NO Conversion Rate Research Articles

Synergistic catalytic oxidation of Hg0 and NH3-SCR of NO over MnCeTiOx catalyst in flue gas

The catalytic oxidation over the selective catalytic reduction (SCR) catalysts is efficient and economical for the removal of elemental mercury (Hg0). Herein, we studied the catalytic oxidation of Hg0 over the MnCeTiOx catalysts with different Ce contents synthesized by a polyethylene glycol-assisted (PEG) co-precipitation method. By increasing the contents of Ce loaded, the oxidizability of MnCeTiOx was reduced, but the NH3-SCR performance and H2O/SO2 resistance were improved. The MnCe(0.1)TiOx catalyst presented high NO conversion rate exceeding 80% at 160–360 °C and gas space hourly velocity (GHSV) of 80, 000 h−1 and Hg0 oxidation efficiency beyond 95% at 100–300 °C and 400, 000 h−1, respectively. The surface-active oxygen including chemisorbed surface O and unsaturated-coordinated surface lattice O acted as the active sites for Hg0 oxidation. The competitive adsorption and oxidation of SO2 and NH3 could suppress the adsorption of Hg0. NO and SO2 could be oxidized into active intermediates, such as NO3-* and SO42-* , which benefited the oxidation of Hg0. However, the NH3 was a strong Lewis base and reducing agent, which could be oxidized to NH2 * or NH* and then hinder the oxidation of Hg0. These results clarified the interaction among the multi-components during the oxidation of Hg0 over the SCR catalysts, which is beneficial to the development of Hg0 treatment techniques in low-temperature flue gas.

Efficient Electron Transfer by Plasmonic Silver in SrTiO3 for Low-Concentration Photocatalytic NO Oxidation.

Photocatalysis presents a feasible option to control low-concentration NO emissions from industrial burning facilities, and increasing excitons in quantity and improving surface activity are the crucial issues to be solved. Plasmonic silver with the orientation of the (111) plane is uniformly distributed on the Ti-O termination of the SrTiO3 (STO) (100) plane (major). The NO conversion rate has a sixfold increment compared to pristine STO. Meanwhile, the toxic NO2 had a significant decline in the absence of water. This high performance could be attributed to the unique property of the localized surface plasmonic resonance of silver particles, which increases the optical response range of the catalyst. Meanwhile, the formation of a Schottky junction could promote the charge separation and enhance the lifetime of excitons via the electron transfer from silver particles to STO. More importantly, the Ag-O bond of the heterojunction increases the charge density of adjacent Ti, preferring to bond with the antibonding orbital electron of adsorbed molecules, which offers a favorable channel for the NO adsorption and activation of reactive oxidation species.

Green Ce-based honeycomb catalyst with excellent water and sulfur dioxide resistances for low-temperature selective catalytic reduction of NOx with ammonia

Low-temperature selective catalytic reduction (SCR) is effective and promising for converting NOx in flue gas into N2, with wide application prospects. However, low-temperature denitration (DeNOx) catalysts are susceptible to SO2 and H2O poisoning. Here, we prepared a monolithic Mn-Fe-Ce/Al2O3 catalyst that exhibited excellent DeNOx performances at low temperatures. At 110 °C, the NO conversion rate of the catalyst was> 90%, exhibiting excellent resistances to H2O and SO2·H2O and SO2 are introduced at the same time, the efficiency is as high as 73%. Furthermore, The catalyst has a porous structure with abundant chemisorbed oxygen spices and exposed active, the reaction pathway on the catalyst proved to be the L-H mechanism based on in situ DRIFTS. This study also explored the mechanisms of low-temperature SCR catalyst poisoning by SO2 and H2O, providing insights into the effects of SO2 and H2O and theoretical support for the development of poisoning-resistant low-temperature SCR catalysts.

Preparation of hollow ceramic photocatalytic membrane grafted with silicon-doped TiO2 nanorods and conversion of high-concentration NO

A silicon-doped TiO2 nanorod (NR) graft hollow ceramic photocatalytic membrane was fabricated by a two-step hydrothermal method. The photocatalytic membranes’ surface morphology, elemental composition, group, elemental chemical valence, roughness, water contact angle and porosity were characterized by SEM-EDX, FTIR, XPS, AFM, contact-angle analysis, and mercury-injection test, respectively. The catalytic properties of the membrane surface were characterized by XRD, UV–Vis spectroscopy and PL. The catalytic separation performance of the photocatalytic membrane was evaluated by the conversion rate of NO to nitrate and the production of the intermediate NO2. Results exhibited 67.11 % higher conversion efficiency of NO (300 ppm) under UV light illumination than the individual photocatalytic system The existence of membrane structure promoted the nitrate selectivity in the photocatalytic NO process. The Si-TiO2 NR photocatalytic membrane, which coupled photocatalysis with the membrane-separation processes, showed great potential application for treatment of the high-concentration NO in thermal power plants, owing to its separation capability, good photocatalytic activity, and reusability.

