Effective Interfacial Charge Transfer Research Articles

Zinc Oxide Sensitized Graphene Quantum Dots “ZnO‐GQDs”: A Hybrid Concept to Study Charge Transfer and its Catalytic Applicability to Synthesize Tetrasubstituted Propargylamines

AbstractInorganic‐organic hybrid nanostructures of graphene quantum dots (GQDs) have received much intentness in industrial/academic discipline as they may replace traditional quantum semiconductors, due to their superiority in terms of chemical inertness, biocompatibility and low toxicity. In the present work, graphene quantum dots (GQDs) have been synthesized by an inexpensive facile bottom‐up approach exhibiting one step pyrolysis of L‐glutamic acid. The synthesized GQDs found to have an excitation wavelength dependence of the emission wavelength. The effect on optical and structural properties of GQDs are then studied by varying the synthesis reaction time. The morphological alterations in GQDs were observed when the reaction time increases i. e. spherical to sheet like which may be attributed to interconnecting graphene quantum dots (GQDs), which are termed as ‘GQD sheets.’ The synthesized GQDs are further coupled with zinc oxide (ZnO) to form ZnO : GQDs nano‐composites, which shows an effective interfacial charge transfer from ZnO to GQDs leading to an enhancement in the photo absorption of ZnO from UV to visible region. The coupled ZnO : GQDs nano‐composites were then explored for the catalytic applicability to synthesize tetrasubstituted propargylamines via KA2 mechanism showing closeness to ideal green chemistry metrics.

Two-dimensional sulfur- and chlorine-codoped g-C3N4/CdSe-amine heterostructures nanocomposite with effective interfacial charge transfer and mechanism insight

The poor utilization of visible light and the speedy recombination of photoexcited carriers limit the further development of carbon nitride polymer (CN) photocatalysts. It is a valid means for enhancing the photocatalytic ability to ameliorate the electronic and physicochemical properties via modifying the structure of CN. The sulfur- and chlorine-codoped graphite CN (S/Cl-CN) was successfully fabricated with low-cost ammonium chloride and thiourea as precursors. The introduction of Cl atoms will establish interlayer channels to promote interlayer charge migration and up-shifted conduction-band level. S atom is appropriate to be incorporated into the CN framework to replace N atom, which is beneficial to adjust the band gap. Then, inorganic-organic CdSe-diethylenetriamine (D) grown in situ are employed to fabricate a S/Cl-CN/CdSe-D heterojunction. S/Cl-CN/CdSe-D heterojunction exhibits greater hydrogen evolution activity compared to CN, S-CN, Cl-CN, S/Cl-CN, CdSe-D and CN/CdSe-D. Finally, Step-scheme (S-scheme) photocatalytic mechanism based on S/Cl-CN/CdSe-D heterostructure was proposed.

Controlled Synthesis of Au Nanocrystals-Metal Selenide Hybrid Nanostructures toward Plasmon-Enhanced Photoelectrochemical Energy Conversion

A simple method for the controllable synthesis of Au nanocrystals–metal selenide hybrid nanostructures via amino acid guiding strategy is proposed. The results show that the symmetric overgrowth mode of PbSe shells on Au nanorods can be precisely manipulated by only adjusting the initial concentration of Pb2+. The shape of Au–PbSe hybrids can evolve from dumbbell-like to yolk-shell. Interestingly, the plasmonic absorption enhancement could be tuned by the symmetry of these hybrid nanostructures. This provides an effective pathway for maneuvering plasmon-induced energy transfer in metal–semiconductor hybrids. In addition, the photoactivities of Au–PbSe nanorods sensitized TiO2 electrodes have been further evaluated. Owing to the synergism between effective plasmonic enhancement effect and efficient interfacial charge transfer in these hybrid nanostructures, the Au–PbSe yolk-shell nanorods exhibit an outstanding photocurrent activity. Their photocurrent density is 4.38 times larger than that of Au–PbSe dumbbell-like nanorods under light irradiation at λ > 600 nm. As a versatile method, the proposed strategy can also be employed to synthesize other metal–selenide hybrid nanostructures (such as Au–CdSe, Au–Bi2Se3 and Au–CuSe).

