Ternary Heterojunction Photocatalyst Research Articles

Constructing a CeFeO3/LaFeO3/ZnIn2S4 double Z-scheme heterojunction for photocatalytic atrazine degradation under visible light irradiation

The limited light absorption range and rapid recombination of interfacial charges were deemed to be the main restriction of the photocatalysts for atrazine (ATZ) degradation, and the construction of Z-scheme heterojunction was an effective strategy. Herein, a CeFeO3/LaFeO3/ZnIn2S4 (CFO/LFO/ZIS) double Z-scheme ternary heterojunction photocatalyst was fabricated by the in-situ precipitation and hydrothermal method. The photocatalytic ATZ degradation efficiency of optimized heterojunction reached 52% within 175 min under visible light irradiation, which was 3.1, 3.7 and 1.7 times higher than that of CFO, LFO and ZIS, respectively. The enhanced photocatalytic activity was due to the excellent light capture capacity and improved photogenerated charge separation in CFO/LFO/ZIS double Z-scheme heterojunction photocatalyst. Meanwhile, some environmental factors on the influence of photocatalytic ATZ degradation performance were systematically investigated. Quenching experiments confirmed that ·OH, h+ and 1O2 were the main active species during the photocatalytic ATZ degradation process. The possible photogenerated charge separation route was proposed via the analysis of the IEF effects between CFO, LFO and ZIS. Finaly, the possible ATZ degradation pathway was deduced by LC-MS measurement and toxicity assessment of the intermediates were also evaluated by the Toxicity Estimation Software Tool (TEST). This work not only provided a potential magnetic recyclable ferrate based double Z-scheme heterojunction photocatalyst for enhancing photogenerated charge separation and light absorption, but also evaluated the intermediate toxicity and related environmental factors on the activity of photocatalyst, which was facilitating the practical application for the degradation of ATZ.

A facile synthesis of metal vanadate incorporated with metal oxide/rare earth metal oxide composite for photocatalytic application

In this work (Ag2O/BiVO4) binary and (Ag2O/BiVO4/Eu2O3) ternary heterojunction photo-catalysts have been synthesized through a hydrothermal technique for the purpose of photocatalytic degradation of hazardous dyes. The facile synthesized composites of (Ag2O/BiVO4) and (Ag2O/BiVO4/Eu2O3)have been prepared using a hydrothermal process. The synthesized composites used to degrade the Methylene blue and Congo-red dyes under sunlight. The X-ray diffraction confirms the crystalline structure of synthesized composites. The calculated crystalline sizes for (Ag2O/BiVO4) and (Ag2O/BiVO4/Eu2O3) are 9.9 nm and 2.84 nm respectively. The morphology of samples has been analyzed by SEM while the absorption spectrum and bonding of molecules were observed using FTIR in the range of 600–4000 cm−1. The elemental percentage of synthesized material is determined by using EDX spectroscopy and UV spectroscopy used to study optical properties. Using Tauc plot calculated band gap of (Ag2O/BiVO4)is 1.84 eV and (Ag2O/BiVO4/Eu2O3) is 1.65 eV. The degradation efficiency of composites(Ag2O/BiVO4) (Ag2O/BiVO4/Eu2O3) towards a dye MB is 38% and 41% respectively, while these composites were found to degrade the dye CR 82% and 99%respectively in the exposure of sunlight. Both synthesized composites showed excellent %age degradation toward acidic dye (CR). The outcomes of synthesized composites indicates that suitable optical absorption, better segregation of charge carries and reduction of electron-hole recombination these factor effectively contribute to enhance photocatalytic activity towards acidic dye CR.

G-C3N4 as ballistic electron transport “Tunnel” in CsPbBr3-based ternary photocatalyst for gas phase CO2 reduction

