Photocurrent Spectra Research Articles

Layer-dependent exciton polarizability and the brightening of dark excitons in few-layer black phosphorus

The evolution of excitons from 2D to 3D is of great importance in photo-physics, yet the layer-dependent exciton polarizability hasn’t been investigated in 2D semiconductors. Here, we determine the exciton polarizabilities for 3- to 11-layer black phosphorus—a direct bandgap semiconductor regardless of the thickness—through frequency-resolved photocurrent measurements on dual-gate devices and unveil the carrier screening effect in relatively thicker samples. By taking advantage of the broadband photocurrent spectra, we are also able to reveal the exciton response for higher-index subbands under the gate electrical field. Surprisingly, dark excitons are brightened with intensity even stronger than the allowed transitions above certain electrical field. Our study not only sheds light on the exciton evolution with sample thickness, but also paves a way for optoelectronic applications of few-layer BP in modulators, tunable photodetectors, emitters and lasers.

Non-equilibrium Green’s function approach for simulation asymmetric source-drain silicene-based photodetectors

Photodetectors based on Armchair-Silicene-Nanoribbons (ASiNR) with asymmetric source (Ir-doped silicene) and drain (Cu-, Ag-, or Au-doped silicene) contacts have been simulated employing tight-binding approximation coupling to Non-Equilibrium Green’s Function (NEGF) approach. Monochromatic 1 kW cm−2 illumination in the range of 0.1–10 eV has been used for the simulation of the photocurrent, photoresponsivity, quantum efficiency, and detectivity. It is shown that the highest peak in the photocurrent spectrum occurs at the 273 nm incident wavelength for all devices, and the Ir-Cu device has presented enhanced photodetector characteristics than Ir-Ag and Ir-Au devices. It is also found that only transitions between two subbands with identical indexes are allowed. Moreover, the first peak in the photocurrent spectrum is related to the main band gap of ASiNR. Additionally, the simulated dark and total currents versus source-drain voltage reveal that photocurrent caused a negative shift in the total current proportional to incident light intensity.

Investigation of charge dynamics in dinuclear cobalt phthalocyanine ammonium sulfonate (PDS) modified Ti-Fe2O3 photoanodes for photoelectrochemical water oxidation

The kinetic competition between water oxidation/electron extraction processes and recombination behaviors is a key consideration in the development of efficient photoanodes for solar-driven water splitting. Investigating the photogenerated charge behaviors could guide the construction of high-efficiency photoanodes. In this study, the charge carrier kinetics involved in photoelectrochemical water oxidation of PDS/Ti-Fe2O3 were analyzed using surface photovoltage (SPV), transient photovoltage (TPV), short-pulse transient photocurrent (TPC) and photoelectrochemical impedance spectra (PEIS). The TPC results indicate the interfacial electric field introduced by the PDS loading increases the electron extraction and suppresses the bulk recombination, enhancing the spatial separation of photogenerated charges, which is consistent with the SPV and TPV results. Besides, the surface recombination of the back electron (BER) is also attenuated, which enhances the long-lived holes at the surface of PDS/Ti-Fe2O3 photoanode. Similarly, as obtained by PEIS fitting, the loading of PDS accelerates holes transfer at the photoanode/electrolyte interface, and increases the utilization of long-lived holes. In other word, the recombination behaviors of photogenerated charges are restrained both in the bulk and surface of the photoanode after the deposition of PDS, leading to enhanced PEC performance. These findings highlight the importance of understanding charge carrier dynamics in the design of high-efficient photoanodes.

