Photocatalytic Oxidation Of NOx Research Articles

Constructing multiple active sites of Bi2WO6 for efficient photocatalytic NO removal and NO2 inhibition

Insufficient photocatalytic NOx oxidation capacity will lead to excessive toxic by-products (NO2), which still seriously restrict its practical application. Herein, the multiple active sites (Cl, Bi0 and OVs) modified Bi2WO6 has been established by in-situ synthesis method. The synergistic effect of multiple active sites greatly increased the photo-electric properties of the Bi2WO6, resulting in the boosting photocatalytic NOx deep oxidation to nitrate. The visible light driven OVs-Bi@BWO-Cl catalyst exhibited a highest NO conversion efficiency (67.3 %) with extremely low NO2 concentration (17.9 ppb). The synergism of structural regulation from the OVs with Cl-doping and surface plasmon resonance of Bi0 significantly enhanced light absorption and provided a fast charge transport channel, improving the separation efficiency of photo-generated carriers. The in-situ DRIFTS and density functional theory (DFT) results shown that the synergistic effect by multiple active sites could enhance the adsorption and activation of reactants to accelerate the processes of H2O/O2-to-ROS and decrease the energy barrier of NO removal to promote deep oxidation of NO-to-NO3−. This work can provide ideas for the design and preparation of the catalyst for safe photocatalytic environment purification.

Br vacancy engineering in Cs3Bi2Br9 for photocatalytic NO oxidation under visible light.

Photocatalysis using the visible light of the sun is an environmentally friendly method of eliminating the NOx pollutant from the ambient air. Although Cs3Bi2Br9, a semiconductor with a band gap of 2.54eV, may be a strong absorber of visible light, its photocatalysis towards the abatement of NOx is unknown. In this study, Cs3Bi2-xPbxBr9-x (0 ≤ x ≤ 0.0789) are used for the photocatalytic oxidation of NOx. A significant NO oxidation efficiency (80%) is observed over Cs3Bi2-xPbxBr9-x (x = 0.0443) under visible light, which is attributable to the Br vacancy (VBr) brought about by Pb2+ doping. The presence of VBr increased the ionic selectivity of in the oxidized NO. At higher Pb doping level, two HONOs adsorbed on the VBr, linked, and then reduced by hot electrons to produce N2O22-. The di-azo coupling could passivate the activation of NO on the VBr. This work advances the defect engineering of halide for the photo-driving solid-gas reaction in air.

One-step fluorine-free synthesis of delaminated, OH-terminated Ti3C2: High photocatalytic NOx storage selectivity enabled by coupling TiO2 and Ti3C2-OH

Difficulties associated with MXene fabrication typified by an environmentally hazardous fluorine-based etching process followed by delamination and fluorine reduction steps create obstacles against the expansion of this outstanding material and its application in air purification. Herein, we demonstrate a one-step hydrothermal process that involves alkali (NaOH)-assisted aluminum etching in the presence of a delaminating agent (hydrazine) for synthesis of delaminated, OH-terminated MXene (Ti3C2-OH). The process does not require the use of fluorine-containing compounds and produces Ti3C2-OH sheets without the need for post-synthesis treatment. Ti3C2-OH shows a strong synergistic effect as a co-catalyst when coupled with TiO2 during photocatalytic oxidation of NOx. Excellent NOx storage selectivity (91 %) and a positive DeNOx index (+ 0.30) were achieved at NO conversion of 54 %. The photocatalytic activity of the hybrid shows high sensitivity to the surface chemistry of the co-catalyst as Ti3C2-OH outperforms delaminated, F-terminated Ti3C2 (fabricated via the traditional process), which shows low NOx storage selectivity (65 %) and a negative DeNOx index (−0.05) at NO conversion of 47 %. We envision that these findings will benefit ongoing efforts aimed at developing effective alternative methods for MXene synthesis and provide a pathway for rational design of efficient NOx abatement photocatalysts.