Perovskite CsPbBr3 quantum dot shows great potential in artificial photosynthesis, attributed to its outstanding optoelectronic properties. Nevertheless, its photocatalytic activity is hindered by insufficient catalytic active sites and severe charge recombination. In this work, a CsPbBr3@Ag-C3N4 ternary heterojunction photocatalyst is designed and synthesized for high-efficiency CO2 reduction. The CsPbBr3 quantum dots and Ag nanoparticles are chemically anchored on the surface of g-C3N4 sheets, forming an electron transfer tunnel from CsPbBr3 quantum dots to Ag nanoparticles via g-C3N4 sheets. The resulting CsPbBr3@Ag-C3N4 ternary photocatalyst, with spatial separation of photogenerated carriers, achieves a remarkable conversion rate of 19.49 μmol·g−1·h−1 with almost 100 % CO selectivity, a 3.13-fold enhancement in photocatalytic activity as compared to CsPbBr3 quantum dots. Density functional theory calculations reveal the rapid CO2 adsorption/activation and the decreased free energy (0.66 eV) of *COOH formation at the interface of Ag nanoparticles and g-C3N4 in contrast to the g-C3N4, leading to the excellent photocatalytic activity, while the thermodynamically favored CO desorption contributes to the high CO selectivity. This work presents an innovative strategy of constructing perovskite-based photocatalyst by modulating catalyst structure and offers profound insights for efficient CO2 conversion.

Synthesis and characterization of Fe2SiO4/Fe2O3/g-C3N4 ternary heterojunction photocatalyst with enhanced photocatalytic activity under visible light

Ultrasonic-assisted co-precipitation is used for the first time to prepare Z-scheme Fe2SiO4/Fe2O3/g-C3N4 ternary heterojunction photocatalysts. Their morphology, crystal structure, specific surface area, optical properties, composition, and photocatalytic behavior have been thoroughly examined. When compared to single-component and binary Fe2SiO4/Fe2O3 heterojunction photocatalysts, ternary Fe2SiO4/Fe2O3/g-C3N4 heterojunction photocatalysts exhibit the most profitable performance for degradation of erythrosine under simulated light. It is likely that this is due to the high rate of separation migration of photoexcited charge carriers, the formation of Z-scheme heterojunction, and the specific surface area. Based on the results of active species trapping experiments, a possible Z-scheme mechanism could explain the significantly reduced photocatalytic rate of ternary heterojunction photocatalysts. It has been demonstrated that superoxide radicals play a significant role in the photodegradation process. A kinetic analysis revealed that the higher efficiency (97.9%) was associated with a higher rate constant (k = 0.0345 min‒1). A Fe2SiO4/Fe2O3/g-C3N4 nanocomposite is an excellent choice for large-scale applications because of its exceptional stability and recyclability.

Construction of a visible light responsive dual Z-scheme NH2-MIL-101(Fe)/CdS/g-C3N4 ternary heterojunction photocatalyst for efficient CO2 photoreduction to methanol

The photocatalytic CO2 reduction reaction using various semiconductors is exceedingly difficult due to the recombination of photo-exited electron-hole (e−, h+), inefficient irradiated light utilization, and lower adsorption capacity of CO2. An efficient design of the photocatalyst system is required to address this issue. The metal–organic frameworks (MOFs), particularly NH2-MIL-101(Fe) (NML-101(Fe)), have demonstrated exceptional efficiency in CO2 adsorption, and reduction because of its large surface area, efficient charge separation capacity, and ligand-to-metal charge transfer effect (LMCT). The synergistic effect of semiconductors CdS, g-C3N4 (GCN), and metal–organic framework on efficient photocatalytic CO2 conversion to CH3OH was investigated here. The successful synthesis and design of a dual Z-scheme NML-101(Fe)/CdS/GCN (NMCG(X)) ternary hetero-nanostructured system (THS) was demonstrated, in which CdS nanoparticles and NML-101(Fe) are deposited on the surface of GCN to form a dual Z-scheme mechanism with excellent photocatalytic performance. After 8 h of visible light irradiation, NMCG8 nanocomposites containing 37.5 % GCN, 25 % CdS, and 37.5 % NML-101(Fe) exhibit 1.53 times higher methanol production (53.89 µmolg−1) than pure NML-101(Fe) (35.11 µmolg−1). The efficient reduction of CO2 was largely attributed to the systematic transportation of photo-exited e− and h+ mediated by the dual Z-scheme mechanism, as demonstrated by PL spectra, electrochemical impedance spectra (EIS) studies, and Transient photocurrent response testing.

