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[Display omitted] Converting CO 2 into chemicals and fuels by solar energy can alleviate global warming and solve the energy crisis. In this work, CoAl-LDO/MoO 3−x (LDO/MO) composites were successfully prepared and achieved efficient CO 2 reduction under visible light. The CoAl-layered double oxides (CoAl-LDO) evolved from CoAl-layered double hydroxide (CoAl-LDH) exhibited a more robust structure, broader light absorption, and improved CO 2 adsorption ability. The local surface plasmon resonance (LSPR) effect excited by nonstoichiometric MoO 3−x broadened the photo-response range of CoAl-LDO/MoO 3−x. In addition, constructing step-scheme (S-scheme) heterojunctions could simultaneously optimize the migration mechanism of photogenerated electrons and holes, and retain carriers with strong redox ability. Therefore, the production rates of CO and CH 4 on the optimal LDO/MO composite were 7 and 9 times higher than the pristine CoAl-LDH, respectively. This work hybridizes oxidation photocatalysts and LDO-based materials to optimize the charge separation and migration mechanisms, which guides the modification of LDO-based materials. [ABSTRACT FROM AUTHOR]

In this research, a ternary Cu-CuTCPP/Cu2O/CoAl-LDH composite with a dual Z-scheme heterostructure was fabricated based on a Cu2O photocatalyst and applied in photocatalytic CO2 reduction. The physicochemical properties of the prepared catalysts and the possible reaction mechanism in CO2 reduction were analyzed and studied by various characterization methods. The activity of CO2 reduction significantly increased, especially forming C2 products. The optimal yield of C2H4 and C2H6 reached 1.56 and 1.92 μmol g−1 h−1 respectively, which was 14.45 and 17.45 times that from using the Cu2O monomer. In addition, the selectivity of C2 products reached 37.4%. The satisfactory C2 yield was mainly due to the fact that Cu1+δ2(COO)3 nodes in Cu-CuTCPP contained adjacent Cu sites, which effectively promoted the C–C coupling reaction. Moreover, the dual Z-scheme heterojunction stimulated the separation of photogenerated electron–hole pairs and diminished the recombination rate. This work contributes to the development of novel photocatalysts with a dual Z-scheme heterojunction and facilitates the generation of valuable C2 products. [ABSTRACT FROM AUTHOR]

The photocatalytic reduction of CO2 to hydrocarbons is expected to simultaneously alleviate the energy crisis and greenhouse effect. Herein, the ternary BiOCl/C/Cu2O catalysts with different mass ratios were compounded using a simple hydrothermal method, revealing better photocatalytic activity than the monomer. In the absence of sacrificial agents and photosensitizers, 25% BiOCl/C/Cu2O showed optimal photocatalytic performance. The CO and CH4 yields over 25% BiOCl/C/Cu2O reached 26.77 and 9.86 μmol g−1 h−1, which is 2.9 and 8.7 times higher than that of the pristine Cu2O, respectively. The ameliorative activity can be attributed to the construction of the Z-scheme heterostructure and carbon layer, which are conducive to the transfer and separation of photogenerated carriers. This study offers valuable references for the design and investigation of a Z-scheme heterojunction using a carbon layer as an electron transfer medium. [ABSTRACT FROM AUTHOR]

[Display omitted] Photocatalytic reduction of CO 2 to high-energy products is an effective way to utilize solar energy and mitigate the greenhouse effect. In this paper, a series of CQDs/Bi 12 O 17 Cl 2 /NiAl-LDH (C/BOC/LDH) photocatalysts were prepared via a one-pot hydrothermal method, demonstrated excellent photocatalytic CO 2 reduction performance. In the case of only water without any photosensitizer and sacrificial agent, the CO production rate on C/0.3BOC/LDH reached 16.4 μmol·g-1h−1, which is 6.7 times higher than that of the original LDH. The construction of Z-scheme heterojunctions inhibited the recombination of electrons with holes. The unique up-conversion PL behavior of CQDs benefitted the absorption of energy in the NIR by the photocatalyst. This study provides meaningful assistance for the design and construction of a ternary photocatalytic system with Z-scheme heterojunction and carbon-based co-catalyst. [ABSTRACT FROM AUTHOR]

Facilitating the separation of photoexcited electron-hole pairs and enhancing the migration of photogenerated carriers are essential in photocatalytic reaction. CoS/g-C 3 N 4 /NiS ternary photocatalyst was prepared by hydrothermal and physical stirring methods. The optimized ternary composite achieved a hydrogen yield of 1.93 mmol g−1 h−1, 12.8 times that of bare g-C 3 N 4 , with an AQE of 16.4% at 420 nm. The enhanced photocatalytic activity of CoS/g-C 3 N 4 /NiS was mainly ascribed to the synergistic interaction between the Z-scheme heterojunction constructed by CoS and g-C 3 N 4 and the NiS co-catalyst featuring a large amount of hydrogen precipitation sites, which realized the efficient separation and migration of photogenerated carriers. In addition, the CoS/g-C 3 N 4 /NiS heterojunction-co-catalyst system exhibited excellent photocatalytic stability and recyclability. • CoS/g-C 3 N 4 /NiS ternary photocatalyst was prepared by hydrothermal and physical stirring methods. • A large amount of hydrogen precipitation sites are available on CoS/g-C 3 N 4 /NiS ternary photocatalyst. • The Z-scheme heterojunction combined with the co-catalyst promoted the separation and migration of photogenerated carriers. [ABSTRACT FROM AUTHOR]

[Display omitted] As a renewable green energy, hydrogen has received widespread attention due to its huge potential in solving energy shortages and environment pollution. In this paper, a one-step solvothermal method was applied to grow ultra-thin g-C 3 N 4 (UCN) nanosheets and NiS nanoparticles on the surface of ZnIn 2 S 4 (ZIS). A ternary NiS/ZnIn 2 S 4 /ultra-thin-g-C 3 N 4 composite material with dual high-speed charge transfer channels was constructed for the advancement of the photocatalytic H 2 generation. The optimal ternary catalyst 1.5wt.%NiS/ZnIn 2 S 4 /ultra-thin-g-C 3 N 4 (NiS/ZIS/UCN) achieved a H 2 evolution yield reached to 5.02 mmolg−1h−1, which was 5.23 times superior than that of pristine ZnIn 2 S 4 (0.96 mmolg−1h−1) and even outperform than that of the best precious metal modified 3.0 wt%Pt/ZnIn 2 S 4 (4.08 mmolg−1h−1). The AQY at 420 nm could be achieved as high as 30.5%. The increased photocatalytic performance of NiS/ZIS/UCN could be ascribed to the type-I heterojunctions between intimated ZIS and UCN. In addition, NiS co-catalyst with large quantity of H 2 evolution sites, could result in efficient photo-induced charges separation and migration. Furthermore, the NiS/ZIS/UCN composite exhibited excellent H 2 evolution stability and recyclability. This work would also offer a reference for the design and synthesis of ternary co-catalyst with heterojunction composite for green energy conversion. [ABSTRACT FROM AUTHOR]

