Chemical etching preparation of BiOI/Bi2O3 heterostructures with enhanced photocatalytic activities

Structure-phase transformation of bismuth oxide to BiOCl/Bi24O31Cl10 shoulder-by-shoulder heterojunctions for efficient photocatalytic removal of antibiotic

Developing heterojunction photocatalyst with well-matched interfaces and multiple charge transfer paths is vital to boost carrier separation efficiency for photocatalytic antibiotics removal, but still remains a great challenge. In present work, a new strategy of chloride anion intercalation in Bi2O3 via one-pot hydrothermal process is proposed. The as-prepared Ta-BiOCl/Bi24O31Cl10 (TBB) heterojunctions are featured with Ta-Bi24O31Cl10 and Ta-BiOCl lined shoulder-by-shouleder via semi-coherent interfaces. In this TBB heterojunctions, the well-matched semi-coherent interfaces and shoulder-by-shoulder structures provide fast electron transfer and multiple transfer paths, respectively, leading to enhanced visible light response and improved photogenerated charge separation. Meanwhile, a type-II heterojunction for photocharge separation has been obtained, in which photogenerated electrons are drove from the CB (conduction band) of Ta-Bi24O31Cl10 to the both of bilateral empty CB of Ta-BiOCl and gathered on the CB of Ta-BiOCl, while the photogenerated holes are left on the VB (valence band) of Ta-Bi24O31Cl10, effectively hindering the recombination of photogenerated electron-hole pairs. Furthermore, the separated electrons can effectively activate dissolved oxygen for the generation of reactive oxygen species (·O2-). Such TBB heterojunctions exhibit remarkably superior photocatalytic degradation activity for tetracycline hydrochloride (TCH) solution to Bi2O3, Ta-BiOCl and Ta-Bi24O31Cl10. This work not only proposes a Ta-BiOCl/Bi24O31Cl10 shoulder-by-shoulder micro-ribbon architectures with semi-coherent interfaces and successive type-II heterojunction for highly efficient photocatalytic activity, but offers a new insight into the design of highly efficient heterojunction through phase-structure synergistic transformation strategy.

Fabrication of the flower-like Z-scheme heterojunction photocatalyst Bi-BiOI/UiO 66 for enhanced photodegradation of acetaminophen in simulated wastewater

Acetaminophen is a representative contaminant of emerging persistent organic pollutants that can cause environmental problems when it enters municipal wastewater. An innovative flower-like Z-scheme photocatalyst Bi-BiOI/UiO 66 heterojunction composite was designed and constructed via a one-step solvothermal method. Investigations demonstrated that the Z-scheme structure strongly contributes to increasing the degradation efficiency of micropollutants. The results indicate that the bandgap energy (Eg) of the Bi-BiOI/UiO 66 composite decreases significantly from 3.22 eV to 2.43 eV, in comparison with that of pure copper-based UiO 66. Under suitable conditions (5 mg/L Ace, pH 3, 0.05 g/L), the organic pollutants in the water can be removed completely. A k value of 5.67 × 10-2 min-1 for the Bi-BiOI/UiO 66 heterojunction composite was found to effectively represent the acetaminophen photodegradation process. The reaction mechanism of acetamide in aqueous solution is also discussed. The Bi in Bi-BiOI can use surface plasmon resonance to form an electric field and accelerate the separation of photogenerated electrons and holes. This study highlights the potential of a novel photocatalyst for practical application.

2D g-C3N4 nanosheets functionalized with nickel-doped ZrO2 nanoparticles for synergistic photodegradation of toxic chemical pollutants

