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A new homojunction is developed by in situ decorating g-C3N4 (CN) nanosheets with a C–N compound broken by s-triazine units (BST). The BST fragments rapidly transfer photogenerated electrons from the CN conduction band to generate hydrogen.

SSZ-13 has been commercialized as a catalyst in diesel engines for the selectivity catalytic reduction of nitrogen oxides (NO

TiNb2O7 (TNO) as a promising candidate anode for lithium-ion batteries (LIBs) shows obvious advantages in terms of specific capacity and safety, but which undergoes the intrinsic poor electrical and ionic conductivity. Herein, we propose a simple synthesis strategy of mesoporous TNO via a polymeric surfactant-mediated evaporation-induced sol-gel method, using polyvinylpyrrolidone (PVP) with different molecular weights (average Mw: 10000/58000/1300000) as the regulating agent, which greatly affects the lithium storage performance of the as-prepared TNO. The optimized TNO (i.e., PVP of 58000) delivers a high reversible capacity of 303.1 mAh/g at 1 C, with a retention rate of 73.4% (222.5 mAh/g) after 300 cycles. Even at 5 C, a high reversible capacity of 185.6 mAh/g can be achieved, with a retention rate of 72.3% after 1000 cycles. The superior lithium storage behavior is attributed to the fine mesoporous framework consisting of interconnected TNO nanocrystallites with high specific surface area and high mesoporosity, which greatly increases the active sites, improves the Li+ diffusion kinetics and alleviates volume fluctuation induced by the repetitive Li+ insertion-extraction processes.

A new variety of CdS/NiO core-shell p-n heterojunction is synthesized by in-situ chemically depositing NiO shell on single-crystal CdS nanorods for the first time. With this method, the range of NiO shell thickness can be accurately controlled within a few nanometers. The optimized CdS/NiO sample (CSN0.5) with a NiO shell layer of 1.5 nm exhibits a highly efficient photocatalytic H2 evolution rate of 731.7 μmol/h (corresponding to 243.9 mmol/g/h) without using co-catalyst, which is among the highest value of all the CdS-based photocatalysts. The apparent quantum efficiency (AQE) of CSN0.5 at 365 nm wavelength reaches 28.19%. The remarkably enhanced photocatalytic performance can be attributed to a hydrogen spillover effect induced by ascorbic acid in CdS/NiO, which promotes the transmission of adsorbed H* from hydrogen-rich NiO (electron-poor region) to hydrogen-poor CdS (electron-rich region) where the adsorbed H* reacts in time with the photogenerated electron to produce H2, facilitating the H2 evolution reaction. This work provides a method to promote the photocatalytic H2 evolution reaction by using hydrogen spillover effect.

Lithium sulfur batteries (LSBs) with high energy density hold some promising applications in the wearable and flexible devices. However, it has been still challenging to develop a simple and feasible approach to prepare flexible LSB cathodes with both robust mechanical strength. Herein, flexible S@C-CNTs cathodes with controllable thicknesses are successfully fabricated via a facile blade-coating method. Due to the strong cohesion among CNTs bundles and the well-designed structure, the flexible S@C-CNTs cathodes are demonstrated to be with a combination of impressive mechanical strength and enhanced electrochemical performance. For the flexible S@C-CNTs cathodes with the sulfur mass loading of 4 mg cm−2, the areal capacity is close to 3.0 mA h cm−2, and the breaking stress is up to 5.59 MPa with 7.77% strain. Meanwhile, the pouch cell exhibits excellent cyclic stability at both flat/bent conditions. All demonstrate that the flexible S@C-CNTs cathodes may satisfy the demands of practical application. Moreover, this methodology is suitable for designing other flexible battery electrodes, such as flexible Si@C-CNTs anodes for lithium ion batteries, flexible P@C-CNTs anodes for sodium/potassium ion batteries, etc.