• Cr and Mn atoms are the main active sites over CrMn 1.5 O 4 (1 0 0) surface. • A reaction scheme for the reduction of NO on the surface of CrMn 1.5 O 4 catalyst is proposed. • The generation of N 2 is accomplished in two main steps. • The energy barrier for the reaction to generate NO 2 is extremely low and contributes significantly to the reduction of NO. A comprehensive study of the catalytic behavior of CrMn 1.5 O 4 catalysts in the selective catalytic reduction (SCR) of nitrogen oxides (NO x) using NH 3 as the reductant was presented. The active sites for NO x reduction and NH 3 adsorption on the CrMn 1.5 O 4 surface were identified by density functional theory (DFT) calculations. The study elucidates the mechanism of NH 3 dehydrogenation and NO reduction, revealing key intermediates and reaction pathways. DFT calculation results showed that the chromium and manganese atoms on the surface, participating in the specifically d − sp hybridization with NH 3 , NO, played a key role in adsorption, and that NH 3 dehydrogenation led to the formation of NH 2 , which was a key intermediate in the selective catalytic reduction reaction. To further understand the process of NO generation to NO 2 and N 2 O on the surface of CrMn 1.5 O 4 catalyst, the chain reaction steps of NO reduction were proposed. Among them, NO was oxidized to NO 2 , and the very low reaction energy barrier contributed greatly to the fast SCR reaction, while the generation of the unwanted product N 2 O had a relatively high energy barrier, so the reaction was not easy to occur. These findings contribute to a deeper understanding of the intricate catalytic behavior of CrMn 1.5 O 4 catalysts, which will aid in the development of better SCR catalysts for the effective removal of NO x in industrial settings. [ABSTRACT FROM AUTHOR]

• MnCoO x @TiO 2 nanocage catalysts derived from the Prussian blue analogue exhibited excellent SCR performance and SO 2 tolerance. • The SCR reaction pathways based on both L-H and E-R mechanisms were investigated. • More ad-NH 3 and ad-NO x species with higher reactivity are available on the surface of the MnCoO x @TiO 2 catalyst. • The synergistic effect of the MnCoO x core and TiO 2 shell is crucial to the SCR reaction and SO 2 resistance. By annealing the self-assembled Mn 3 [Co(CN) 6 ] 2 ·nH 2 O@Ti(OH) 4 , MnCoO x @TiO 2 double-walled nanocage catalysts were obtained. Excellent low-temperature NH 3 -SCR performance (above 90 % NO conversion efficiency at 200–325 °C), acceptable stability, and exceptional SO 2 resistance were demonstrated. According to a series of characterizations, the MnCoO x @TiO 2 catalysts were found to have an enlarged specific surface area, improved surface acidity and redox ability, enhanced dispersion of active components, and abundantly formed adsorbed oxygen (O ads) species, which consequently exhibited the improved deNO x performance. Meanwhile, the coating of the TiO 2 shell reduced the basic sites to adsorb SO 2 , hence leaving a certain proportion of active metal oxides preserved. Apparently, the MnCoO x @TiO 2 catalysts were observed to have an enhanced SO 2 -resistant ability. [ABSTRACT FROM AUTHOR]

Graphite carbon nitride (g‐C3N4), as a non‐metallic photocatalyst, possesses special band structure, excellent stability and unique surface properties, which has become a focus of attention for photocatalytic application. However, pure g‐C3N4 is subject to the limit of visible light response, small specific surface area and rapid recombination of photogenerated carriers, which leads to its low photocatalytic efficiency. Due to the unique electronic structure, various quantum dots (QDs) can be applied to modify g‐C3N4 to improve the photocatalytic activity. Thus, we highlight these QDs modified g‐C3N4‐based composites by emphasizing their synthesis, their physicochemical properties as well as their photocatalytic applications in CO2 reduction, hydrogen production and pollutants degradation in this review. At last, critical summaries and some perspectives on the challenges and directions in this research field are also presented. [ABSTRACT FROM AUTHOR]

Promoting the separation of photogenerated electron–hole pairs and enhancing the charge carrier transfer are critical in photocatalysis. In our work, a ball-flower-like NiS/Zn3In2S6/g-C3N4 photocatalyst fabricated by a hydrothermal method exhibited superior performance for photocatalytic water splitting. The optimized 2.0% NiS/Zn3In2S6/g-C3N4 rivaled noble metal based Pt/g-C3N4 and showed an apparent quantum efficiency (AQE) of 24.3% at 420 nm, with a H2 yield of 4.135 mmol g−1 h−1, which was 30.4 and 9.51 times that of pure g-C3N4 and binary Zn3In2S6/g-C3N4 composites, respectively. The experimental and characterization results suggested that the heterojunction formed between Zn3In2S6/g-C3N4 and the decorating NiS co-catalyst cooperatively suppressed the electron–hole recombination and facilitated the charge carrier transfer, thus resulting in significant improvement of the H2 evolution performance. Moreover, the increased specific surface area and the enhanced visible-light absorption also contributed to superior water splitting performance. The prepared ternary catalytic system with the heterojunction and non-noble metal co-catalyst has great potential as an alternative to noble metals for achieving cost-efficient water splitting systems. [ABSTRACT FROM AUTHOR]

In this study, a remarkable offset deactivation effect of K and P on MnEuOx SCR catalyst has been found. Experimental results showed that the NO conversion over K−P poisoned catalyst was close to 80 % at 250 °C. Several characterization techniques containing NH3‐TPD, XPS, H2‐TPR, XRD and in situ DRIFT were used to reveal the mechanism of the offset effect. The characterization of NH3‐TPD and H2‐TPR suggested that the introduction of P on MnEuOx‐K could improve its surface acidity and redox ability. Moreover, the content of chemisorbed oxygen and Mn4+ were markedly restored under the situation that the toxic elements were coexistent on catalyst surface. The strong interaction between K and P might be the major reason for the offset deactivation effect. More specifically, PO3− species were preferentially bonded with the surface potassium species and released MnO2 active sites poisoned by K. Therefore, the highly active MnO2 sites might be protected and the catalytic activity could be restored. [ABSTRACT FROM AUTHOR]

Effectively harnessing solar energy for the conversion of CO2 into valuable chemical energy presents a viable solution to address energy scarcity and climate change concerns. Nonetheless, the limited light absorption and sluggish charge kinetics significantly hinder the photoreduction of CO2. In this study, we employed a facile sol–gel method combined with wetness impregnation to synthesize Cu-doped TiO2 coated with NiOx nanoparticles. Various characterizations verified the successful incorporation of Cu ions into the TiO2 crystal lattice and the formation of NiOx co-catalysts within the composites. The optimal performance attained with CTN-0.5 demonstrates an output of 11.85 μmol h−1 g−1 for CO and 9.51 μmol h−1 g−1 for CH4, which represent a 4.4-fold and 15.6-fold increase, respectively, compared to those achieved with pure TiO2. The induced Cu defect band broadens the light absorption by decreasing the conduction band edge of TiO2, while NiOx upshifts the valence band of TiO2 because of the interaction of valence orbitals. Light irradiation EPR and FTIR tests suggest that the collaboration of CuOx and NiOx promotes the formation of oxygen vacancies/defects and a rapid charge transfer pathway, thereby provides numerous active sites and electrons to enhance CO2 photoreduction performance. [ABSTRACT FROM AUTHOR]