Study of the performance of nitrogen-doped modified activated carbon as catalyst carrier for the selective catalytic reduction of NO with NH3 at low temperatures

Nitrogen-doped modified activated carbons (ACs) were prepared from coconut shell, date shell and almond shell using the urea modification method. NO tests of NH3 selective catalytic reduction (NH3-SCR) were conducted to evaluate the efficiency of different types of nitrogen-doped modified AC as denitration catalyst carriers between 50–220°C. Both AC and nitrogen-doped modified AC had catalytic effects on NO conversion; the nitrogen-doped modified AC had high denitrification activity in the low-temperature region, and NAC1-10 achieved an NO conversion rate of 65.7% at 50°C. The low-temperature denitrification activity of urea-modified AC was twice that of the untreated AC at all temperatures. The O2 concentration in the SCR reaction system had a significant effect on the NO conversion rate of the nitrogen-doped modified AC. As the O2 concentration increased from 0 to 1 vol%, the NO conversion rate increased rapidly from 22 to 65% and remained stable at 65%. A series of characterisation tools were used to determine the structure and physicochemical properties of the nitrogen-doped modified AC, including BET, XRD, elemental analysis, and FTIR. Nitrogen-doped AC showed good air velocity adaptability and low-temperature stability, suggesting that it is a promising carrier for NH3-SCR catalysts.

Study on Double-Layer Ignition Sintering Process Based on Autocatalytic Denitrification of Sintering Layer

An efficient sintering process was proposed based on the autocatalytic denitrification of the sintered ore. The catalytic denitrification of sintered ore, the effect of double-layer ignition sintering process on the emission reduction in nitrogen oxides, and the impact on the quality of sintered ore were studied. The results showed that the catalyzed reduction of NO with sinter ore as a catalyst has a significant effect; when the airspeed reaches 3000 h−1, the temperature is 500 °C, and the conversion rate of NO can reach 99.58%. The sinter yield of double-layer ignition sintering is increased, solid fuel consumption is slightly reduced, falling strength is slightly increased, and drum strength is slightly decreased. Under the conditions of layer height proportion of 320/400 mm (lower/upper) and ignition time interval of 10 min, the yield, drum strength, shatter strength, and solid fuel consumption reached 61.60%, 54.82%, 46.75%, and 69.55%, respectively. NOx concentration under the 16% baseline oxygen content (c(NOx)’) in the flue gas of double-layer ignition sintering is reduced to a certain extent, and the generation time of NOx is greatly shortened. The double-layer ignition sintering process can reduce the emission of nitrogen oxides in the sintering process under the condition of guaranteeing the quality of sinter, which has great economic and environmental benefits.

Waste straw derived Mn-doped carbon/mesoporous silica catalyst for enhanced low-temperature SCR of NO

This work proposed a new strategy for the high value utilization of waste straw, in which a Mn-doped carbon/mesoporous silica composite catalyst was prepared by simultaneous utilization of carbon and silicon source from straw for low-temperature denitration. The results showed that the NO conversion rate reached 93% at 180℃ for the composite catalyst with Si/C mass ratio of 35% (Mn/ACMS (35%)). This was significantly higher than those of the activated carbon catalyst (Mn/AC) and mesoporous silica catalyst (Mn/MS), i.e., 58% and 50%, respectively. The SEM images showed that mesoporous silica nanoparticles were dispersed evenly on the carbon surface to form composite materials. XPS results indicated that Mn/ACMS (35%) catalyst showed higher content of chemically adsorbed oxygen (Oα) and Mn4+ (54.67% and 46.81%) than Mn/AC catalyst (34.38% and 17.49%) and Mn/MS catalyst (32.71% and 30.18%), which was responsible for the improved catalytic activity. Moreover, NH3-TPD results revealed that Mn/ACMS (35%) had high surface acidity of 6.47mmol·g-1, significantly higher than Mn/AC catalyst of 1.51mmol·g-1, which was beneficial for adsorbing NH3. H2-TPR results suggested that Mn/ACMS (35%) catalyst had much higher H2 consumption of 1.32mmol·g-1 than Mn/AC and Mn/MS catalyst, suggesting better redox performance. The results demonstrated that the straw derived Mn-doped carbon/mesoporous silica composite catalyst can be a potential material for low-temperature denitration.

