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Here, we demonstrate a strategy to construct highly active CoxP/SrTiO3(Al) for overall water splitting. The as-prepared CoxP/SrTiO3(Al) photocatalyst shows a stable HER rate of 1.36 mmol−1 h−1 and OER rate of 0.635 mmol−1 h−1.

TiO2/Cu-SSZ-13 composited SCR catalysts were prepared to improve urea decomposition activity and prevent urea-derived deposition in low-temperature urea-SCR.

To improve the hydrothermal durability of Cu-SSZ-13 selective catalytic reduction (SCR) catalyst, a thin Al2O3 modification layer was coated on the external surface of Cu-SSZ-13 by a chemical liquid deposition (CLD) method. The high-temperature SCR activity of the Al-modified Cu-SSZ-13 can be maintained upon 750-800 °C hydrothermal aging, and over-oxidation of NH3 is largely inhibited. Based on H2-TPR and EPR results, it is revealed that CuAl2O4-like species forms upon Al modification and converts further to CuAlO2-like species during aging. The high affinity of Al-containing species (i.e., Al2O3 and CuAl2O4-like species) with Cu(OH)2 is suggested by DFT calculations, indicating that Cu(OH)2 detached from ion-exchange sites are captured by Al to form CuAlO2-like species instead of CuO-like species. The passivation of aggregated Cu species by coated Al leads to somewhat weakened low-temperature SCR activity, but successfully preserves the high-temperature SCR performance upon aging, which can be applied to high-temperature SCR scenarios.

Aluminum-doped strontium titanate SrTiO3(Al), has been demonstrated as the suitable photocatalyst for overall water splitting. Noble metals, such as RhCrOx, are widely applied to accelerate the photocatalytic hydrogen evolution. Herein, Ni single atoms anchored on nitrogen-doped graphene (Ni SA-NG) are adopted to replace noble metal as hydrogen (H2) evolution cocatalysts for SrTiO3(Al)/CoOx photocatalyst. The prepared Ni SA-NG/SrTiO3(Al)/CoOx photocatalyst exhibits remarkable activity for photocatalytic overall water splitting with the H2 evolution rate of 498 μmol g−1 h−1 and oxygen (O2) evolution rate of 230 μmol g−1 h−1, respectively. Ni SA-NG not only improves the efficiency of photogenerated charge transfer and separation through the Ti–O–C bonds acting as the electron transfer freeway, but also provides highly active sites to accelerate the surface H2 evolution rate. This research provides a valuable method to construct SrTiO3-based photocatalyst without noble metal cocatalysts.

The influences of gaseous, weakly adsorbed, and strongly adsorbed NH

In this study, a V2O5-Sb2O3/TiO2 monolithic catalyst was modified by introducing WO3. The WO3-modified catalyst exhibited enhanced catalytic activity in the measuring temperature range of 175–320 °C. The changes in dispersion of vanadia species were investigated by ultraviolet-visible (UV-Vis) spectroscopy and H2 temperature-programmed reduction (H2-TPR). A durability test was conducted in a wet SO2-containing atmosphere at 220 °C for 25 h. The sulfate deposition was estimated by temperature-programmed decomposition (TPDC) of sulfates, thermo-gravimetric (TG) analysis, and temperature-programmed desorption (TPD) of NH3. Isothermal SO2 oxidation and temperature-programmed surface reaction (TPSR) of NH4HSO4 with NO were performed. Based on these characterizations, effects of WO3 modification on the sulfate tolerance of the catalyst were explored.

Noble metal-free MoS2/g-C3N4 photocatalysts have been synthetized by one step thermal treatment of thiourea and sodium molybdate, which has intimate contact interfaces between g-C3N4 and MoS2. The hydrogen generation rate of MoS2/g-C3N4 photocatalyst is 280 µmol·g−1·h−1, 40 times as that of pristine g-C3N4. The enhanced activity is attributed to the in-situ generated intimate interfaces, which leads to enhanced absorption of visible light and higher efficiency of charges separation.