Fe (III) clusters modified Bi12O17Cl2 nanosheets photocatalyst for boosting photocatalytic performance through interfacial charge transfer effect

A series of novel Fe(III) clusters modified Bi12O17Cl2 (Fe/Bi12O17Cl2) photocatalysts have successfully fabricated. Their chemical structure, element composition, surface feature, light response ability and photocatalytic activity were measured. The results revealed that Fe(III) clusters uniformly loaded on Bi12O17Cl2 nanosheets surface, which resulted Fe/Bi12O17Cl2 possessing improved visible light harvesting efficiency and introduced interfacial charge transfer effect in Fe/Bi12O17Cl2 photocatalyst, conducing to photoinduced charge efficiently separation. Its photocatalytic ability was performed by degrading organic dye (Rhodamine b). Comparing with the degradation rate of Bi12O17Cl2 (0.0743 min−1), that of Fe/Bi12O17Cl2 photocatalyst was obviously enhanced (0.157 min−1). Clearly, Fe/Bi12O17Cl2 photocatalyst had the improvement of photoproperty. Then, the results of trapping experiments revealed the key active species were O2− and h+. Lastly, a reasonable photocatalytic mechanism over Fe/Bi12O17Cl2 photocatalyst was shown.

Fe(III) modified Bi2O4 nano-rods for boosting photocatalytic performance through interfacial charge transfer effect

A novel Fe(III) modified Bi2O4 (Fe–Bi2O4) photocatalyst was prepared via the wet impregnation method, and measured through XRD, XPS, TEM, BET and DRS to analyze crystal structure, feature, textural and optical properties. Measurement results verified that Fe(III) formed nanoparticles loaded on the Bi2O4 nano-rod surface, which could contribute to accelerate photoinduced electrons efficient transfer and separation by interfacial charge transfer effect. When Fe–Bi2O4 photocatalyst was applied for decomposing rhodamine (RhB), the optimal photocatalyst (Fe–Bi2O4(45 wt%)) exhibited higher reaction rate constant in comparison to pure Bi2O4. Meanwhile, different radical scavengers tests revealed that h+ and ·O2− exhibited the major role in photocatalysis course. Finally, combined with above experimental results, a probable photocatalytic mechanism for Fe–Bi2O4 hybrid photocatalyst was presented.

Accelerating charge transfer at an ultrafine NiFe-LDHs/CB interface during the electrocatalyst activation process for water oxidation.

Owing to the combination of intriguing activity and conductivity, hybrid compositions of layered double hydroxides (LDHs) and carbon-based materials have been extensively and widely applied to evolve oxygen gas during water splitting. Here, a facile in situ nucleation strategy was used to construct ultrafine NiFe-LDH nanosheets monodispersed on a carbon black (CB) substrate. Notably, this work displayed the interfacial impact of combining CB with NiFe-LDHs on electrocatalyst activation. Interestingly, the optimized NiFe-LDHs/CB composite displays a fast activation rate and excellent water oxidation performance on a glassy-carbon electrode (an overpotential of 226 mV at 10 mA cm-2; a Tafel slope of 57 mV dec-1). This is due to the high active area, low impedance and ultra-high active metal atom utilization rate, accelerating charge transfer at the interface during the activation process. More importantly, this work highlights the interfacial charge transfer effect during the activation process and supplies clues for designing electrocatalysts.

Interaction Mechanisms of Insensitive Explosive FOX-7 and Graphene Oxides from Ab Initio Calculations.

