3N4 Heterojunction Photocatalysts Research Articles

Visible-light-driven photocatalytic inactivation of Escherichia coli by 0D/2D CeO2/g-C3N4 heterojunction: bactericidal performance and mechanism

Photocatalytic inactivation has been considered as a promising strategy to address the biohazards threat to human health. However, acquiring an efficient photocatalytic system with the merits of visible-light response is still challenging. In this study, a novel visible-light-driven 0D/2D CeO2/g-C3N4 heterojunction photocatalyst was fabricated and the photocatalytic bactericidal performance of CeO2/C3N4 composites were evaluated by using Escherichia coli K-12 (E. coli K-12). The results showed that 7 log cfu/mL Escherichia coli was completely inactivated by the optimal 8% CeO2/g-C3N4 composites within 3 h visible-light irradiation, but only 0.4 and 1.4 log cfu/mL Escherichia coli were inactivated by CeO2 and g-C3N4, respectively. This finding indicated that the CeO2/g-C3N4 composite has outstanding photocatalytic bactericidal performance over the bare CeO2 or g-C3N4, which should be attributed to the effective separation and migration of photoinduced electron-hole pair. In addition, the result of trapping experiments indicated that the major active species of E. coli K-12 inactivation are photoinduced hole and superoxide radicals. Furthermore, the Z-scheme charge migration mechanism was proposed for the photocatalytic bactericidal process of CeO2/g-C3N4 basing on the bactericidal performance and redox potential of the catalysts. This work confirmed that the constructing of the CeO2/g-C3N4 heterojunction is anticipated to be an effective strategy for water disinfection under visible-light illumination in a sustainable manner.

Fabrication of La2O3/g-C3N4 Heterojunction with Enhanced Photocatalytic Performance of Tetracycline Hydrochloride

In this study, La2O3/g-C3N4 heterojunction photocatalysts doped with different dosages of La2O3 were constructed by a facile ultrasound-assisted calcination approach. The as-prepared photocatalysts were characterized by XRD, FTIR, FESEM, TEM, XPS, PL and DRS to verify the composite photocatalysts’ purity and to investigate their structural, morphological and elemental composition, and their energy band. According to the results, a type of pure rod–sheet-shaped, heterostructured nanoparticle was successfully obtained. Decorated with 10% La2O3, 2 g/L of the composite sample had a 93% degradation rate for 20 mg/L tetracycline hydrochloride within 2 h under visible light at a pH of 7. After four successive photocatalytic runs, satisfactory stability and reusability was exhibited, with 70% of the tetracycline hydrochloride being removed in the final experiment. Electrons (e−), photogenerated holes (h+), superoxide radical anions (·O2−) and hydroxyl radicals (·OH) were the fundamental active species during the photocatalytic process and were investigated via quenching experiments. Furthermore, possible photocatalytic mechanisms were analyzed in this work.

Zeolite 4A supported CdS/g-C3N4 type-II heterojunction: A novel visible-light-active ternary nanocomposite for potential photocatalytic degradation of cefoperazone

The CdS/g-C3N4 heterojunction photocatalyst supported on 4A zeolite was successfully synthesized using a simple chemical precipitation method. The physicochemical characteristics of the as-prepared ternary composite were assessed using X-Ray diffraction (XRD), field emission- scanning electron microscopy (FE-SEM), energy dispersive X-Ray (EDX), transmission electron microscopy (TEM), N2 adsorption–desorption, differential reflectance spectroscopy (UV–Vis-DRS), and photoluminescence (PL) techniques. The results confirmed the successful synthesis of the CdS/g-C3N4/4AZ nanocomposite and introduction of the CdS and g-C3N4 on the substrate of 4A zeolite. Cefoperazone (CFP) antibiotic was tested as the model pollutant to assess the photocatalytic performance of the synthesized nanocomposite under visible light irradiation. The response surface methodology (RSM) and artificial neural network (ANN) showed desirable reasonability for the prediction of the CFP degradation efficiency. More than 93% of CFP with a concentration of 17 mg L-1 degraded in the presence of the 0.4 g L-1 of the catalyst at pH of 9 after 80 min treatment time (RSM-based optimization results). The pH of the solution, irradiation time, catalyst dosage, and the initial concentration of the CFP affected degradation efficiency with a percentage impact of 37, 29, 19, and 15 %, respectively (ANN-based modeling results). The addition of 1 mM of isopropanol, benzoquinone, and sodium oxalate reduced the CFP degradation efficiency from 93.23% to 85.18, 41.16, and 32.47%, respectively, proving the decisive role of the °O2– and h+ in the photodegradation process. The kinetic studies indicated the following of the process from the Langmuir-Hinshelwood’s pseudo-first-order model (kapp = 3.71 × 10-2 min−1). The structure of the identified by-products using GC-MS analysis confirmed that CFP mainly decomposed through the cleavage of C-S, C-N, and N-N bonds. Moreover, the formation of the aliphatic compounds and carboxylic acids as by-products confirmed nearly complete mineralization of the CFP to non-toxic products.