NOx emissions are a major environmental problem, and the selective catalytic reduction (SCR) is the most effective method to convert NOx in flue gas into harmless N2 and H2O. In this work, a new carrier, CuCeOy microflower assembled from a large number of copper-cerium mixed oxide nanosheets, is firstly developed to load vanadium-tungsten mixed oxides (VWOx) for the SCR of NOx with NH3. The resultant optimal VWOx/CuCeOy catalyst exhibits significantly enhanced low-temperature de-NOx performance with the NOx conversion of 60% at 180 °C, over 90% from 240 °C to 390 °C under the gas hourly space velocity (GHSV) of 36,000 h−1. The reason can be mainly attributed the fact that the transfer of electrons among Ce, Cu and V ions is very easy to occur via the following equations Ce3++Cu2+ ↔ Ce4++Cu+, V5+ + Cu+ ↔ V4+ + Cu2+, V4+ + Ce4+ ↔ V5+ + Ce3+, which effectively decreases the apparent activation energy (Ea = 16.59 kJ/mol) of NH3-SCR de-NOx reaction. In addition, the enhanced reducibility and a large number of Bronsted acid sites also contribute the low-temperature de-NOx performance. Both Eley-Rideal and Langmuir-Hinshelwood mechanisms are included in the NH3-SCR de-NOx reaction over the VWOx/CuCeOy catalyst.

In this work, a new kind of CdS/CdSe/CuS hollow nanospheres (HNPs) is successfully synthesized by one-step synthesis via vulcanization and selenization in aqueous solution, without using any additional templates, for the first time. The three components of CdS, CdSe and CuS in the HNPs are thoroughly combinated with each other at nano-scale, which creates a large quantity of intimate contact interfaces. As a result, the optimal CdSe30Cu2S HNPs exhibit an excellent photocatalytic H2 evolution rate of 723 μmol h−1 (10 mg of catalyst) without adding any noble metal co-catalysts, which is 6.5 times higher than that of the pristine CdS HNPs. The hollow structure enhances the light absorption and provides the inner surface as active sites for the infiltrated water to receive the inner-shell electrons quickly for H2 evolution and the CdS/CdSe/CuS heterostructure with CuS acting as the co-catalyst forms three charge transfer pathways to promote the separation and migration of the photo-induced electrons and holes, resulting in the enhanced photocatalytic performance. This work may provide a strategy for the design and synthesis of other photocatalysts for highly efficient H2 evolution.

Recently, Mn-based catalysts doped/modified by rare earth elements for the selective catalytic reduction (SCR) of NOx with NH3 are becoming a new research hotspot. In current work, Dy-doped MnFe oxides with the morphology of one-dimensional nanowire are successfully prepared by using electrospinning method for the first time, and the catalytic performances for the NH3-SCR of NOx are investigated in detail. It is found several positive factors are introduced due to the doping of Dy with an appropriate amount, such as the enhanced surface Mn4+ concentration and surface chemical adsorption of oxygen, the increased adsorption capacity for NH3 and NO. Theoretical calculation reveals that the Dy-doping causes the larger depletion of electron density of mainly O atoms on the surface of MnFeDy than that of MnFe case, which energetically favors the adsorption of NH3 and NO molecules. Our results fully confirm that Dy is an effective doped element of Mn-based catalysts for developing SCR catalysts with excellent low-temperature de-NOx performance.

CoMoO4 nanoparticles have been successfully in-situ formed and simultaneously embedded within the porous carbon nanofibers (CoMoO4/CNFs) via a facile electrospinning-annealing strategy. The porous CoMoO4/CNFs exhibit a specific surface area of 255.3 m2/g and a pore volume of 0.52 cc/g with average pore diameter of 43.5 nm. The carbon content in the CoMoO4/CNFs can be readily controlled by adjusting the annealing temperature. When examined as anode materials for lithium ion batteries (LIBs), the CoMoO4/CNFs demonstrate superior electrochemical performance, delivering a high reversible capacity of 802 mA h/g after 200 cycles at 200 mA/g and a high-rate capacity of 574 mA h/g at 2000 mA/g. The excellent lithium storage behavior can be attributed to the incorporation of CoMoO4 nanoparticles into the porous N-doped graphitic carbon nanofibers, which efficiently buffer the volume changes of CoMoO4 upon lithiation/delithiation and maintain the overall electrode conductivity/integrity.