Utilizing photocatalysts to split water into H2 and H2O2 simultaneously is an ideal but challenging process to obtain clean H2 energy and high valuable H2O2. Most of the photocatalysts currently studied for the overall water splitting are converting water into H2 and O2, resulting in further need of gas separation. Here, we reported a photocatalyst which can utilize the nano-Au based localized surface plasmonic resonance (LSPR) effect to produce H2 and H2O2 simultaneously. Nitrogen doped graphene quantum dots (N-GQDs) pieced together into large graphene through a catalytic process by chloroauric acid, in which dodecahedron nano-Au particles can also be obtained concurrently. Then Au wrapped up by graphene can be in situ formed with good interfaces. Photocatalytic activity tests revealed that the as prepared graphene@Au catalysts show efficient photocatalytic overall water splitting activity with a H2 evolution rate of 65.6 μmol g−1 h−1 and H2O2 generation rate of 49.7 μmol g−1 h−1. This work provides a feasible route for the facile fabrication of graphene through the bottom-up polycondensation of N-GQDs by amide bonds and new insights into the synthesis of photocatalysts for overall water splitting into H2 and H2O2.

Preparing stable highly dispersed Pt based electrocatalyst is promising to reduce material expense of H2 product via electrocatalytic water splitting. However, it is still a great challenge to obtain stable single atomic Pt catalysts which can be applied in acidic electrolyte. In the present work, we synthesized Pt atomic clusters on carbon quantum dots (CQDs) grafting multiwall carbon nanotube (CNT) (Pt content: 1 wt.%) catalysts and then loading the catalysts on carbon cloth (Pt content: 0.01 mg▪cm–2) for activity test. The overpotential of 29 mV versus RHE was obtained over 1%Pt/CQDs/CNT catalysts at the current density of 10 mA▪cm–2, and the Tafel slope of 22 mV decade–1 was obtained, too. Especially, the catalysts showed significant stability in hydrogen evolution reactions (HER) in acidic solution, of which the overpotential was still smaller than that of 20%Pt/C after 10,000 CV cycles. CQDs provided coordinating sites for dispersing Pt atomic clusters and improved the H+ concentration in adjacent area around the Pt clusters. This method provides a general strategy to design the highly efficient electrocatalysts with ultra‐low precious metals for H2 evolution in acidic electrolyte.

A high-quality hybrid Cs0.15FA0.85PbI3 thin film is deposited through doping of carbon nanodots (CNDs) into perovskite precursor solution. The corresponding inverted planar perovskite solar cells (PSCs) of ITO/PTAA/Cs0.15FA0.85PbI3/PC61BM/BCP/Ag exhibit an improvement in efficiency from 17.36% to 20.06%, which could be attributed to the passivation of the defects at the crystallized perovskite thin film and enhanced perovskite phase uniformity. The results of electron trap density indicate that the addition of CNDs significantly reduces the defects density at the perovskite thin film and the recombination of charge carriers in transport process is minimized. These results demonstrate that low-cost CNDs are effective additives for passivating defects, further reducing charge carrier recombination and improving device efficiency.

A quasi-operando NH3 temperature-programmed reduction method (NH3-TPR), with N2:Cu = 1:1, is developed to quantify total Cu(II) ions in Cu-SSZ-13 quenched from SCR-relevant reactions, and its accuracy is confirmed by in situ EPR. [Cu(OH)]+-Z and Cu2+-2Z can be further distinguished by NH3 reduction temperatures, and their different reducibility in SCR is revealed.

Pt/Al2O3 catalysts with mean Pt particle size ranged from 2.7 to 7.1 nm were synthesized by chemical reduction method, and the sulfated counterparts were prepared by impregnation of sulfuric acid. The turnover frequency of platinum for soot oxidation under loose contact conditions in a feed flow containing NO and O2 are positively correlated with the size of platinum. The sulfated Pt/Al2O3 exhibits higher catalytic activity for soot oxidation in the presence of NO despite their reduced ability for NO2 production. Such a contradiction is more significant for those catalysts with smaller platinum particles. Herein, the catalysts were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM), inductive coupled plasma (ICP) emission spectrometry, CO chemisorption, thermogravimetric analysis (TGA), NH3 temperature-programmed desorption (NH3-TPD), NO temperature-programmed oxidation (TPO) and NOx temperature-programmed desorption (TPD). Possible effect of Pt particle size for the catalytic oxidation of soot in the presence of NO was presented based primarily on the promoted NO2 transfer efficiency onto the soot pushed by the acidic catalysts.