Photocatalytic NOx mitigation under relevant conditions using carbon nanotube-modified titania

Although a majority of photocatalysts exhibit improved NO conversion to NO2, the performance in the oxidation of NO2, the more toxic form of NOx, to nitrate remains a challenge; in addition, the performance of hybrid photocatalysts under practical conditions is unclear. This study demonstrates the use of carbon nanotube-TiO2 (CNT-TiO2) photocatalyst films for effective transformation of NOx into nitrates. Using the objective figure of merit for NOx abatement, DeNOx index, the catalyst performance in a laminar-flow reactor was evaluated under simulated conditions that are relevant in abating NOx. The conditions probed include relative humidity (RH), initial NOx concentration, reactor geometry (headspace distance), and state of the catalyst (fresh vs. recycled). Our results reveal CNT-TiO2 significantly outperforms P25 despite exhibiting comparable NO conversion at low RH. P25 experiences a 66% reduction in DeNOx at high RH compared to low RH while CNT-TiO2 only incurs a 27% reduction. For recycled photocatalysts, this disparity becomes even more pronounced; CNT-TiO2 experiences a 49% reduction in DeNOx at high RH, whereas P25 experiences a 134% reduction. In addition, mass transfer from the bulk airflow limits NO conversion when the reactor headspace is too large (>3 mm), due to limited diffusion of NOx to the photocatalyst surface. Our findings highlight the importance of headspace distance, a parameter that has mostly been overlooked in reactor design for photocatalytic oxidation of NOx, but which dictates the optimal catalyst configuration for flue gas treatment. The remarkable DeNOx activity of CNT-TiO2 over a wide range of RH levels is rationalized based on the ratio of physisorbed-to-chemisorbed water on the photocatalyst surface.

Singlet Oxygen and Mobile Hydroxyl Radicals Co-operating on Gas-Solid Catalytic Reaction Interfaces for Deeply Oxidizing NOx.

Learning from the important role of porphyrin-based chromophores in natural photosynthesis, a bionic photocatalytic system based on tetrakis (4-carboxyphenyl) porphyrin-coupled TiO2 was designed for photo-induced treating low-concentration NOx indoor gas (550 parts per billion), achieving a high NO removal rate of 91% and a long stability under visible-light (λ ≥ 420 nm) irradiation. Besides the great contribution of the conventional •O2- reactive species, a synergic effect between a singlet oxygen (1O2) and mobile hydroxyl radicals (•OHf) was first illustrated for removing NOx indoor gas (1O2 + 2NO → 2NO2, NO2 + •OHf → HNO3), inhibiting the production of the byproducts of NO2. This work is helpful for understanding the surface mechanism of photocatalytic NOx oxidation and provides a new perspective for the development of highly efficient air purification systems.

Oxygen vacancy configuration in confined BiVO4-Bi2S3 heterostructures promotes photocatalytic oxidation of NO

Oxygen vacancy configuration is a promising means for tuning the electronic structure and determining the adsorption/desorption mode of the reactants in photocatalytic NOx oxidation. We report here that the formation of oxygen vacancies (OVs) can activate free NO and O2 molecules via a changed oxidation route, leading to fast conversion of NO into NO3-. The boosted NO oxidation reaction was conducted on novel OVs-induced BiVO4-Bi2S3 heterojunctions with the shape of double-deck hollow nanospheres assembled by a hard-templating treatment, followed by an annealing process. Abundant OVs were incorporated into the lattice of the as-synthesized heterojunctions, which significantly decreased the recombination level of the photo-exited carriers, leading to the promotion of the exchange of adsorbed ambiance oxygen and lattice oxygen, and the formation of reactive oxygen species and the final highly-efficient removal of NO under visible-light illumination. This work verifies the role of defective and hierarchical interface configuration on catalytic NOx oxidation and provides a viable methodology for the discovery of advanced photocatalysts via surface engineering.