Hydrothermal carbonization carbon induced synthesis of flower-like C/Bi/BiOI heterojunction with heightened photocatalytic Cr(VI) reduction

Modification with metallic Bi and formation heterojunction with carbon material are considered as the compelling strategies to address the shortcoming of bismuth oxyhalide in photocatalytic Cr(VI) reduction. However, the simultaneous and in-situ synthesis of metallic Bi and hydrothermal carbonization carbon (HC) on BiOI to fabricate a ternary heterojunction photocatalyst remains a challenge yet, and the synergistic mechanism between the localized surface plasmon resonance (LSPR) effect and HC is still indistinct. Herein, a ternary heterojunction photocatalyst comprising metallic Bi, HC, and flower-like BiOI was designed and synthesized through the in-situ induction of HC. During the solvothermal synthesis, a portion of Bi3+ was reduced to metallic Bi nanoparticles, and simultaneously gauzy HC was formed. In the ternary heterojunction, the metallic Bi nanoparticles displayed strong LSPR effect, and the coated HC was conducive to transferring photogenerated electrons and enriching Cr(VI). Due to the synergistic effect of metallic Bi and HC, multiple channels for photogenerated carrier transfer were constructed. Deriving from the excellent light-harvesting, accelerated transfer/separation, and restrained recombination of photogenerated carriers, the ternary heterojunction of flower-like C/Bi/BiOI showed superior photocatalytic Cr(VI) reduction. The reaction rate constant of photocatalytic Cr(VI) reduction was about 26 times higher than that of BiOI.

Recent updates on g-C3N4/ZnO-based binary and ternary heterojunction photocatalysts toward environmental remediation and energy conversion

Background: The utilization of photocatalytic materials has garnered significant consideration due to their distinctive properties and diverse applications in environmental remediation and energy conversion. In photocatalysis, several wide and narrow band gap photocatalysts have been discovered. Amongst several photocatalysts, g-C3N4 photocatalyst is becoming the interest of the research community due to its unique properties. But as a single photocatalyst, it is inherited with certain confines for instance higher photocarrier recombination rate, lower quantum yield, low specific surface area, etc. However, the heterojunction formation of g-C3N4 with other wide band gap photocatalysts (ZnO) has improved its photocatalytic properties by overcoming its limitations.
 Methods: The synergistic interaction amid g-C3N4 and ZnO photocatalysts enhanced optoelectrical properties superior mechanical strength and improved photocatalytic activity. The nanocomposite exhibits excellent stability, high surface area, efficient separation, and migration of photocarriers, which are advantageous for applications in photocatalytic energy conversion and environmental remediation. The g-C3N4-ZnO nanocomposite represents a material comprising g-C3N4 and ZnO photocatalysts which exhibit a broad absorption range, efficient electron-hole separation, and strong redox potential. The combination of these two distinct materials imparts enhanced properties to the resulting nanocomposite, making it suitable for various applications. Henceforth, current review, we have discussed the photocatalytic properties of g-C3N4 and ZnO photocatalysts and modification strategies to improve their photocatalytic properties.
 Significant Findings: This article offers an inclusive overview of the g-C3N4-ZnO-based nanocomposite, highlighting its photocatalytic properties and potential applications in several pollutant degradation and energy conversion including hydrogen production and CO2 reduction.

Dual Z‐scheme ternary heterojunction photocatalyst with enhanced visible‐light photocatalytic degradation of organic pollutants

AbstractPhotocatalysis technology driven by solar energy is considered to be promising for solving energy crisis and environmental problems. Graphitic carbon nitride has been widely researched in the photocatalysis field due to its suitable band positions, non‐toxicity, easy synthesis, high stability, and low cost. However, the slow separation and rapid recombination of photogenerated carriers, the poor visible light response and the low specific surface area seriously limit the photocatalytic activity of g‐C3N4. Here, firstly, g‐C3N4 nanosheets with a large specific surface area of 152.2 m2 g−1 which provide more surface‐active sites for photocatalysis were prepared by secondary calcination method. Next, MoS2 and metal–organic framework (MIL‐101(Cr)) were tightly bonded on g‐C3N4 nanosheets to form ternary g‐C3N4/MoS2/MIL‐101(Cr) heterojunction photocatalyst. In which, a ternary dual Z‐scheme heterojunction photocatalyst composed of g‐C3N4, MoS2, and MIL‐101(Cr) was constructed to facilitate the separation and the migration of photogenerated charges. At the same time, MoS2 enhanced the visible light response of the ternary photocatalyst. The optimal ternary photocatalyst displayed the highest activity for methyl orange degradation (degradation efficiency of 98% in 60 min) under visible light irradiation. Finally, a photocatalytic mechanism of a dual Z‐scheme electron transfer channel and h+‐·O2− double oxidation sites were proposed and discussed.