A series of La1–xCexMnO3+δ (x = 0, 0.05, 0.1, 0.2, and 0.3) perovskites and Mn–Ce mixed oxides were prepared. Their physico-chemical properties were systematically characterized and the NO oxidation activities of the catalysts were investigated. The La0.9Ce0.1MnO3+δ has the best activity among all of the catalysts, with a maximum NO conversion of 85% at 300 °C. The characterization results indicate that the doping of Ce improves the properties of the perovskites in terms of the specific surface area, the average valence state of Mn ions, the number of reactive oxygen species and the NOx desorption behaviors. The Mn–Ce mixed oxide calcined at 500 °C shows a similar NO oxidation activity with La0.9Ce0.1MnO3+δ. However, the activity of the mixed oxide obtained at 750 °C decreases a lot, which results from the loss of active sites and active oxygen species.

Cu-SSZ-13 catalyst, as the most popular selective catalytic reduction on filter (SCRF) catalyst in diesel exhaust purification, may suffer from severe alkali deposition derived from engine oil, urea solution and biodiesel fuel. These accumulated deposits inevitably affect both of the NOx reduction and soot oxidation reactions. Unlike deactivation effect of alkali impurities on Cu-SSZ-13 catalyst for NH3-SCR process, which has been extensively studied and well documented, the impact of alkali deposition on soot oxidation over SCRF catalyst is still poorly understood. Herein, we reported the influence of potassium salts deposition on soot oxidation of Cu-SSZ-13 catalyst. Compared with the fresh Cu-SSZ-13, these K-impregnated catalysts show promoted activities toward soot oxidation with the promotion effect of K2SO4 > K2CO3 > K3PO4. The generated copper compounds instead of potassium salts are found to be responsible for the enhanced catalytic activity. The NO oxidation over the K2CO3-impregnated catalyst is accelerated by CuOx clusters, resulting in a low ignition temperature toward soot oxidation in the presence of NOx. Contrarily, K2SO4- and K3PO4-impregnated catalysts show higher ignition temperature values because the generated copper sulfates and phosphates present weakened NO oxidation activities especially in the low-temperature region. This work provides new insight into understanding the affecting mechanism of alkali impurities on SCRF catalysts. The generated Cu species induced by the deposition of different potassium salts, rather than alkali species themselves, are responsible for the promoted soot oxidation activity of the K-impregnated Cu-SSZ-13 as a SCRF catalyst.

Pt@g-C3N4/CeO2 photocatalyst was prepared by calcination of g-C3N4/CeO2 mixture followed by impregnating Pt. Under the irradiation of visible light with the presence of water vapor at room temperature, Pt@g-C3N4/CeO2 showed significant performance for remediation of NOx. The deNOx mechanism was studied by modified in-situ FTIR. The results proved that NO was prone to adsorb on the surface of Pt@CeO2 and oxidized to nitrite for storage. Then, the photoinduced hydrogen on Pt@g-C3N4 component could diffuse into the vicinity of nitrite through the spillover effect of Pt and reacted with nitride to produce N2 and H2O.

Constructing Z-scheme heterojunctions is considered as an effective strategy to obtain catalysts of high efficiency in electron–hole separation in photocatalysis. Unfortunately, suitable heterojunctions are difficult to fabricate because the direct interaction between two semiconductors may lead to unpredictable negative effects such as electron scattering or electron trapping due to the existence of defects which causes the formation of new substances. Furthermore, the van der Waals contact between two semiconductors also results in bad electron diffusion. In this work, a MOF-derived carbon material as a Z-scheme photocatalyst was synthesized via one-step thermal treatment of MoS2 dots @Fe-MOF (MIL-101). Under visible light irradiation, the well-constructed Z-scheme (MoS2, γ-Fe2O3)/graphene photocatalyst shows 2-fold photocatalytic oxygen evolution activity (4400 μmol g−1 h−1) compared to that of γ-Fe2O3/graphene (2053 μmol g−1 h−1). Based on ultraviolet photoelectron spectrometry (UPS), Mott–Schottky plot, photocurrent and photoluminescence spectroscopy (PL) results, the photo-induced electrons from the conduction band of γ-Fe2O3 could transport quickly to the valence band of MoS2 via highly conductive graphene as an electron transport channel, which could significantly enhance the electron–hole separation efficiency as well as photocatalytic performance.