A comprehensive study of char reaction kinetics: Does CO always promote NO reduction on char surface?

This investigation focuses on the NO reduction process over chars and quantifies the effects of CO on char-NO reactivity under different conditions. Kinetic data were measured in a lab-scale fixed-bed reactor at temperatures between 1023 K and 1223 K, involving three coal chars with coal ranks ranging from lignite to anthracite. Experimental results show that CO can promote the reduction of NO over chars at low temperatures. However, there is a significant decrease in NO conversion rate at high temperatures compared to the case without CO present in the gas. The promotion or inhibition effects of CO on char-NO reactivity will become more obvious if the CO concentration is higher. Moreover, the consumption rate of NO is about the same as the generating rate of CO2 under high-level CO conditions, while a considerable amount of CO is generated during the direct reduction of NO by carbon. Further analysis based on Langmuir adsorption theory also indicates that char plays a catalytic role in NO reduction rather than acting as a reactant when CO is added. In addition, under the same temperature and gas conditions, the reactivity of SC lignite char is roughly five times higher than that of HP bituminous char and ten times higher than that of WH anthracite char, namely, the increase of coal rank leads to the decline in char-NO reactivity. Besides, the char made from higher rank coal has a broader range of temperature at which the CO presents a positive effect on NO reduction. Finally, a simple expression was proposed to calculate the NO reduction rate on char surface based on the experimental data, which can be easily applied in the description of nitrogen chemistry for fluidized bed combustion.

Catalytic effect of rare earth tailing on NO[formula omitted] reduction in CO reburning

The effect of catalytic denitration performance of rare earth tailing was experimentally investigated at 300–900 °C. The rare earth tailing was separated to magnetic separation tailing and magnetic separation concentrate by high intensity magnetic separation. A fixed-bed reactor was used to evaluate the catalytic denitration performance of rare earth tailing, magnetic separation tailing, and magnetic separation concentrate. The X-ray Diffraction (XRD), Advanced Mineral Identification and Characterization System (AMICS), Scanning Electron Microscope (SEM) and H2 Temperature Programmed Reduction (H2-TPR) were used to characterize the three tailing. The results showed that it was difficult for CO to react directly with NO. When the temperature was 900 °C, the NO conversion rate was only 6.4%. After adding three minerals, the NO conversion rate increased significantly. When the reaction temperature was 500 °C–700 °C, the NO conversion rate of magnetic separation tailing was higher than that of rare earth tailing and magnetic separation concentrate. With the increase in the CO volume fraction, the NO conversion rate of the three minerals increased first and then decreased. The increase in the volume fraction of CO2 and SO2 had little effect on the conversion rate of NO, the incorporation of O2 seriously affected the conversion rate of NO.

NO reduction by semi-coke and tailing combined catalyst

The combined catalyst of semi-coke and tailing were used to study the NO reduction rate and CO production in the laboratory fixed-bed reactor. The experimental results indicate that the combined denitration method of semi-coke and tailing has significantly better NO conversion rate, CO production, and N2 selectivity than denitration of semi-coke alone. The increase in reaction temperature and the introduction of O2, CO2, and SO2 increased the effect of the combined coke-tailing catalytic denitration to varying degrees. The combined catalytic denitration effect of semi-coke and magnetic separation tailing was superior to the combined catalytic denitration effect of semi-coke and rare-earth tailing.

Activity Test and Mechanism Study of 3DOM Ce0.8M0.1Zr0.1O2 (M=Cr, Sn, Fe, Co, Ni, Mn, Cu) Catalyst in the Selective Catalytic Reduction of NO by CO**