Photochemical Transformation Pathways of Nitrates from Photocatalytic NOx Oxidation: Implications for Controlling Secondary Pollutants

Photochemical Transformation Pathways of Nitrates from Photocatalytic NOx Oxidation: Implications for Controlling Secondary Pollutants

High-concentration N-doped La2Ti2O7 nanocrystals: Effects of nano-structuration and doping sites on enhancing the photocatalytic activity

A series of N-doped La2Ti2O7 nanocrystal for photocatalytic NOx oxidation are successfully prepared by a two-steps process including hydrothermal reaction and heat treatment under NH3 flow. The effects of different nitrogen doping amounts on the structure, optical property and photocatalytic activity of the obtained N-doped La2Ti2O7 are investigated. The photocatalytic activity and stability of the N-doped La2Ti2O7 samples are evaluated through photocatalytic oxidation of NOx under UV and visible light irradiation. The nanosheet morphology of N-doped La2Ti2O7 is originated from La2Ti2O7 precursor synthesized by hydrothermal reaction. The addition of triethanolamine (TEA) in the hydrothermal reaction largely affects the morphology of La2Ti2O7 to form nanocrystal. The light absorption of La2Ti2O7 nanocrystal is cut off at 338 nm, while the N-doped La2Ti2O7 nanocrystals exhibit the extended light absorption up to 560 nm. It is found that the N doping into La2Ti2O7 enhances absorption in the visible light region to exhibit higher activity for photocatalytic oxidation of NO gas. The optimized N-doped La2Ti2O7 nanocrystal with 4.79 at% of nitrogen dopant possesses the best photocatalytic NOx oxidation activity under both ultraviolet and visible light irradiation compared with N-doped La2Ti2O7 samples obtained by hydrothermal reaction without TEA or flux synthesis of La2Ti2O7 and the subsequent treatment with NH3. The enhancement of photocatalytic activity should originate from simultaneous achievement of large specific surface area and strong visible light absorption due to the large amount of nitrogen dopants.

Transformation of amorphous Bi2O3 to crystal Bi2O2CO3 on Bi nanospheres surface for photocatalytic NOx oxidation: Intensified hot-electron transfer and reactive oxygen species generation

• Amorphous Bi 2 O 3 shell on the surface of Bi nanospheres was transformed to crystal Bi 2 O 2 CO 3 . • Bi 2 O 2 CO 3 shell reduced the transmission resistance of hot electrons excited from Bi core. • The generation of reactive oxygen species were enhanced over Bi@crystal Bi 2 O 2 CO 3. • •O 2 − radicals were the major reactive oxidation species contributing to the oxidation of NO x . • Generation mechanisms of ROS were proposed over Bi@crystal Bi 2 O 2 CO 3 photocatalyst. The inevitable amorphous Bi 2 O 3 on the surface of plasmonic Bi nanospheres serving as the recombination center of hot electron-hole pairs, hindered the transfer of photo-generated hot electrons and production of reactive oxygen species (ROS) seriously. In this study, Bi@amorphous Bi 2 O 3 was transformed to Bi@crystal Bi 2 O 2 CO 3 by secondary hydrothermal reaction. Bi@Bi 2 O 2 CO 3 core–shell photocatalyst exhibited higher visible-light catalytic activity (34.1%) than Bi@Bi 2 O 3 did (12.3%) in terms of NO x removal. Photoelectrochemical, surface photovoltage spectroscopy spectra and Kelvin probe force microscopy measurement results indicate that Bi 2 O 2 CO 3 shell reduced the transmission resistance of hot electrons excited from Bi core. O 2 -TPD, trapping experiments and density functional theory further confirmed that the transferred hot electrons were a help for ROS generation and •O 2 − radicals were the major contributor. This study not only addresses the unsettled issue of surface amorphous Bi 2 O 3 , but also provides a facile method to transform the amorphous shell to crystal phase of core–shell photocatalyst and new insights into the hot electrons separation and the formation of main ROS over the surface crystal transition of plasmonic Bi.