Water electrolysis is one of the most feasible ways to utilize clean and renewable energy sources in the form of hydrogen energy. However, the anodic oxygen evolution reaction (OER) is a slow kinetic process, so it is of great significance to develop efficient oxygen evolution catalysts (OECs). Many studies have shown that Ce plays an important role in high-performance transition-metal-based OECs. We discuss and summarize possible causes for the improved OER activity and stability with emphasis on the hybrids of cerium and transition metals, including cerium-doped catalysts, ceria-support catalysts and ceria-loaded catalysts. Finally, current challenges for the Ce-containing catalysts are identified, pointing to the future directions for propelling the water electrolysis research.

CeNbTi catalyst was poisoned in different sulfur poisoning atmospheres at 300 °C for 6 h and then was evaluated for selective catalytic reduction (SCR) of NOx with NH3. The catalyst deactivation upon SO2 exposure was effectively inhibited in the presence of NH3. Temperature-programmed decomposition (TPD) analyses were applied to identify deposit species on the poisoned catalysts by comparison with several groups of reference samples. Diffuses reflectance infrared Fourier transform spectroscopy (DRIFTS) over CeNbTi catalysts with different poisoning pretreatments and gas purging sequences were designed to investigate the roles of NH3 in the removal of surface sulfites and sulfates. More ammonium sulfates including ammonium bisulfate and ammonium cerium sulfate were generated instead of inert cerium sulfate in these conditions. The mechanisms about the formation and transformation of surface deposits upon sulfur poisoning w/wo NH3 were explored, which provided a basis for developing Ce-based mixed oxides as SCR catalysts for stationary sources.

A facile way to synthesize multilayer nitrogen-doped graphene (NG) from amorphous activated carbon (AC) without metal catalyst was successfully developed via ammonia-assisted hydrothermal method at 200 °C. The method's crucial advantage relied on harnessing unique ammonia hydrothermal mechanisms to change the amorphous carbon into multilayer graphene and provide an energy-save and metal-free approach. The NG products were consisted of 2–10 graphitic layers, which could form highly conductive network for electrodes. The hydrothermal process could trigger the reduction of oxygenates on the base unit (graphite nanocrystallites) of amorphous carbon by ammonia, leading to growth of basic units to multi-layer graphene. Compared with the traditional preparation via high temperature and pressure processing or catalytic graphitization by transition metals, the as-prepared multilayer graphene via metal-free and “green” method in a relative mild condition represented a high surface area and pore volume. The NG was used as electrode material of supercapacitors and showed high capacitance retention.

Herein, we fabricated honeycomb ceramics with different porosities and pore shapes via the layer-by-layer deposition of cordierite (2MgO·2Al2O3·5SiO2) particle ink, obtaining proper rheological properties using a direct-writing technology. No collapses as well as minimal cracking and bending were observed in the internal structure of the samples after calcination. We measured and compared the internal porosity and specific surface area of honeycomb ceramics with the same pore shape but different pore dimensions, as well as the same pore dimension but different pore shapes. The samples were both loaded with an γ-Al2O3 washcoat and Pd-based catalyst using the same method for the catalytic combustion of toluene. The different porosity and pore shape influenced the catalytic efficiency. This study may provide some useful guidelines for fabrication of honeycomb ceramics by direct writing technology, which could be used to remove volatile organic pollutants(VOCs).

Solid-state ion-exchange (SSIE) is an effictive method to prepare Cu-SSZ-13, but usually requires high temperatures or assistance of NH3 for catalyst activation. Herein, an environmentally friendly...

