Charge Separation Rate Research Articles

Outstanding photocatalytic activity of WS2/TiO2 quantum dots for ciprofloxacin removal

This investigation aims to efficiently removing ciprofloxacin (CIP) by Z-scheme heterojunction of WS2/TiO2 quantum dots (QDs) under visible light. Interestingly, the photodegradation rate of CIP over WS2/TiO2 (2:1) photocatalysts is much better (2.73- and 3.87-folds) than bare WS2 and TiO2. Great surface area, the construction of the Z-scheme heterostructure, superior efficiency of visible light absorption, and reinforced charge separation rate played dominant aspects in expanding the photocatalytic action of pollutants removal. In addition, the Z-Scheme heterojunction photocatalyst not only decrease the recombination rate of electron-hole pair, but also supports the charge of interfacial transfer ability and enhance photodegradation efficiency. This study proposes new visions for the design of potential Z-scheme visible-light photocatalysts for the degradation of antibiotics in environmental field.

Ag2CO3/α-AgAl0.3Ga0.3In0.4O2 composites with enhanced charge separation rate for visible-light driven photodegradation of methyl blue

Ag2CO3/α-AgAl0.3Ga0.3In0.4O2 composites with different molar ratios were prepared in this study using a hydrothermal method combined with a precipitation reaction. Polyhedral Ag2CO3 particles were dispersed over the surface of the α-AgAl0.3Ga0.3In0.4O2 sheets, confirming the formation of Ag2CO3/α-AgAl0.3Ga0.3In0.4O2 composites. The UV–vis absorption of the composites was effectively regulated from 530 to 644 nm by controlling the molar ratio of α-AgAl0.3Ga0.3In0.4O2 to Ag2CO3. Photoelectrochemical analysis showed that the separation efficiency of photoinduced electrons and holes was enhanced in the composites. While eliminating methyl blue (MB) under visible light, the photocatalytic activity of the composites was higher than that of bare α-AgAl0.3Ga0.3In0.4O2 and Ag2CO3. In particular, 0.3-Ag2CO3/α-AgAl0.3Ga0.3In0.4O2 eliminated 90% of MB within 90 min. This was mainly attributed to the formation of an internal electric field between α-AgAl0.3Ga0.3In0.4O2 and Ag2CO3 with a matchable energy band, which strengthened the separation and migration of the photoinduced carriers. Additionally, a possible photodegradation process for MB in the Ag2CO3/α-AgAl0.3Ga0.3In0.4O2 composites was proposed.

Combined Biological and Photocatalytic Degradation of Dibutyl Phthalate in a Simulated Wastewater Treatment Plant

The removal of organic pollutant in wastewater has become a major priority in water treatment. In this study, organic pollutant dibutyl phthalate (DBP) has been biologically and photocatalytically degraded in wastewater using modified transition metal dichalcogenides. The as-synthesized nanoparticles were characterized using various characterization techniques, which includes XRD, Raman, FT-IR, SEM, TEM, UV-Vis, XPS, PL, EIS, and photocurrent responses. The nanoparticles synthesized by slightly modified hydrothermal method depicted a hexagonal phase, as evidenced by XRD and Raman analyses. The biological degradation of 69% dibutyl phthalate was achieved. Moreover, the total organic carbon removal efficiency of 70% was further achieved. Incorporating biological and photocatalytic systems significantly improved dibutyl phthalate removal in secondary effluent by three folds when compared to the unilateral operating setup. The optimized parameters such as pH = 7, 5 ppm and DBP concentration with the addition of 10 mg catalysts loading were employed for the photocatalytic degradation of dibutyl phthalate in water. Pristine WS2 exhibited photocatalytic efficiencies of 46% after 60 min illumination. The use of dual system 3% Ce/Gd-WS2 exhibited the highest photodegradation of 85%, with a chemical oxygen demand of 80% and total organic carbon of 77%. The enhanced activity by the composite is attested to the formation of heterojunction exhibiting excellent charge separation and low rate of recombination. The 3% Ce/Gd-WS2 can be used up to seven times and still achieve a degradation of 56%.