Energetic material–graphene oxide (EM–GO) composites exhibit excellent thermal stability and insensitivity to mechanical stimuli. The interfacial interactions play an important role in affecting the structural and electrical properties of EM–GO composites. FOX-7 crystal with a wave-shaped layer structure is an ideal prototype system for matching with oxygen-rich GO monolayers to form FOX-7–GO composites. Here, we conducted a systematic investigation on FOX-7–GO composites by dispersion-corrected density functional approach. Our results revealed that there exists relatively strong interaction in the FOX-7–GO interface, which stems from the synergistic effect of interfacial charge transfer and hydrogen bonds. The electronic structure analyses demonstrated that GO can hybridize with FOX-7 to reduce charge accumulation on the FOX-7 surface. These theoretical results are useful for clarifying the interfacial effects on the sensitivity of FOX-7–GO composites.

Visible-light-driven, hierarchically heterostructured, and flexible silver/bismuth oxyiodide/titania nanofibrous membranes for highly efficient water disinfection

Constructing a flexible inorganic membrane photocatalyst for efficient visible-light-driven water disinfection is highly desired but remains a great challenge. Herein, we fabricated a flexible and heterostructured silver/bismuth oxyiodide/titania (Ag/BiOI/TiO2) nanofibrous membrane by combining the electrospinning technique with simple successive ionic layer adsorption and reaction (SILAR) and photodeposition process. In this ternary nanocomposite, ultrathin BiOI nanoplates were firmly anchored onto TiO2 nanofibers, while Ag nanoparticles were uniformly decorated on the surface of both BiOI and TiO2. Benefiting from the large surface area, improved visible-light absorption, and the effective interfacial charge transfer induced by multi-heterojunctions, the resultant Ag/BiOI/TiO2 membrane exhibited superior photocatalytic disinfection activity (7.5 log inactivation of E. coli within 1 h) under visible light illumination. Moreover, the plasmonic Z-scheme charge transfer mode was also proposed for Ag/BiOI/TiO2 system according to the band structure and reactive species analysis. More significantly, the Ag/BiOI/TiO2 membrane-based photoreactor could be facilely constructed for high-efficiency disinfection of high volume contaminated water, and the membrane still maintained good structural integrity and mechanical flexibility after utilization. This work may open up new avenues for designing and constructing flexible high-performance photocatalytic membranes for environmental applications.

Amino-Assisted NH2-UiO-66 Anchored on Porous g-C3N4 for Enhanced Visible-Light-Driven CO2 Reduction.

Constructing heterostructured photocatalysts is an efficient method to improve photocatalytic carbon dioxide (CO2) reduction. Herein, holey g-C3N4 (HGN) with rich amino groups (-NHx) was hybridized with NH2-UiO-66 (NUZ) via a facile in situ growth method. NUZ nanocrystals were anchored on HGN via NHx-Zr-O chemical bonding, leading to the uniform dispersion and avoiding the leaching of NUZ, thus showing excellent stability in photocatalysis. The chemically bonded interfacial charge transfer effect originated from the NHx-Zr-O formation efficiently accelerated the separation and migration of charge carriers, improving the photoactivity. Benefiting from the NHx-Zr-O formation, the optimized NUZ/HGN-35% heterojunctions exhibited outstanding activity in the photoreduction of CO2 to CO (31.6 μmol g-1 h-1), which was about 2 and 3 times higher than that of pure NUZ and HGN under visible-light irradiation. This study is expected to provide useful insights for constructing composites with strong interaction for CO2 reduction, H2 production, and N2 reduction.