Construction of a novel double S-scheme heterojunction CeO2/g-C3N4/Bi2O4 for significantly boosted degradation of tetracycline: Insight into the dual charge transfer mode

Constructing dual S-scheme heterojunction, as one kind of new strategy for the reinforcement of photocatalytic property, shows significant advantages in facilitating the migration of photoinduced charges and achieving high redox potentials. Herein, a novel double S-scheme heterojunction CeO2/g-C3N4/Bi2O4 was designed and synthesized successfully. The photodegradation of tetracycline (TC) over CeO2/g-C3N4/Bi2O4 was carried out under the irradiation of visible light. The double S-scheme interfacial charge transmission mode of CeO2/g-C3N4/Bi2O4 was investigated according to Fermi level, band structure, and the in-depth analysis of in situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) and electron spin resonance (ESR) spectra. The CeO2/g-C3N4/Bi2O4 exhibits excellent catalytic activity with a high TC removal efficiency of 94 % and a remarkable mineralization efficiency of 51 %. The rate constant (0.05811 min−1) of TC degradation for CeO2/g-C3N4/Bi2O4 is 12.9, 7.8, 4.3, 2.2, and 3.1 times those for g-C3N4, CeO2, Bi2O4, g-C3N4/Bi2O4 and CeO2/g-C3N4, separately. The prominently boosted activity may be due to two factors. Firstly, the successful creation of the double S-scheme electron migration channel greatly boosts the transmission of photogenerated carriers, represses the recombination of electrons with holes, and ensures the strongest redox potential of CeO2/g-C3N4/Bi2O4. Secondly, the introduction of Bi2O4 with excellent visible-light absorption broadens the optical absorption region of CeO2/g-C3N4/Bi2O4. Additionally, the influence of the typical environmental factors (pH, inorganic anions, cations, and natural humus) on the photodegradation of TC was explored. The three probable pathways for TC degradation were inferred via analyzing intermediates. The current work offers a novel outlook for enhancing the activity of ternary heterojunction photocatalysts applied in environmental restoration.

Construction of dual Z-scheme g-C3N4/BiVO4 (0 4 0)/In2S3 photocatalyst for efficient photocatalytic degradation and sterilization under solar light irradiation

A novel ternary heterojunction photocatalyst, g-C3N4/BiVO4/In2S3, is synthesized via a hydrothermal method, exhibiting superior photocatalytic activity in tetracycline (TC) degradation and Escherichia coli (E. coli) inactivation. The first-order kinetic constant of TC degradation by MCN/BVO/InS-1 under simulated solar light is 3.6, 1.8, 2.9 and 1.4 times that of MCN, BVO, InS, and MCN/BVO, respectively. More than 90 % of E. coli can be inactivated within 60 min by MCN/BVO/InS composite. After three consecutive cycles of experiments, the prepared photocatalyst showed continuous excellent stability. In this system, superoxide radicals (∙O2-) dominate TC degradation, while photogenerated h+ is key in E. coli inactivation. TC degradation pathways are analyzed by LC-MS/MS and theoretical calculations. A dual Z-scheme electron transfer mechanism is proposed. Furthermore, the ecotoxicity of TC and its degradation intermediates is examined through the application of the Toxicity Estimation Software Tool (T.E.S.T.) and Quantitative Structure-Activity Relationship (QSAR) model. The findings of the MCN/BVO/InS photocatalyst could provide insights for designing and optimizing novel photocatalytic systems with broader applications in the remediation of waterborne contaminants.

Fabrication of Ti3C2/TiO2/SrTiO3 ternary heterojunction photocatalyst with efficient charge separation for enhanced hydrogen evolution

In this work, a ternary Ti3C2/TiO2/SrTiO3 composite with heterogeneous network structure was prepared by two-step in situ hydrothermal synthesis method, which mainly involved the growth of TiO2 nanosheets and fibrous SrTiO3 sequentially on the Ti3C2 substrate using the Ti source inherent in Ti3C2 as the reaction site. The Ti3C2/TiO2/SrTiO3 heterojunction exhibited enhanced photocatalytic hydrogen evolution activity. When the doping amount of SrTiO3 was 5 wt%, the hydrogen evolution rate of 5MTS under full solar irradiation reached 14322.6 μmol·g−1·h−1, which was 10.6 times the rate of the Ti3C2/TiO2 composite without modified SrTiO3. Meanwhile, the 5MTS composites showed good stability in the photocatalytic hydrogen evolution cycle test. The enhanced activity and recyclability are mainly attributed to the strong light absorption ability, fast separation of photogenerated electron-hole pairs, and abundant catalytic active sites. In addition, the synthesis method utilizing an intrinsic Ti source also enhances the interfacial contact between Ti3C2, TiO2, and SrTiO3. This study provides an effective reference for the construction of perovskite-based or Ti3C2 co-catalyzed heterostructures and their application for the conversion of solar power to hydrogen energy.