The photocatalytic removal of toxic chemical pollutants from wastewater has garnered significant attention in recent times owing to its notable removal efficiency, cost-effectiveness, and eco-friendly characteristics. Nonetheless, this catalytic process necessitates augmented charge separation and distinctive interface properties to facilitate catalytic reactions for water treatment applications. Therefore, in the current study, novel g-C3N4/Ni-doped ZrO2 heterostructured hybrid catalysts have been synthesized via a hydrothermal approach. Microscopic studies reveal that ZrO2 nanospheres were distributed on the layered-like 2D structure of g-C3N4 nanosheets. Electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (UV-DRS), and photoluminescence (PL) characterizations were employed to investigate the impact of bandgap, electron-hole recombination, charge transfer, and interface properties on the catalytic performance of g-C3N4/ZrO2 hybrids. XRD analysis confirmed that the Ni-ions do not disturb the host lattice crystal structure and heterostructure development between g-C3N4 and doped ZrO2 sample. Structurally, Ni-doped nanoparticles were found to be equally superficially dispersed on g-C3N4 sheets. Optical analysis results suggest that the hybrid catalyst possesses a narrow bandgap of 2.56 eV. The synthesized photocatalyst degraded rhodamine B (RhB) and tetracycline (TC) with ∼92% and ∼89% degradation efficiency, respectively. Heterostructured hybrid catalysts showed superior degradation rate constants than other catalysts. This might be attributed to the sufficient separation of electron-hole due to the development of a heterojunction. The radical scavenging experiments suggested that O2●- and ●OH radicals contributed substantially to the dye elimination activity of the composite. Therefore, the synthesized novel nanohybrid catalysts in this study present an efficient and straightforward synthesis method for the efficient removal of toxins from wastewater under visible light irradiation.

Novel g-C3N4/BiVO4 heterostructured nanohybrids for high efficiency photocatalytic degradation of toxic chemical pollutants

Novel heterostructured hybrid catalysts are essential for the efficient photocatalytic removal of organic pollutants from wastewater generated by the pharmaceutical and textile industries. In this study, novel g-C₃N₄/BiVO₄ nanohybrid catalysts were prepared using a solvothermal technique, and examined their structural and optical properties using different characterizations. The X-ray diffraction analysis confirmed the monoclinic crystal phase of BiVO₄. Field emission scanning electron microscopy (FESEM) images revealed that g-C₃N₄ sheets anchored on the surface of BiVO₄ nanospheres. X-ray photoelectron spectroscopy (XPS) analysis confirmed the oxidation states of g-C₃N₄/BiVO₄ composite sample. UV-Vis DRS spectroscopy analysis revealed that the composite (2.08 eV) sample had a reduced bandgap compared to other samples. The photocatalytic properties of the prepared samples were tested in the presence of organic methylene blue (MB) and antibiotic tetracycline (TC) pollutants under visible light illumination. The hybrid composite catalyst exhibited enhanced photocatalytic degradation efficiency of MB (88%) and TC (89%) pollutants at elevated rate constants of 0.0128 and 0.01174 min^-1, respectively. The improved catalytic performance of the composite catalyst is due to the heterojunctions between g-C₃N₄ and BiVO₄ that successfully reduced the rate of charge carrier recombination in the catalyst system. Scavenger experiments revealed that O₂^●- and h⁺ radicals played a main role in the degradation of the chemical pollutants. The developed g-C₃N₄/BiVO₄ heterostructured catalyst is a suitable candidate for removing contaminants from industrial wastewater because of its facile fabrication and exceptional photocatalytic activity under visible light irradiation.

Exceptional visible-light photoelectrocatalytic activity of dual Z-scheme Bi@BiOI-Bi2O3/C3N4 heterojunction for simultaneous remediation of Cr(VI) and phenol

Developing highly efficient and stable photocatalysts remains a major challenge for the remediation of environmental pollutants. In this work, the Bi⁰ decorated BiOI-Bi₂O₃/C₃N₄ heterojunction (Bi@BiOI-Bi₂O₃/C₃N₄) film was fabricated through ultrasonic stripping, I^- etching and in situ UV-reduction processes and then characterized thoroughly by various analytical techniques. The characteristics of simultaneous mitigation of phenol and Cr(VI) were evaluated over Bi@BiOI-Bi₂O₃/C₃N₄ photoanode under visible light. The results exhibited that both phenol and Cr(VI) were removed completely by the photoanode at 2.5 V within 1.5 h, superior to our previous report. The synergy of the surface plasmon resonance (SPR) effect of Bi⁰ and ternary heterojunction accelerated the separation and transfer of photo-induced charge carrier and thus heavily promoted the removal efficiency. Moreover, the excellent stability of this photoanode was hold with no considerably activity attenuation after 4 cycles. Finally, a dual Z-scheme charge transfer process was presented. This work offers an attractive pathway to construct highly active photoelectrode with promising application for simultaneous remediation of organics and heavy metals in wastewater.