• The B-TiO 2 /CuInS 2 Z-scheme heterojunction with visible light response was prepared. • B-TiO 2 /CuInS 2 could convert CO 2 into CO and CH 4 with the yields 21.39 and 4.83 µmol g−1 h−1. • Both boron doping and CuInS 2 sensitization can effectively improve the utilization of visible light. • The synergistic effect of B doping Z-scheme heterojunction optimized the separation and migration of photogenerated carriers. Photocatalytic reduction CO 2 into valuable solar fuels is a promising strategy to alleviate the greenhouse effect and the energy crisis on Earth. In this work, a B-TiO 2 /CuInS 2 photocatalyst has been synthesized through a simple hydrothermal-calcination method for efficient reducing CO 2 into CO and CH 4. Boron doping and sensitization of CuInS 2 ensure the excellent visible light response capacity of the composite catalyst. The synergistic effect between oxygen vacancies and Z-scheme heterojunction also endow the photocatalyst with strong carrier separation capability. Consequently, the optimized B-TO/CIS-2.5 sample exhibited the best CO (21.39 μmol g−1 h−1) and CH 4 (4.83 μmol g−1 h−1) production, approximately 9 and 14 times higher than that of TO and B-TO, respectively. This study provides a reliable approach for developing photocatalysts with boosted CO 2 reduction activity and high stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • The CoAl-LDH/CGCNN-Metal NPs ternary photocatalysts with visible light response were prepared. • CoAl-LDH/CGCNN-Au NPs could convert CO 2 into CO, CH 4 , C 2 H 4 , and C 2 H 6 with the yields of 5.93, 17.68, 1.25 and 2.15 µmol g−1h−1. • The synergistic effect between S-scheme heterojunction and metal NPs could improve the light absorption capacity and the separation of photogenerated electron-hole pairs. Converting CO 2 into high-value products by photocatalysis can alleviate the global greenhouse effect and energy crisis. In this work, CoAl-LDH/CGCNN-Metal NPs (AC-M) ternary photocatalysts were synthesized by calcination, hydrothermal, and ultrasonic self-assembly methods. In pure water, the best sample AC-Au could convert CO 2 into CO, CH 4 , C 2 H 4 , and C 2 H 6 with the yields of 5.93, 17.68, 1.25 and 2.15 µmol g−1h−1, respectively, and exhibited good stability within 5 cycles (30 h). The synergistic effect between S-scheme heterojunction and metal NPs could broaden the composite's photo-response range and promote the separation of photogenerated carriers. Furthermore, the metal NPs could also serve as the electron-rich centers to improve the chemisorption of CO 2 and convert it into C 1 and C 2 products under visible light. This work can provide meaningful guidance for studying the efficient reduction of CO 2 to C 1 and C 2 products by S-scheme heterojunction/metal NPs ternary photocatalytic system. [ABSTRACT FROM AUTHOR]

A sequence of Cr-modified CeZr 2 O x catalysts were synthesized through the co-precipitation way and applied in selective catalytic reduction (SCR) of NO x with ammonia. The optimal catalyst (Cr 1 CeZr 2 O x) exhibited the excellent NH 3 -SCR activity and high SO 2 resistance. From the characterization results, Cr species in Cr 1 CeZr 2 O x could suppress the formation of ZrO 2 crystals, which could also contribute to stronger surface acidity and reducibility. Besides, more Ce3+ and surface adsorbed oxygen species were observed on Cr 1 CeZr 2 O x catalyst. On the basis of in situ DRIFT experiments, it could be confirmed that the NH 3 -SCR process on Cr 1 CeZr 2 O x was promoted through Langmuir-Hinshelwood (L-H) mechanism. Besides, the improved NO oxidation and more ad-NO x and ad-NH 3 also played a vital role for the superior low-temperature SCR activity of Cr 1 CeZr 2 O x. Unlabelled Image • Cr 1 CeZr 2 O x catalyst shows higher SCR activity and SO 2 tolerance. • The addition of Cr on CeZr 2 O x catalyst could generate more ad-reactants. • Cr in CeZr 2 O x catalyst could improve the reactivities of ad-reactants. [ABSTRACT FROM AUTHOR]

Sb-modified Mn/TiO 2 catalyst synthetized by sol–gel method exhibited outstanding performance in simultaneous Hg0 oxidation and NO reduction under SCR conditions at low temperature. NO removal (>90%) and Hg0 oxidation (>80%) were simultaneously obtained over MnSb/TiO 2 -0.25 catalyst in 200–300 °C with a GHSV of 54,000 h−1. Moreover, MnSb/TiO 2 -0.25 catalyst exhibited excellent tolerance to SO 2 and H 2 O. Characterization results suggested that the well-dispersed Mn, Sb and Ti species, along with the enriched Mn4+ and surface oxygen species on Mn-Sb/TiO 2 -0.25 catalyst should play a critical role in its excellent catalytic performance. The formed HgO had little inhibition effect on NO reduction over MnSb/TiO 2 -0.25 catalyst. And the coexistence of NO and O 2 has a promotion effect on Hg0 oxidation, while NH 3 exhibited an inhibition effect on oxidation of Hg0. In SCR reaction process, the Hg0 oxidation efficiency was suppressed, but this effect could be basically eliminated by using a relatively low GHSV value. Thus using MnSb/TiO 2 -0.25 for simultaneous Hg0 oxidation and NO reduction in SCR reactor may be workable in coal-burning power plants. Based on the results of experiments and characterizations, the mechanism of synchronous removal of Hg0 and NO on MnSb/TiO 2 -0.25 catalyst could be described as:Hg0(ad)+O α (O β)→HgO(ad), NO(g)+NO 2 (ad)+NH 3 (ad)→N 2 +H 2 O. Image 1 • NO removal (>90%) and Hg0 oxidation (>80%) are achieved on MnSb/TiO 2 -0.25 catalyst. • MnSb/TiO 2 -0.25 catalyst exhibits good SO 2 /H 2 O resistance. • The reaction mechanism of simultaneous removal of NO and Hg0 is proposed. [ABSTRACT FROM AUTHOR]