The effect of Ni and Co co-catalysts on the catalytic activity of mesoporous graphitic carbon nitride/black phosphorus/molybdenum disulfide heterojunctions in solar-driven hydrogen evolution

In this work, a ternary heterojunction photocatalyst composed of mesoporous graphitic carbon nitride, black phosphorus, and molybdenum disulfide (m-CN/BP/MoS2) was firstly fabricated for the visible-light-driven hydrogen evolution reaction (HER) via water splitting. The photocatalytic activity of m-CN/BP/MoS2 photocatalyst was further improved by incorporating Ni and Co co-catalysts, denoted as m-CN/BP/MoS2-Y (Y: Ni, Co). The final quaternary nanocomposites were experimentally demonstrated in the form of mixed heterojunctions (type-I, type-II, and Schottky junctions) to manipulate the photogenerated carriers with the aim of reducing their recombination rate and increasing the light-harvesting ability of the pristine components. To find the best combination of different semiconductors in the heterojunction to ensure the highest photocatalytic HER activity, the loading ratio of each component was optimized one-by-one by considering the rate of HER under the same conditions. The photocatalytic HER activity of m-CN/BP/MoS2-Ni (5 wt%) and m-CN/BP/MoS2-Co (0.5 wt%) photocatalysts reached up to 21.668 mmol g−1 and 29.179 mmol g−1 for 8 h in the presence of triethanolamine electron donor under visible light irradiation, which were about 11 and 15 times higher than that of m-CN/BP binary heterojunctions, 4 and 5 times higher than that of m-CN/BP/MoS2 ternary heterojunctions, respectively. Ni or Co co-catalysts enhanced charge separation and thus increasing the rate of H2 evolution owing to their suitable d-band levels. This present study supplies a strategy to design efficient photocatalysts for solar fuel production without using non-noble metal cocatalysts.

Rational design of high temperature processed TbVO4/Nb2O5/carbon aerogel photocatalyst for prompt degradation of emerging pollutants

This present study investigates the construction of novel ternary heterojunction photocatalysts using terbium vanadate (TbVO4), niobium pentoxide (Nb2O5), and carbon aerogel (CG), to increase the photocatalytic performances under visible light. The X-ray diffraction (XRD) outcomes confirmed that the TbVO4 and Nb2O5 present themselves in a highly crystalline nature due to the high-temperature synthesis process. The successful combination of carbon aerogel and Nb2O5 into the TbVO4 lattice is further established by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) studies. The UV-DRS results confirmed that the materials comprising of both carbon aerogel and Nb2O5 present an expressive improvement in visible light activity, which leads to a drop-in band gap energy of the ternary TbVO4/Nb2O5/carbon aerogel photocatalyst. The improved charge separation in the ternary system was further confirmed by the electron spin resonance (ESR) and photoluminescence (PL) studies. The experimental results reveal that Nb2O5 and carbon aerogel were successfully incorporated in the TbVO4, increasing its surface area and structural photostability, thereby increasing its photocatalytic performance in the removal of pollutants under visible light. Compared with TbVO4 and Nb2O5, the outcomes illustrate that the TbVO4/Nb2O5/carbon aerogel displays the optimum photocatalytic removal rate and outstanding chemical stability in the removal of sulfamethoxazole. It shows a degradation efficiency of 92.3 in 90 min, which is 5 and 7 times as high as TbVO4 and Nb2O5, respectively. Based on the trapping experiments, h+, OH, and O2− improved the sulfamethoxazole photodegradation process. Finally, a novel, recyclable photocatalyst was made, which underwent a brand-new pathway for the degradation of various emerging pollutants.