Core‐crown Quantum Nanoplatelets with Favorable Type‐II Heterojunctions Boost Charge Separation and Photocatalytic NO Oxidation on TiO2

AbstractFunctionalization of TiO2 (P25) with oleic acid‐capped CdSe(core)/CdSeTe(crown) quantum‐well nanoplatelets (NPL) yielded remarkable activity and selectivity toward nitrate formation in photocatalytic NOx oxidation and storage (PHONOS) under both ultraviolet (UV‐A) and visible (VIS) light irradiation. In the NPL/P25 photocatalytic system, photocatalytic active sites responsible for the NO(g) photo‐oxidation and NO2 formation reside mostly on titania, while the main function of the NPL is associated with the photocatalytic conversion of the generated NO2 into the adsorbed NO3− species, significantly boosting selectivity toward NOx storage. Photocatalytic improvement in NOx oxidation and storage upon NPL functionalization of titania can also be associated with enhanced electron‐hole separation due to a favorable Type‐II heterojunction formation and photo‐induced electron transfer from the CdSeTe crown to the CdSe core of the quantum well system, where the trapped electrons in the CdSe core can later be transferred to titania. Re‐usability of NPL/P25 system was also demonstrated upon prolonged use of the photocatalyst, where NPL/P25 catalyst surpassed P25 benchmark in all tests.

Environmental impact of nano-functionalized construction materials: leaching of titanium and nitrates from photocatalytic pavements under outdoor conditions

There is a growing use of nano-functionalized construction materials, which contain nanoparticles embedded in their bulk or deposited on their surfaces. In the case of photocatalytic materials, nano-TiO2 is usually added to provide it's functionality. One concern about these materials, in addition to release of nanoparticles as airborne, is that they can be leached into the aquatic environment. Moreover, water eutrophication could be caused due to the increase in NO3− as a product of the photocatalytic oxidation of NOx in runoff. In this paper, a systematic long term campaign assessing these potential side effects in the real outdoor environment has been carried out. Rainwater leachates from 4 m2 slabs of 7 different photocatalytic materials exposed outdoors in two different locations (platforms) were collected and analysed over more than 800 days. Ti, NO3−, pH and conductivity were analysed. Ti was found in the leachates of almost every material, without a clear relation with the type of application (percolated cementitious slurry, suspension/emulsion or TiO2 built-in). The highest concentration found was of 60 μg/L, which seems to be rather small when comparing with some threshold values for drinking water. In all the cases, the detected TiO2 nanoparticles from water leachates were embedded in large microparticle agglomerates coming from the construction material matrix, which are less dangerous than nanoparticles. Nitrates were leached in clear relation with the NOx oxidation photocatalytic performance, and the observed concentrations were not higher than those in the recycled water used by the Madrid City Council to clean the streets.

Enhancement of photocatalytic NOx abatement on titania via additional metal oxide NOx-storage domains: Interplay between surface acidity, specific surface area, and humidity

In this work, we propose a simple and effective preparation procedure to obtain ternary mixed oxides composed of titania (TiO2, P25), alumina (γ-Al2O3) and calcium oxide (CaO) functioning as efficient photocatalytic NOx oxidation and storage (PHONOS) catalysts that are capable of facile NOx abatement under ambient conditions in the absence of elevated temperatures and pressures with UVA irradiation. In this architecture, titania was the photocatalytic active component and CaO and/or γ-Al2O3 provided NOx storage domains revealing dissimilar specific surface areas (SSA) and surface acidities. We show that photocatalyst formulation can be readily fine-tuned to achieve superior photocatalytic performance surpassing conventional P25 benchmark in short (1 h) and long term (12 h), as well as humidity-dependent photocatalytic tests. We demonstrate the delicate interplay between the surface acidity, SSA and humidity and provide detailed mechanistic insights regarding the origin of photocatalytic activity, selectivity and deactivation pathways.