The MoS 2 /TiO 2 heterojunction composites photocatalysts exhibits excellent photocatalytic performance, and they were resoundingly synthesized by a one-step hydrothermal experimental method combined with mild calcination (300 °C) under an argon atmosphere. Under the visible light irradiation, the photocatalytic activity of MoS 2 /TiO 2 heterojunction composites were tested for photocatalytic reduction of CO 2 and it exhibited superior performance and stability. The consequences show that the pure MoS 2 demonstrates a poor photocatalytic activity because of its high electron-hole recombination, and the maximum yields of CO and CH 4 on 10% MoS 2 /TiO 2 heterojunction composite are 268.97 μmol/g.cat and 49.93μmol/g.cat, respectively, which are about 5.33 times and 16.26 times of pure TiO 2 (P25). The improved photocatalytic activity of 10% MoS 2 /TiO 2 heterojunction composite could be put down to the high-efficiency separation of photogenerated electron-hole pairs, strong response to visible light and the narrowed band gap. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Sb doping could improve the SCR activity and SO 2 resistance effectively for Cu/TiO 2 catalyst. • The addition of Sb on Cu/TiO 2 catalyst could promote the adsorption of NH 3 and NOx species. • Sb in CuSb/TiO 2 -0.4 catalyst could enhance the reactivities of adsorbed reactants. Abstract The Cu/TiO 2 catalysts modified by Sb were compounded through the sol-gel way and put into use for the selective catalytic reduction (SCR) of NOx with NH 3. Experimental results suggested that CuSb/TiO 2 -0.4 exhibited the excellent NOx conversion and SO 2 tolerance. Subsequently, the relationship between surface physicochemical properties and catalytic performance was also investigated by different characterization methods. From characterizations, the introduction of Sb for Cu/TiO 2 could promote the generation of more Cu2+, surface adsorbed oxygen species and surface acid sites on CuSb/TiO 2 -0.4 catalyst. Furthermore, Sb species on CuSb/TiO 2 -0.4 could contribute to the formation of more surface ad-NOx and ad-NH 3 species, which would enhance the NH 3 -SCR process effectively through both the Langmuir-Hinshelwood (L-H) and Eley-Rideal (E-R) mechanisms. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Eu could facilitate the separation and transfer of photogenerated electron-hole pairs. • The Eu/C 3 N 4 composites have superior photocatalytic performance in both CO 2 reduction and H 2 evolution. • In-situ FTIR analysis indicates that the HCOOH is a major intermediate during the CO 2 conversion progress. • Massive photogenerated carriers existed in Eu/g-C 3 N 4 are favorable to the CO 2 photoconversion to CH 4. Abstract The high-efficiency photocatalytic CO 2 reduction and H 2 evaluation performance are quite attractive and desired for clean energy utilization and environmental pollution alleviation. Herein, the novel visible-light activated Eu (III) doped g-C 3 N 4 composites with different contents (2%, 4%, 6%, 8% and 10%) were successfully synthesized for the first time. The Eu (III) species acted as the Lewis acids could trap photoexcited electrons with superior ability. The photocatalytic activity of Eu/g-C 3 N 4 catalysts exhibited superior performance and stability in both CO 2 photoreduction and H 2 production with the presence of water under the visible light irradiation. A maximum CH 4 and H 2 yields of 22.8 μmol/(h·g-cat) and 78.1 μmol/(h·g-cat), respectively, had been obtained on 8% Eu/g-C 3 N 4 catalyst, which was about 2.2 and 7.3 times as high as the pure g-C 3 N 4. In situ FTIR analysis discloses that HCOOH is a major intermediate during the CO 2 conversion progress. The Mott–Schottky method also indicated massive photogenetated carriers existed in Eu/g-C 3 N 4 catalysts that in favor of the CO 2 conversion to CH 4. The origin of such remarkable photocatalytic activities could be explained as follows: (i) Eu3+ species captured photogenerated electrons and inhibited the recombination of photogenerated electron-hole pairs; (ii) the doped Eu3+ narrowed the band gap and enhanced the visible-light absorption capacity; (iii) the introduction Eu3+ increased the activated specific surface area. This work may provide meaningful guidelines for rare earth mental application on improving the performance of photocatalyst. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • TiO 2 nanotubes and nanorods have been prepared by a one-step hydrothermal method. • Oxygen vacancies and defects are easily formed. • Fast charge transport and transfer are observed in TiO 2 nanotubes/nanorods catalysts. Abstract The one dimension (1D) TiO 2 nanotubes and nanorods were successfully prepared via a one-step hydrothermal method. The structure and properties of the catalysts were characterized by means of X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Electron paramagnetic resonance (EPR), N 2 adsorption-desorption, UV–vis diffuse reflectance and photoluminescence (PL) spectroscopy. Meanwhile, the photoelectrochemical properties were recorded through Mott-Schottky, transient photo-current responses and electrochemical impedance spectroscopy curves (EIS). The results showed that 1D TiO 2 nanostructures catalysts had a high specific surface area, enhanced visible light response and superior electron transport properties. The photocatalytic activities of catalysts for reduction CO 2 were investigated under 9 h irradiation of a 300 W Xe arc lamp equipped with UV 420 nm bandpass filter. The maximum yields of CH 4 over the TiO 2 nanotubes (TNT) and TiO 2 nanorods (TNR) were 19.16 μmol/g.cat and 12.71 μmol/g.cat, respectively, which were approximately 2.33 folds and 1.48 folds higher than TiO 2 nanoparticles (TNP). The enhanced photocatalytic activity of TiO 2 nanotubes and nanorods could be ascribed to the presence of oxygen vacancies and defects formed during the calcination process and its special structures, which accelerates the transfer of electrons. Besides, the better activity of TNT than TNR may be ascribed to its unique hollow tubular structure and larger surface area. [ABSTRACT FROM AUTHOR]

Abstract Removal of NO and Hg0 simultaneously was achieved on Nb-modified MnTiO x catalyst. Experimental results revealed that high NO conversion (>95%) and Hg0 oxidation (>95%) in 200–300 °C were available on Mn 0.15 Nb 0.02 TiO x catalyst with a GHSV of 108,000 h−1. The excellent catalytic performance of Mn 0.15 Nb 0.02 TiO x catalyst should be originated from its high reducibility and massive surface chemisorbed oxygen species. Moreover, the introduction of Nb into MnTiO x catalyst greatly enhanced its resistance to SO 2 and H 2 O. Neither gaseous Hg0 nor HgO formed on catalyst surface could affect the NH 3 -SCR reaction. NO had a promotion effect on Hg0 oxidation, while NH 3 was detrimental to Hg0 oxidation owing to the inhibited adsorption of Hg0 by NH 3. Under SCR reaction conditions, an inhibition impact on Hg0 oxidation could be detected, but this negative effect could be avoided by using more catalyst sample. Highlights • Over 95% NO conversion and Hg0 oxidation is available over Mn 0.15 Nb 0.02 TiO x catalyst. • The presence of Nb in Mn 0.15 Nb 0.02 TiO x catalyst could improve is resistance to SO 2 /H 2 O. • The reaction mechanism of simultaneous removal of NO and Hg0 is proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • The modification of TiO 2 support with Zr could enhance the K resistance of Ce/TiZrO x catalyst. • The use of TiZrO x support could promote the adsorption of NH 3 and NO x species. • The SCR reaction over Ce/TiZrO x catalyst is accelerated via l -H route. Potassium, as one of the alkali metals, could cause significant deactivation on the Ce-based SCR catalysts. In this work, Zr-doping was found to efficiently enhance the K tolerance of Ce/TiO 2 catalyst. The BET, XRD, Raman, XPS, H 2 -TPR, NH 3 -TPD, O 2 -TPD and NO x -TPD were adopted for exploring the mechanism of the promoted anti-K-poisoning property of Ce/TiO 2 catalyst. The obtained results demonstrated that Ce/TiO 2 with the addition of Zr exhibited larger specific surface area, higher dispersion of Ce species, higher redox property and more acid sites. As a result, the factors mentioned above could efficiently enhance the K tolerance of Ce/TiO 2 catalyst. By virtue of the in situ DRIFT analysis, the SCR reaction over Ce/TiZrO x catalyst was accelerated via Langmuir-Hinshelwood (L-H) mechanism. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • NH 3 treatment could enhance the SCR activity and stability of CeO 2 catalyst. • NH 3 treatment could promote the adsorption of reactant species on CeO 2 catalyst. • The reactivity of ad-NH 3 species on CeO 2 catalyst is improved after NH 3 treatment. Abstract In this study, NH 3 treatment of CeO 2 was found to significantly enhance its NH 3 -SCR performance. The NH 3 -treated CeO 2 was characterized by BET, XRD, TPR and XPS. The obtained results revealed the excellent SCR activity and stability of CeO 2 catalyst treated by NH 3 should be originated from the dropped crystallinity, better reducibility, along with the production of more Ce3+ and surface adsorbed oxygen. Furthermore, in situ DRIFT study has been carried out and the results indicated that the Langmuir-Hinshelwood (L-H) mechanism could be applied for explaining the SCR reaction route over CeO 2 -N. [ABSTRACT FROM AUTHOR]