Tailoring the redox ability of carbon nitride quantum dots/reduced graphene oxide-black phosphorus (CNQDs@rGOBP) ternary heterojunctions for photodegradation of organic pollutants

The direct utilization of solar energy in chemical transformations has paved the way for widespread use of photocatalysis for degradation. However, the state-of-the-art photocatalytic systems for various applications have not yet reached the desired level due to poor visible-light absorption and the high-cost requirements of the developed photocatalysts. Recently, the combination of different semiconductors via band engineering has been regarded as a highly efficient strategy to construct metal-free photocatalysts. In this study, a novel ternary heterojunction photocatalyst was fabricated by decorating reduced graphene oxide/black phosphorus binary heterojunctions (rGOBP) with carbon nitride quantum dots (CNQDs) via the ultrasound-assisted liquid exfoliation method. Different ratios of rGOBP binary and CNQDs@rGOBP ternary heterojunctions were prepared to investigate how the content is correlated synergistically to the coupling of the materials at their interfaces, thus possessing a superior photophysical properties. Combining the polar functional groups of as-synthesized rGO and CNQDs with the non-bonding electrons of BP on the surface led to the formation of a chemically stable photocatalyst with high catalytic performance. Harmonizing the salient features of each material boosted the degradation efficiency of organic pollutants 2.5 times in aqueous media compared to their pristine components. The photocatalytic performance of CNQDs@rGOBP heterojunctions was screened by studying different pollutants and catalyst concentrations. Moreover, the photogenerated charge migration pathway was proved by considering the results of the scavenger experiments and changes in the work functions of materials. A nonclassical type-I heterojunction, occurring at the farthest charges of band edges, was proposed as the underlying mechanism behind the superior photocatalytic activity of CNQDs@rGOBP ternary heterojunctions.

Novel dual S-scheme BiOI/AgI/Bi2WO6 heterojunction with enhanced photocatalytic activity for highly efficient removal of organic pollutants

To improve the catalytic performance of Bi2WO6, a dual S-scheme BiOI/AgI/Bi2WO6 ternary heterojunction photocatalyst was successfully constructed. Under visible light irradiation, 93.6% of 2,4-dinitrophenylhydrazine (2,4-DNPH) was removed by BOI/AI/BWO within 30 min, and the apparent rate constant was 30 times that of pure Bi2WO6. In addition, the methyl orange (MO) and tetracycline (TC) degradation rates were 87% and 94%, respectively. Therefore, BOI/AI/BWO exhibited more remarkable photocatalytic performance for the elimination of organic pollutants and aqueous solution containing antibiotics. Cyclic voltammetry test indicated that ternary heterojunction photocatalyst can able to provide more active surface area. Quenching experiments and electron paramagnetic resonance (EPR) analysis revealed that ∙O2− and h+ are main active species. Characterization test and mechanism analysis indicated that excellent photocatalytic performance of ternary heterostructure was ascribed to dual S-scheme charge transfer mechanism leaded to efficient photoexcited carrier separation and strong redox capacity. This research could provide a new strategy to design high-efficiency dual S-scheme photocatalyst for environmental remediation.

One-pot fabrication CoS2 modified MoS2-g-C3N4 ternary heterostructure composites with enhanced photocatalytic hydrogen production from water

In this work, we prepared several CoS2-MoS2-g-C3N4 ternary heterojunction photocatalysts in-situ synthesized at one-pot high temperature processing. The spectroscopic and optoelectronic properties of the samples were analyzed by fluorescence and electrochemical methods, while the photocatalytic hydrogen production activity and stability of the different samples were investigated under visible light conditions (λ ≥ 420 nm). The results showed that the 0.02-CoS2-MoS2-g-C3N4 sample exhibited excellent photocatalytic production performance. It's because of the improved separation and transport capacity of photogenerated electrons and holes, which based on the effect of heterojunction between MoS2 and g-C3N4. The introduction of CoS2 could be further enhance the photocatalytic hydrogen production performance due to the increased active center and reducing the reaction energy barrier. This study can provide a new insight in the practical applications for photocatalytic hydrogen production.

Ti3C2@g-C3N4/TiO2 Ternary Heterogeneous Photocatalyst for Promoted Photocatalytic Degradation Activities

Ternary heterojunction photocatalysts can improve the transport and separation of photogenerated electrons and holes, which could promote their reduction and oxidation properties for environmental and energy applications. In this research, the ternary photocatalyst Ti3C2@TiO2/g-C3N4 was successfully synthesized via direct electrostatic self-assembly during hydrothermal process. Ti3C2 MXene was used to optimize the interfacial carrier transport and separation between the interfaces. The obtained ternary heterostructured photocatalyst had a higher photocatalytic degradation performance for removing rhodamine B (RhB) and 4-chlorophenol (4-CP). The synergistic effect of heterojunction between g-C3N4 and TiO2 and Schottky barrier presented among TiO2 and Ti3C2 suppressed the recombination of the photogenerated electron–hole pairs. Moreover, the Ti3C2 can serve as an active site for the adsorption and activation of organic pollutants resulting from sufficient functional groups (F− here).