S-scheme g-C3N4/ZnO heterojunction photocatalyst with enhanced photodegradation of azo dye

BackgroundThe low specific surface area (SSA) and high charge recombination rate of g-C3N4 (hereafter referred to as CN) limit its applications for dye photodegradation. A photocatalyst that enhanced the SSA and retarded the charge recombination rate of g-C3N4 was developed in this study. MethodsIn this study, a g-C3N4/ZnO S-scheme heterojunction photocatalyst was prepared via template method. Zeolitic-imidazolate-framework-8 (ZIF8) was used as a template of g-C3N4 and as a precursor of ZnO. This method addressed the two above-mentioned limitations of CN simultaneously. Significant findingsIt was confirmed that when calcination temperature was controlled at 450 °C, g-C3N4/ZnO S-scheme heterojunction was successfully fabricated to enhance the specific surface area and charge separation rate of g-C3N4. CN/ZIF8-450 displayed optimal AR1 decolorization performance (95%), which was 1.6 times higher than that of CN (43%), when the reaction time was 1 h. The excellent performance of CN/ZIF8-450 was attributed to its high specific surface area (182.8 m2/g), 3.4 times higher than that of CN (53.6 m2/g), and low charge recombination rate due to the S-scheme heterojunction. The main reaction species in this system were ·O2- and h+. This study provided a simple approach to overcoming the limitations of CN in dye wastewater treatment.

0D/2D CsPbBr3 Nanocrystal/BiOCl Nanoplate Heterostructure with Enhanced Photocatalytic Performance

Abstract0D‐2D p–n type CsPbBr3/BiOCl heterojunction photocatalyst is successfully fabricated via the electrostatic self‐assembly process. On the basis of the photoluminescence and photocurrent density results, the CsPbBr3/BiOCl composite exhibits a higher charge separation rate than pure BiOCl and CsPbBr3. The degradation of Rhodamine B (RhB) result shows that the CsPbBr3/BiOCl composite obtains the highest degradation rate of close to 100% within 60 min, which is significantly higher than those of pure CsPbBr3 (84.21%) and BiOCl (73.57%) because the p–n type heterojunction photocatalyst can promote the separation of photogenerated charge carriers. The free radical capture experiment demonstrates that •O2− plays a major role in the photodegradation of RhB. This study may provide insights into designing advanced photocatalysts for the clean‐ups of environmental pollutants.

Reaction Kinetics of Photoelectrochemical CO2 Reduction on a CuBi2O4-Based Photocathode.

The CO2 reduction reaction (CO2RR) is an essential step in natural photosynthesis and artificial photosynthesis to provide carbohydrate foods and hydrocarbon energy in the carbon-neutral cycle. However, the current solar conversion efficiencies and/or product selectivity of the CO2RR are very sluggish due to its complicated multiple-step charge transfer reactions. Here, we systematically investigate the charge transfer reaction rate during CO2 reduction on CuBi2O4 photocathodes, where the surface is modified with 3-aminopropyltriethoxysilane (APTES). We discover that the surface amine group increases the charge separation rate, significantly enhancing the surface charge transfer reaction rate. However, the surface acidity has less influence on the first-order reaction, indicating that a rate-determining step (RDS) exists in the early stage of the photoelectrochemical cell (PEC) processes. Moreover, the intensity-modulated photocurrent spectroscopy (IMPS) confirms that both surface charge transfer and the recombination rate on APTES-coated CuBi2O4 are larger than bare CuBi2O4 while possessing comparable charge transfer efficiencies. Overall, the surface charge transfer reactions under the PEC condition require designing more effective nanostructured photoelectrodes and powerful characterization methods to intrinsically increase the charge separation and transfer rate while reducing the recombination rate.

Microwave-assisted synthesis of organic–inorganic hybrid porous g-C3N4/CdS–diethylenetriamine S-scheme heterojunctions with enhanced visible light hydrogen production

The activity of photocatalysts depends, to a large extent, on the separation of internal charge carriers, thereby enhancing the redox ability. S-scheme photocatalysts have shown good hydrogen-production performance, not only with good performance, but also with high reproducibility. In particular, two-dimensional (2D)/2D S-scheme heterojunction materials have attracted a great deal of attention because of the rapid charge separation and transfer rate between the interfaces. In this work, a porous g-C3N4/CdS–diethylenetriamine (PCN/CS–D) S-scheme heterojunction is designed and fabricated by a facile microwave method. The designed PCN/CS–D photocatalyst has a hydrogen-evolution rate of 12 547 μmol g−1 h−1, which is 15.6 and 2.4 times as high as that of PCN (806 μmol g−1 h−1) and CS–D (5209 μmol g−1 h−1), respectively. The combination of PCN and CS–D improves the separation of electron–hole pairs and the rate of charge transfer.