Evidence for plasmonic hot electron injection induced superior visible light photocatalysis by g-C3N4 nanosheets decorated with Ag–TiO2(B) and Au–TiO2(B) nanorods

Hot electrons produced by the surface plasmon decay can be efficiently utilized to drive photochemical reactions on a semiconductor surface. Considering this aspect of plasmonics, we have evaluated the visible light photocatalytic performance of Ag–TiO2(B)–C3N4 and Au–TiO2(B)–C3N4 heterostructures in the degradation of rhodamine B (RhB) and phenol. The synergetic effect of plasmonic hot electron injection and interfacial charge transfer in the heterostructures lead to 6–9 fold enhancement in the photodecomposition rate of RhB (phenol) over TiO2(B) and C3N4. Time-resolved photoluminescence study shows fast charge transfer through the integrated network of the heterostructure. The photocurrent is measured at 470 nm, 510 nm and 575 nm, near the plasmonic excitations of Ag and Au as well as under white light illumination (400–800 nm). Plasmonic systems show more than 6-fold enhancement in photocurrent over bare TiO2(B) under illumination near monochromatic plasmonic excitation. The overall photocurrent resulting from white light illumination is 2-fold stronger than that under plasmonic excitation. The increase is due to the contribution from Ti3+ excitation, hot electron injection, and charge transfer from TiO2(B) to C3N4. We propose that Ti3+ states in TiO2(B) provide channels for direct hot electron transfer from metal to semiconductor facilitating charge separation for participation in photocatalysis.

Strongly Compressed Few-Layered SnSe2 Films Grown on a SrTiO3 Substrate: The Coexistence of Charge Ordering and Enhanced Interfacial Superconductivity.

High pressure has been demonstrated to be a powerful approach of producing novel condensed-matter states, particularly in tuning the superconducting transition temperature (Tc) of the superconductivity in a clean fashion without involving the complexity of chemical doping. However, the challenge of high-pressure experiment hinders further in-depth research for underlying mechanisms. Here, we have successfully synthesized continuous layer-controllable SnSe2 films on SrTiO3 substrate using molecular beam epitaxy. By means of scanning tunneling microscopy/spectroscopy (STM/S) and Raman spectroscopy, we found that the strong compressive strain is intrinsically built in few-layers films, with a largest equivalent pressure up to 23 GPa in the monolayer. Upon this, unusual 2 × 2 charge ordering is induced at the occupied states in the monolayer, accompanied by prominent decrease in the density of states (DOS) near the Fermi energy (EF), resembling the gap states of CDW reported in transition metal dichalcogenide (TMD) materials. Subsequently, the coexistence of charge ordering and the interfacial superconductivity is observed in bilayer films as a result of releasing the compressive strain. In conjunction with spatially resolved spectroscopic study and first-principles calculation, we find that the enhanced interfacial superconductivity with an estimated Tc of 8.3 K is observed only in the 1 × 1 region. Such superconductivity can be ascribed to a combined effect of interfacial charge transfer and compressive strain, which leads to a considerable downshift of the conduction band minimum and an increase in the DOS at EF. Our results provide an attractive platform for further in-depth investigation of compression-induced charge ordering (monolayer) and the interplay between charge ordering and superconductivity (bilayer). Meanwhile, it has opened up a pathway to prepare strongly compressed two-dimensional materials by growing onto a SrTiO3 substrate, which is promising to induce superconductivity with a higher Tc.

Cover Feature: Efficient Visible‐Light‐Driven Hydrogen Generation on g‐C3N4 Coupled with Iron Phosphide (ChemPhotoChem 7/2019)

The Cover Feature illustrates the low-cost Fe2P as a cocatalyst hybridized with g-C3N4 for photocatalytic H2 generation under visible-light exposure. The enhanced photocatalytic H2 generation performance was attributed to the effective interfacial charge transfer between Fe2P and g-C3N4. The study demonstrates significant potential for the application of noble-metal-free Fe2P. More information can be found in the Article by Z. Sun et al. on page 540 in Issue 7, 2019 (DOI: 10.1002/cptc.201800260).