CeO2/WO3-TiO2 (CeWTi) and Nb2O5-CeO2/WO3-TiO2 (NbCeWTi) catalysts were prepared by a sol-gel precipitation method. Both the catalysts exhibit high selective catalytic reduction of NOx with NH3 (NH3-SCR) activities at 270–500 °C. The sulfur tolerances of the catalysts were evaluated at 270 °C by adding H2O and SO2 in the feeding gas and NbCeWTi exhibited a significantly improved resistance. The thermogravimetric (TG) and mass spectrographic (MS) results indicated that much less sulfates formed on NbCeWTi and existed mainly in the form of ammonium hydrogen sulfate species which protected Cex+ active sites effectively from attacking of SO2. According to the results of temperature-programmed desorption of ammonia (NH3-TPD), H2 temperature-programmed reduction (H2-TPR) and SO2 oxidation, loading niobia on CeWTi inhibited the SO2 oxidative adsorption and SO3 production which basically reduced sulfur poisoning of the catalyst. Additionally, the niobia modification ensured the formation of nitrates from the competitive adsorption of SO2 and hereby facilitated the nitrate SCR route based on the in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS).

NaOH-promoted Pt/TiO2 catalysts are successfully prepared by a facile impregnation method assisted by NaOH and tested for the toluene oxidation reaction under visible light irradiation. Keeping molar ratio of Pt:Na = 1:8, the 0.1Pt-Na/TiO2 catalyst (0.1 mol% Pt) shows excellent catalytic performance with more than 60% of toluene conversion at 45 °C and achieving total toluene removal at 280 °C, which is significantly better than 0.1Pt/TiO2 catalyst. The structures and properties of catalysts are characterized by XRD, SEM, N2 adsorption, XPS and UV–vis spectra. The positively charged Pt species stabilized by NaOH are the most active sites for photo-thermal catalyzing toluene oxidation. The influence of Pt loading and the effect of supports (active TiO2 and inert Al2O3) are also discussed.

Developing single-atom catalysts is extremely attractive for maximizing atomic efficiency and activity. However, the properties a nd roles of atomic catalysts in catalyzing water splitting reactions remain unclear. Here we report atomic palladium on graphitic carbon nitride with low palladium loading (0.1 wt%). The hydrogen evolution of this graphitic carbon nitride increases from 1.4 to 728 µmol g−1 h−1 under visible light irradiation, which is also 10 times higher than that of palladium nanoparticles (3 wt%) counterpart. The electronic structure of graphitic carbon nitride is modified after isolated palladium is introduced, which results in efficient charge separation, appropriate sites for adsorption for hydrogen, as well as accumulation of photoinduced electrons. Our results suggest that the pyridine nitrogen in the adjacent cavity to the palladium rather than the isolated palladium site is the active site which differs to that of the palladium nanoparticle counterpart. Stable single-atomic and noble-metal free catalysts are crucial in light driven hydrogen evolution but their behavior upon visible light irradiation remains unclear. Here the authors develop and analyze atomic palladium on graphitic carbon nitride with enhanced catalytic activity under visible light.

Copper catalysts were widely developed for CO2 conversion, but suffered severe sintering at temperatures higher than 300 °C. Platinum was the most active and stable metal for RWGS reactions. However, the high price and scarcity of platinum restrained its application. Downsizing the metal particles can significantly improve the atom efficiency of the precious metal but the size effect of Pt on RWGS reactions was still unclear. In the present work, the single atomic Pt on SrTiO3 was prepared using an impregnation leaching method, and the catalyst showed significant activity for an RWGS reaction, achieving a CO2 conversion rate of 45%, a CO selectivity of 100% and a TOF of 0.643 s−1 at 500 °C. The structures of the catalysts were characterized using XRD, STEM and EXAFS. Especially, the size effect of Pt in RWGS was researched using in situ FTIR and DFT calculations. The results reveal that single Pt atoms are the most active species in RWGS via a “–COOH route” while larger Pt cluster and nanoparticles facilitate the further hydrogenation of CO. The reaction between formate and H* is the rate determination step of an RWGS reaction on a catalyst, in which the reaction barrier can be lowered from 1.54 eV on Pt clusters to 1.29 eV on a single atomic Pt.