AbstractA series of three‐dimensionally ordered macroporous (3DOM) Ce0.8M0.1Zr0.1O2(M=Cr, Sn, Fe, Co, Ni, Mn, Cu) catalysts are synthesized and used in CO selective catalytic reduction of NOx. The results show that the NO conversion rate of 3DOM Ce0.8Cu0.1Zr0.1O2 catalyst at a lower temperature (150 °C) is close to 60 %. Besides, 3DOM Ce0.8Cu0.1Zr0.1O2 kept a stable NO removal efficiency within a wide range of gas hourly space velocity (GHSV) and long reaction time and exhibited remarkable resistance to H2O and SO2 poisoning, both individually and simultaneously. At the same time, the formation of the 3DOM structure not only improves the reduction performance and surface active sites of the catalyst, but also forms more oxygen defects and Ce3+ in the catalyst due to the strong synergistic effect of metal ions and ceria, which improves the surface oxygen concentration of the composite oxide catalyst and further improves the catalytic activity. In addition, the doping of copper ions on the surface of the 3DOM Cu‐CZ catalyst can improve the activity of the catalyst and it can get trapped by CO to form Cu+‐CO, which plays an important role in the NO+CO reaction at low temperature. The existence of oxygen vacancy at high temperature is beneficial to the activation of O2 and the dissociation of NO in the process of CO oxidation. The reaction of NO+CO over 3DOM Cu‐CZ catalyst follows L−H and E−R mechanism respectively.

Simultaneous catalytic oxidation of NO and Hg0 over LaBO3 (B = Co, Mn, Ni, and Cu) perovskites

Perovskite catalysts have emerged as potential candidates for simultaneous catalytic oxidation of NO and Hg0 present within the coal-derived flue gas. LaBO3 (B = Co, Mn, Ni, and Cu) perovskites were synthesized by sol–gel method. LaMnO3 and LaCoO3 exhibited better simultaneous oxidation activities among LaBO3 (B = Co, Mn, Ni, and Cu) perovskites (LaMnO3 > LaCoO3 > LaNiO3 > LaCuO3). The experimental results revealed that the simultaneous oxidation conversions of LaCoO3 and LaMnO3 for NO and Hg0 oxidation were all around 80% at 285 °C. The oxidation conversions of NO and Hg0 by LaNiO3 were less than 70%, and for LaCuO3, the NO conversion rate was up to 50%, while Hg0 was less than 20%. The excellent simultaneous oxidation activities of LaBO3 (B = Co, Mn, Ni, and Cu) perovskites originated from the B-site ion activities in the order of Mn4+ > Co3+ > Ni2+ > Cu2+. And surface area, OL/OA ratio and reducibility showed the following trends: LaMnO3 > LaCoO3 > LaNiO3 > LaCuO3. Furthermore, as typical LaMnO3 and LaCoO3 perovskites, the Hg0 would compete with NO for adsorption on the surface, resulting in a decrease in NO oxidation. However, the NO increased the Hg0 conversion, which was related to NO2 oxidized from NO. The reaction mechanisms of LaMnO3 and LaCoO3 were obtained from the characterizations of XPS, NO-TPD, in situ DRIFTS and Hg-TPD. Hg0 was oxidized to HgO, not Hg(NO3)2. NO was converted into free nitrate species and gradually enriched on the perovskite surface; consequently, it turned into NO2.

Study on the CO-SCR anti-sulfur and denitration performance of V-doped OMS-2 catalysts

A catalyst with high NO conversion rate and good sulfur resistance is the key to CO-SCR. Herein, the V-doped OMS-2 molecular sieves were successfully synthesized through the hydrothermal method. The resulting catalyst was characterized by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscope(TEM) and specific surface area analyzer (BET). The results showed that the addition of V increased the average grain size of OMS-2 and the concentration of oxygen vacancies. Meanwhile, V replaced the K site in OMS-2 and participated in the oxidation-reduction reaction together with Mn. Compared with the V0-OMS-2, the NO conversion rate of V0.2-OMS-2 in a sulfur-free environment increased from 60% to 81% at 150 °C and 75%–94% at 300 °C. The NO conversion rate could still maintain as 80% at 300 °C in a sulfur-containing environment.

Effects of sulfation on hematite for selective catalytic reduction of nitrogen oxides with ammonia

Hematite (α-Fe2O3) is a promising candidate for NH3 selective catalytic reduction (NH3-SCR) of NOx due to its good sulfur resistance. However, the activity of pure α-Fe2O3 is very low. In this work, α-Fe2O3 obtained excellent N2 selectivity and medium–high temperature activity via a simple surface sulfation method. The α-Fe2O3-350 (sulfated at 350 °C) sample showed an NO conversion rate of ~ 100% in the range of 275–350 °C and exhibited excellent H2O and SO2 resistance ability at 300 °C. Furthermore, pure α-Fe2O3 was used as a model catalyst to fully uncover the effect of sulfation on FeOx-based catalysts in NH3-SCR reactions. Structural characterization indicated that the degree of surface sulfation of the catalyst would be deepened with increasing temperature, and the states of sulfate species on α-Fe2O3 changed from surface sulfates to bulk-like sulfates. Although sulfation treatment reduced the redox properties of α-Fe2O3, it significantly increased its surface acidity and thus the activity. Excessive bulk-like sulfates induced a decrease in activity. Sulfation inhibited the adsorption of NOx on the α-Fe2O3 catalyst surface and reduced the thermal stability of nitrates at medium–high temperature. Thus, the Langmuir-Hinshelwood (L-H) mechanism was inhibited, and the reaction mainly followed the Eley-Rideal (E-R) mechanism.

