity and stability. However, the efficiency of active site utilization in 2D materials still needs to be improved because the catalytic reduction centers are located in the basal layer and it is difficult for Au(III) to access them. Herein, we demonstrate the application of D-A and D-π-A type one-dimensional (1D) conjugated polymers for the photoenhanced gold recovery from electronic waste. The two synthesized 1D conjugated polymers, named BTP-DET (D-π-A type) and BTP-TDB (D-A type), exhibit a wide light absorption range and excellent chemical stability. Benefiting from the superior charge separation and migration efficiency of the D-π-A skeleton, BTP-DET exhibits a small optical band gap of 1.60 eV, which is significantly smaller than that of BTP-TDB (1.78 eV), and thus enables the extraction of the gold with a higher capacity of BTP-DET (2580.8 mg g−1) under visible light, than the BTP-TDB (2072.7 mg g−1). This work paves the way for exploring low dimensions of conjugated polymers for photocatalysis.

Highly efficient photoelectrochemical aptasensor based on CdS/CdTe QDs co-sensitized TiO2 nanoparticles designed for thrombin detection.

A photoelectrochemical (PEC) sensor for the sensitive detection of thrombin (TB) was established. Co-sensitized combination of TiO2 nanoparticles combined with modified cadmium sulfide and cadmium telluride quantum dots (CdS/CdTe QDs) was utilized as a photoactive material. Successful growth of CdS/CdTe quantum dots on mesoporous TiO2 films occuredby successive ion-layer adsorption and reaction. This interesting formation of co-sensitive structure is conducive to enhancing the photocurrent response by improving the use rate of light energy. Additionally, the step-level structure of CdS/CdTe QDs and TiO2 NPs shows a wide range of visible light absorption, facilitating the dissociation of excitons into free electrons and holes. Consequently, the photoelectric response of the PEC analysis platform is significantly enhanced. This constructed PEC aptasensor shows good detection of thrombin with a low detection limit (0.033pM) and a widelinear range (0.0001-100nM) in diluted actual human serum samples. In addition, this PEC aptasensor also has the characteristics of good stability and good reproducibility, which provides a novel insight for the quantitative measurement of other similar analytes.

Highly Effective Fe-Doped Nano Titanium Oxide for Removal of Acetamiprid and Atrazine under Simulated Sunlight Irradiation

Pesticides are widely detected in large quantities in the environment, posing an ecological threat to the human body and ecology. Semiconductor nanomaterials such as nano-titania (nTiO2) have strong photocatalytic degradation efficiency for pollutants. However, the wide bandgap and limited light absorption range inhibit nano-titania’s practical application. Therefore, nTiO2 was modified by Fe3+ doping using the microwave hydrothermal method to improve its photocatalytic performance in this study. Fe-nTiO2 doped with a 1.0% mass ratio was used due to its high photocatalytic performance. Its maximum degradation efficiencies for ACE and ATZ under a 20 W xenon lamp were 88% and 88.5%, respectively. It was found that Fe3+ doping modification distorted the spatial morphology of nTiO2 and shortened the bandgap to facilitate the photocatalytic reaction. The electron paramagnetic resonance results showed that the reactive radicals (1O2, ·OH) produced by photogenerated electrons (e−) and holes (h+) of Fe-nTiO2 were the main active species in the degradation of ACE and ATZ. Additionally, the application of Fe-nTiO2 significantly enhanced the growth of lettuce under sunlight; the degradation efficiencies of ACE and ATZ in lettuce were 98.5% and 100%, respectively. This work provides new insights into the removal of organic contaminants by photocatalysts under sunlight in agriculture.

Decoration of Bi2MoO6 nanosheets with NH2-UiO-66 for boosting visible-light photocatalytic activities

Constructing heterostructured photocatalysts for organic contaminants elimination is promising in the area of environmental purification. For boosting the photocatalytic performance, modulating the heterojunction interface can enhance solar light utilization and facilitate the transporation of photoinduced charge carriers. In this research, octahedral NH2-UiO-66 nanoparticles with large surface area and wide light absorption range were prepared and further employed to in-situ construction of NH2-UiO-66/Bi2MoO6 nanocomposite. The optimized NH2-UiO-66/Bi2MoO6 nanocomposite displays enhanced photocatalytic activities in the elimination of rhodamine B (RhB) and tetracycline (TC). The corresponding degradation rate constant is about 4 and 1.76 times larger than that of individual Bi2MoO6. Combined with the photochemical and electrochemical results, it can be speculated that the higher photocatalytic performance is assigned to the accelerative photoinduced carrier transfer by the formation of well-contacted heterostructured interface. This study provides a theoretical basis for further developing organic–inorganic hybrid catalyst with significant improvement of photocatalytic properties in wastewater treatment.