Ultrahigh Charge Separation Achieved by Selective Growth of Bi4O5I2 Nanoplates on Electron-Accumulating Facets of Bi5O7I Nanobelts

Ultrahigh charge separation was observed in Bi₄O₅I₂/Bi₅O₇I two-dimensional (2D)/one-dimensional (1D) hierarchical structures (HSs) constructed by selective growth of 2D monocrystalline Bi₄O₅I₂ nanoplates on the electron-accumulating (100) facet of 1D monocrystalline Bi₅O₇I nanobelts. In addition to the presence of type-II heterojunction between Bi₄O₅I₂ and Bi₅O₇I elementary entities in 2D/1D HSs, the type-II (100)/(001) surface heterojunction in Bi₅O₇I nanobelt substrates was also confirmed by means of density functional theory (DFT) calculations and selective photoreduction/oxidation deposition experiments. The synergistic effect of two kinds of heterojunctions in Bi₄O₅I₂/Bi₅O₇I 2D/1D HSs endowed them with ultrahigh charge carrier separation and transfer characteristics. In contrast with the control sample (BB40-C) constructed by growing Bi₄O₅I₂ nanoplates on whole four sides of Bi₅O₇I nanobelts, Bi₄O₅I₂/Bi₅O₇I 2D/1D HSs demonstrated significantly enhanced charge transfer between Bi₅O₇I nanobelt substrates and Bi₄O₅I₂ nanoplates, owing to respective electron and hole accumulations on (100) and (001) facets of Bi₅O₇I substrates caused by (100)/(001) surface heterojunction. The enhanced separation behavior was successfully verified by steady/transient-state photoluminescence, electrochemical techniques, and photocatalytic degradation experiments. Based on the above effective charge separation of Bi₄O₅I₂/Bi₅O₇I 2D/1D HSs as well as the routine advantages for 2D/1D HSs, such as the excellent charge transport in monocrystalline elementary entities, much higher specific surface area, and enhanced light absorption by multiple reflections, the optimal BB40 HSs demonstrated ultrahigh photocatalytic performance than the control samples, whose apparent rates for Rhodamine B [or tetracycline hydrochloride (TC)] degradation were 7.1 (2.9 for TC), 10.3 (4.7 for TC), and 2.2 (1.7 for TC) times those of pristine Bi₅O₇I nanobelts, Bi₄O₅I₂ nanoplates, and BB40-C, respectively. It is hoped that this crystal facet selection during the heterostructure construction in this work could provide a new strategy or some enlightenment for the exploration of highly active 2D/1D HSs or other-dimensional heterostructure nanomaterials applied in the fields of photocatalysts, solar cells, sensors, and others.

Direct electrospinning preparation of Z-scheme mixed-crystal Bi2O3/g-C3N4 composite photocatalysts with enhanced visible-light photocatalytic activity

A novel Z-scheme mixed-crystal Bi₂O₃/g-C₃N₄ composite photocatalyst was successfully prepared by a simple electrospinning–calcination approach.

Construction of ultrathin MoS2/Bi5O7I composites: Effective charge separation and increased photocatalytic activity

Ultrathin MoS₂ nanosheet hybridized Bi₅O₇I (MoS₂/Bi₅O₇I) nanorods were synthesized via a reactable ionic liquid assisted solvothermal process for the first time. The photocatalytic activity of MoS₂/Bi₅O₇I nanorods was determined by photodegrading bisphenol A (BPA), tetracycline hydrochloride (TC) and ciprofloxacin (CIP) under visible light irradiation. Experimental results showed that MoS₂/Bi₅O₇I owned the excellent photocatalytic properties and photostability. The efficient visible light driven photocatalytic performance was due to a larger specific surface area of MoS₂, which increased the close interfacial contact between pollutants and photocatalysts. Meanwhile, the introduction of ultrathin MoS₂ nanosheet was conducive to the separation and utilization of photoinduced charge carriers, thus further suppressed high recombination rate in pure Bi₅O₇I nanorods. Moreover, a possible charge transfer path in MoS₂/Bi₅O₇I composite material was also put forward.