Boosting photocatalytic nitrogen reduction reaction by Jahn-Teller effect

Compared with traditional the Haber-Bosch process, photocatalytic ammonia production has attracted a considerable attention due to its advantages of low energy consumption and sustainability. In this work, we mainly study the photocatalytic nitrogen reduction reaction (NRR) on MoO3·0.55H2O and α-MoO3. Structure analysis shows that compared to α-MoO6, the [MoO6] octahedrons in MoO3·0.55H2O obviously distort (Jahn-Teller distortion), leading to the formation of Lewis acid active sites that favors the adsorption and activation of N2. X-ray photoelectron spectroscopy (XPS) further confirms the formation of more Mo5+ as Lewis acid active sites in MoO3·0.55H2O. Transient photocurrent, photoluminescence and electrochemical impedance spectra (EIS) confirmed that MoO3·0.55H2O has a higher charge separation and transfer efficiency than α-MoO3. Density functional theory (DFT) calculation further confirmed that the N2 adsorption on MoO3·0.55H2O is more favorable thermodynamically than that on α-MoO3. As a result, under visible light irradiation (λ ≥ 400 nm) for 60 min, an ammonia production rate of 88.6 μmol·gcat-1 was achieved on MoO3·0.55H2O, which is about 4.6 times higher than that on α-MoO3. In comparison to other photocatalysts, MoO3·0.55H2O exhibits an excellent photocatalytic NRR activity under visible light irradiation without using sacrificial agent. This work offers a new fundamental understanding to photocatalytic NRR from the viewpoint of crystal fine structure, which benefits designing efficient photocatalysts.

Anisotropic excitonic photocurrent in β−Ga2O3

Polarization-dependent photocurrent spectra are measured on a (001) $\ensuremath{\beta}\text{\ensuremath{-}}{\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$ Schottky photodetector, where the linear polarization of light is rotated within the ab plane. Three spectral peaks at 4.92, 5.15, and 5.44 eV are observed that vary in intensity with the optical polarization direction. The peak transition energies are consistent with excitons previously reported in $\ensuremath{\beta}\text{\ensuremath{-}}{\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$ due to interband transitions modified by the valence-band $p$-orbital anisotropy and the electron-hole Coulombic attraction. The measured polarization dependence of the photocurrent matches our predictions based on electromagnetic simulations of anisotropic absorption using the complex dielectric function tensor extracted from previous ellipsometry studies. These results illustrate the dominance of excitonic absorption and photocurrent in $\ensuremath{\beta}\text{\ensuremath{-}}{\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$ both below and above the band gap, demonstrate a combined theoretical/experimental understanding of anisotropic photocarrier generation, and validate previous atomistic band-structure calculations in this low-symmetry ultrawide-band-gap semiconductor.

Terahertz photocurrent spectrum analysis of AlGaAs/GaAs/GaAsBi multi-junction solar cells

Characterizing subcells in two-terminal multi-junction (M-J) solar cells is challenging due to the lack of direct electrical access. This work presents a novel contactless spectral characterization technique for analysing individual subcells. The technique involves probing terahertz (THz) radiation generated by femtosecond laser pulse excitation and varying the exciting wavelength to selectively absorb light in the desired subcell. The registered THz pulse integral is then proportional to the induced photocurrent in that subcell. The THz photocurrent spectroscopy technique is demonstrated on GaAs and AlGaAs single-junction solar cells, as well as on the triple-junction AlGaAs/GaAs/GaAsBi solar cell. The results show that the recently developed GaAsBi-based subcell, with a nominal energy bandgap of 1.0 eV, exhibits improved electron–hole separation efficiency and can enhance energy harvesting by M-J solar cells.

Long-Range Energy Transfer in Strongly Coupled Donor-Acceptor Phototransistors.

Strong light-matter coupling offers a way to tailor the optoelectronic properties of materials. Energy transfer between strongly coupled donor-acceptor pairs shows remarkable efficiency beyond the Förster distance via coupling through a confined photon. This long-range energy transfer is facilitated through the collective nature of polaritonic states. Here, the cooperative, strong coupling of a donor (MoS2 monolayer) and an acceptor (BRK) generates mixed polaritonic states. The photocurrent spectrum of the MoS2 monolayer is measured in a field effect transistor while coupling the two oscillators to the confined cavity mode. The strongly coupled system shows efficient energy transfer, which is observed through the photoresponsivity even the donor and acceptor are physically separated by 500 Å. These studies are further correlated with the Hopfield coefficients and the overlap integral of the lower polaritonic and uncoupled/dark states. Cavity detuning and distance-dependent studies support the above evidence. These observations open new avenues for using long-range interaction of polaritonic states in optoelectronic devices.