A series of dandelion-like Fe-CeO2/CdS (FeCex/Cdy) nanoflowers with different molar ratios of Fe-CeO2 to CdS are synthesized by solvothermal method for the first time. The FeCex/Cdy nanoflowers are assembled by a large number of nanoparticles with the diameter of about 3 nm, and the introduction of Fe ions and the couple of CdS quantum dots (QDs) efficiently enhanced the relative percentage of Ce3+ in CeO2. The as-obtained FeCe1/Cd1 heterostructure exhibits the highest photocatalytic H2 evolution ability of 108.9 μmol/h, which is 20.5, 6.1 and 7.1 times higher than CeO2, Fe-CeO2 and CdS, respectively. This significantly enhanced photocatalytic performance can be mainly attributed to the synergy between the electronic anchoring effect of Fe3+/Fe2+ and Ce4+/Ce3+ redox couples and the internal electric field constructed by the II-type heterojunction between Fe-CeO2 and CdS. This work provides a new idea for the design of efficient photocatalysts by combining the advantages of heterostructure and ion anchoring effect.

We report an amorphorization-hybridization strategy to enhance lithium storage by casting atomically mixed amorphorized SnO2/MoO3 into porous foam-like carbon nanoflakes (denote as SnO2/MoO3@CNFs, or SMC in short), which are simply prepared by annealing tin(II)/molybdenum(IV) 2-ethylhexanoate within CNFs under ambient atmosphere at a low temperature (300 °C). The SnO2/MoO3 loading amount within CNFs can be easily adjusted by controlling the Sn/Mo/C precursors. When examined as lithium ion battery (LIB) anode materials, the amorphorized SnO2/MoO3@CNFs with carbon content of 32 wt% (also denote as SMC-32, in which the number represents the carbon content) deliver a high reversible capacity of 1120.5 mA h/g after 200 cycles at 200 mA/g and then 651.5 mA h/g after another 300 cycles at 2000 mA/g, which is much better than that of the crystalline SnO2/CNFs (carbon content of 34 wt%), MoO3/CNFs (carbon content of 22.7 wt%), or SnO2/MoO3@CNFs (with lower carbon contents of 11 and 25 wt%). The electrochemical measurements as well as the ex situ structure characterization clearly suggest that combination of amorphorization and hybridization of SnO2/MoO3 with CNFs synergistically contributes to the superior lithium storage performance with high pseudocapacitive contribution.

Element doping has been extensively employed to modulate the physicochemical properties of semiconductors. In this work, Se-doped CdS quantum dots (QDs) with varied Se doping level are fabricated via a solvothermal procedure. Due to the introduction of Se, the Fermi level position of CdS is elevated to a higher position, leading to the effective capture of photogenerated electrons by the trapping sites, which greatly inhibits the recombination of electron-hole pairs and thus prolong the charge carriers’ lifetime. Furthermore, due to the introduction of Se, the density of charge carriers in CdS is significantly enhanced, which is conducive to the production of more photo-generated electrons and holes. It is because of the two favorable factors that the photocatalytic performance of the resultant CdS0.9Se0.1 QDs is greatly improved with a remarkable hydrogen evolution rate of 29.12 mmol h−1 g−1 under simulated solar irradiation (320–780 nm) without any co-catalysts, which is 23.5 times that of the pristine CdS QDs under the same conditions. Moreover, the apparent quantum efficiency (AQE) over CdS0.9Se0.1 QDs reaches 27.1% at 400 nm without co-catalyst addition. This work confirms the feasibility of suppressing the recombination of electron-hole pairs by adjusting the capture level with impurity doping for exploring highly efficient photocatalysts.

Interfacial manipulation of nanostructured heterojunction photocatalysts to enhance charge separation and transfer is highly desirable to achieve a high photocatalytic activity. In this work, a well-designed non-noble-metal Mo2C@C/g-C3N4 heterostructure is constructed, in which the intercalated carbon nanosheets serve as a binder to form an excellent interfacial contact between Mo2C and g-C3N4. In addition, large quantities of carbon quantum dotsare found to be homogeneously embedded in the carbon nanosheets. The as-obtained Mo2C@C/g-C3N4 hybrid exhibits a remarkably improved photocatalytic H2 evolution rate of 52.1 μmol h−1 under visible-light irradiation (λ ≥ 420 nm) without co-catalyst, which is up to nearly 260 times higher than that of pristine g-C3N4 (0.2 μmol h−1) under the same conditions. The significant increase in photocatalytic activity mainly results from the fast charge migration and separation between Mo2C and g-C3N4 facilitated by the conducting carbon nanosheets as an efficient electron mediator. Moreover, the carbon quantum dots embedded in the carbon support also promotes solar energy utilization. This work highlights a feasible strategy to explore highly efficient photocatalysts via interfacial engineering on heterojunction composites.