Mn and Fe oxides co-effect on nanopolyhedron CeO2 catalyst for NH3-SCR of NO

The active components Mn and Fe oxides were loaded on the surface of CeO2 catalyst with nanopolyhedrons morphology (CeO2-NPs) by impregnation method to improve the CeO2-NPs catalyst catalytic performance. The activity test results showed that the activity order of these catalysts within the temperature of 100–300 °C was Fe-Mn-Ce > Mn-Ce > Ce catalyst, and the NO conversion rate of Fe-Mn-Ce catalyst was the highest at 200 °C, which was about 98%. The performances of these catalysts were further investigated by SEM, XRD, XPS, Raman spectra, H2-TPR, NH3-TPD and in situ DRIFT. The results indicated that Fe-Mn-Ce catalyst possessed the best reducibility and surface acidity of the three catalysts. According to the XPS and Raman spectra tests, the sequences of the ratio of Oα/(Oα+Oβ) and Ce3+/(Ce3++Ce4+) were both Fe-Mn-Ce > Mn-Ce > Ce catalyst, which indicated that the Fe-Mn-Ce catalyst possessed the most oxygen vacancy and further improved the catalytic activity of the catalyst. Moreover, the Fe-Mn-Ce catalyst also exhibited the best tolerance to SO2 of the three catalysts at 225 °C. In general, simultaneous loading of manganese and iron oxides on the CeO2-NPs catalyst could effectively improve the low temperature SCR performance of the catalyst.

NO catalytic performance analysis of gasoline engine tapered variable cell density carrier catalytic converter.

Improving the flow field uniformity of catalytic converter can promote the catalytic conversion of NO to NO2. Firstly, the physical and mathematical models of improved catalytic converter are established, and its accuracy is verified by experiments. Then, the NO catalytic performances of standard and improved catalytic converters are compared, and the influences of structural parameters on its performance are investigated. The results showed that: (1) The gas uniformity, pressure, drop and NO conversion rate of the improved catalytic converter are increased by 0.0643, 6.78%, and 7.0% respectively. (2) As the cell density combination is 700 cpsi/600 cpsi, NO conversion rate reaches the highest, 73.7%, and the gas uniformity is 0.9821. (3) When the tapered height is 20 mm, NO conversion rate reaches the highest, 72.4%, and the gas uniformity is 0.9744. (4) When the high cell density radius is 20 mm, NO conversion rate reaches the highest, 72.1%, and the gas uniformity is 0.9783. (5) When the tapered end face radius is 20 mm, NO conversion rate reaches the highest, 72.0%, and the gas uniformity is 0.9784. The results will provide a very important reference value for improving NO catalytic and reducing vehicle emission.

Effect of synergy between oxygen vacancies and graphene oxide on performance of TiO2 for photocatalytic NO removal under visible light

It is important to find an effective way to enhance the photocatalytic NO removal efficiency of black-TiO2. In this work, we used a simple hydrothermal method to synthesize the black TiO2-GO composite. One of the black TiO2-GO composites, B-TiO2-3GO (black TiO2-GO composites with graphene content of 3 wt%), exhibits remarkably high activity toward the photocatalytic removal of NO, with a NO conversion rate of 50.4% which is greater than that of pure black TiO2 (33.9%). The experimental results revealed that the TiO2-GO nanocomposite photocatalyst has the high absorption ability from large surface area and well mobility of charge carriers, which can enhance its photocatalytic activity. What’s more, the UV–vis (DRS)spectra, XPS and NO-TPD-MS indicated that the synergy between H2O2, oxygen vacancies and GO. Finally, a possible photocatalytic NO removal mechanism over the B-TiO2-GO composite is also presented based on the results of the band structures, the free radical capture experiments and electron spin resonance (ESR) tests. This work would provide a strategy to design HNO3/H2O2-resistant deNOx photocatalyst in the pollutant purification field.