Ab Initio Study of Optical Properties of Hybrid Films Based on Bilayer Graphene and Single-Walled Carbon Nanotubes

In recent years, the possibility of combining graphene and carbon nanotubes has attracted much attention from researchers attempting to obtain new multifunctional hybrid materials with promising properties. Optoelectronics shows potential as a field of application for such hybrid structures. The variety of existing structural configurations of graphene-nanotube hybrids requires preliminary detailed studies of their optical properties by computer simulation methods. In this paper, we consider island-type graphene-nanotube hybrid films formed by AB-stacked bilayer graphene and single-walled carbon nanotubes (SWCNTs). In this case, bilayer graphene is located above the surface of the nanotube, forming areas with an increased density of carbon atoms, creating so-called “islands.” To meet the conditions of a real experiment, we chose chiral SWCNTs (12,6) with a diameter of 1.2 nm, which are most often synthesized in real experiments. All constructed atomistic models of bilayer graphene-chiral SWCNT films were tested for thermodynamic stability at room temperature and proved their suitability for research. Using Kubo-Greenwood formalism, we calculated the complex optical conductivity tensor and absorbance coefficient in the wavelengths of ultraviolet, visible, and near-infrared radiations. The photocurrent spectra are calculated based on the obtained absorption spectra and solar radiation spectra on the earth’s surface (AM1.5) and outside the earth’s atmosphere (AM0). The results of calculations revealed regularities in the influence of structural parameters (nanotube diameter, graphene width) on the optical and optoelectronic properties of graphene-chiral SWCNT (12,6) with an island structure.

Optoelectronic and Optomechanical Properties of Few-Atomic-Layer Black Phosphorus Nanoflakes as Revealed by In Situ TEM.

The optoelectronic signatures of free-standing few-atomic-layer black phosphorus nanoflakes are analyzed by in situ transmission electron microscopy (TEM). As compared to other 2D materials, the band gap of black phosphorus (BP) is related directly to multiple thicknesses and can be tuned by nanoflake thickness and strain. The photocurrent measurements with the TEM show a stable response to infrared light illumination and change of nanoflakes band gap with deformation while pressing them between two electrodes assembled in the microscope. The photocurrent spectra of an 8- and a 6-layer BP nanoflake samples are comparatively measured. Density functional theory (DFT) calculations are performed to identify the band structure changes of BP during deformations. The results should help to find the best pathways for BP smart band gap engineering via tuning the number of material atomic layers and programmed deformations to promote future optoelectronic applications.

Efficient Narrowband Photoconductivity of the Excitonic Resonance in Two-Dimensional Ruddlesden-Popper Perovskites Due to Exciton Polarons.

Filter-less, wavelength-selective photodetectors made of perovskite usually rely on the charge collection narrowing mechanism, which intrinsically limits the response times. Using the narrow excitonic peak of, e.g., two-dimensional (2D) Ruddlesden-Popper perovskites as direct absorbers to realize color-selective photodetectivity promises faster responses. However, one major challenge in realizing such devices remains the separation and charge carrier extraction of the tightly bound excitons. Here, we report on filter-less color-selective photoconductivity in 2D perovskite butylammonium lead iodide thin film devices, exhibiting a distinct resonance in the photocurrent spectrum with a full width at half-maximum of 16.5 nm that correlates to the excitonic absorption. Our devices exhibit unexpectedly efficient charge carrier separation with an external quantum efficiency of ≤8.9% at the excitonic resonance, which we trace back to the involvement of exciton polarons. Our photodetector achieves response times of 150 μs and a maximum specific detectivity of 2.5 × 1010 Jones at the excitonic peak.

Unveiling the Linear Photogalvanic Effect in a Two-Dimensional Organic Tin Halide Perovskite: (CH3)2NH2SnI3

Hybrid organic–inorganic halide perovskites (HOIPs) with intrinsic noncentrosymmetry are an emerging class of semiconducting materials that has been revolutionizing the field of optoelectronics including second-order nonlinear optics (NLO). Following an upsurge in three-dimensional (3D) perovskites, more recently, low-dimensional perovskite materials have displayed desirable NLO responses attributed to structural diversity, strong quantum confinement, and remarkable exciton effect. Herein, using first-principles methods, we elucidate a linear photogalvanic effect (LPGE) photocurrent (shift photocurrent, SPC) with a maximum amplitude of ∼430 μAV–2 in a quasi-two-dimensional (2D) lead-free HOIP, (CH3)2NH2SnI3 (DMASnI3). The simulated SPC whose prominent peaks occur predominantly in the ultraviolet (UV) range is about 8-fold larger in magnitude compared to its 3D counterpart. From the orbital characteristics of the initial and final states, the calculated SPC is attributed to the contributions from the electronic properties of Sn and I whose p-states control the band edges. The organic-cation orientation indirectly influences the bandgap size, valence and conduction band edge behavior, as well as the position of the Fermi level, slightly altering the LPGE photocurrent spectrum. The findings of this work demonstrate the quasi-2D organic tin triiodide perovskite as a promising lead-free alternative for NLO devices.