Photocatalytic hydrogen evolution from water splitting driven by visible light is a promising approach to solve energy crisis and environmental problems, and noble-metal-free co-catalysts for boosting the hydrogen evolution reaction are highly desired. Herein, we explore a novel noble-metal-free Fe2P–Co2P co-catalyst for the first time to boost the photocatalytic performance of graphitic carbon nitride (g-C3N4). The resultant Fe2P–Co2P/g-C3N4 with optimum ratio exhibits a hydrogen production rate of 347 μmol h−1 g−1 in the absence of noble-metal co-catalyst, which is 87 times higher than that of pristine g-C3N4 under the same conditions. The significant enhancement in the photocatalytic performance of Fe2P–Co2P/g-C3N4 can be ascribed to the Schottky junction formed between Fe2P–Co2P and g-C3N4, which produces a strong driving force for the transfer of electrons from g-C3N4 to Fe2P–Co2P, promoting the separation and transfer of photogenerated electrons and holes. Furthermore, due to the synergistic effects between the two metal phosphides (Fe2P and Co2P), the Schottky junction in Fe2P–Co2P/g-C3N4 can produce stronger driving force than that in Fe2P/g-C3N4 and Co2P/g-C3N4, resulting in the fact that the hydrogen production rate over Fe2P–Co2P/g-C3N4 is much higher than that over Fe2P/g-C3N4 and Co2P/g-C3N4. This work may shed light on the careful design of co-catalyst by utilizing the synergistic effect of different components.

Crystal facets usually play an important role in the catalytic activity of inorganic single crystals. In this work, two α-Mn2O3 single crystals with an octahedron (exposed with (1 1 1) facet) and a truncated octahedron (exposed with both (1 1 1) and (0 0 1) facets) were successfully prepared by a simple solvent-thermal reaction, and their catalytic activities were evaluated by the selective catalytic reduction (SCR) of NOx with NH3. The results show that the catalytic performance of the α-Mn2O3 single crystal with a truncated octahedron was enhanced in comparison with the α-Mn2O3 single crystal with an octahedron by the exposure of a small fraction of (0 0 1) facets. This can be attributed to the new active sites created by charge redistribution on the surface of the (0 0 1) facets, which provides more adsorption sites, facilitating the further adsorption and reaction of NH3 and NO molecules, and thereby enhancing the catalytic performance. This work should provide new insight into the understanding of crystal-facet-dependent reactivity and important guides for the design and preparation of SCR catalysts with high activity.

1,2-dichloroethane (1,2-DCE) is a representative industrial chlorinated volatile organic compound (CVOC) making great hazardous to the environment and human health. In this work, LaSrMnCoO6 (LSMC) double perovskite-type materials with high thermal stability and coke resistance in 1,2-DCE oxidation were prepared by a facile sol-gel method. Based on this, a series of CrOx/LaSrMnCoO6 catalysts (Cr/LSMC, CrOx loading = 5 to 20 wt.%) which combine the merits of CrOx (high activity and chlorine tolerance) and LaSrMnCoO6 were synthesized and adopted in deep oxidation of 1,2-DCE for the first time. As expected, obvious synergistic effects between CrOx and LSMC on 1,2-DCE destruction were observed. Amongst, 10 wt.% CrOx/LaSrMnCoO6 (10Cr/LSMC) shows the best catalytic activity with 90% of 1,2-DCE destructed at 400 °C. Furthermore, the outstanding catalytic durability and water resistance of 10Cr/LSMC in 1,2-DCE oxidation were also demonstrated. In addition to this, the reaction pathway of 1,2-DCE decomposition over Cr/LSMC materials was discussed based on the results of online product analysis. We found that the enhanced catalytic performance of Cr/LSMC materials can be reasonably attributed to their high reducibility, excellent 1,2-DCE adsorption capability, and large amounts of surface active lattice oxygen species. It can be anticipated that the Cr/LSMC catalysts are promising materials for CVOC elimination and the results from this work could also provide some new insights into the design of catalysts for CVOC efficient destruction.