A ball-flower like NiO/g-C 3 N 4 heterojunction composite was synthesized via a hydrothermal deposition method combined with subsequent calcination route. The NiO/g-C 3 N 4 heterojunction exhibited a superior performance in CO 2 photoreduction. A maximum CO yields of 4.17 μmol/(h g-cat) had been obtained on 40% NiO/g-C 3 N 4 composite, which was 2.5 and 7.6 times as high as the pure g-C 3 N 4 and NiO respectively. The promotion mechanism could be ascribed to the perfect band matching and efficient internal charge transfer within the p-n junction, which results in high-efficiency separation of photogenerated electron-hole pairs, strong visible-light response and high specific surface area. [ABSTRACT FROM AUTHOR]

Z-Scheme MoS2/g-C3N4 heterojunction photocatalysts were fabricated using a hydrothermal deposition procedure together with a calcination route, and then applied for CO2 photoreduction. Experimental results indicated that the 10% MoS2/g-C3N4 heterojunction displayed the best photocatalytic performance. Furthermore, the maximum CO yields of 58.59 μmol (g-cat)−1 under 7 h-visible light irradiation was up to 2.94 times that of the unadulterated g-C3N4. The enhanced photocatalytic performance of 10% MoS2/g-C3N4 catalyst was due to the favored visible light response, the efficient separation of photogenerated electron–hole pairs as well as its larger specific surface area. [ABSTRACT FROM AUTHOR]

Ammonia selective catalytic reduction (NH 3 -SCR) of nitrogen oxides is an effective and well-established technology for NO x removal, but current commercial denitrification catalysts based on V 2 O 5 -WO 3 /TiO 2 have some obvious disadvantages, including narrow operating temperature windows, toxicity, poor hydrothermal stability, and unsatisfied SO 2 /H 2 O tolerance. To overcome these drawbacks, it is imperative to investigate new types of highly efficient catalysts. In order to design catalysts with outstanding selectivity, activity, and anti-poisoning ability, core-shell structured materials have been widely applied in the NH 3 -SCR reaction, which exhibits numerous advantages including the large surface area, the strong synergy interaction of core-shell materials, the confinement effect, and the shielding effect from the shell layer to protect the core. This review summarizes recent developments of core-shell structured catalysts for NH 3 -SCR, including basic classification, synthesis methods, and a detailed description of the performance and mechanisms of each type of catalyst. It is hoped that the review will stimulate future developments in NH 3 -SCR technology, leading to novel catalyst designs with improved denitrification performance. [Display omitted] • Core-shell structured materials have been widely applied in the NH 3 -SCR reaction. • Core-shell structured SCR catalyst shows high catalytic activity. • Core-shell structure could protect the active components from deactivation. [ABSTRACT FROM AUTHOR]

In this work, Mo-modified Mn/TiO 2 catalysts synthetized by co-precipitation method were applied in the SCR abatement of NOx by NH 3 . Ranging from 50 to 400 °C, Mn/TiO 2 modified with Mo showed higher efficiency in SCR reaction than Mn/TiO 2 without Mo. Among Mn/TiO 2 catalysts with different Mo doping amount, MnMo/TiO 2 -0.04 catalyst showed not only the highest SCR activity but also the best N 2 selectivity. Furthermore, MnMo/TiO 2 -0.04 also exhibited stronger resistance to SO 2 poisoning compared with Mn/TiO 2 . On the basis of the characterization means including BET, XRD, H 2 -TPR, XPS and NH 3 -TPD, MnMo/TiO 2 -0.04 was characterized with the decreased crystallinity, the increased reducibility and more surface acid sites, along with the enrichment of surface adsorbed oxygen species and Mn 4+ species. Furthermore, the analysis results of in situ DRIFT study showed that Langmuir-Hinshewood (L-H) model should be employed in explaining the accelerated SCR reaction over MnMo/TiO 2 -0.04. [ABSTRACT FROM AUTHOR]

Mn/TiO 2 catalyst is a promising candidate for future utilization in low-temperature NH 3 -SCR reaction, but its bad resistance to SO 2 is still a great challenge for practical application. In this study, Eu was successfully used as the additive to improve its resistance to SO 2 under SCR conditions, while the pretreatment of Mn/TiO 2 and MnEu/TiO 2 catalyst by SO 2  + O 2 had a strong deactivation effect on them. In situ DRIFT study clarified that the deactivation of Mn/TiO 2 -S (SCR + SO 2 ), Mn/TiO 2 -S (SO 2  + O 2 ) and MnEu/TiO 2 -S (SO 2 +O 2 ) were mainly originated from the inhibited adsorption of NH 3 and NOx species, as well as the formation of a large amount surface sulfate species on them, which had a strong blacking effect on the SCR reactions over the three catalysts via both E-R and L-H routes. After the addition of Eu, SCR reaction over MnEu/TiO 2 catalyst with the existence of SO 2 took place through L-H pathway, accompanied by the generation of less surface sulfate species, which brought about the excellent SO 2 tolerance of MnEu/TiO 2 catalyst under SCR conditions. [ABSTRACT FROM AUTHOR]

Fe was used as the modifier to improve the performance of CeZr2Ox catalyst for the selective catalytic reduction (SCR) reaction with ammonia. Experimental results revealed that proper Fe species (Fe/Ce molar ratio = 2) could effectively improve the SCR activity of CeZr2Ox, along with the elevated resistance to SO2 and H2O. The characterization results including BET, XRD, H2-TPR and NH3-TPD confirmed that Fe species in Fe2CeZr2Ox catalyst could inhibit the formation of ZrO2 crystals and lead to higher reducibility and surface acidity. In addition, more Ce3+ and surface active oxygen species could be detected on Fe2CeZr2Ox compared with CeZr2Ox. By means of in situ DRIFT technique, it could be deduced that the SCR reaction process over Fe2CeZr2Ox was accelerated mainly through theL-H pathway due to the advanced adsorption of NH3 and NOx species, along with the promoted NO conversion to NO2. Therefore, the modification of CeZrOx catalyst by Fe had a significant stimulation effect on its low-temperature SCR performance. [ABSTRACT FROM AUTHOR]