G-C3N4 modified with non-precious metal Al with LSPR as an efficient visible light catalyst.

The issue of water pollution has emerged as a formidable challenge, prompting a pressing need for solutions. The utilization of metal nanoparticles with surface plasmon resonance and semiconductor composite photocatalysts is regarded as a highly effective approach to solve this problem. g-C3N4 is an effective catalyst for the degradation of organic pollutants. Its photocatalytic performance is usually enhanced by the use of the noble metal Au Ag. However, the high cost of these materials limits their application. In this study, we present the synthesis of Al NPs/g-C3N4 nanocomposites using the bridging effect of ligands. The characterized of transmission electron microscopy (TEM), X-ray diffractometer (XRD) and ultraviolet-visible spectroscopy (UV-Vis) proved that Al NPs/g-C3N4 with a wider light absorption range were successfully synthesized. The effects of ligands, (glutathione (GSH), glutamic acid (GAG), and cysteine (CYS)), Al diameter (40 to 200 nm) and the ratio of Al to g-C3N4 (1:1 to 5:1) on the photocatalytic degradation of methylene blue (MB) by Al NPs/g-C3N4 were also evaluated. The results showed that the optimum degradation efficiency of Al NPs/g-C3N4 for MB at 5 mg/L reached 100% within 60 min, which was 11 times higher than that of pure g-C3N4. The principal analysis of Al enhancing the photocatalytic performance of g-C3N4 was studied through transient photocurrent spectroscopy (TPC), electrochemical impedance spectroscopy (EIS), and steady-state transient fluorescence spectroscopy (PL). The results confirmed that hot carriers generated by localized surface plasmon resonance (LSPR) of Al nanoparticles increase the carrier concentration. In addition, the Schottky barrier generated by Al and g-C3N4 could also improve the carrier separation rate and increase the carrier lifetime. This work is expected to solve the problem of organic wastewater treatment and lay the foundation for subsequent research on photocatalysis.

Milling Processing, Morphology, and Optical Characterization of Powders from Natural Pigments as a Potential Sensitizing Material for Optical Sensors and Dye-Sensitized Solar Cells

Dye-Sensitized Solar Cells (DSSC) and optical fiber-based-sensors sensitized with organic dyes play a fundamental role in modern technology, particularly in the family of photovoltaic power generation devices and measurement of chemical variables. DSSC is low-cost, highly efficient, and easy to manufacture. Therefore, they are a suitable option for many engineering applications. This paper deals with natural pigment extraction (spirulina, carrots (beta-carotene), and beetroot) at different milling and temperature conditions. Nanoparticles were fabricated using an SPEX mill and a planetary ball mill. The particle size distribution, absorbance (UV-Vis), and powder morphology were obtained using Field Emission Scanning Electron Microscopy (FESEM). Herein, the optical characterization of modified TiO2 powder at different temperatures and milling conditions is performed. Results indicate that each natural dye is sensitive to operational temperature. In addition, the absorbance of the pigments is affected by milling conditions and particle size distribution. During SEM characterization, rounded particles were observed in the starting materials with average sizes of more than 15 microns in diameter until they were reduced to nanometer ranges close to 100 using SPEX milling. The observed absorption spectra range from 400nm to 642 nm for spirulina. Moreover, the experimental results show that the intensity of the absorption peaks is affected by the temperature, which indicates a degradation of the dye. Therefore, different combinations of natural dyes will be feasible to improve the wide range of light absorption of the visible spectra and stability of DSSCs and optical fiber-based sensors.

Doping and strain modulation of the electronic, optical and photocatalytic properties of the GaN/C2N heterostructure.

The electronic, optical and photocatalytic properties of GaN/C2N van der Waals heterostructures are investigated using the first-principles theory, and effective regulation through element doping or strain is achieved further. The results show that the GaN/C2N heterostructure exhibits a type-II band alignment with an indirect band gap of 2.25 eV, which benefits photocatalytic water splitting. In this study, both type-I and type-II band alignments can be obtained through doping or strain modulation. Doping with P or As atoms reduces the band gap of the GaN/C2N heterostructure and transforms it to a type-I direct bandgap semiconductor, which makes the doped GaN/C2N heterostructure more suitable for optoelectronic devices. In addition, the GaN/C2N heterostructure retains type-II band alignment and has a decreased band gap under tensile strain (0 to +4%), which is more favorable for photocatalytic water splitting. Compressive strain (0 to -4%) converts the type-II band alignment to type-I, resulting in a wider light absorption range, making the GaN/C2N heterostructure more suitable for optoelectronic devices. These theoretical results are helpful for the design of GaN/C2N vdW heterostructures in the fields of optoelectronic devices and photocatalysts.