Enhanced photocatalytic NOx oxidation and storage under visible-light irradiation by anchoring Fe3O4 nanoparticles on mesoporous graphitic carbon nitride (mpg-C3N4)

Several mesoporous graphitic carbon nitride (mpg-C3N4) photocatalysts were synthesized by using a hard-templating method comprising thermal polycondensation of guanidine hydrochloride over silica spheres at three different temperatures (450, 500 and 550 ℃). After structural characterization of these mpg-C3N4 photocatalysts, they were tested in NO(g) photo-oxidation under visible (VIS) light. The effects of polycondensation temperature on the structure and photocatalytic performance of mpg-C3N4 in NO photo-oxidation were studied. The results revealed that polycondensation temperature has a dramatic effect on the photocatalytic activity of mpg-C3N4 in NO photo-oxidation, where mpg-C3N4 synthesized at 500 ℃ (mpg-CN500) showed the best performance in NOx abatement as well as a high selectivity towards solid state NOx storage under VIS light illumination. Photocatalytic performance of the mpg-CN500 was further enhanced by the anchoring of 8.0 ± 0.5 wt.% Fe3O4 nanoparticles (NPs) on it. Fe3O4/mpg-CN500 photocatalyst showed both high activity and high selectivity along with extended reusability without a need for a regeneration step. Enhanced photocatalytic NOx oxidation and storage efficiency of Fe3O4/mpg-CN500 photocatalyst was attributed to their mesoporous structure, high surface area and slow electron-hole recombination kinetics, efficient electron-hole separation and facile electron transfer from mpg-CN500 to Fe3O4 domains enhancing photocatalytic O2 reduction, while simultaneously suppressing nitrate photo-reduction and decomposition to NO2(g).

Photocatalytic oxidation of nitrogen oxides over {001}TiO2: the influence of F- ions.

A series of anatase TiO2 nanosheets with different percentage of {001} facets ({001}TiO2) were synthesized through a hydrothermal route using tetrabutyltitanate as a titanium precursor and HF as a shape controlling agent. The amount of HF exhibits an obvious influence on the structures and activities of TiO2 samples. The adsorbed surface F- ions on the {001} facets of the anatase TiO2 were removed by washing them with NaOH solution. The as-prepared catalysts were characterized by X-ray diffraction, Brunner-Emmet-Teller measurements, ultraviolet-visible diffuse reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy techniques, and X-ray photoelectron spectroscopy analysis. The results indicated that all the as-prepared catalysts showed an anatase crystalline and nanosheet structure, as well as a strong ultraviolet light absorbance. With the increase of HF content, the crystallite size and the percentage of {001} facets increased first and later decreased, state the opposite change observed in BET. When the content of HF was 4.4mL, the percentage of {001} facets reached the maximum up to 61.62%. After all samples were treated with 0.1M NaOH solution, the percentage of {001} facets increased to a maximum of 64.46%. All the samples washed by NaOH solution exhibited much higher photocatalytic activity for NOx oxidation under UV light irradiation than P25, {101}TiO2, and {001}TiO2 without NaOH washing, suggesting that the surface F- ions inhibited the photocatalytic NOx oxidation. Moreover, the results showed that the NaOH-washed {001}TiO2 has a high humidity tolerance.