The deactivation of SCR catalyst caused by K species contained in the fly ash would suppress its DeNOx performance. In this study, it was manifested that the modification of Ce/TiO 2 catalyst with P could enhance its K tolerance. To understand the promotion mechanism, the fresh and poisoned catalyst samples were subjected to the characterization techniques including BET, XRD, XPS, H 2 -TPR, NH 3 -TPD and in situ DRIFT. The results elucidated that the introduction of P species could increase the reducibility of Ce species and generate more surface chemisorbed oxygen, along with the strengthened surface acidity for NH 3 adsorption. It seemed that the NH 3 -SCR reaction mechanism over Ce/TiO 2 catalyst was a combination of L-H mechanism (<200 °C) and E-R mechanism (≥200 °C). After the addition of P species, the NO oxidation over Ce/TiO 2 catalyst was also accelerated, accompanied by the broadened temperature window for the NH 3 -SCR reaction under the control of L-H mechanism. The promoted NH 3 species adsorption and the generated more NO 2 over P-Ce/TiO 2 catalyst were conducive to the NH 3 -SCR reaction through L-H pathway, which might be the primary reason for its good K resistance. [ABSTRACT FROM AUTHOR]

Using photocatalysis to reduce carbon dioxide to hydrocarbons is a promising way to mitigate the greenhouse effect and the energy crisis simultaneously. However, conventional photocatalytic technology is inefficient due to its low utilization of the full spectrum. Photothermal effect can combine the advantages of photocatalysis and thermocatalysis to overcome inherent defects and elevate the catalytic activity by one order of magnitude compared with single photocatalysis. This review focuses on the generation and promotion mechanism of photothermal effect on photocatalytic reduction of CO 2. In addition, the developments of several practical catalysts with photothermal effect are presented, including non-precious metal-based catalysts, precious metal-based catalysts, and oxygen vacancy-riched catalysts. Eventually, the prospects and challenges of the applications of the photothermal effect are in consideration, which is instructive for the discovery of non-expensive and efficient photothermal catalysts for photocatalytic reduction of CO 2. [Display omitted] • The photothermal effect is particularly beneficial to CO 2 photocatalytic process. • The origin of photothermal effect is explained. • The promoting mechanism of photothermal effect on CO 2 reduction is summarized. • Several excellent photothermal catalysts for CO 2 reduction are presented. [ABSTRACT FROM AUTHOR]

[Display omitted] • CeSm/TiO 2 catalyst exhibits high low-temperature SCR activity. • The SCR reaction over CeSm/TiO 2 catalyst was controlled by L-H mechanism (<200 °C). • The promoted NO oxidation and NH3 adsorption are mainly responsible for the excellent performance of CeSm/TiO 2 catalyst. CeSmOx mixed oxide catalysts supported on TiO 2 prepared by coprecipitation method were used for selective catalytic reduction of NOx with NH 3. The results showed that the addition of Sm could effectively enhance the low-temperature SCR activity and SO 2 /H 2 O resistance of Ce/TiO 2 catalyst, and the appropriate mole ratio of Sm to Ce was 0.3. Characterization results indicated that the introduction of Sm could promote the formation of Ce3+ and chemisorbed oxygen species on catalyst surface, which was favorable to the generation of NO 2. Moreover, the doping of Sm could also promote the adsorption of NH 3 and NOx species on Ce/TiO 2 catalyst. The results of in situ DRIFT study revealed that the NH 3 -SCR reaction over CeSm/TiO 2 -0.3 catalyst was mainly controlled by the Langmuir−Hinshelwood mechanism in the low temperature range (<200 °C). Thereafter, the promoted NO oxidation and the enhanced NH 3 adsorption should play a major role for the excellent low-temperature SCR performance of CeSm/TiO 2 -0.3 catalyst. [ABSTRACT FROM AUTHOR]

A series of MnEuOx catalysts were prepared by the co-precipitation method and used for selective catalytic reduction of NOx with NH 3 . It was found that the modification of MnOx catalyst by Eu with a Eu/Mn molar ratio of 0.1 could greatly enhance its SCR activity and broaden its operating temperature window, accompanied by good resistance to SO 2 and H 2 O. From the characterization results of N 2 adsorption, XRD, XPS, H 2 -TPR, it could be concluded that the larger surface area resulted from the inhibited crystallization of MnOx, the enrichment of surface Mn 4+ and chemisorbed oxygen, and the higher reducibility all made a contribution to the high SCR activity of MnEuOx-0.1 catalyst. Furthermore, the results of in situ DRIFTS study revealed the NH 3 -SCR reactions over MnOx and MnEuOx-0.1 were mainly controlled by L-H mechanism (<150 °C) and E-R mechanism (>150 °C) respectively, and the contribution of E–R mechanism became more important with increasing reaction temperature. The enhanced NO oxidation and NH 3 adsorption should be mainly contribute to the distinguished SCR performance of MnEuOx catalyst in the lower temperature range (<150 °C) and higher temperature range (>150 °C) respectively. [ABSTRACT FROM AUTHOR]

The deactivation mechanism of alkali metals on the SCR catalyst of Ce/TiO 2 was investigated by TPD and DRIFT studies. It could be found that the addition of Na or K on Ce/TiO 2 catalyst would restrict the adsorption of NH 3, accompanied by the generation of new sites for the adsorption of NO x species. But the new-absorbed NO x species were not active in the NH 3 -SCR reaction. The results of in situ DRIFT study indicated that the addition of Na and K did not change the SCR reaction mechanism, which was the combination of the Eley–Rideal and the Langmuir–Hinshelwood mechanisms. [ABSTRACT FROM AUTHOR]

• Co 2 B/CN triggered the water splitting reaction from visible to NIR regions. • "SPR effect" that noble metal featured was fabricated in the amorphous Co 2 B nanosheets. • Optimized Co 2 B/CN catalyst showed the activity for H 2 evolution outperformed Pt/CN. • Amorphous featured Co 2 B nanosheets provided massive active sites for reaction. • The promoted charge transfer and the inhibited e-/h+ recombination are available on Co 2 B/CN. Developing noble-metal-free photocatalysts to address the challenges of high recombination rate of electrons and holes and poor optical response is high desirable for water splitting. Herein, cobalt boride (Co 2 B) nanosheets with amorphous phases ordered in short-range but disordered in long-range was fabricated, and coupled with graphic carbon nitride (CN) photocatalysts in the form of B(δ−)–Co(δ+)–N(δ−) bonding states through an in-situ chemical reduction method. The optimized Co 2 B/CN nanohybrids exhibited a H 2 evolution rate of 56.86 μmol/h with the highest AQY up to 22.8 %, outperforming than that of Pt decorated CN. Theoretical calculation by DFT verify the characterization results and show that Co active sites on Co 2 B have better performance of adsorbing H atoms and desorbing hydrogen. The disordered structure of Co 2 B nanosheets contributed to water splitting performance by providing abundant active sites while metallic nature of Co 2 B facilitated electrons transfer and inhibited the recombination of electrons and holes. Moreover, theoretical calculation suggested that the high concentration of free carriers endowed Co 2 B with an resembled SPR effect, thereby increasing the light response of CN and triggering the reaction from visible-light region extended to the near-infrared region up to 800 nm. [ABSTRACT FROM AUTHOR]