In this work, a novel strategy, one-step vulcanization of Cd(OH)Cl nanorods in the presence of ZnCl2 and Na2PdCl4, is successfully developed to synthesize CdS/ZnS/PdS nanotubes (NTs) for the first time. In this method, the three components (CdS, ZnS and PdS) are fully combined together at the nano-scale in the CdS/ZnS/PdS NTs, creating a large number of intimate contact interfaces. As a result, the optimized CdS/ZnS/PdS NTs exhibit a significantly enhanced photocatalytic H2 evolution rate of 1021.1 μmol h−1 (10 mg of catalyst), which is 11.4 and 16.3 times higher than that of pristine CdS NTs and ZnS nanoparticles (NPs), respectively, and is the maximum reported value for CdS-based photocatalysts under similar experimental conditions. Moreover, the apparent quantum efficiency of the optimal sample can reach 26.1% at 365 nm wavelength. The improved photocatalytic performance can be attributed to the synergistic effects of the hollow tubular structure, the CdS/ZnS heterostructure and the PdS co-catalyst. Due to the hollow tubular structure, both the inner and outer surfaces of CdS/ZnS/PdS NTs can act as reaction sites to rapidly consume electrons and holes, effectively suppressing their recombination. Both the CdS/ZnS heterostructure and PdS co-catalyst can efficiently promote the separation and transfer of charge carriers. This work may provide a new method for the design and construction of new photocatalysts with highly efficient H2 production.

A series of hierarchical porous carbons (HPCs) with different morphologies and well-developed porosity have been successfully synthesized via a facile and flexible template-free method using hierarchical assembly of polyimide as carbon precursor. Amongst, cornflower-like hierarchical porous carbon (FC4) displays the best CO2 capture property with an adsorption capacity up to 4.05 and 2.87 mmol g−1 at 273 and 298 K, respectively. The excellent CO2 capture capability of FC4 can be owing to the cooperative effect of moderate meso-/macropore channels and abundant framework micropores, which are conducive to diffusion and capture of CO2 adsorbate. Moreover, FC4 shows superior stability and recyclability and CO2 trapping selectivity with CO2/N2 initial and final adsorption ratios of 24 and 6.4, respectively. It can be anticipated that the FC4 is a promising adsorbent in the adsorption and separation of carbon dioxide under actual conditions.

A novel photocatalyst with core@shell structure was prepared by alternately assembling titania nanosheets (TNS) and reduced graphene oxide (r-GO) on coal fly ash (CFA) microspheres via the layer-by-layer (LBL) assembly approach. The as-prepared samples CFA@(r-GO/TNS)n were characterized by SEM, HRTEM, XRD, FTIR, Raman, XPS, UV–vis, PL and their photocatalytic activities were evaluated by the photodegradation of methylene blue (MB) under UV irradiation. The results showed that TNS and r-GO wrapped on the surface of CFA alternately and tightly, which was very helpful not only to avoid the detachment of TNS and r-GO from the surface of CFA in the progress of using, but also to reduce the recombination of photogenerated electrons and holes due to excellent mobility of charge carriers on the surface of r-GO. The layer number of wrapped r-GO/TNS was found to be an important factor in the photocatalytic activity of composite. In our experimental conditions, CFA@(r-GO/TNS)8 presented the best photocatalytic activity, and the degradation efficiency of MB was improved to 55% from 32% of CFA@(r-GO/TNS)2. The improvement could be attributed to several advantageous factors by introduction of r-GO, such as the fast charge-carrier transfer, the reduction of the charge recombination rate, the improved light harvesting and the larger specific surface area.