Improving the Selectivity of Photocatalytic NOx Abatement through Improved O2 Reduction Pathways Using Ti0.909W0.091O2Nx Semiconductor Nanoparticles: From Characterization to Photocatalytic Performance

In this paper, we provide detailed insight into the electronic–crystallographic–structural relationship for Ti0.909W0.091O2Nx semiconductor nanoparticles, explaining the mutual electronic and magnetic influence of the photoinduced stable N- and W-based paramagnetic centers, their involvement in the photoinduced charge-carrier trapping, and their role in improving the nitrate selectivity of the photocatalytic oxidation of NOx to nitrates. In particular, reduced tungsten species in various crystallographic environments within the anatase host lattice were observed as playing a fundamental role in the storage and stabilization of photogenerated electrons. Here, we show how these reduced centers can catalyze multielectron transfer events without the need for rare and expensive platinum-group metals (PGMs). This allows for the versatile and elegant configuration of redox potentials. As a result, electron-transfer processes that are kinetically inaccessible with metal oxides such as TiO2 can now be accessed, en...

Chemical Synthesis and Characterization of ZnO–TiO2 Semiconductor Nanocomposites: Tentative Mechanism of Particle Formation

The compounds of ZnO–TiO2 can combine the characteristics of the individual oxides which has allowed them to be used as photocatalysts in general, photodegradants in the degradation of dyes, photocatalytic oxidation of NOx, antimicrobial, among other applications. In this study, ZnO–TiO2 semiconductor nanocomposites were synthesized in a controlled way at low temperature. These samples of ZnO–TiO2 were characterized using thermal analysis (TDA/TGA), IR and UV–Vis absorption spectroscopies, X-ray diffraction, and scanning electron microscopy. The primary particles showed a nanometric size (< 100 nm) and spheroidal morphology. All samples presented zincite as the main crystalline phase. When Ti4+ was added, the peaks of the diffractograms shifted slightly with respect to pure ZnO. This indicates the formation of a solid solution. Zn2TiO4 was observed in doped ZnO samples treated at 700 °C. The UV–Vis absorption spectra showed a band in the range between 350 and 425 nm, with a maximum around 375 nm (3.31 eV). With the addition of Ti4+, the nanocomposites showed a better absorbance in the visible range. Considering the nature of the synthesis process used, a mechanism was proposed to explanation of the formation of Nanocomposites.

Different Roles of Water in Photocatalytic DeNOx Mechanisms on TiO2: Basis for Engineering Nitrate Selectivity?

The nitrate selectivity of TiO2 has important consequences for its efficiency as a NOx depollution photocatalyst. Most emphasis is typically given to photocatalyst activity, a measure of the rate at which NOx concentrations are reduced, but a reduction in NOx concentration (mainly NO + NO2) is not necessarily a reduction in atmospheric NO2 concentration because the catalytic process itself generates NO2. With NO2 being considerably more toxic than NO, more emphasis on nitrate selectivity, a measure of the NOx conversion to nitrate, and how to maximize it, should be given in engineering photocatalytic systems for improved urban air quality. This study, on the importance of adsorbed water in the photocatalytic oxidation of NOx, has identified important correlations which differentiate the role that water plays in the oxidation of NO and NO2. This observation is significant and offers insights into controlling nitrate selectivity on TiO2 and the potential for increased effectiveness in environmental photocatalyst applications.

Doped and undoped anatase-based plates obtained from paper templates for photocatalytic oxidation of NOX

Titanium dioxide is frequently used for the photocatalytic degradation of organic and inorganic pollutants present in the air, such as NOx. In this work, biomorphic anatase-based plates were manufactured using paper as an innovative template for fixation of TiO2. Ceramics with microstructure similar to paper were produced by infiltration of titanium isopropoxide (TTiP) and dopants, followed by hydrolysis in NH4OH, air drying, and calcination at temperatures up to 1000°C. After heat treatment, the samples were characterized by XRD, TG/DTA, BET, EPR, and SEM. Anatase was obtained as the major phase at 800°C and remained present up to 1000°C. In tests of photocatalytic efficiency of produced plates for degradation of NOx gases, the best performance was obtained with a biomorphic anatase-based plate prepared using TTiP doped with 5% Zr4+, corresponding to 100% degradation of NOx in 35min.