Heavy metals (such as Zn and Pb) have a deactivation effect on the catalyst for selective catalytic reduction of NO with NH 3 . In this study, it was found that the modification of Mn/TiO 2 catalyst by Nb could greatly enhance its Zn resistance. From the characterization results of BET, XRD, H 2 -TPR, NH 3 -TPD, it may be concluded that the introduction of Nb into Mn/TiO 2 catalyst would lead to its lower crystallinity, more acid sites and higher concentrations of Mn 4 + and surface chemisorbed oxygen. The results of in situ DRIFT study reveal that the NH 3 -SCR reactions over Mn/TiO 2 and Mn-Nb/TiO 2 all obey both the Langmuir-Hinshelwood mechanism and the Eley–Rideal mechanism, and the doping of Nb on Mn/TiO 2 catalyst could promote the adsorption of NH 3 and NOx species on it. All these features make a contribution to the high SCR activity and good Zn resistance of Mn-Nb/TiO 2 catalyst. [ABSTRACT FROM AUTHOR]

A series of Mn/TiWO x catalysts were prepared and used in NH 3 -SCR reaction for NO x emission control. The experimental results showed that the SCR activities of Mn/TiWO x catalysts are higher than that of Mn/TiO 2 catalyst. After that, several characterization techniques including XRD, H 2 -TPR, NH 3 -TPD, XPS were used to investigate the effect of TiWO x support on the SCR performance of Mn/TiWO x (1:1) catalyst. The stronger reducibility and NH 3 adsorption capacity, and more surface chemisorbed oxygen of Mn/TiWO x (1:1) should all contribute to its better SCR performance. Moreover, Mn/TiWO x (1:1) catalyst shows higher N 2 selectivity, better SO 2 tolerance and stability than Mn/TiO 2 catalyst. The results of in situ DRIFT study revealed that the NH 3 -SCR reactions over Mn/TiO 2 and Mn/TiWO x (1:1) were all followed the Langmuir–Hinshelwood mechanism, in which the SCR reaction takes place between the adsorbed NH 3 species and NO x species. [ABSTRACT FROM AUTHOR]

The effect of HF treatment on the performance of ceria for selective catalytic reduction of NO with NH 3 was investigated in this study. The experimental results showed that HF treatment could greatly enhance the SCR performance of ceria within the temperature range of 100–400 °C. From the characterization results of Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), temperature programmed reduction of hydrogen (H 2 -TPR), temperature programmed desorption of ammonia (NH 3 -TPD) and X-ray photoelectron spectroscopy (XPS), the good performance of HF-treated ceria may be attributed to its lower crystallinity, better reducibility, higher NH 3 adsorption capacity, and the enrichment of surface chemisorbed oxygen. And the results of in situ DRIFT study indicate that the NH 3 -SCR reactions on CeO 2 and CeO 2 -F mainly follow the Eley–Rideal mechanism. [ABSTRACT FROM AUTHOR]

In this work, Bi 7 O 9 I 3 /Cd 0.5 Zn 0.5 S QDs/WO 3−x ternary heterojunction with full spectrum response was prepared and applied in the photodegradation of phenol. The results of photocatalytic experiments showed that the prepared Bi 7 O 9 I 3 /Cd 0.5 Zn 0.5 S QDs/WO 3−x heterojunction had the highest performance under full spectrum, visible and near-infrared light irradiation, and the reaction rates were 4.02, 3.75 and 5.71 times that of pure Bi 7 O 9 I 3 , respectively. This performance improvement results from the construction of double S-scheme heterojunction and the full-spectrum response, which had effective charge distribution and migration as well as an excellent response to sunlight. In addition,·OH and·O 2 - took the lead role in the process of photodegradation. Combined with the free radical-trapping experiment, ESR experiment and DFT theoretical calculation, the photocatalytic mechanism of double S-scheme system was proposed. This work is contributory to designing novel photocatalytic materials with dual S-scheme heterojunction and the efficient purification of wastewater in environmental remediation. [Display omitted] • Bi 7 O 9 I 3 /Cd 0.5 Zn 0.5 S QDs/WO 3−x ternary heterojunction with full spectrum response was prepared. • The degradation efficiency of BCW-2 heterojunction to phenol reached 100% under full-spectrum irradiation within 90 min. • ·OH and·O 2 - took the lead role in the process of photodegradation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nb modification can promote the adsorption of reactants on CuCeO x catalyst. • The SCR reaction on CuCeNbO x -0.4 catalyst mainly follows the L-H and E-R mechanisms. • The formed dual redox cycle on CuCeNbO x -0.4 catalyst favors the low-temperature SCR reaction. CuCeO x and CuCeNbO x - k with different Nb doping ratios were obtained by the citric acid method and applied in NH 3 -SCR process. The activity test results elucidated that the addition of Nb effectively ameliorated the low-temperature SCR performance. Among them, CuCeNbO x -0.4 catalyst had the finest SCR activity (more than 90% in 185–370 °C), highest N 2 selectivity, excellent SO 2 &H 2 O resistance and thermal stability. Numerous characterization analysis demonstrated that CuCeNbO x -0.4 had the largest specific surface area, the strongest surface acidity and the most excellent redox properties. The conclusions of in situ DRIFT manifested the Nb modification generated more activated species, enhanced the reactivity of ad-NH 3 and ad-NO x species, and the SCR reaction on CuCeNbO x -0.4 mainly followed the Langmuir-Hinshelwood (L-H) and Eley-Rideal (E-R) mechanisms. Furthermore, the Nb doping also formed the dual redox cycle (Cu2+ + Nb4+ ↔ Cu+ + Nb5+, Cu2+ + Ce3+ ↔ Cu+ + Ce4+), which facilitated the low-temperature SCR reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • MnCe/TiO 2 -FL shows fabulous SCR performance and superior resistance to SO 2 /H 2 O. • More ad-NH 3 and ad-NOx species are available on the surface of MnCe/TiO 2 -FL. • The redox cycle "Mn4+ + Ce3+ ↔ Mn3+ + Ce4+" greatly promote the SCR reaction over MnCe/TiO 2 -FL. In this work, a flower-like TiO 2 support was firstly synthesized via the hydrothermal method, and then Mn and Ce were loaded onto the synthesized flower-like TiO 2 carrier by impregnation for the selective catalytic reduction of NO with NH 3 (NH 3 -SCR). The activity test results manifested that the flower-like MnCe/TiO 2 (MnCe/TiO 2 -FL) catalyst exhibited marvelous SCR performance (almost 100% NO conversion in the range of 150–250 °C) and satisfactory resistance to SO 2 and H 2 O. Based on a series of characterization experiments, it could be found that the MnCe/TiO 2 -FL catalyst possessed a larger surface area, higher Ce3+ and Mn4+ content, superior surface acidity and redox performance, which greatly ameliorated to the SCR performance of the MnCe/TiO 2 -FL catalyst. Furthermore, the accelerated surface adsorbed oxygen mobility and the increased quantity of active species also promoted to the SCR activity of MnCe/TiO 2 -FL at low temperatures. [ABSTRACT FROM AUTHOR]

The poisoning mechanism of Cl on Ce/TiO 2 catalyst was investigated based on temperature programmed desorption (TPD) and the in situ diffuse reflectance infrared transform spectroscopy (DRIFT) studies. The results of NH 3 -TPD and NO-TPD indicated that the addition of Cl on Ce/TiO 2 catalyst would inhibit the adsorption of NH 3 species and NOx species on it. As can be seen from the results of in situ DRIFT study, the NH 3 -SCR reaction over Ce/TiO 2 and Ce/TiO 2 -Cl were all followed both the Eley-Rideal mechanism and the Langmuir-Hinshelwood mechanism. And the decreased adsorption ability of NH 3 species and NOx species on the surface of Ce/TiO 2 -Cl should be mainly responsible for its low SCR activity. [ABSTRACT FROM AUTHOR]