Photocatalytic BiOX Mortars under Visible Light Irradiation: Compatibility, NOx Efficiency and Nitrate Selectivity

The use of new photocatalysts active under visible light in cement-based building materials represents one interesting alternative to improve the air quality in the urban areas. This work undertakes the feasibility of using BiOX (X = Cl and I) as an addition on mortars for visible-light-driven NOx removal. The interaction between BiOX photocatalysts and cement matrix, and the influence of their addition on the inherent properties of the cement-based materials was studied. The NO removal by the samples ranking as follows BiOCl-cem > BiOI-cem > TiO2-cem. The higher efficiency under visible light of BiOCl-cem might be ascribed to the presence of oxygen vacancies together with a strong oxidation potential. BiOI-cem suffers a phase transformation of BiOI in alkaline media to an I-deficient bismuth oxide compound with poor visible light absorbance capability. However, BiOI-cem showed considerably higher nitrate selectivity that resulted in the highest NOx global removal efficiency. These results can make its use more environmentally sustainable than TiO2 and BiOCl cement composites.

Asymmetric synthesis of Au-CdSe core-semishell nanorods for plasmon-enhanced visible-light-driven hydrogen evolution

The metal-semiconductor heterostructure is an important candidate for photocatalysis due to its efficient charge transport and separation. A controllable morphology and ideal interfaces are critically significant for improving the heterostructure photocatalytic performance. By controlling the concentration of Cd²⁺ to control the reaction environment (pH value) and reaction rate, the CdSe nanocrystal is overgrown on the side or tip of the Au nanorods, which leads to a strong interaction between the excitons of CdSe nanocrystals and the plasmons of Au nanorods. Both kinds of Au-CdSe heterorods exhibit good hydrogen productivity. Particularly, the lateral Au-CdSe heterorods exhibit excellent photocatalytic efficiency due to the larger contact interface of Au and CdSe and the strong local field of the CdSe nanocrystals grown on one side of the Au nanorods being enhanced by the transverse plasmon resonance in the visible region. We provide an approach to modulate the combination of the asymmetric metal nanoparticle and the semiconductor shell; these core-semishell heterostructures have potential applications ranging from photocatalysis to photonic nanodevices.

Insights into the mechanism of the enhanced visible-light photocatalytic activity of a MoS2/BiOI heterostructure with interfacial coupling

The mechanism of the enhanced visible-light photocatalytic activity of MoS₂/BiOI heterostructure under interfacial coupling.

Bismuth-Based Photocatalysts for Solar Photocatalytic Carbon Dioxide Conversion

Photocatalytic CO₂ conversion into solar fuels is an effective means for simultaneously solving both the greenhouse effect and energy crisis. In the past ten years, bismuth-based photocatalysts for environmental remediation have experienced a golden period of development. However, solar photocatalytic CO₂ conversion has only been developed over the past five years and, until now, no reviews have been published on bismuth-based photocatalysts for the photocatalytic conversion of CO₂ . For the first time, solar photocatalytic CO₂ conversion systems are reviewed herein. Synthetic methods and photocatalytic CO₂ performances of bismuth-based photocatalysts, including Sillén-structured BiOX (X=Cl, Br, I); Aurivillius-structured Bi₂ MO₆ (M=Mo, W); and Scheelite-structured BiVO₄ , Bi₂ S₃ , BiYO₃ , and BiOIO₃ , are summarized. In addition, activity-enhancing strategies for this photocatalyst family, including oxygen vacancies, bismuth-rich strategy, facet control, conventional type II heterojunction, Z-scheme heterojunction, and cocatalyst deposition, are reviewed. Finally, the main mechanistic research methods, such as in situ FTIR spectroscopy and theoretical calculations, are presented. Challenges and research trends reported in studies of bismuth-based photocatalysts for photocatalytic CO₂ conversion are discussed and summarized.

Intercalation of Bi2O3/Bi2S3 nanoparticles into highly expanded MoS2 nanosheets for greatly enhanced gas sensing performance at room temperature

Synthesizing a gas sensor based on heterostructured nanomaterials (NMs) via a controllable morphology by a facile hydrothermal method is an area of frontier research. In the present work, we designed a facile strategy to synthesize a controllable morphology and composition for three component heterojunctions (MoS₂-Bi₂O₃-Bi₂S₃) NMs using different hydrothermal reaction times. The Bi₂S₃ easily form as an intermediate phase due to the strong interaction of the Bi₂O₃ with MoS₂ nanosheets (NSs). The as fabricated heterojunctions MB-5 NMs exhibited a sensitive response to NO_x gas (R_a/R_g = 10.7 at 50 ppm), with an ultra-fast response time of only 1 s (s) at room temperature (RT) in air. The detection limit was predicted to be as low as 50 ppb. This sensational behaviour of the sensor reveals the outstanding morphological structure and synergistic effect of the MoS₂ NSs with Bi₂O₃ nanoparticles (NPs), which was realized by the flow of electrons across MoS₂-Bi₂O₃-Bi₂S₃ interfaces through band energy alignment.