The interactions between metals and oxide supports, so-called metal-support interactions (MSI), are of great importance in heterogeneous catalysis. Pd-based automotive exhaust control catalysts, especially Pd-based three-way catalysts (TWCs), have received considerable research attention owing to its prominent oxidation activity of HCs/CO, as well as excellent thermal stability. For Pd-based TWCs, the dispersion, chemical state and thermal stability of Pd species, which are crucial to the catalytic performance, are closely associated with interactions between metal nanoparticles and their supporting matrix. Progress on the research about MSI and utilization of MSI in advanced Pd-based three-way catalysts are reviewed here. Along with the development of advanced synthesis approaches and engine control technology, the study on MSI would play a notable role in further development of catalysts for automobile exhaust control.

Reverse water gas shift reaction (RWGS) is an important process which plays a vital role in many CO2 utilization related reactions. Noble metals are the most active catalysts in RWGS, but the high price and low reserve strangled their applications. In the present work, we reported a non-transition-metal MgAl2O4 catalyst which showed outstanding activity and stability at high temperatures in the RWGS reaction and improved performance after doping of single atomic Nin+. The catalyst can obtain 46% of CO2 conversion in durability test of 75 h at 800 °C under high weight hourly space velocities (225 000 ml g-1 h-1). The adsorption sites, possible reaction route, and effects of Nin+ single atoms on the (111) surface of MgAl2O4 for RWGS were investigated by in situ DRIFTS and DFT calculations. The results indicated that the rate determining reaction step of RWGS on MgAl2O4 and Ni (SA)/MgAl2O4 were both the reaction of OH* + H* → H2O* + *, but the energy barrier was significantly reduced after introducing single atomic Nin+. Nin+ atoms can increase the hydroxyl coverage on the surface of catalyst and Al3+ sites near the Nin+ ion are considered as the predominant active sites for RWGS reactions.

A quasi-operando NH3 temperature-programmed reduction method (NH3-TPR), with N2:Cu = 1:1, is developed to quantify total Cu(ii) ions in Cu-SSZ-13 quenched from SCR-relevant reactions, and its accuracy is confirmed by in situ EPR. [Cu(OH)]+-Z and Cu2+-2Z can be further distinguished by NH3 reduction temperatures, and their different reducibility in SCR is revealed.

Constructing Z-scheme heterojunctions is considered as an effective strategy to obtain catalysts of high efficiency in electron-hole separation in photocatalysis. Unfortunately, suitable heterojunctions are difficult to fabricate because the direct interaction between two semiconductors may lead to unpredictable negative effects such as electron scattering or electron trapping due to the existence of defects which causes the formation of new substances. Furthermore, the van der Waals contact between two semiconductors also results in bad electron diffusion. In this work, a MOF-derived carbon material as a Z-scheme photocatalyst was synthesized

Heterogeneous thermocatalysis is widely used for the removal of VOCs. However, it is energy-consuming because it must operate at high temperatures. Combining thermocatalysis with photocatalysis makes it possible for the efficient abatement of VOCs at low temperatures. In this work, Pd–Ag@CeO2 photothermal catalyst was synthesized via synthesizing ceria-coated Ag nanoparticles followed by loading Pd nanoparticles by the liquid-phase reduction method. The catalyst has a core–shell structure which induces strong electron interactions between Pd/Ag and CeO2 and significantly improves the light harvest, charge separation and dissociative adsorption of Pd–Ag@CeO2 in the visible region. The Pd–Ag@CeO2 catalyst has a good catalytic performance in toluene oxidation, showing the T50 of Pd–Ag@CeO2 at only 88 °C under visible light irradiation. Finally, the possible catalytic mechanism has also been proposed for the oxidation of toluene under visible light irradiation.

A series of Cu–SAPO-34 catalysts with different copper contents were prepared using a modified ion-exchange method, i.e., impregnation–activation. Controlled amounts of well-dispersed active copper species and integrated physical properties were obtained by this method. The Cu–SAPO-34 catalysts retained the CHA structure, high specific surface area, and pore volume of the H–SAPO-34. Based on a combined analysis of UV–vis spectra and H2-TPR, these common laboratory techniques enabled the identification of the different copper species present in the catalysts. Only isolated copper ions balanced by two framework charges were present in the catalysts at copper contents ≤ 0.8 wt%. With increasing the Cu content, isolated Cu2+ ions charge-balanced by one negative charge became dominant. Further higher Cu contents could result in formation of copper oxides after consumption of all ion-exchange sites.