Enhanced photocatalytic activity of Pt-doped TiO2 for NOx oxidation both under UV and visible light irradiation: A synergistic effect of lattice Pt4+ and surface PtO

Various platinum doped TiO2 with different doping ratios was successfully synthesized by a facile sol–gel method. The structural and optical properties of as-synthesized samples were characterized by the X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and UV–vis diffuse reflectance spectroscopy (DRS). The results showed that all samples were anatase crystals and showed extended absorption into visible light region. The Pt states in the samples were investigated by energy dispersive spectrometer (EDS) and X-ray photoelectron spectra (XPS) analyses. The results revealed that Pt4+ ions were doped into TiO2 crystal lattice with a part of PtO deposited on the TiO2 surface. Pt doped TiO2 exhibited a significantly enhanced activity than pure TiO2 and P25 for the photocatalytic oxidation of NOx under irradiation of UV light, simulate sunlight and visible light. An obviously suppressed recombination rate of photo-generated carriers in the Pt doped TiO2 was demonstrated by photoluminescence (PL) spectroscopy measurements. These results suggested that the synergistic effect of two Pt species coexisted in the catalysts played an important role in the improvement of photocatalytic performance. The photocatalytic reaction mechanisms of NOx oxidation on the catalyst under UV and visible light irradiation were discussed in detail.

Mechanism of visible light photocatalytic NO(x) oxidation with plasmonic Bi cocatalyst-enhanced (BiO)2CO3 hierarchical microspheres.

Semimetal bismuth (Bi), as an emerging non-noble metal-based cocatalyst and plasmonic photocatalyst, has attracted significant attention. In this work, a one-pot solvent-controlled synthesis strategy was utilized for the in situ-deposition of plasmonic Bi nanoparticles onto the surfaces of (BiO)2CO3 microspheres (BOC-WE) using bismuth citrate, sodium carbonate, and ethylene glycol as precursors. The introduction of the Bi nanoparticles has a pivotal effect on the morphology, optical and photocatalytic performance of the pristine (BiO)2CO3. The results indicated that the Bi nanoparticles were generated on the surface of (BiO)2CO3 microspheres via the in situ reduction of Bi(3+) by ethylene glycol. The Bi-deposited (BiO)2CO3 microspheres were used for the photocatalytic purification of NOx in air under visible light irradiation. Significantly, the BOC-WE samples exhibited a drastically promoted photocatalytic performance with a NOx removal ratio (η) of 37.2%, superior to pristine (BiO)2CO3 (η = 19.1%), outperforming other well-known visible light photocatalysts, such as C-doped TiO2 (η = 21.8%), BiOBr (η = 21.3%), BiOI (η = 14.9%) and C3N4 (η = 25.5%). The conspicuously enhanced photocatalytic capability can be attributed to the synergistic effects of the surface plasmon resonance (SPR) effect, increased visible light absorption and the efficient separation of electron-hole pairs induced by the Bi nanoparticles. The Bi nanoparticles can act as a non-noble metal-based cocatalyst for strengthening photocatalytic performance, which is similar to the behavior of noble metals (Au, Ag) in enhancing photocatalysis. The mechanism of visible light photocatalytic NOx oxidation was investigated. DMPO-ESR spin-trapping results demonstrated that hydroxyl radicals were confirmed to be the main active species for NOx photo-oxidation. Due to the SPR effect of Bi, the BOC-WE could produce more hydroxyl radicals than BOC, which was responsible for the enhanced NO photo-oxidation ability. Moreover, the BOC-WE photocatalysts showed high photochemical stability under repeated irradiation. This work demonstrates the feasibility of utilizing low cost Bi cocatalysts as a substitute for noble metals to enhance the performance of other photocatalysts. This work could not only provide new insights into the in situ fabrication of Bi/semiconductor nanocomposites, but also pave a new way for the modification of photocatalysts with non-noble metals as cocatalysts to achieve an enhanced performance for environmental and energetic applications.