Tuning dimensionality TiO2/g-C3N4 heterostructure for enhanced elemental mercury removal performance under visible-light

TiO2/g-C3N4 (TCN) heterojunction photocatalysts with dimensionality tuning was prepared, g-C3N4 successfully shifted from 3D (3DBG) to 2D (2DGN). Compared with 2DGN and TiO2, all the as-prepared heterostructure samples exhibited significantly enhanced photoactivities under light irradiation. Through the photocatalytic mercury removal experiment on samples with different doping ratios, the effect of oxygen species such as hydrocarbons or surface-adsorbing molecular H2O and doping amount on the performance of photocatalytic oxidation were investigated. Finally, the photocatalytic reaction mechanism of charge transfer in the dimensional adjustable Z-scheme heterojunction was proposed. This work provides a new strategy for developing efficient photocatalysts to control mercury.

Combining SnO2-x and g-C3N4 nanosheets toward S-scheme heterojunction for high selectivity into green products of NO degradation reaction under visible light

NOx emissions cause many negative impacts on the living environment. The photocatalysis of semiconductors is superior for nitric oxide (NO) degradation due to their low redox potential. In this report, we combine SnO2-x/g-C3N4 heterojunction photocatalyst toward the high selectivity into green products under visible light illumination. Results show that SnO2-x/g-C3N4 heterojunction degraded 40.8% of NO, which is 1.6 times higher than that of g-C3N4. In addition, the selectivity coefficient of SnO2-x/g-C3N4 is higher 3 times than both pure SnO2-x and g-C3N4. Furthermore, SnO2-x/g-C3N4 expresses a superior stability for NO photocatalytic-degradation after five cycles. The scavenger trapping test results, and electron spin resonance (ESR) analysis also provide more understanding of the charge transfer mechanism of materials. SnO2-x/g-C3N4 heterojunction shows a high removal efficiency of NO gas, making it an up-and-coming environmental treatment candidate.

H2O2 production and in situ sterilization over a ZnO/g-C3N4 heterojunction photocatalyst

In this work, a novel ZnO/g-C3N4 heterojunction catalyst was prepared by a thermal polycondensation process and has been applied for H2O2 production and in situ sterilization in natural waters irradiated by simulated sunlight. The H2O2 production efficiency of this process was measured, and its in situ sterilization ability in natural waters was evaluated. In addition, the remaining sterilization ability of the process was also assessed. The ZnO/g-C3N4 heterojunction catalyst with 10 wt% ZnO exhibited the best performance in H2O2 production of 5312.45 μmol·L−1 after 8 h, which was nearly 2.65 times greater than that of pure g-C3N4. Moreover, the bactericidal rate reached 97.4% on 10% ZnO/g-C3N4 after 60 min, while 47.3% on pure g-C3N4. H2O2 and sunlight alone had limited bactericidal effects, only 10.3% and 27.6%. It was proven that the H2O2 generated in situ achieved high-efficiency bacterial inactivation through the effect of sunlight excitation. ·OH and ·O2– were verified to play main roles in the inactivation of bacteria, which contributed to about 44.2% and 40.4% respectively. In addition, the mold was completely inactivated after 20 min and had similar mechanism of bacterial inactivation, showing good applicability of this process. This work may provide new ideas for realizing the in situ disinfection using sunlight as driving force and cleaning treatment of natural water bodies.