Accelerating the discovery of high-performance donor/acceptor pairs in photovoltaic materials via machine learning and density functional theory

The gigantically unexplored chemical space for the combinations of donor and acceptor poses a mammoth challenge in enhancing power conversion efficiency. Herein, a strategy integrating machine learning and density functional theory was proposed to assist the rational screening of prominent donor/acceptor pairs. Notably, 10 promising donor/acceptor pairs were ultimately sieved out with power conversion efficiency lager than 18.22%. Furthermore, the density functional theory computation expressed that the new donor/acceptor pair of D18/BTP-eC9 possessed stronger absorption intensity, while the KCS/KCR (ratio of charge separation rate and charge recombination rate) and μe (electron mobility) were larger than those of the best known D18/Y6 with the increments of 201.31% and 125.98% respectively. The SHapley Additive exPlanations analysis revealed that the two most important features of A_nR08 and D_D/Dtr12 were positively related to the improvement of power conversion efficiency. It was found that A_nR08 was positively associated with π-conjugation strength, and high D_D/Dtr12 suggested the highly fused chemical structure, indicating the practical clues in discovering top-performing donor/acceptor pairs.

Orientated dominating charge separation via crystal facet homojunction inserted into BiOBr for solar-driven CO2 conversion

Herein, BiOBr with (110)/(102) facet homojunction (BiOBr-2) was designed via crystal facet reconstruction in order to achieve the optimal interfacial charge separation rate, thus realizing the maximal photocatalytic CO2 conversion efficiency of the intrinsic photocatalyst. Without any co-catalysts and sacrificial reagents, BiOBr-2 exhibits 100% selectivity towards CO in pure water with an apparent quantum yield of up to 1.03% at 400 nm, much higher than 0.24% of BiOBr with a single (110) lateral facet. After light irradiation for 10 h, the CO yield of BiOBr-2 is 65.0 μmol g−1 h−1, 2.1 and 4.5 times higher than that of BiOBr with a single (110) or (102) lateral facet, respectively. DFT calculation further authenticates an unanticipated separation path bridged between (110) and (102) facets, which realizes dramatical in-situ spatial separation efficiency of electrons and holes in BiOBr-2. This study presents a novel approach to realizing superior charge separation and catalytic activity by optimizing intrinsic catalyst for artificial photosynthesis.

Phycocyanin Fusion Constructs for Heterologous Protein Expression Accumulate as Functional Heterohexameric Complexes in Cyanobacteria.

Overexpression of heterologous proteins from plants, bacteria, and human as fusion constructs in cyanobacteria has been documented in the literature. Typically, the heterologous protein "P" of interest is expressed as a fusion with the abundant CpcB β-subunit of phycocyanin (PC), which was placed in the leader sequence position. The working hypothesis for such overexpressions is that CpcB*P fusion proteins somehow accumulate in a soluble and stable form in the cytosol of the cyanobacteria, retaining the activity of the trailing heterologous "P" protein of interest. The present work revealed a substantially different and previously unobvious picture, comprising the following properties of the above-mentioned CpcB*P fusion constructs: (i) the CpcB*P proteins assemble as functional (α,β*P)3CpcG heterohexameric discs, where α is the CpcA α-subunit of PC, β*P is the CpcB*P fusion protein, the asterisk denotes fusion, and CpcG is the 28.9 kDa PC disc linker polypeptide CpcG1. (ii) The (α,β*P)3CpcG1 complexes covalently bind one open tetrapyrrole bilin co-factor per α-subunit and two bilins per β-subunit. (iii) The (α,β*P)3CpcG1 heterohexameric discs are functionally attached to the Synechocystis allophycocyanin (AP) core cylinders and efficiently transfer excitation energy from the assembled (α,β*P)3CpcG1 heterohexamer to the PSII reaction center, enhancing the rate of photochemical charge separation and electron transfer activity in this photosystem. (iv) In addition to the human interferon α-2 and tetanus toxin fragment C tested in this work, we have shown that enzymes such as the plant-origin isoprene synthase, β-phellandrene synthase, geranyl diphosphate synthase, and geranyl linalool synthase are also overexpressed, while retaining their catalytic activity in the respective fusion construct configuration. (v) Folding models for the (α,β*P)3CpcG1 heterohexameric discs showed the recombinant proteins P to be radially oriented with respect to the (α,β)3 compact disc. Elucidation of the fusion construct configuration and function will pave the way for the rational design of fusion constructs harboring and overexpressing multiple proteins of scientific and commercial interest.