Gadolinium (Gd) has been used as a dopant to modify MnOx for enhanced catalytic performance and sulfur resistance in the application of the selective catalytic reduction (SCR) of NOx with NH3 for the first time. The results show that the introduction of Gd with proper amount can effectively restrain the crystallization of MnOx, enhance the specific surface area, increase the concentrations of surface Mn4+ and chemisorbed oxygen species, and enhance the amount and the strength of surface acid sites. The MnGdO-2 catalyst (Gd-modified MnOx with the mole ratio of Gd/Mn = 0.1) exhibits optimal catalytic performance among all prepared catalysts with a 100% NO conversion performance in a wide temperature window from 120 to 330 °C and a 100% N2 selectivity from 150 to 300 °C under a high space velocity of 36,000 h−1. In-situ DRIFT spectra reveal that the Gd doping can promote the NH3 adsorption on the catalyst pre-adsorbed with NOx species, facilitating the reactive NH4+ species taking part in the SCR reaction. More importantly, MnGdO-2 catalyst presents stronger resistance to water vapor or sulfur poisoning in comparison with pure MnOx catalyst, which can be ascribed to these facts that Gd-modification restrains the transformation of MnO2 to Mn2O3 and the generation of MnSO4, impedes the decrease in Lewis acid sites and the increase in Bronsted acid sites, and alleviates the competitive adsorption between the NO and SO2. This work may provide new insights into the effects of rare earth modification on the de-NOx mechanism and the SO2 resistance mechanism of MnOx catalysts.

A series of Sm-modified MnOx-TiO2 (SMT) catalysts are prepared and characterized. The results show that the introduction of Sm can effectively restrain the crystallization process of MnOx and TiO2, enhance the specific surface area, increase the surface concentration of chemisorbed oxygen species and the amount of strong surface acid sites, and reduce the surface concentration of Mn4+. The catalytic performances of the SMT catalysts are evaluated by the selective catalytic reduction (SCR) of NOx with NH3. It is found that SMT-0.3 catalyst (a 0.3 mol rate of Sm/Mn) exhibits a 100% NOx conversion in a wide operating temperature window from 180 to 390 °C, and a 100% N2 selectivity from 120 to 390 °C under a GHSV of 36,000 h−1, which is obviously better than MnOx-TiO2 without Sm addition. In-situ DRIFT spectra reveal that, at low temperature (below 200 °C), absorbed NH3 species can react with gas-phase NO over MnOx-TiO2 catalyst following Eley-Rideal (E-R) mechanism, while the NH3-SCR of NO over SMT-0.3 follows both E-R and Langmuir-Hinshelwood (L-H) mechanisms. However, at high temperature (above 200 °C), the SCR reaction over MnOx-TiO2 is via “standard SCR” process, but the SCR reaction over SMT-0.3 is through “fast SCR” reaction.

A series of NiyCo1-yMn2Ox microspheres (MSs) (y = 0.1, 0.3, 0.5, 0.7, 0.9) were synthesized successfully by a hydrothermal method. Their physicochemical properties of the as-prepared NiyCo1-yMn2Ox MSs were explored by using a series of characterizations, and their catalytic performances were evaluated by the selective catalytic reduction (SCR) of NOx with NH3. It was found that there are the synergetic effects between Ni and Co, which have an important impact on the surface physicochemical properties of NiyCo1-yMn2Ox MSs, such as the roughness of the surface, the stacking molding, the crystal structure, the specific surface area, the concentrations of surface Mn4+, Co3+ and Ni2+, the reducibility, and the proportion of weak acid and strong acid sites, etc, which further affect the reaction mechanism of de-NOx of NiyCo1-yMn2Ox MSs, and finally dominate their catalytic performances for the SCR of NOx with NH3. Among all NiyCo1-yMn2Ox MSs, Ni0.7Co0.3Mn2Ox exhibits the optimal catalytic performance for the SCR of NOx, which is much better than CoMn2Ox and NiMn2Ox. This work may shed light on the deliberately designed Mn-based SCR catalysts with high activity by taking advantage of the synergetic effects between components.