Visible light-induced photo-degradation of methylene blue by n–p heterojunction CeO2/CuS composite based on ribbon-like CeO2 nanofibers via electrospinning

Composite of n-type CeO2/p-type CuS heterojunctions as adsorbent/photocatalysts were successfully synthesized based on electrospinning technique, calcination and hydrothermal methods following growth of CuS nanostructures on the primary CeO2 nanofibers, while laterally were characterized by FE-SEM, EDS, XRD, DRS and FT-IR. Present composite in aqueous solutions was applied for methylene blue (MB) degradation was investigated under visible light radiation (LED). DRS analysis illustrates that CeO2/CuS n–p heterojunction exhibited enhanced absorption in the visible region with band gap of 2.55. Under optimal conditions (3.0 mg L−1 MB, 1 g L−1 of CeO2/CuS dosage and 40 min irritation time at pH of 6.0) lead to 89.80% photocatalytic decomposition of MB. The CeO2/CuS composite nanofiber as photocatalyst exhibited enhanced visible-light absorption and reduced charge recombination, as compared to bare CeO2 ribbon-like nanofibers, due to the interfacial charge transfer effect among the CuS species and CeO2. The first-order kinetics based on Langmuir–Hinshelwood (L–H) model was able for effective fitting empirical data, while its rate constant (kobs), L–H rate constants (kr) and L–H adsorption constants (KA) were 0.0625 min−1, 0.157 mg min−1 L and 0.24 L mg−1 by CeO2/CuS in optimum condition. The reusability of CeO2/CuS composite is relatively undesirable in view of the recycling of photocatalysts.

Band gap tuning of g-C3N4 via decoration with AgCl to expedite the photocatalytic degradation and mineralization of oxalic acid

A series of functional organic–metal AgCl-decorated graphitic carbon nitride (AgCl-CNx) composites were synthesized and applied for the degradation of oxalic acid (OA) under visible light. The highest photocatalytic activity was achieved with AgCl decoration ratio of 1.0 (denoted as AgCl-CN1.0). The pseudo-first-order constant for OA degradation was 0.0722 min−1 with the mineralization efficiency of 90.80% after 60 min reaction in the photocatalytic process with AgCl-CN1.0. A variety of characterization techniques including Brunauer–Emmett–Teller, X-ray diffraction, scanning electron microscope, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectra, ultraviolet–visible diffuse reflectance spectra, photoluminescence, and Mott–Schottky were utilized to elucidate the physicochemical, microstructure, and optical properties contributing to the improvement of the photocatalytic performance. The results showed that AgCl-CN1.0 had an oblate flaky erythrocyte-like structure with a moderate band gap energy of ~3.00 eV. In addition, the effects of the key parameters (i.e., AgCl-CN1.0 dosage, initial OA concentration, solution pH, and presence of natural organic matter) on OA degradation were systematically investigated. Radical scavenger experiments indicated that photogenerated holes, electrons, superoxide anion radicals, and hydroxyl radicals were the dominant reactive species. Moreover, AgCl-CN1.0 exhibited excellent stability and reusability for OA degradation without detectable Ag+ release in the solution over multiple reaction cycles. The efficient OA mineralization could be mainly ascribed to the moderate specific surface area, increased numbers of active sites, and effective interfacial charge transfer of AgCl-CN1.0. Overall, the AgCl-CN1.0 composite was demonstrated to be a highly efficient, stable, and recoverable photocatalyst.

Light‐Activated Rapid Disinfection by Accelerated Charge Transfer in Red Phosphorus/ZnO Heterointerface