Onion-liked carbon-embedded graphitic carbon nitride for enhanced photocatalytic hydrogen evolution and dye degradation

Limited light absorption and low charge separation rate are the main obstacles for graphitic carbon nitride (g-C3N4)-based photocatalyst. Here, onion-liked carbon (OLC), a carbon nanostructure with multilayer graphitic shells, was embedded into the g-C3N4 matrix to enhance the photocatalytic performance. Due to its high degree of sp2 hybridization and good electrical conductivity, the OLC can broaden visible light adsorption, narrow the band gap of g-C3N4, and serve as electron acceptor to promote the separation of photo-generated carrier. Thus, the g-C3N4/OLC composites show an increased hydrogen evolution rate of 3086 μmol g−1 h−1, 4.44 times higher than pure g-C3N4. Furthermore, the H2 evolution rate is highly related to the sp2/sp3 ratio of OLC. In addition, efficient photocatalytic degradation of RhB was also achieved (0.1171 min−1). The photocatalytic mechanism was then elucidated through a series of spectrochemical and photochemical test. This work demonstrates the significant applicability of OLC in designing carbon-based photocatalyst with highly-efficient photocatalytic activity towards future solar energy conversion and pollutants degeneration.

Direct Z-Scheme NiWO4/CdS nanosheets-on-nanorods nanoheterostructure for efficient visible-light-driven H2 generation

Exploiting efficient catalysts is of interest for solar-driven water splitting. Herein, a novel NiWO 4 /CdS nanosheets-on-nanorods direct Z-Scheme heterostructure was developed by using a facile in-situ approach. The optimized NiWO 4 /CdS heterostructure shows a H 2 evolution rate of 26.43 mmol g −1 h −1 exceeding that of bare CdS by more than 75 folds. Systematic investigations reveal the nanostructures with numerous active sites, intimate contact interface, and enhanced charge separation rate synergistically account for the outstanding performance of the NiWO 4 /CdS. Moreover, the band structures were detailedly analyzed and the tentative photocatalytic mechanism was proposed, which could contribute to deeply understanding the catalytic process and guide the synthesis of the efficient heterostructure. These findings and strategies may have great significance in promoting the development of highly efficient and low-cost photocatalysts. • A novel NiWO 4 /CdS Z-scheme heterostructure was first constructed by using a facile approach. • The NiWO 4 /CdS exhibits a H 2 evolution rate of 26.43 mmol g −1 h −1 far acceding that of CdS. • The good performance was attributed to the formation of the well-defined heterostructure. • The band energy level and photocatalytic mechanism were detailedly investigated.

Linker dependent symmetry breaking charge separation in 9,10-bis(phenylethynyl)anthracene dimers

Fast symmetry breaking charge separation (SB-CS) rate and slow CS recombination rate were achieved simultaneously via tuning the molecular geometry.

In situ fabrication of a novel CdS/ZnIn2S4/g-C3N4 ternary heterojunction with enhanced visible-light photocatalytic performance.

In this study, a novel g-C3N4-based ternary heterojunction was rationally designed and constructed by the in situ growth of ZnIn2S4 nanosheets and CdS nanoparticles onto the g-C3N4 nanosheets using a facile two-step oil-bath method. Through optimizing the proportion of ZnIn2S4 and CdS component, g-C3N4 nanosheets coupled with ZnIn2S4 nanosheets and CdS nanoparticles (denoted as CdS/ZnIn2S4/g-C3N4) exhibited obviously higher photocatalytic properties for RhB removal than the single-component and dual-component systems. Among the as-obtained ternary photocatalysts, it was found that the ternary CdS/ZnIn2S4/g-C3N4-0.2 photocatalyst displayed the optimum photocatalytic property (96%) within a short time (30 min), which was almost 27.42 and 1.17 times higher than that of pure g-C3N4 and binary ZnIn2S4/g-C3N4-0.7 composite. The excellent activity of the ternary CdS/ZnIn2S4/g-C3N4 heterostructure is assigned to the synergetic effects of CdS nanoparticles, ZnIn2S4 nanosheets and g-C3N4 nanosheets, which not only broaden the visible-light absorption range, but also improve the charge mobility and separation rate, thus boosting the visible-light-driven photocatalytic property of g-C3N4.