Advanced Two-Dimensional Heterojunction Photocatalysts of Stoichiometric and Non-Stoichiometric Bismuth Oxyhalides with Graphitic Carbon Nitride for Sustainable Energy and Environmental Applications

Semiconductor-based photocatalysis has been identified as an encouraging approach for solving the two main challenging problems, viz., remedying our polluted environment and the generation of sustainable chemical energy. Stoichiometric and non-stoichiometric bismuth oxyhalides (BiOX and BixOyXz where X = Cl, Br, and I) are a relatively new class of semiconductors that have attracted considerable interest for photocatalysis applications due to attributes, viz., high stability, suitable band structure, modifiable energy bandgap and two-dimensional layered structure capable of generating an internal electric field. Recently, the construction of heterojunction photocatalysts, especially 2D/2D systems, has convincingly drawn momentous attention practicably owing to the productive influence of having two dissimilar layered semiconductors in face-to-face contact with each other. This review has systematically summarized the recent progress on the 2D/2D heterojunction constructed between BiOX/BixOyXz with graphitic carbon nitride (g-C3N4). The band structure of individual components, various fabrication methods, different strategies developed for improving the photocatalytic performance and their applications in the degradation of various organic contaminants, hydrogen (H2) evolution, carbon dioxide (CO2) reduction, nitrogen (N2) fixation and the organic synthesis of clean chemicals are summarized. The perspectives and plausible opportunities for developing high performance BiOX/BixOyXz-g-C3N4 heterojunction photocatalysts are also discussed.

Photocatalytic degradation of naproxen by Bi2MoO6/g-C3N4 heterojunction photocatalyst under visible light: Mechanisms, degradation pathway, and DFT calculation

In this research, a 2D/2D Bi2MoO6/g-C3N4 heterojunction photocatalyst, which can be driven by visible light, was fabricated through a hydrothermal coprecipitation method. Naproxen was used as the target organic contaminant to evaluate the photocatalytic performance of Bi2MoO6/g-C3N4. The composite photocatalyst showed promoted photocatalytic activity, among which BMO/CN50−50 with a mass ratio 50/50 exhibited the fastest degradation rate, the degradation rate was 3.9 and 2.5 times higher than that of g-C3N4 and Bi2MoO6, respectively. Scavenger experiments and EPR measurements demonstrated that hole (h+) and superoxide radical (O2−) play a leading role in the degradation reactions. Moreover, the degradation pathway was suggested in the light of identified intermediates by Liquid Chromatography-Mass Spectrometry (LC–MS/MS) and DFT analysis. Furthermore, the Quantitative Structure-Activity Relationship (QSAR) analysis was used to evaluate the toxicity of identified degradation intermediates.

A novel Z-scheme CeO2/g-C3N4 heterojunction photocatalyst for degradation of Bisphenol A and hydrogen evolution and insight of the photocatalysis mechanism

CeO2/g-C3N4 heterojunction photocatalyst had been successfully fabricated through a one-step in-situ pyrolysis formation of 3D hollow CeO2 mesoporous nanospheres and 2D g-C3N4 nanosheets together with simultaneous removal of carbon sphere templates after heat treatment. The sample shows high catalytic performances for photocatalytic hydrogen generation and photocatalytic oxidation of Bisphenol A (BPA) under visible light irradiation, and the catalytic degradation route of BPA was suggested by the degradation products determined by GC–MS. The enhancing catalytic activity was attributed to the effective interfacial charge migration and separation. Finally, it was proposed that the CeO2/g-C3N4 heterojunction photocatalyst could follow a more appropriate Z-scheme charge transfer mechanism, which was confirmed by the analysis of experiment and theoretical calculation results.