Development of bismuth-functionalized graphene oxide to remove radioactive iodine

Bismuth-functionalized graphene oxide shows high performance in the removal of radioactive iodine.

Natural sunlight driven highly efficient photocatalysis for simultaneous degradation of rhodamine B and methyl orange using I/C codoped TiO2 photocatalyst

Increasing the efficiency of dye degradation is a critical issue for the application for photocatalysis. It is one of the greatest challenges to enhance the utilization of photo generated carriers in semiconductor, especially for sunlight irradiation. In this study, I/C-codoped TiO₂ was synthesized by a simple solvothermal-calcination method. The codoping interstitial carbon and substitutional iodine not only widened the light absorption range of the TiO₂ photocatalysts, but also enhanced the separation of photo-induced carriers. The photocatalytic activities of RhB and MO degradation over the 4-I/C-TiO₂ photocatalyst could reach 98.2% and 94.2% after 25 min visible light irradiation (λ ≥ 400 nm), respectively. Notably, 4-I/C-TiO₂ showed good activity for MO and RhB mixed degradation and could also accomplish the photocatalytic degradation in the above mixed system under natural sunlight irradiation. According to the dark catalytic experiment, I/C-codoping could effectively accelerate the formation of hydroxyl radicals from the generated H₂O₂, which was formed for the enhanced photocatalytic activity of dye degradation. The gained knowledge may provide some insights into the photocatalytic degradation over the codoped TiO₂ catalyst.

Temperature-Program Assisted Synthesis of Novel Z-Scheme CuBi₂O₄/β-Bi₂O₃ Composite with Enhanced Visible Light Photocatalytic Performance

Novel Z-Scheme CuBi₂O₄/β-Bi₂O₃ composite photocatalysts with different mass ratios and calcination temperatures were firstly synthesized by the hydrothermal method following a temperature-programmed process. The morphology, crystal structure, and light absorption properties of the as-prepared samples were systematically characterized, and the composites exhibited enhanced photocatalytic activity toward diclofenac sodium (DS) degradation compared with CuBi₂O₄ and β-Bi₂O₃ under visible light irradiation. The optimal photocatalytic efficiency of the composite, achieved at the mass ratio of CuBi₂O₄ and β-Bi₂O₃ of 1:2.25 and the calcination temperature of 600 °C is 92.17%. After the seventh recycling of the composite, the degradation of DS can still reach 82.95%. The enhanced photocatalytic activity of CuBi₂O₄/β-Bi₂O₃ is closely related to OH^•, h⁺ and O₂^•−, and the photocatalytic mechanism of CuBi₂O₄/β-Bi₂O₃ can be explained by the Z-Scheme theory.

Intensive photocatalytic activity enhancement of Bi5O7I via coupling with band structure and content adjustable BiOBrxI1-x

Band structure and component content are the key factors for determining the activity of semiconductor heterojunction. In this study, a novel Bi₅O₇I/BiOBr_xI_1-x heterostructure was synthesized by a simple hydrobromic (HBr) acid etching method through transforming partial of Bi₅O₇I to I^- ion doped BiOBr (BiOBr_xI_1-x) at room temperature without adding extra dopant. Both the band structure and component content of Bi₅O₇I/BiOBr_xI_1-x alter with the additive HBr acid. The Bi₅O₇I/BiOBr_xI_1-x (S3.0) sample exhibits the best photocatalytic activity, 6 times higher than that of pure Bi₅O₇I, for the degradation of methyl orange under visible-light (λ > 420 nm). The activity enhancement of Bi₅O₇I/BiOBr_xI_1-x is primarily ascribed to the improved separation efficiency of photocharges, originated from the adjustable band structure and component content. The significant findings of this paper provide a facile way to construct highly efficient semiconductor heterojunction via playing the synergetic effect of adjustable band structure and component content for purifying organic pollutants in wastewater.

Green synthesis of balsam pear-shaped BiVO4/BiPO4 nanocomposite for degradation of organic dye and antibiotic metronidazole

A novel balsam pear-shaped BiVO₄/BiPO₄ composite photocatalyst for a highly efficient degradation of organic dye and antibiotic was fabricated.