Fabrication of N-rich graphitic carbon nitride supported CeO2 for improved photocatalytic charge separation and electrochemical electron transfer properties

Environmental issues have become a worldwide problem due to the trace-level contamination of toxic pollutants in aqueous environments, which affects wildlife and human health. Hence, it's essential to need to remove toxic pollutants from wastewater systems. In this work, CeO2 nanoparticles with various weight percentages of nitrogen-rich carbon nitride (C3N5 or CN) heterostructure have been prepared by a simple ultrasonication method. The physical and chemical properties of as-prepared materials were identified by various techniques (XRD, FT-IR, UV-DRS, BET, TEM, and EDX). The optimized CeO2@CN (3) heterostructure showed the best degradation performance and low-level determination towards paracetamol (PC) compared to all other sole and binary heterostructures. The CeO2@CN (3) exhibits a remarkable conversion percentage (99.8 %), and rate constant (0.2361 min−1). The major active photodegradation species were investigated by radical scavenging experiments and improved electron transfer properties were confirmed via photoluminescence and photocurrent spectra. The photodegradation mechanism and kinetic rate were also investigated and discussed. The effective catalytic activity of optimized CeO2@CN (3) heterostructure is majorly ascribed to the stronger interfacial effects and faster electron transfer which reduced the recombination. Moreover, the CeO2@CN (3) modified electrode showed good selectivity and high reproducibility. The PC sensor exhibits a wide sensing linear range from 0.04 – 546 µM, the detection limit is found to be 0.0011 µM and the sensitivity is 0.467 μA μM−1cm−2. This method was useful for determining the PC in real samples.

Improved Visible-Light Photocatalytic H2 Evolution of G-C3N4 Nanosheets by Constructing Heterojunctions with Nano-Sized Poly(3-Thiophenecarboxylic Acid) and Coordinating Fe(III).

It is highly desirable to enhance the photogenerated charge separation of g-C3N4 by constructing efficient heterojunctions, especially with an additional organic constitution for solar-hydrogen conversion. Herein, g-C3N4 nanosheets have been modified controllably with nano-sized poly(3-thiophenecarboxylic acid) (PTA) through in situ photopolymerization and then coordinated with Fe(III) via the -COOH groups of modified PTA, forming an interface of tightly contacted nanoheterojunctions between the Fe(III)-coordinated PTA and g-C3N4. The resulting ratio-optimized nanoheterojunction displays a ~4.6-fold enhancement of the visible-light photocatalytic H2 evolution activity compared to bare g-C3N4. Based on the surface photovoltage spectra, measurements of the amount of •OH produced, photoluminescence (PL) spectra, photoelectrochemical curves, and single-wavelength photocurrent action spectra, it was confirmed that the improved photoactivity of g-C3N4 is attributed to the significantly promoted charge separation by the transfer of high-energy electrons from the lowest unoccupied molecular orbital (LUMO) of g-C3N4 to the modified PTA via the formed tight interface, dependent on the hydrogen bond interaction between the -COOH of PTA and the -NH2 of g-C3N4, and the continuous transfer to the coordinated Fe(III) with -OH favorable for connection with Pt as the cocatalyst. This study demonstrates a feasible strategy for solar-light-driven energy production over the large family of g-C3N4 heterojunction photocatalysts with exceptional visible-light activities.

Mechanism for Long Photocurrent Time Constants in α-Ga2O3 UV Photodetectors

Deep centers and their influence on photocurrent spectra and transients were studied for interdigitated photoresistors on α-Ga2O3 undoped semi-insulating films grown by Halide Vapor Phase Epitaxy (HVPE) on sapphire. Characterization involving current-voltage measurements in the dark and with monochromatic illumination with photons with energies from 1.35 eV to 4.9 eV, Thermally Stimulated Current (TSC), Photoinduced Current Transients Spectroscopy (PICTS) showed the Fermi level in the dark was pinned at Ec−0.8 eV, with other prominent centers being deep acceptors with optical thresholds near 2.3 eV and 4.9 eV and deep traps with levels at Ec−0.5 eV, Ec−0.6 eV. Measurements of photocurrent transients produced by illumination with photon energies 2.3 eV and 4.9 eV and Electron Beam Induced Current (EBIC) imaging point to the high sensitivity and external quantum efficiency values being due to hole trapping enhancing the lifetime of electrons and inherently linked with the long photocurrent transients. The photocurrent transients are stretched exponents, indicating the strong contribution of the presence of centers with barriers for electron capture and/or of potential fluctuations.