A visible-light-driven 3D Z-scheme photocatalyst by loading BiOI nanosheets onto g-C3N4 microtubes for efficient degradation of tetracycline and p-chlorophenol

A facile step-by-step synthetic route was developed to synthesize the three-dimensional (3D) BiOI/g-C3N4 heterojunction photocatalyst by loading BiOI nanosheets onto g-C3N4 microtubes. And adjusting the material ratio easily controlled the amount of BiOI nanosheets on BiOI/g-C3N4 photocatalyst (BiOI/CN-0.5, BiOI/CN-1, BiOI/CN-3 and BiOI/CN-7). The photocatalytic properties were investigated by degradations of tetracycline (TC) and p-chlorophenol (4-CP) with visible-light irradiation. Eminently, the BiOI/CN-1 photocatalyst exhibited the best performance with the degradation rate of 86.98% TC in 90 min (the degradation rate 68.95% 4-CP in 240 min), which was much higher than pure BiOI or g-C3N4 as photocatalyst. Moreover, the BiOI/CN-1 photocatalyst possessed high stability and could be reused without much decrease in photocatalytic activity after four recycles. The significant separation and transfer property of photogenerated charge carriers were identified by photocurrent and PL spectroscopy, which contributed to the excellent degradation character of BiOI/CN-1 photocatalyst. In addition, active species capture experiment showed that the h+, OH and O2− were active radicals in the degradation process. And then, the Z-scheme transfer process of photogenerated charges for promoting catalytic performance was unveiled.

Magnetically separable Z-scheme FeSiB metallic glass/g-C3N4 heterojunction photocatalyst with high degradation efficiency at universal pH conditions

Synthesizing efficient catalysts to degrade hazardous pollutants in wastewater, especially in alkaline conditions, is pivotal for water remediation. A magnetically separable Z-scheme FeSiB metallic glass (MG)/g-C3N4 photocatalyst with high activity under visible-light irradiation is prepared via ball milling. The photocatalyst exhibits a sufficient degrading capability to acid orange 7 (AO7) in acidic, neutral and alkaline solutions, and also shows excellent reusability. The photocatalytic efficiency of the composite can be optimized by modifying the weight ratio of FeSiB MG and g-C3N4 powders. Heterojunction structure is formed at the interface of g-C3N4 and FeSiB MG due to the shearing stress from ball milling, leading to the improvement of the separation efficiency of the photo-generated electron-hole pairs. This results in the enhancement in photocatalytic activity for the composite. Besides, the FeSiB MG/g-C3N4 photocatalyst can be recycled from solution conveniently due to their high saturation magnetization. This study offers a magnetically separable photocatalyst that can degrade azo dyes at universal pH conditions.

Z-Scheme LaCoO3/g-C3N4 for Efficient Full-Spectrum Light-Simulated Solar Photocatalytic Hydrogen Generation.

Photocatalytic decomposition of water is the most attractive method for the sustainable production of hydrogen, but the development of a highly active and low-cost catalyst remains a major challenge. Here, we report the preparation of LaCoO3/g-C3N4 nanosheets and the utilization of LaCoO3 instead of noble metals to improve the photocatalytic activity for the production of hydrogen. First, LaCoO3 was successfully prepared by the sol–gel method, and then a series of highly efficient Z-scheme LaCoO3/g-C3N4 heterojunction photocatalysts were synthesized by the solvothermal method. Various characterization techniques (X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy (DRS), photoluminescence (PL), transient photocurrent response test, electron paramagnetic resonance (EPR)) confirm that the heterostructure and interfacial interaction had been formed between LaCoO3 nanoparticles and g-C3N4 nanosheets. In the photocatalytic water splitting test, LaCoO3/g-C3N4-20 wt % exhibited the highest photocatalytic activity of 1046.15 μmol h–1 g–1, which is 3.5 and 1.4 times higher than those of LaCoO3 and g-C3N4, respectively. This work leads to an inexpensive and efficient LaCoO3/g-C3N4 photocatalysis system for water splitting or other photocatalytic applications.

Facile fabrication of CeF3/g-C3N4 heterojunction photocatalysts with upconversion properties for enhanced photocatalytic desulfurization performance

Cerium fluoride (CeF3) semiconductor with upconversion property was constructed on graphite carbonitride (g-C3N4) nanosheets by microwave hydrothermal method. The X-ray diffraction, transmission election microscopy, Fourier transform infrared, and X-ray photoelectron spectra techniques were used to characterize the CeF3/g-C3N4 nanocomposite. The study shows that CeF3 has upconversion property and can convert visible light (Vis) and near-infrared light (NIR) into ultraviolet light (UV). Moreover, CeF3 and g-C3N4 can form well-defined heterojunction and promote the effective separation of photogenerated electrons and holes. The synergistic effect of the CeF3/g-C3N4 nanocomposite was evaluated by photocatalytic degradation of dibenzothiophene (DBT). The optimum photocatalyst of CeF3/g-C3N4 (40 wt%) composites exhibit the highest photocatalytic desulfurization rate of the model oil under visible light radiation.