AbstractA red phosphorus (RP)/ZnO heterojunction thin film is developed to harvest solar or light emitting diode (LED) light for rapid, effective, ecofriendly, lower‐cost, and safe disinfection, which is convenient for universal and large‐scale deposition. The most stable geometrical structure of the RP/ZnO heterojunction, i.e., an RP (001) plane and a ZnO (002) plane, exhibits charge redistribution largely at the interface region. Therefore, the effective interfacial charge transfer and the improved separation efficiency of photogenerated electron–hole pairs can strongly boost reactive oxygen species (ROS)‐generation reactions to enhance photocatalytic bacterial inactivation. The excellent light‐activated point‐of use disinfection can be achieved even through LED light of phone. Additionally, the RP/ZnO heterojunction also possesses excellent solar light‐to‐heat conversion efficiency, leading to further lethality to bacteria through hyperthermia. Antibacterial efficacy of 99.96 ± 0.03% against Staphylococcus aureus at 5 min and 99.97 ± 0.02% against Escherichia coli at 4 min can be attributed to the synergetic antibacterial activity of solar photocatalysis and photothermal effect (more than 50 °C in 2 min). This platform provides a surface strategy for designing synergetic photocatalytic and photothermal materials to fully harvest solar energy for not only water disinfection but also antibacterial surfaces in medical facilities, touch screen devices, or seawater desalination.

Synergistic effect of surface oxygen vacancies and interfacial charge transfer on Fe(III)/Bi2MoO6 for efficient photocatalysis

Novel Fe(III) clusters grafted Bi2MoO6 nanosheets with surface oxygen vacancies (denoted as F/BMO-SOVs) heterostructured composite have been firstly fabricated via a reliable calcination process combined with impregnation approach. The surface oxygen vacancies (SOVs) in Bi2MoO6 were formed due to controlled calcination process. The presence of Fe (III) clusters was confirmed by HRTEM, XPS, and UV–vis DRS. Under visible light irradiation, the optimum molar ratio of 15% F/BMO-SOVs achieved 93.4% degradation efficiency of phenol within 180 min, representing nearly 80 times higher activity than the pure Bi2MoO6, confirmed by both absorption spectrum and TOC measurement. The dramatically enhanced photocatalytic activity is attributed to the synergistic effect between the SOVs, Fe(III) clusters and Bi2MoO6, which not only narrows the band gap, improving the visible light response ability, but also facilitates the direct interfacial charge transfer (IFCT) from the SOVs to the surface Fe(III) clusters, greatly promoting the efficient separation of photogenerated electron-hole pairs. According to the trapping experiments and ESR measurements results, ·O2−, ·OH, and h+ all participated in the phenol photodegradation process over F/BMO-SOVs. Thus, this work not only provides a synergistic effect between SOVs, Fe(III) clusters and Bi2MoO6 involving an IFCT process, but also proposes an efficient approach to fabricating highly active photocatalysts in environmental remediation and solar fuel synthesis.

Fabrication of pyrimidine/g-C3N4 nanocomposites for efficient photocatalytic activity under visible-light illumination

In this work, a series of pyrimidine/g-C3N4 photocatalysts has been synthesized via a facile solvothermal method for the first time. The structure, elemental composition and morphology of the photocatalysts were characterized by FT-IR, SEM, XPS, N2 adsorption-desorption isotherms and BET characterization methods. The photocatalytic activity of the pyrimidine/g-C3N4 materials was investigated by the degradation of rhodamine solution under visible-light illumination. The pyrimidine/g-C3N4 photocatalyst with 1 wt% of pyrimidine shows the highest photocatalytic activity for the degradation of RhB, which can be mainly ascribed to the effective interfacial charge transfer within the pyrimidine/g-C3N4 photocatalyst and the cooperation effect of the excellent contact interface between g-C3N4 and pyrimidine. The main active species during the photodegradation process are determined by the radical trapping experiments, proving that the superoxide radical (•O2−) and the hydroxyl radical (•OH) play the main role in the photocatalytic reactions.