Metal–Semiconductor–Metal Photodetectors Based on β-MgGaO Thin Films

Ultrawide-bandgap (UWBG) deep-ultraviolet photodetectors have received great attention due to their versatile applications in the fields of scientific research, civilian infrastructure, military defense, etc. In this perspective, we fabricated deep-ultraviolet β-MgGaO metal–semiconductor–metal photodetectors with interdigital Pt/Au metal contacts. β-Phase MgGaO ternary alloy thin films of different Mg atomic percentages were grown using oxygen plasma-assisted molecular beam epitaxy. Ultrawide bandgaps of 5.03, 5.09, 5.15, and 5.22 eV were achieved for thin films with and without Mg2+ incorporation, and light transmittances of all samples were around 90% in the visible region. Raman spectra indicate that Mg2+ atoms have replaced the position of Ga3+ ions in both octahedral and tetrahedral chains. The responsivity of the detectors was investigated. The irradiation wavelength-, temperature-, and power-dependent I–V curves, photocurrent spectra, and dynamics of the photocurrents were measured. This work suggests that UWBG β-MgGaO semiconductors have a potential for deep-ultraviolet photodetectors and other photonic device applications.

Pt loading to promote hydrogen evolution from ammonia-borane hydrolysis of Ni2P under visible light

Ammonia borane is a promising hydrogen storage material that can be handled easily and release hydrogen at room temperature in the presence of a catalyst. Attaching noble metal to transition metal phosphide is needed to improve the dehydrogenation from ammonia borane. Here, a catalyst Pt@Ni2P is reported to enhance the hydrogen evolution rate in dark and visible light. The incorporation of Pt with Ni2P exhibit partially positive Ptδ+ and partially negative Ni2Pδ− as manifested by X-ray photoelectron spectrum, which serve as active sites for ammonia borane and water, respectively. Moreover, visible light irradiation further accelerates the electron transfer from Ptδ+ to Ni2Pδ− as exhibited by electrochemical impedance spectroscopy and transient photocurrent spectra. Subsequently, Pt loading over Ni2P plays a vital role in improving H2 evolution rate via ammonia borane hydrolysis. With the incorporation of 2% Pt, the hydrogen generation rate from ammonia borane hydrolysis is increased by 4.0-fold in dark, and visible light irradiation further increases the activity by 5.7-fold compared with pristine Ni2P. The visible light enhances the turn-off frequency from 4.7 min−1 to 10.3 min−1 and reduces the activation energy from 52.0 kJ·mole−1 to 43.4 kJ·mole−1 compared with dark. The performance of Pt@Ni2P is also outstanding compared with reported catalysts and is expected to be used economically in practical applications.

Plasmonic-driven charge separation through combining Ag nanoparticles (Ag NPs) to form a double Z-scheme heterostructure in WO3/BiOCl/g-C3N4 for the photocatalytic degradation of antibiotics.

Integrating a heterojunction system with the impact of surface plasmon resonance (SPR) is an executable and innovative tactic for photocatalyst amelioration. Ag nanoparticle (Ag NP)-modified WO3/BiOCl/g-C3N4 (WB-CN) was favorably fabricated through in situ photo deposition assembly to form double heterojunctions (A-WBCN). The degradation performance of A-WBCN is better than that of pure g-C3N4 (CN) and WO3/BiOCl (WB), it can degrade more than 90% of OFLX within 20 minutes, due to Ag NPs performing as a bridge for electron mediators, apart from the implications of SPR in A-WBCN. The results of UV diffuse reflectance spectroscopy indicate that loading with Ag NPs can expand the light absorption range of WB-CN to near-infrared. The photoluminescence spectra and transient photocurrent spectra indicate that Ag NP loading significantly improves the separation efficiency of photogenerated carriers. Density functional theory (DFT) simulation results show that the introduction of Ag NPs can change the direction of carrier movement, resulting in bending of the energy bands of WB and CN, improving the redox ability of A-WBCN, and improving its photocatalytic efficiency. In addition, the intermediate products of OFLX was determined by HPLC-MS analysis. The spin electron resonance (ESR) results indicate that ˙O2- and ˙OH are the main active species in photocatalytic degradation. This work furnishes a fresh idea for upgrading photocatalytic performance and advancing electron transfer.