Design of 2D–2D NiO/g-C3N4 heterojunction photocatalysts for degradation of an emerging pollutant

The release of a large number of antibiotics to the environment has created a shade of sorrow in the scientific community. Herein, two-dimensional (2D)–2D NiO/g-C3N4 photocatalysts were synthesized and applied for the photodegradation of tetracycline hydrochloride antibiotic. This 2D–2D heterojunction catalyst showed effective photoactivity due to the large contact area promoting the interfacial charge transfer rate. The improved photoactivities were attributed to the formation of complete face-to-face heterojunctional channels between two nanosheets of NiO and g-C3N4, which play a major contribution in the transfer of excited charges in the nanocomposite. Besides, the formation of Z-type heterojunction protects the high redox ability of two semiconductors. The photocatalytic activities were high at neutral pH values and decreased when pH values were changed. The photocatalytic activities were also checked in the presence of certain anions such as sulfate, chloride, carbonate), nitrate, and phosphate. Finally, a possible schematic mechanism was planned for charge separation in the nanocomposite. 2D-2D NiO/g-C3N4 photocatalysts demonstrate high photocatalytic activity for degradation of tetracycline hydrochloride antibiotic due to the large contact area and Z-scheme heterojunction promoting the interfacial charge transfer rate.

A facile one-step strategy to construct 0D/2D SnO2/g-C3N4 heterojunction photocatalyst for high-efficiency hydrogen production performance from water splitting

Fabricating 0D/2D heterojunctions is considered to be an efficient mean to improve the photocatalytic activity of g-C3N4, whereas their applications are usually restricted by complex preparation process. Here, the 0D/2D SnO2/g-C3N4 heterojunction photocatalyst is prepared by a simple one-step polymerization strategy, in which SnO2 nanodots in-situ grow on the surface of g-C3N4 nanosheets. It shows the outstanding photocatalytic H2 production activity relative to g-C3N4 under the visible light, which is due to the formation of 0D/2D heterojunction significantly contributing to the separation of photogenerated charge carriers. In particular, the H2 production rate over the optimal SnO2/g–C3N4–1 sample is 1389.2 μmol h−1 g−1, which is 6.06 times higher than that of g-C3N4 (230.8 μmol h−1 g−1). Meanwhile, the AQE value of H2 production over the SnO2/g–C3N4–1 sample reaches up to a maximum of 4.5% at 420 nm. This work develops a simple approach to design and fabricate g–C3N4–based 0D/2D heterojunctions for the high-efficiency H2 production from water splitting.

Study on the Photocatalysis Mechanism of the Z-Scheme Cobalt Oxide Nanocubes/Carbon Nitride Nanosheets Heterojunction Photocatalyst with High Photocatalytic Performances

An efficient Z-scheme Co3O4/g-C3N4 heterojunction photocatalyst was developed via in-situ forming Co3O4 nanocubes on the g-C3N4 nanosheet in the hydrothermal process. The obtained photocatalyst exhibited high photocatalytic activity for the visible-light-driven catalytic reduction of Cr(VI) and catalytic oxidation of tetracycline (TC). Among the as-synthesized catalysts, Co3O4/g-C3N4-0.04 (the mass ratio of g-C3N4 to Co3O4 is 0.04) sample exhibits the most efficient catalytic activities. The photocatalytic reduction and photocatalytic oxidation efficiencies of Co3O4/g-C3N4-0.04 can obtain 81.3 and 92.6 %, respectively. Moreover, the TC is mineralized in the course of photocatalytic degradation, 72.2% of TOC is removed from the reaction system. In addition, the apparent quantum efficiency for the removal of Cr(VI) was also obtained and the the Co3O4/g-C3N4-0.04 could achieve the highest apparent quantum efficiency among the samples. The enhancing photocatalytic activities originated from the efficient interfacial charge migration and separation obtained in Co3O4/g-C3N4-0.04, which is preliminarily confirmed by the photoluminescence spectra, time-resolved photoluminescence spectra and the photoelectrochemical characterizations. Finally, we speculate that the Co3O4/g-C3N4 heterostructures follow a more reasonable Z-scheme charge transfer in this study, which is confirmed by analyzing the results of electron paramagnetic resonance, radical scavenging experiments, and theoretical calculations.