Synthesis of a novel nitrogen-doped K2Ti6O13 nanorod with visible-light-driven water splitting performance promoted by fabrication of 1D/2D heterostructure

Although developments of visible-light-responsive nitrogen-doped oxide photocatalysts for promising solar water splitting have inspired extensive interests, the poor charge separation and low H2 evolution rate are still challenges. Here this work reports a novel nitrogen-doped 1D K2Ti6O13 nanorod (denoted as KTON hereafter) that exhibits obvious visible-light-responsive water splitting performance. The H2 evolution rate was significantly promoted by fabricating 1D KTON nanorod and 2D graphitic carbon nitride heterostructure (denoted as KTON/C3N4), which was 18.65 μmol·h−1 with an apparent quantum yield of 0.04% at 420 nm. The detailed structural characterizations demonstrated formation of intimate interface to cause remarkably promoted charge separation and 10 times of promoted H2 evolution rate on the type II heterostructure compared to KTON. Moreover, the heterostructure showed excellent photochemical stability in the experimental region. The work not only reports a novel visible-light-responsive water splitting photocatalyst, but also demonstrates the feasibility of fabricating intimate heterostructure between inorganic and organic/polymeric photocatalyst for promoting charge separation and photocatalytic performance.

Investigation of adsorption-photocatalytic synergistic mechanism of globular TiO2–ZrO2–SiO2 composites by a synergy factor

Synergy is essential to maximize the photocatalytic performance of the catalyst, which makes the preparation of photocatalytic materials with the synergistic effect of adsorption and catalysis become an attractive research direction. Therefore, we have prepared TiO 2 –ZrO 2 –SiO 2 nano-powders by simple Pechini sol-gel method, which can effectively improve the synergistic effect of adsorption and degradation of photocatalytic materials. The results demonstrate that TiO 2 –ZrO 2 –SiO 2 possesses excellent photocatalytic performance and adsorption ability. And it can be deduced that in the TiO 2 –ZrO 2 –SiO 2 system, SiO 2 is as for adsorbent, and TiO 2 and ZrO 2 act synergistically as a photocatalyst. The enhanced photocatalytic ability of TiO 2 –ZrO 2 –SiO 2 is attributed to the acceleration of mass transfer by adsorption process, narrowed bandgap (Eg = 2.9 eV) and effective charge separation rate resulting from the formation of Ti–O–Zr. This work also studied the synergy effect between adsorption and photocatalytic properties in TiO 2 –ZrO 2 –SiO 2 , and synergy factor β is used to evaluate the synergistic effect. Moreover β > 1 in first 30 min of visible light irradiation demonstrates that the remarkable synergistic effect exists in TiO 2 –ZrO 2 –SiO 2 compound system. • TiO 2 –ZrO 2 –SiO 2 photocatalyst with both adsorption and photocatalytic properties was successfully prepared. • β (synergy factor) which explains the adsorption-photocatalytic synergistic effect of TiO 2 –ZrO 2 –SiO 2 system is remarkable. • The adsorption-photocatalytic performance can be regenerated.

Bridge-Length- and Solvent-Dependent Charge Separation and Recombination Processes in Donor-Bridge-Acceptor Molecules.

The photoinduced intramolecular charge separation (CS) and charge recombination (CR) phenomena in a series of donor-bridge-acceptor (D-B-A) molecules are intensively investigated as a means of understanding electron transport through the π-B. Pyrene (Pyr) and triarylamine (TAA) moieties connected via phenylene Bs of various lengths are studied because their CS and CR behaviors can be readily monitored in real time by femtosecond transient absorption (fs-TA) spectroscopy. By combining the steady-state and fs-TA spectroscopic measurements in a variety of solvents together with chemical calculations, the parameters that govern the CS behaviors of these dyads were obtained, such as the solvent effects on free energy and the B-length-dependent electronic coupling (VDA) between D and A. We observed the sharp switch of the CS behavior with the increase of the solvent polarity and B-linker lengths. Furthermore, in the case of the shortest distance between D and A when the electron coupling is sufficiently large, we observed that the CS phenomenon occurs even in low-polar solvents. Upon increasing the length of B, CS occurs only in strong polar solvents. The distance-dependent decay constant of the CS rate is determined as ∼0.53 Å-1, indicating that CS is governed by superexchange tunneling interactions. The CS rate constants are also approximately estimated using Marcus electron transfer theory, and the results imply that the VDA value is the key factor dominating the CS rate, while the facile rotation of the phenylene B is important for modulating the lifetime of the charge-separated state in these D-B-A dyads. These results shed light on the practical strategy for obtaining a high CS efficiency with a long-lived CS state in TAA-B-Pyr derivatives.