Heterophase-structured nanocrystals as superior supports for Ru-based catalysts in selective hydrogenation of benzene

ZrO₂ heterophase structure nanocrystals (HSNCs) were synthesized with tunable ratios of monoclinic ZrO₂ (m-ZrO₂) to tetragonal ZrO₂ (t-ZrO₂). The phase mole ratio of m-ZrO₂ versus t-ZrO₂ in ZrO₂ HSNCs was tuned from 40% to 100%. The concentration of the surface hydroxyl groups on m-ZrO₂ is higher than that on t-ZrO₂. ZrO₂ HSNCs have different surface hydroxyl groups on two crystalline phases. This creates more intimate synergistic effects than their single-phase counterparts. The ZrO₂ HSNCs were used as effective supports to fabricate heterophase-structured Ru/ZrO₂ catalysts for benzene-selective hydrogenation. The excellent catalytic performance including high activity and selectivity is attributed to the heterogeneous strong/weak hydrophilic interface and water layer formed at the m-ZrO₂/t-ZrO₂ catalyst junction.

Bi metal-modified Bi4O5I2 hierarchical microspheres with oxygen vacancies for improved photocatalytic performance and mechanism insights

In this work, we firstly synthesized metallic Bi-modified Bi₄O₅I₂ nanocomposites with oxygen vacancies via a facile one-pot solvothermal method.

Enhanced p-cresol photodegradation over BiOBr/Bi2O3 in the presence of rhodamine B

Co-adsorption of rhodamine B accelerates the photodegradation of p-cresol over hetero-epitactic BiOBr/Bi₂O₃ composites.

Facile synthesis of AgI/BiOI-Bi2O3 multi-heterojunctions with high visible light activity for Cr(VI) reduction

AgI sensitized BiOI-Bi2O3 composite (AgI/BiOI-Bi2O3) with multi-heterojunctions was prepared using simple etching-deposition process. Different characterization techniques were performed to investigate the structural, optical and electrical properties of the as-prepared photocatalysts. It was found that the ternary AgI/BiOI-Bi2O3 composite exhibited: (1) improved photocurrent response, (2) smaller band gap, (3) greatly reduced charge transfer resistance and (4) negative shift of flat band potential, which finally led to easier generation and more efficient separation of photo-generated electron-hole pairs at the hetero-interfaces. Thus, for the reduction of Cr(VI), AgI/BiOI-Bi2O3 exhibited excellent photocatalytic activity under visible light irradiation at near neutral pH. AgI/BiOI-Bi2O3 was optimized when the initial molar ratio of KI to Bi2O3 and AgNO3 to Bi2O3 was 1:1 and 10%, respectively. The estimated kCr(VI) on optimized AgI/BiOI-Bi2O3 was about 16 times that on pure Bi2O3. Good stability was also observed in cyclic runs, indicating that the current multi-heterostructured photocatalyst is highly desirable for the remediation of Cr(VI)-containing wastewater.

In situ Fabrication of α-Bi2O3/(BiO)2CO3 Nanoplate Heterojunctions with Tunable Optical Property and Photocatalytic Activity

Exploring the full potential use of heterojunction photocatalysts containing bismuth has attracted considerable interest in recent years. Fabrication of well-defined heterojunction photocatalysts with precise modulation of their chemical composition is crucial for tuning their optical properties and photocatalytic activity. In this study, we fabricated nanoplate α-Bi₂O₃/(BiO)₂CO₃ heterojunctions through in situ thermal treatment of (BiO)₂CO₃ nanoplates synthesized using a facile hydrothermal process. Characterization results showed that the as-prepared Bi₂O₃/(BiO)₂CO₃ heterojunctions possessed distinct crystal interface and exhibited pronounced structural and optical modulation, resulting in significant improvement of their photocatalytic activity for NO removal under simulated solar light irradiation compared with pristine (BiO)₂CO₃. Electron spin resonance spectroscopy showed that ⋅OH radicals were the major reactive species involved in NO degradation, which is consistent with the theoretical analysis. The heterojunction formation can not only broaden the light absorption range but also improve the charge separation of photo-induced electron–hole pairs. This study is an important advancement in the development of semiconductor heterojunctions towards achieving functional photocatalysts.