The water resistance enhanced strategy of Mn based SCR catalyst by construction of TiO2 shell and superhydrophobic coating

The Mn-based catalyst with hollow spherical structure was prepared by hydrothermal method and used for selective catalytic reduction (SCR) of NO with NH3. Mn-based catalysts exhibit excellent de-NOx performance at low-temperature, but narrow operating temperature window and poor water resistance restrict its application. Effectively expanding the operating temperature window and improving the H2O resistance of the Mn-based catalyst are the keys to industrial application. In this article, the H-MnO2 catalyst was prepared by hydrothermal method and modified by kinetic adsorption and vapor deposition methods. The TiO2 layer can effectively limit the excessive redox performance and improve the acidity of the catalyst surface, the NO conversion above 90% at 140–380 °C of H-MnO2@TiO2 catalyst. The phenyltrimethoxysilane was deposited on the surface of the H-MnO2@TiO2 catalyst by vapor deposition method. The NO conversion rate of the H-MnO2@TiO2@HL catalyst exceeds 80% in the temperature range of 180–380 °C. When the H2O was introduced, the NO conversion rate increases from 70% to 85% at 180 °C. The in situ DRIFTs results showed NH3 and NO could be adsorbed and activated on the catalyst surface, and the catalytic reaction follows Langmuir-Hinshelwood (L-H) mechanism. Under the presence of H2O, the NH4+ bonding to Brønsted acid sites were inhibited but the NH3 bonding to Lewis acid site was almost unaffected. In summary, through two-step modification, the operating temperature window and water resistance of Mn-based catalysts are effectively improved. It can be seen that a reasonable structure design can effectively improve the comprehensive performance of the catalyst.

A Green CeO2−WO3/TiO2 Medium‐Low Temperature de‐NOx Catalyst for Selective Catalytic Reduction of NOx with NH3

AbstractA series of CeO2−WO3/TiO2 catalysts were synthesized by the co‐precipitation method and used for selective catalytic reduction (SCR) of NO with NH3 under medium‐low temperature conditions with metatitanic acid as Ti source. A more reasonable weight ratio of CeO2 and WO3 was explored. The catalytic activity enhanced with the increase of cerium content, but the catalytic activity changed slightly in the temperature range of 240 °C to 400 °C when the cerium content exceeded 15 %. Tungsten could enhance the sulfur resistance by adjusting the degree of crystallization, acidity in the SCR process. When the weight ratio of CeO2 to WO3 was 15: 8, the conversion rate of NO was more than 90 % in the temperature range of 240 °C to 440 °C. For 15 %CeO2‐8 %WO3/TiO2 catalyst, the NO conversion was maintained around 84 % when the mixed gas was introduced SO2. At the same time, we have optimized the selection of carriers, metatitanic acid as a carrier was better than titanium dioxide.

Enhanced solar photocatalytic degradation of nitric oxide using graphene quantum dots/bismuth tungstate composite catalysts

• A novel method for the preparation of graphene quantum dots/bismuth tungstate (GQDs/BWO) composite photocatalysts. • Performance evaluation of enhanced sunlight responsive photocatalytic performance of GQDs/BWO composite for nitric oxide degradation. • The formation of Z-scheme heterojunction between GQDs and Bi 2 WO 6 . • The mechanism of photocatalysis of the GQDs/BWO photocatalysts. Composite (GQDs/BWO) materials for enhanced photocatalysis are hydrothermally produced by combining graphene quantum dots (GQDs) with bismuth tungstate (Bi 2 WO 6 ). These GQDs/BWO nanomaterials are evaluated for photocatalysis, at different GQDs loadings, for the degradation of gaseous nitric oxide with concentrations of 10–11 ppm. Results show that 10GQDs/BWO has the best photocatalytic performance among competitors for NO degradation. The NO conversion rate reaches 73% during 30 min, which is 3.84 times higher than that of pure Bi 2 WO 6 . This is because GQDs not only have a good electron transfer ability, but also form a direct Z-scheme heterojunction with Bi 2 WO 6 . These features promote electron-hole separation efficiency of the composite catalyst, and inhibit their recombination. This performance results from the increase in the surface area of the composite and to the increase in light absorption. The selectivity for the formation of NO x - ( S N O x - ) increased from 66 to 88%, and the DeNO x index increased from −0.003 to 0.43 after the introduction of GQDs. Active species scavenger experiment, Mott-Schottky (MS) tests and density functional theory (DFT) calculations are used to evaluate the mechanism of photocatalytic NO. Furthermore, cyclic tests show that 10GQDs/BWO catalysts maintain their chemical stability for NO degradation over 8000s.