Enhanced photo-degradation of pollutants in three dimensions by rGO/Bi12O15Cl6/InVO4: LED-light photocatalytic performance and mechanism investigation

Novel Z-scheme rGO/Bi12O15Cl6/InVO4 ternary heterojunction photocatalyst was successfully prepared using reduced graphene oxide (rGO) as the electronic medium. The optimum sample 0.3% rGO/Bi12O15Cl6/InVO4 can degrade 99.1% Rhodamine B (RhB) and 77.48% tetracycline (TC) in 75 min, and can inactivate Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) within 30 min under the LED light. The crystal structure, morphology, composition, specific surface area, photoelectric chemical properties, and photodegradation properties were studied. Compared with binary Bi12O15Cl6/InVO4 and single photocatalyst, rGO/Bi12O15Cl6/InVO4 ternary heterojunction photocatalyst presented the best degradation and antibacterial performance, which is mainly due to the introduction of rGO, which can enhance the absorption of photons, and the separation and migration efficiency of photoexcited carriers. The capture experiment of active substances showed that both h+ and •O2− were the main active substances in the photocatalytic process. The probable photocatalytic degradation pathway of TC was proposed by mass spectrometry (MS) determination of the intermediate. The experimental results show that Z-scheme rGO/Bi12O15Cl6/InVO4 is a promising photocatalyst.

Construction of sandwich-like Ag/UiO-66@g-C3N4 Z-scheme ternary heterojunction for photocatalytic CO2 conversion to CH3OH and CO

Photocatalysis technology to convert CO2 into fuels is considered as one promising strategy to mitigate the greenhouse effect and energy crisis. Herein, the Z-scheme Ag/UiO-66@g-C3N4 (AUiO@CN) composites exhibit an improved CO2 photoreduction activity owing to the increased specific surface area, strong redox capacity, rapid separation of photoinduced h+/e− pairs and fast transfer of e− at the interface. As a result, CH3OH and CO evolution rates of AUiO@CN composite are roughly 3.09 and 2.40 times higher than those of g-C3N4, respectively. The Quantum yield (QY) of CO and CH3OH for AUiO@CN are 0.0217 % and 0.0986 %. The ESR characterization and a series of electrochemical results confirmed the Ag NPs acted as e− mediator, which could promote the photogenerated charge separation and transport and CO2 reduction ability. This work not only provides a simple photo-deposition assisted grinding calcination method to prepare ternary composites, but also shows that the prepared ternary heterojunction photocatalyst can realize an efficient photocatalytic CO2 conversion to methanol and CO.

Hierarchical CdS/Ni3S4/Ni2P@C Photocatalyst for Efficient H2 Evolution under Visible-Light Irradiation.

Structural and morphological modulations play a crucial role in increasing the surface active sites of semiconductor photocatalysts for visible-light-driven water splitting. To fabricate a novel CdS/Ni3S4/Ni2P@C heterostructure, we first prepared carbon-encapsulated Ni3S4/Ni2P (Ni3S4/Ni2P@C) with a high surface area by sequential carbonization and phosphorization of a Ni-metal-organic framework (MOF) precursor. Combined characterization and photoelectrochemical measurement results reveal that the assembly of CdS nanowires and highly porous Ni3S4/Ni2P@C can enhance the visible-light response capability of the CdS/Ni3S4/Ni2P@C heterostructure catalyst by reducing the forbidden band gap of CdS. The hydrogen production rate of 21.56 mmol h-1 g-1 for CdS/Ni3S4/Ni2P@C with a Ni3S4/Ni2P@C mass fraction of 10 wt % was 26 times higher than that of CdS in a photolytic aquatic hydrogen system. A possible mechanism for the photocatalytic enhancement of the Ni3S4/Ni2P@C co-catalyst was systematically investigated and discussed. This research opens a new strategy for constructing ternary heterojunction photocatalysts via MOF precursors.