Hierarchically micro-mesostructured Pt/K-Al-SiO2 catalysts with regular nanorod (Pt/KA-NRS) and spherical nanoflower-like (Pt/KA-SNFS) morphologies were prepared. The existence of Al atoms generates Brønsted acid sites and reduces silanol groups over the supports, promoting the dispersion of Pt nanoparticles and stability of catalysts. Potassium atoms balance the negative charge of supports and enhance O2 mobility. The Pt/KA-NRS catalysts exhibit unexceptionable low temperature activity, CO2 selectivity, and stability for MEK oxidation. Amongst, 0.27 wt.% Pt/KA-NRS completely converts MEK at just 170 °C (activation energy as low as 37.22 kJ·mol−1), more than 100 °C lower than other typical Pt/Pd supported catalysts reported in the literature. Diacetyl and 2,3-butandiol are the main intermediates during MEK activation, which convert into H2O and CO2 through aldehydes and acids. The excellent catalytic activity of Pt/KA-NRS is ascribed to their regular morphology, high Pt0 content and dispersion, excellent MEK adsorption capacity and superior O2/CO2 desorption capability under low temperature.

The design of efficient and stable photocatalyst plays a critical role in the photocatalytic hydrogen evolution from water splitting. Herein, we develop a novel ZnS/CdS/ZnO ternary heterostructure by the in-situ sulfuration of CdS/ZnO, which includes four contact interfaces: CdS-ZnS interface, ZnS-ZnO interface, CdS-ZnO interface and ZnS-CdS-ZnO ternary interface, forming three charge carrier-transfer modes (type-I, type-II and direct Z-scheme) through five carrier-transfer pathways. As a result, the separation and transfer of photoexcited electron-hole pairs are promoted significantly, resulting in a high hydrogen evolution rate of 44.70 mmol h−1 g−1, which is 2, 3.7 and 8 times higher than those of binary heterostructures, CdS/ZnO, CdS/ZnS and ZnS/ZnO, respectively, and 26.5, 280 and 298 times higher than those of single CdS, ZnO and ZnS, respectively. As a counterpart ternary heterostructure, CdS/ZnS/ZnO contains only two interfaces: CdS-ZnS interface and ZnS-ZnO interface, which form two charge carrier-transfer modes (type-I and type-II) through two carrier-transfer pathways, leading to its much lower hydrogen evolution rate (27.25 mmol h−1 g−1) than ZnS/CdS/ZnO ternary heterostructure. This work is relevant for understanding the charge-transfer pathways between multi-interfaces in multicomponent heterojunctions.

The meso-porous TiO2 and Sm-doped meso-porous TiO2 were synthesized by a sol-gel method. Polyethylene glycol, with different added content, was added as a structure-directing agent. The prepared meso-porous TiO2 was characterized by nitrogen adsorption, X-ray diffraction and ultraviolet-visible diffuse reflectance spectroscopy, and the photocatalytic performance was evaluated by the decomposition of methyl orange. The results revealed that PEG plays a key role in creating porous structure during the heat-treatment. The photocatalytic performance of TiO2 is improved by adding proper content PEG, and Sm-doping can further promote the photocatalytic performance.

A series of highly active de-NO x catalysts, Eu-modified MnO x -TiO 2 (MnTiEu), was prepared by an inverse co-precipitation method. Their physiochemical properties were investigated by XRD, TEM, EDS, BET, XPS and H 2 -TPR in detail, and their catalytic activities were evaluated by the selective catalytic reduction (SCR) of NO with NH 3 . The results showed that the introduction of Eu with proper amount into MnO x -TiO 2 can effectively restrain the crystallization process of MnO x and TiO 2 , enhance specific surface area, increase the concentration of both surface Mn 4 + and chemisorbed oxygen species, improve the stability of Mn 4 + and Mn 3 + , reduce the amount of surface acid sites, enhance the strength of surface acid sites. The obtained MnTiEu-0.3 catalyst (the molar rate of Eu/Mn was 0.3 and the mole rate of Mn/Ti was 0.1) exhibited a 100% NO x conversion activity in a wide temperature window from 180 to 390 °C and a 100% N 2 selectivity from 120 to 390 °C under a high space velocity of 36,000 h − 1 . Furthermore, MnTiEu-0.3 catalyst presented stronger resistance to concurrent H 2 O and SO 2 poison in comparison with MnO x -TiO 2 catalyst without Eu addition. In - situ DRIFT spectra suggested that NH 3 can be adsorbed on both Lewis and Bronsted acid sites. For MnO x -TiO 2 catalyst, both coordinated NH 3 species on Lewis acid sites and NH 4 + species on Bronsted acid sites can react with gas-phase NO following E-R mechanism. As regards MnTiEu-0.3, the NH 3 -SCR of NO follows both Eley-Rideal and Langmuir-Hinshelwood mechanisms, in which the Eley-Rideal mechanism is predominated.