MoS2/Ag3PO4 heterojunction photocatalysts have attracted great attention in dye degradation and water oxidation, in which Z-scheme plays a critical role in the catalytic performance as a result of energy band structure alignment between MoS2 and Ag3PO4. Creating metal sites at composite interfaces as recombination centers of photo-generated electrons from conduction band (CB) of Ag3PO4 and holes from valence band (VB) of MoS2 is an effective strategy to enhance the charge separation efficiency and photocatalytic performance. Strong coupled MoS2/Ag dots/Ag3PO4 ternary heterojunction photocatalysts were fabricated by one-pot precipitation method, in which highly dispersed Ag dots are located at the MoS2/Ag3PO4 interfaces and MoS2 is bonded with PO43- in the form of Mo-O-P. The fabricated MoS2/Ag dots/Ag3PO4 photocatalyst presents a 2.8-fold enhancement of photocatalytic activity of water oxidation compared to that of pristine Ag3PO4, which is achieved for the first time. The great enhancement of photocatalytic performance can be ascribed to the improved Z scheme mechanism with strongly coupled MoS2/Ag dots/Ag3PO4 ternary interfaces, in which highly dispersed Ag dots serve as efficient recombination centers resulting in the improved separation of photo-generated holes and electrons of Ag3PO4 as well as photocatalytic activity of oxygen evolution.

Noble metal free MoS2/g-C3N4 catalyst has attracted intense attentions for visible light photocatalytic hydrogen evolution as a result of its earth abundance, low cost and unique heterojunctions stacked with two dimensional sheets. However, the low charge separation efficiency resulted from the poor conductivity of g-C3N4 and MoS2, and lack of abundant active sites from coordinative unsaturated atoms in MoS2, restricts the photocatalytic hydrogen evolution activity and stability enhancement of MoS2/C3N4 composite catalysts. Herein, CoMoS2/rGO/g-C3N4 catalysts with ternary heterojunctions are prepared by facile solvothermal method, which exhibit high visible light photocatalytic activity and stability for hydrogen evolution. The optimal hydrogen evolution rate of CoMoS2/rGO/g-C3N4 catalysts is 684 μmol g−1 h−1 when the content of CoMoS2 is 2% and the content of rGO is 0.5%. The stability of CoMoS2/rGO/C3N4 catalysts just decrease about 3% after 4 cycling runs for 16 h. The good catalytic performances of catalysts are attributed to the synergistic effect among the g-C3N4 nanosheets, rGO nanosheets and CoMoS2 nanosheets. The high conductivity of rGO nanosheets enhances the electron-hole separation and charge transfer, and Co doping increases the active sites for hydrogen evolution due to the increase of unsaturated atoms in CoMoS2 nanosheets.

Noble metal-free NiS/P-S codoped g-C3N4 (PSCN) nanocomposites were fabricated by combination of thermal copolymerization using ammonium O, O- diethyl dithiophosphate as P-S precursor and ion-exchange precipitation. The optimal H2-generation rate of NiS/PSCN is 30.5 μmol h− 1, which is 1.9 times higher than that of NiS/pristine g-C3N4. The codoping of P and S into g-C3N4 not only enhances the light harvesting, but also promotes the charge separation. Noble metal-free NiS loaded onto PSCN serves as electron trapping centers and active sites for hydrogen evolution which further enhances the photocatalytic H2 evolution activity of PSCN.