Na has a serious deactivation effect on Mn/TiO 2 catalyst for selective catalytic reduction of NO with NH 3 . In this study, it was found that Sb had a promotion effect on the Na resistance of MnOx/TiO 2 catalyst. Then the promotion mechanism was investigated based on the characterization results of BET, XRD, H 2 -TPR, NH 3 -TPD, XPS and in situ DRIFT. The results of H 2 -TPR and NH 3 -TPD showed that the addition of Sb on MnOx/TiO 2 could enhance the redox ability and surface acidity respectively, and the results of DRIFT indicated that the addition of Sb on MnOx/TiO 2 could generate strong Lewis acid sites on the catalyst surface for NH 3 adsorption. Therefore, the doping of Sb has a promotion effect on the Na resistance of Mn/TiO 2 catalyst. [ABSTRACT FROM AUTHOR]

Heavy metals have been proven to be of deactivation effect on SCR catalyst. In this paper, the poisoning effect of heavy metals (Zn and Pb) on Mn/TiO 2 catalyst was investigated based on experimental and theoretical study. It was found that both of Zn and Pb had a poisoning effect on Mn/TiO 2 catalyst and the poisoning effect of Zn was more obvious. The characterization results indicated that the doping of heavy metals on Mn/TiO 2 surface would lead to a great decrease of reducibility, surface acidity and NO adsorption ability. The results of XPS characterization revealed the decrease of Mn 4+ atomic concentration and chemisorbed oxygen species caused by the doping of heavy metals. Based on the above mentioned unfavorable properties, the doping of heavy metals would cause a serious deactivation of Mn/TiO 2 catalyst. From the results of DFT calculations, it could be concluded that the doping of heavy metals on Mn/TiO 2 catalyst resulting in a great decrease of NH 3 adsorption capacity and NO adsorption ability, which agrees well with the experimental results. [ABSTRACT FROM AUTHOR]

The CeOx@MnOx catalyst with a core–shell structure was prepared and used for catalytic oxidation of NO. It was found that CeOx@MnOx catalyst showed higher intrinsic catalytic activity than CeMnOx catalyst prepared by citric acid method. Based on the characterization results of N 2 adsorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), temperature-programmed reduction (H 2 -TPR) and X-ray photoelectron spectroscopy (XPS), we may conclude that the excellent catalytic performance of CeOx@MnOx catalyst is related to its low crystallinity, good reducibility, and high concentrations of Mn 4 + and active oxygen species. [ABSTRACT FROM AUTHOR]

Lead salts poisoning was a great challenge for the catalysts application in selective catalytic reduction (SCR) reaction of NO x with NH 3 in stationary sources. Herein, several typical transition metal (Cu, Co and Zr) oxides modified Mn-Ce/AC catalysts were prepared by impregnation method, and the effects of Cu, Co and Zr doping on resistance PbCl 2 poisoning for the catalyst were investigated. The addition of three transition metal oxides improved the PbCl 2 resistance of Mn-Ce/AC catalyst and maintained excellent low-temperature denitrification activity of the catalyst. The lead resistance performance of the three metal oxides followed: Cu > Co > Zr oxides. The NO conversion of Cu-doping catalyst after PbCl 2 poisoning was only ca. 10% lower than that of fresh Mn-Ce/AC catalyst at 225 °C. Cu, Co and Zr doping could decrease the loss of specific surface area caused by poisoning, while Cu-doped catalyst showed lowest crystallinity of active components. Meanwhile, the contents of Mn4+ and chemisorbed oxygen in Cu-doped catalyst were higher than those in Co- or Zr-doped catalysts. Cu, Co and Zr doping improved the surface acidity and redox performance of the poisoned catalysts, with Cu-doped poisoned catalyst exhibiting nearly the same surface acidity and redox performance as the fresh Mn-Ce/AC catalyst. Furthermore, Cu doping could also improve NO adsorption and was in favor to the SCR process. Besides, in situ DRIFTS results showed that the catalytic reaction pathways of all the poisoned or modified catalysts were in accordance with both Langmuir-Hinshelwood (L-H) and Eley-Rideal (E-R) mechanisms. Finally, a possible anti-PbCl 2 poisoning mechanistic model of (Cu, Co and Zr) oxides modified on Mn-Ce/AC catalyst was proposed. [Display omitted] • Cu-modified MC/AC catalyst showed best resistance to PbCl 2 poisoning. • Transition metal oxides alleviated damage of PbCl 2 to MC/AC structure. • Redox ability and acidity of PbCl 2 -poisoned catalyst were promoted by modifying. • NH 3 -SCR reaction on PbCl 2 -poisoned catalyst followed L-H and E-R mechanism. [ABSTRACT FROM AUTHOR]

NO (nitric oxide) is one of the main air pollutants emitted from coal-fired power plants. During the past several decades, capture of NO by liquid phase oxidation and the absorption process has drawn much attention for its advantages of low cost and co-capture of other pollutants. This paper provides a comprehensive review of recent development of liquid phase oxidation and the absorption process for NO capture. The process chemistry, effect of reaction parameters on absorption efficiency, and simultaneous capture with other pollutants in flue gas are critically summarized and reviewed. And the future development of this process is also referred to and discussed in brief. [ABSTRACT FROM AUTHOR]

Ce/TiO 2 is a prospective catalyst used for low temperature selective catalytic reduction (SCR) of NO with NH 3 . In this paper, the poisoning effect of Zn and Pb on the SCR performance of Ce/TiO 2 catalyst was investigated. Experimental results indicated that both Zn and Pb had a poisoning effect on Ce/TiO 2 catalyst, and Pb exhibited more poisoning effect than Zn in most of the reaction temperature range. Combined with the characterization results, we proposed that the enlargement of TiO 2 nanoparticles, the reduced chemisorbed oxygen content and surface acidity all contribute to the deactivation of Zn–Ce/TiO 2 and Pb–Ce/TiO 2 . [ABSTRACT FROM AUTHOR]

Mn/TiO 2 catalyst is of high activity for low temperature selective catalytic reduction (SCR) of NO with NH 3 . And the deposition of alkali metal would lead to the deactivation of Mn/TiO 2 catalyst. In this paper, the poisoning effect of Na and K on Mn/TiO 2 was investigated based on experimental and theoretical study. It was found that K had a stronger poisoning effect than that of Na. The bad performance of K–Mn/TiO 2 may be due to its small surface area, high crystallinity, weak surface acidity, low content of Mn 4+ and chemisorbed oxygen, and bad redox ability. The interpretation of the experimental results is supported by DFT calculations. [ABSTRACT FROM AUTHOR]

The absorption of NO in aqueous solutions of KMnO4and H2SO4was carried out in a stirred tank reactor under atmosphere pressure. The results indicated that the absorption process was under a fast pseudo-mth reaction regime. The reaction between NO and aqueous solutions of KMnO4/H2SO4was found to be first-order with respect both to NO and to KMnO4. The addition of H2SO4to KMnO4solutions increased the absorption rate of NO and increasing reaction temperature was also favorable to the absorption of NO. [ABSTRACT FROM AUTHOR]