The stability of MnO x based low temperature SCR catalysts remained to be a serious issue. This report explored use of multi-walled carbon nanotubes (MWCNTs) network with uniform structure as a “rigid” pore template for synthesis of mesoporous MnO x -TiO 2 SCR catalyst with high surface area and high stability. The results showed that MWCNT network imposed MnO x -TiO 2 catalyst a mesoporous porosity with a narrow pore size distribution centered on ∼13.2 nm and a surface area of 131.6 m 2 g −1 stabilized at 500 °C. The mesoporous structure was formed by interconnected nanoparticles, comprised of crystallized rutile TiO 2 core surrounded by amorphous MnOx, with an average diameter of ∼8 nm. The catalyst exhibited an excellent low temperature SCR activity and selectivity as well as high resistance to deactivation and poison by H 2 O and SO 2 . SnO 2 modification led to degradation of catalytic performance in low temperature (60–180 °C) side, but improvement at high temperature side (240–360 °C), especially at high gas velocity, which can be attributed to change in structure, reactivity of MnO x and surface acidity induced by SnO 2 addition.

MnM2O4 microspheres (M = Co, Cu, Ni) were successfully prepared by a hydrothermal method. The catalytic activities of the as-prepared MnM2O4 microspheres were comparatively investigated by the selective catalytic reduction (SCR) of NO with NH3, and their reaction mechanisms were studied by in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFT). The results showed that MnCo2O4 presented the best low-temperature catalytic activity (nearly 100% NOx conversion in a wide temperature window from 120 to 330 °C under a high gas hourly space velocity (GHSV) of 36,000 h−1), the best N2 selectivity (100% N2 selectivity in the temperature range from 60 to 360 °C), and excellent water resistance. The high catalytic activity of MnCo2O4 was mainly attributed to the large quantity of surface acid sites with dominant Bronsted acid sites rather than Lewis acid sites. In addition, larger SBET and higher surface Mn4+ concentration also had positive effect on its catalytic activity. Contrastively, the least number of surface acid sites with dominant Lewis acid sites rather than Bronsted acid sites over MnCu2O4 resulted in its worst low-temperature catalytic activity. The catalytic activity of MnNi2O4 was in the middle. In-situ DRIFT revealed that the NH3-SCR of NO over MnCo2O4 and MnNi2O4 followed both Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms. For MnCu2O4, the reaction was dominated by E-R mechanism.

Photocatalytic H2 evolution is highly attractive for converting abundant solar energy to valuable fuel. Herein, we report the use of an atomic layer deposition (ALD) technology to fabricate a new class of CdS@ZnO core-shell heterostructure. The rationally designed ultrathin ZnO shell not only allows the light to be absorbed by CdS core, but also provides an intimate heterojunction interface between ZnO shell and CdS core. The amount of ZnO shell coated on CdS core is finely tuned by the number of deposition cycles, and the obtained CdS@ZnO with 100 ALD deposition cycles displays the optimal photocatalytic H2 evolution rate of 11.36 mmol/g/h. When Pt and PdS are used as the co-catalysts, the H2 evolution rates are further enhanced to 71.39 and 98.82 mmol/g/h, respectively, which are 4.1 and 5.7 times higher than the highest reported value (17.40 mmol/g/h) among CdS-ZnO catalyst systems. Detailed characterization reveals that the drastically enhanced photocatalytic activity can be attributed to not only efficient space separation of the photo-induced electrons and holes resulted from the formation of a direct Z-scheme photocatalytic system between crystalline ZnO and CdS, but also the intimate contact at molecular scale between the two semiconductors. Due to the coverage of ALD-prepared crystalline ZnO shell on CdS core, the CdS@ZnO core-shell structures exhibit excellent photostability.