Construction of TiO2-Fe-C3N4 compound: Promotion of interfacial charge transfer effect through facile energy level alignment

An efficient visible-light-driven photocatalyst with interfacial electron transfer (IFCT) effect was prepared by introducing a facile energy level alignment in heterostructured TiO2-Fe-C3N4, where IFCT was promoted strongly due to the effective electron transfer. The Fe (III) clusters grafted on the TiO2 microspheres, extended the photo response of TiO2 from UV to visible light region, resulting in better light absorption capability. What's more, the direct transfer of photoinduced electrons from TiO2/Fe to C3N4 was observed, which promoted the IFCT effect, leaving the high oxidizing holes in the valence band (VB) of TiO2 and conduction band (CB) of C3N4 for further degradation. The TiO2-Fe-C3N4 exhibited much better photocatalytic performance for methyl orange degradation and higher photocurrent under visible light irradiation than the bare TiO2 or C3N4, which was attributed to the synergistic effect between TiO2 and Fe/C3N4 as well as C3N4 and TiO2/Fe. In addition, the photo-induced holes in the VB of the TiO2 microspheres was confirmed by ESR analysis and a possible photocatalytic mechanism of TiO2-Fe-C3N4 composite under visible light irradiation was also proposed.

One-Pot Strategy to Bi₂S₃/BiOCl Heterojunction with Enhanced Photocatalytic Activity.

Bi2S3/BiOCl (denoted as BS-BC) heterojunction photocatalyst has been reported to be able to increase light absorption, promote charge separation and consequently enhance photocatalytic efficiency in comparison with single BiOCl. However, the heterojunction was usually prepared by a two-step method, i.e., BiOCl was firstly prepared and then to BS-BC heterojunction through an ion exchange strategy. In this work, BS-BC was prepared by a one-pot room temperature route, where Bi(NO3)3 dissolved in aqueous urea solution could homogeneously react with a mixture solution of NaCl and thiacetamide (TAA) to form BS-BC heterojunction. The urea could prohibit the hydrolysis of Bi(NO3)3 and accelerate the decomposition of TAA to release S2-, and as a consequence, the heterojunction photocatalyst with small size and large interfacial area could be prepared in several hours. The resulted heterojunction exhibited better visible-light photocatalytic activity for RhB degradation than individual BiOCl or that prepared by a two-step route due to close contact between Bi2S3 and BiOCl, modified band structures and effective interfacial charge transfer.

Highly Efficient Performance and Conversion Pathway of Photocatalytic CH3SH Oxidation on Self-Stabilized Indirect Z-Scheme g-C3N4/I3--BiOI.

A self-stabilized Z-scheme porous g-C3N4/I3--containing BiOI ultrathin nanosheets (g-C3N4/I3--BiOI) heterojunction photocatalyst with I3-/I- redox mediator was successfully synthesized by a facile solvothermal method coupling with light illumination. The structure and optical properties of g-C3N4/I3--BiOI composites were systematically characterized by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, X-ray photoelectron spectroscopy, N2 adsorption/desorption, UV-vis diffuse reflectance spectrum, and photoluminescence. The g-C3N4/I3--BiOI composites, with a heterojunction between porous g-C3N4 and BiOI ultrathin nanosheets, were first applied for the photocatalytic elimination of ppm-leveled CH3SH under light-emitting diode visible light illumination. The g-C3N4/I3--BiOI heterojunction with 10% g-C3N4 showed a dramatically enhanced photocatalytic activity in the removal of CH3SH compared with pure BiOI and g-C3N4 due to its effective interfacial charge transfer and separation. The adsorption and photocatalytic oxidation of CH3SH over g-C3N4/I3--BiOI were deeply explored by in situ diffuse reflectance infrared Fourier transform spectroscopy, and the intermediates and conversion pathways were elucidated and compared. Furthermore, on the basis of reactive species trapping, electron spin resonance and Mott-Schottky experiments, it was revealed that the responsible reactive species for catalytic CH3SH composition were h+, •O2-, and 1O2; thus, the g-C3N4/I3--BiOI heterojunction followed an indirect all-solid state Z-scheme charge-transfer mode with self-stabilized I3-/I- pairs as redox mediator, which could accelerate the separation of photogenerated charge and enhance the redox reaction power of charged carriers simultaneously.