Modelling and Performance Analysis of CuPc and C60 Based Bilayer Organic Photodetector

An optoelectronic device model for organic photodetector based on bilayer structure has been presented. Drift-diffusion and optical-generation model from Synopsys tool have been incorporated and its optoelectronics behavior has been discussed. The model shows an outstanding rectifying behavior under dark condition due to the different work function of the electrodes. Photocurrent density of 6.64 mA/cm2 is found under the illumination of 3 W/cm2. To analyze rectifying behavior of current density-voltage characteristics of the organic photodetector, the curve has been fitted with the Shockley equation. The enhancement of ideality factor of diode current under illumination from that of dark current at forward bias is attributed to enhancement of recombination loss due to generation of photo-carrier and injection of carriers from electrodes. Almost equal probability of photocurrent spectra in the entire spectral region indicates equal probability of exciton generated and dissociated at the interface between CuPc and C60 layers. The detectivity of the proposed photodetector is calculated and it is in order of 1010 Jones at 650 nm due to high dark current density and recombination loss. The presence of interface trap density and large transport distance give evidence of low response speed in the device.

Visible-light-induced V2O5 -TiO2 photocatalysts with high photocatalytic ability for degradation of tetracycline

In this contribution, mesoporous V2O5–TiO2 heterojunctions were constructed utilizing a soft-chemistry approach. The photocatalytic ability of the V2O5–TiO2 nanocomposites was assessed for tetracycline degradation under visible exposure compared to bare TiO2 and P-25. TEM images presented the close contact between the tetragonal TiO2 in the anatase phase and orthorhombic V2O5 with particle sizes between 10 and 20 nm. The obtained V2O5–TiO2 photocatalysts indicated higher photocatalytic performance compared to bare TiO2 and P-25 in the photooxidation of tetracycline. It demonstrated that 3%V2O5–TiO2 nanocomposite exhibited a superb photocatalytic ability in the destruction of tetracycline ∼100% after 120 min, owing to its promoted visible harvest ability, large surface area and enhanced separation efficiency of carriers. Meanwhile, the kinetic rate constant of 3%V2O5–TiO2 nanocomposite was about 9.8 and 29.3 times larger than bare TiO2 and P-25. The photocurrent responses and PL spectra measurements are matched well with the photocatalytic efficiency of the V2O5–TiO2 nanocomposites. The reasonably designed heterojunctions V2O5–TiO2 nanocomposites could enhance the photocatalytic performance by reducing the recombination rate of photoinduced carriers.

Enhancing visible-light degradation performance of g-C3N4 on organic pollutants by constructing heterojunctions via combining tubular g-C3N4 with Bi2O3 nanosheets

In this paper, a novel heterojunction photocatalyst was prepared by depositing Bi2O3 nanosheets on the surface of tubular g-C3N4 (TCN) using a simple solvothermal method. The photocatalytic activity was assessed using Rhodamine B (RhB) and Tetracycline (TC) as the target contaminant under visible light (λ > 420 nm). Compared with single TCN or Bi2O3, the TCN/Bi2O3 composites exhibited enhanced photocatalytic activity. The TCN/Bi2O3-0.5 photocatalyst, in particular, showed the most superior performance. Its removal efficiency of TC reached 94% in 100 min and that of RhB reached 99% in 60 min, with a rate constant (0.06532 min−1) of degrading RhB of 4.9 and 3.9 times higher than that of TCN and Bi2O3, respectively. The results of photoluminescence, photocurrent, and electrochemical impedance spectrum characterization showed that the composite photocatalysts can significantly improve the separation efficiency of the photogenerated carriers, due to the construction of heterojunctions. A possible mechanism of the degradation of target pollutants by the composite catalyst was proposed. The synergistic effect of the increased specific surface area and the heterojunction formed by interfacial contact between Bi2O3 and TCN was primarily responsible for improving photocatalytic performance.