Charge-Separation and Charge-Recombination Rate Constants in a Donor-Acceptor Buckybowl-Based Supramolecular Complex: Multistate and Solvent Effects.

The kinetics of the nonradiative photoinduced processes (charge-separation and charge-recombination) experimented in solution by a supramolecular complex formed by an electron-donating bowl-shaped truxene-tetrathiafulvalene (truxTTF) derivative and an electron-accepting fullerene fragment (hemifullerene, C30H12) has been theoretically investigated. The truxTTF·C30H12 heterodimer shows a complex decay mechanism after photoexcitation with the participation of several low-lying excited states of different nature (local and charge-transfer excitations) all close in energy. In this scenario, the absolute rate constants for all of the plausible charge-separation (CS) and charge-recombination (CR) channels have been successfully estimated using the Marcus–Levich–Jortner (MLJ) rate expression, electronic structure calculations, and a multistate diabatization method. The outcomes suggest that for a reasonable estimate of the CS and CR rate constants, it is necessary to include the following: (i) optimally tuned long-range (LC) corrected density functionals, to predict a correct energy ordering of the low-lying excited states; (ii) multistate effects, to account for the electronic couplings; and (iii) environmental solvent effects, to provide a proper stabilization of the charge-transfer excited states and accurate external reorganization energies. The predicted rate constants have been incorporated in a simple but insightful kinetic model that allows estimating global CS and CR rate constants in line with the most generalized three-state model used for the CS and CR processes. The values computed for the global CS and CR rates of the donor–acceptor truxTTF·C30H12 supramolecular complex are found to be in good agreement with the experimental values.

Visible-light-driven removal of atrazine by durable hollow core-shell TiO2@LaFeO3 heterojunction coupling with peroxymonosulfate via enhanced electron-transfer

Insufficient charge-carriers separation and deteriorated recycling are still bottlenecks limiting practical photocatalytic water purification. Herein, we developed a durable hollow core-shell TiO2@LaFeO3 (TLFO) nanosphere via facile carbon-sphere-templated method and sol-gel process, and applied it as heterojunction photocatalyst coupled with peroxymonosulfate (PMS) for efficient atrazine (ATZ) removal via enhanced electron-transfer. The built-in electric field originated from the three-dimensional heterojunction between TiO2 and LaFeO3, acting as charge transfer driving force, enhanced the charge separation rate. Meanwhile, PMS could function as electron acceptor to boost photogenerated charge separation and maximize reactive oxidant species (e.g., •OH, SO4•−, O2•− and 1O2) production. Therefore, the fabricated TLFO heterojunction exhibited outstanding reusability, and superior ATZ removal efficiency without detectable metal ion leaching. This work successfully demonstrates the synergistic effect and superior hollow structure of TLFO heterojunction with promoted light utilization and PMS activation, which offers potential application for efficient abating environmental pollution using solar energy.

Designing and fabricating a CdS QDs/Bi2MoO6 monolayer S-scheme heterojunction for highly efficient photocatalytic C2H4 degradation under visible light

Achieving efficient photocatalytic degradation of atmospheric volatile organic compounds (VOCs) under sun-light is still a significant challenge for environmental protection. The S-scheme heterojunction with its unique charge migration route, high charge separation rate and strong redox ability, has great potential. However, how to regulate interfacial charge transfer of the S-scheme heterojunction is of significant importance. Here, density functional theory (DFT) calculations were first conducted and predicted that an S-scheme heterojunction could be formed in the CdS quantum dots/Bi2MoO6 monolayer system. Subsequently, this novel heterojunction is constructed by in-situ hydrothermal synthesis of CdS quantum dots on monolayer Bi2MoO6. Under visible-light, this novel S-scheme system gives a high-efficiency photocatalytic degradation rate (6.04 × 10−2 min−1) towards C2H4, which is 30.3 times higher than that of pure CdS (1.99 × 10−3 min−1) and 41.7 times higher than pure Bi2MoO6 (1.45 × 10−3 min−1). Strong evidence for the S-scheme charge transfer path is provided by in-situ XPS, PL, TRPL and EPR.