A novel hydrothermal induced BiVO4/g-C3N4 heterojunctions visible-light photocatalyst for effective elimination of aqueous organic pollutants

In this report, a novel BiVO4/g-C3N4 heterojunction photocatalysts were developed through facile and one step hydrothermal route. Various characterization techniques such as X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), Raman, UV–Visible diffuse reflectance (UV-DRS), Photoluminescence and Brunauer-Emmett-Teller (BET) analysis have been carried out to know the structural, optical and textural behavior of the pure BiVO4 and various BiVO4/g-C3N4 hybrid catalysts. The basic characterization results suggest that interaction between BiVO4 and g-C3N4 was confirmed and a heterojunction was formed on the surface of g-C3N4/BiVO4 composite, which enhanced the separation and transfer of photogenerated electron-hole pairs. Visible light induced photocatalytic degradation test was carried out for all the synthesized catalysts towards rhodamine B (RhB) and 4-chlorophenol (4-CP) dyes. Among the various composite catalysts, the 3:1 mass ratio of BiVO4/g-C3N4 (BVG3) catalyst achieves the optimum photocatalytic activity for the degradation of 4-CP, and reached 95.%, which is 3.7 times better than bare BiVO4 (25%). The hybrid catalyst has also delivered a high apparent constant (0.0821 min−1) and huge stability (loss only 2.25%). The improved photocatalytic mechanism was also discussed.

Novel Cu2ZnSnS4/Pt/g-C3N4 heterojunction photocatalyst with straddling band configuration for enhanced solar to fuel conversion

In the context of efficient conversion of CO2 to high-value carbonaceous fuels, the development of photocatalysts for CO2 reduction having high solar-to-fuel energy efficiency with exceptional selectivity and long-term stability is the prime requisite of current research. Herein, we reported a novel straddling band configuration based Cu2ZnSnS4/Pt-integrated g-C3N4 heterojunction photocatalyst for CO2 reduction to carbonaceous fuels. The heterojunction photocatalyst exhibited an enhanced CO2 reduction with an average CO/CH4 yield rates of 17.351/7.961 μmolg−1 h−1, which is ∼3.31 and ∼5.56 folds higher than pristine g-C3N4. The comprehensive analysis of heterojunction photocatalyst exhibited synergetic effects owing to higher surface area, efficient photon harvesting due to CZTS and multiple charge-transfer pathways together with Z-scheme charge transfer. Moreover, the localized surface-plasmon-resonance (LSPR) and electron sink function of Pt led to an efficient interfacial charge carrier separation, surface site activation for CO2 reduction and in the consequence of that enhanced the photocatalytic performance.

Synergetic effect of piezoelectricity and heterojunction on photocatalytic performance

The less-than-ideal photogenerated electron-hole behaviors is one of the significant reasons for the low photocatalytic efficiency. In this work, organic piezoelectric material, PVDF, was used to restrain the recombination of photogenerated electron-hole of MoS2/g-C3N4 heterojunction photocatalyst, which aimed to enhance the photocatalytic performance. After being compounded with the PVDF, the photocatalytic activity of MoS2/g-C3N4 heterojunction can be increased by 66.8 %, which showed that the MoS2/g-C3N4 heterojunction had an excellent enhancement effect on the photocatalytic efficiency of the composite film. Compared with the pristine g-C3N4 photocatalyst piezoelectric film, the piezoelectric effect of heterojunction piezoelectric films varies with the different amounts of MoS2. Among these different piezoelectric films, the 10-M-CN-P film possess highest photocatalytic performance, possibly due to the best synergistical effect of piezoelectricity and heterojunction.

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.