Ultrasensitive detection of chromium (VI) by a “signal-off” cathodic photoelectrochemical sensor based on AgBr0.8I0.2-Ag-CNTs composite

Hexavalent chromium (Cr(VI)) is highly poisonous and can accumulate in the environment. In this work, we developed a photoelectrochemical (PEC) sensor to detect Cr(VI) content. Firstly, a bean-like AgBr0.8I0.2-Ag-CNTs composite was synthesized through light reduction and hydrothermal method. The physicochemical characterization was investigated and the results revealed that AgBr0.8I0.2-Ag-CNTs possessed a wide visible light absorption range and excellent photoelectrochemical activity. Subsequently, a “signal-off” PEC sensor based on AgBr0.8I0.2-Ag-CNTs as cathodic sensing platform and K3[Fe(CN)6] as photoelectron acceptor was proposed. After photoelectrochemical reduction of Cr(VI) ions, Cr(VI) was reduced to cover AgBr0.8I0.2-Ag-CNTs in the form of Cr(OH)3, which severely blocked the photoelectron transfer from AgBr0.8I0.2-Ag-CNTs to K3[Fe(CN)6] and resulted in a falling photocurrent. Compared with previous PEC sensors based on the direct reduction of Cr(VI) to Cr3+, the proposed sensor showed a wider linear range of 0.1 nM ∼ 5.0 µM and a lower limit of detection (LOD) of 50 pM.

Synthesis and characterization of enhanced visible light-driven C-doped ZnO-2D GO/g-C3N4 heterojunction photocatalyst

Well-designed 2D graphene oxide-modified polymeric graphitic carbon nitride composite nanosheets (GO/g-C3N4) as desirable sensitizers and catalytic substrates for optimising the visible light-driven photocatalytic performance of ZnO-based photocatalysts have been investigated. Herein, 2D GO/g-C3N4 composite nanosheets are first developed by ultrasonic and hydrothermal methods, and then coupled with ZnO nanoparticles to prepare a series of ternary GO/g-C3N4-ZnO heterojunction composites with vary GO loading concentrations. Characterization of the photocatalysts was carried out by SEM, TEM, XPS, XRD, DRS, photoluminescence (PL) spectroscopy; evaluation of the visible light photocatalytic activity was performed by degrading an aqueous methylene blue (MB) solution. XPS studies showed that the formation of a ZnC bond in 15 % GO/g-C3N4-ZnO is due to the replacement of oxygen by carbon, indicating the construction of a hybrid heterojunction composed of C-doped ZnO and visible light sensitive GO/g-C3N4 composite nanosheets. The photodegradation performance of 15 % GO/g-C3N4-ZnO is 5.3, 2.9, and 2.2 times higher than that of pure ZnO, g-C3N4, and g-C3N4-ZnO, respectively. Due to the increase of GO loading in GO/g-C3N4 composite nanosheets, some characteristics of efficient visible light photocatalysis, such as a wider light absorption range, fluorescence quenching in the PL spectrum, excellent optical response in photocurrent measurement, and good stability，were confirmed and can be attributed to the electronic interaction between heterostructures and the effective transfer of photogenerated electrons in these ternary nanocomposites. This work may provide a new promising pathway for the construction of easily prepared 2D GO/g-C3N4 hybrid-modified nanocomposites, which is a hopeful material for wastewater control.

Synthesis of Fe-g-C3N4/FePc/BiVO4 Nanocomposites for Efficient Degradation of RhB

A novel photocatalyst comprising Fe-g-C3N4/FePc/BiVO4 heterostructure was synthesized using hydrothermal and muffle incineration methods. The synthesized catalyst was subjected to characterization using SEM, XRD, EDX, XPS, photocurrent response, and EIS analysis. Results showed that the Fe-g-C3N4/FePc/BiVO4 heterojunction composites significantly enhance the efficiency and stability of degradation of RhB. The unique advantages of the heterojunction composites include a wide range of light absorption and a small electron–hole complexation rate. Compared to pristine Fe-g-C3N4, FePc, and BiVO4, the photocatalytic activity and stability were significantly improved. The formation of a new structure of Fe-g-C3N4 and FePc and BiVO4 successfully adjusted the electron transfer route, resulting in more active sites and improving the efficiency of photogenerated charge separation. Furthermore, a possible mechanism for the photocatalytic degradation of RhB was proposed.