SmMn2O5 nanosheets with high specific surface area and (0 0 1) facet orientation were synthesized by a facile and efficient microwave-assisted hydrothermal strategy. The BET surface area of the leaf-like mullite (SMO-MW) reached 122 m2/g, which was about 4 times to that of counterpart (SMO-HT) prepared by conventional hydrothermal method. The relative intensity ratio of (0 0 1) facet to (2 1 1) in SMO-MW was 0.74 ~ 0.87, which was higher than 0.23 ~ 0.28 in SMO-HT. Compared with SMO-HT, the Mnx+ reduction temperature of SMO-MW declined significantly (ΔT = 63 °C for Mn4+→Mn3+, and ΔT = 76 °C for Mn3+→Mn2+) in the temperature-programmed reduction with H2. Moreover, the weakened Mn-O bonds, higher concentration of Mn4+ ions, and more chemisorbed oxygen were obtained via microwave irradiation. The pre-exponential factors of SMO-MW reached about 9 times comparing with those of SMO-HT, revealing the generation of more active sites. Impressively, the MW-500 calcined at 500 °C exhibited high catalytic performance with a 50% C3H8 conversion at 243 °C, which was competitive with 1 wt% Pd/Al2O3 catalyst. Meanwhile, it kept above 90% propane conversion during 80 h durability test at 285 °C. This study was expected to promote a new strategy on developing efficient mixed oxides catalysts for environmental and energy applications.

Mn/Ce/Ti and Mn/Ce/Nb/Ti catalysts were synthesized using a precipitation method and their catalytic activities for NO selective reduction with NH 3 at low temperatures were evaluated. Nb doping not only improved the activity of the catalyst over a wide temperature range but also restricted the generation of NO 2 and N 2 O. The Mn/Ce/Nb/Ti catalyst displayed 100% NO conversion from 150 to 250 °C and >90% N 2 selectivity below 250 °C. The specific surface area of the catalyst was increased and its surface acidity was strengthened after Nb doping. Moreover, Nb doping increased the NO oxidation ability and lowered the NH 3 oxidation activity of the catalyst. All the above factors contributed to enhancing the overall NH 3 -SCR performance of the Mn/Ce/Nb/Ti catalyst compared with that of the Mn/Ce/Ti one. The long-term stability and resistance to H 2 O and SO 2 of the Mn/Ce/Nb/Ti catalyst were also evaluated.

A photocatalytic CeO 2 @TiO 2 core–shell nanocomposite with enhanced photocatalytic performance was synthesized via a simple hydrothermal route assisted with the Stober method. The TiO 2 coating layer consisting of fine TiO 2 crystallites contributed most of the surface area of the CeO 2 @TiO 2 nanocomposite. The CeO 2 @TiO 2 nanocomposite exhibited a significantly narrower optical band gap than that of the pure TiO 2 . Photocatalytic studies revealed that the CeO 2 @TiO 2 core–shell nanocomposite displayed higher photocatalytic activity than both CeO 2 nanocubes and TiO 2 in degradation of the organic pollutant Rhodamine B. Such varieties in optical band gap and photocatalytic activity were assigned to the heterojunction interfaces formed in CeO 2 @TiO 2 , which could both promote photoinduced charge separation and suppress the recombination of photogenerated electrons and holes. During the process, the reversible oxidation-reduction in Ce(IV)/Ce(III) redox couples also promoted the efficient electron transfer.

Cu-modified SAPO-34 molecular sieves with different Cu loading amounts were prepared by ion-exchange and impregnation methods. Both series of catalysts were hydrothermally treated at 750 °C in 10 vol% H 2 O/air for 24 h. The catalysts were characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), H 2 temperature-programmed reduction (H 2 -TPR), NH 3 temperature-programmed desorption (NH 3 -TPD) and diffused reflectance infrared flourier transform spectroscopy (DRIFTS). All the fresh catalysts show high activity toward the selective catalytic reduction of NO x with NH 3 (NH 3 -SCR) at low temperatures regardless of preparation method. Generally, the hydrothermal aging shifts the operation window of the catalysts towards high temperatures. The improvement in high-temperatures activity is attributed to the migration of surface CuO clusters into the ion-exchanged sites as isolated Cu 2+ during ageing, which suppresses the competitive oxidation of NH 3 . The loss of low-temperatures activity is also related to the decrease in the amount of active surface CuO clusters, inhibiting the oxidation of NO to NO 2 and fast SCR reaction. Interestingly, the amount of Lewis acid sites increase linearly with the increasing isolated Cu 2+ , while the Bronsted acidity is weakened.