Hierarchical Ni–Co–O–C–P hollow tetragonal microtubes grown on Ni foam for efficient overall water splitting in alkaline media

Exploring low-cost and highly efficient non-noble bifunctional electrocatalysts with high performances for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is essential for large-scale sustainable energy systems. Herein, the Ni–Co–O–C–P hollow tetragonal microtubes grown on 3D Ni foam (Ni–Co–O–C–P/NF) was synthesized via a one-step solvothermal method and followed by a simple carbon coating and in situ phosphorization treatment. Benefiting from the unique open and hierarchical nano-architectures, the as prepared Ni–Co–O–C–P/NF presents a high activity and durability for both the HER and OER in alkaline media. The overall-water-splitting reaction requires a low cell voltage (1.54 V @ 10 mA cm⁻²) in 1 M KOH when Ni–Co–O–C–P/NF is used as both the anode and cathode. The highly flexible structure can provide a large amount of exposed active sites and shorten the mass transport distance. Furthermore, bimetallic phosphides also favor the electrocatalysis due to the higher electronic conductivity and the synergetic effect. This work demonstrated a promising bifunctional electrocatalyst for water electrolysis in alkaline media with potential in future applications.

Herein, the Ni–Co–O–C–P hollow tetragonal microtubes grown on 3D Ni foam (Ni–Co–O–C–P/NF) was delicately designed and synthesized, which presented a high activity and durability for electrocatalytic overall-water-splitting in alkaline media.     

High-yield synthesis of Ce modified Fe–Mn composite oxides benefitting from catalytic destruction of chlorobenzene

Ce–Fe–Mn catalysts were prepared by an oxalic acid assisted co-precipitation method. The influence of Ce doping and calcination temperature on the catalytic oxidation of chlorobenzene (as a model VOC molecule) was investigated in a fixed bed reactor. The Mn₃O₄ phase was formed in Ce–Fe–Mn catalysts at low calcination temperatures (<400 °C), which introduced more chemisorbed oxygen, and enhanced the mobility of O atoms, resulting in an improvement of the reduction active of Mn₃O₄ and Fe₂O₃. Additionally, CeO₂ has strong redox properties, and Ce⁴⁺ would oxidize Mn^x+ and Fe^x+. Therefore, the interaction of Ce, Fe and Mn can improve the content of surface chemisorbed oxygen. As compared with Fe–Mn catalysts, the catalytic conversion of chlorobenzene over Ce(5%)–Fe–Mn-400 was about 99% at 250 °C, owing to high specific surface area, Mn₃O₄ phase, and Ce doping. However, with the increase in roasting temperature, the performance of the catalysts for the catalytic combustion of chlorobenzene was decreased, which probably accounts for the formation of the Mn₂O₃ phase in Ce–Fe–Mn-500 catalysts, leading to a decrease in the specific surface area and concentration of chemically adsorbed oxygen. As a result, it can be expected that the Ce–Fe–Mn catalysts are effective and promising catalysts for chlorobenzene destruction.

Ce–Fe–Mn catalysts were prepared by an oxalic acid assisted co-precipitation method.     

Palladium supported on mixed-metal–organic framework (Co–Mn-MOF-74) for efficient catalytic oxidation of CO

Successful monometallic and bimetallic metal–organic frameworks with different Co/Mn ratios have been synthesized under solvothermal conditions. The as-synthesized MOFs followed by deposition of Pd nanoparticles with 0.5 to 7 wt%. The XRD, BET, SEM, TEM, EDAX and FT-IR characterization results reveal that bimetallic MOFs and Pd nanoparticles were finely dispersed on the prepared MOFs surfaces. XRD results confirm the formation of the desire MOFs and show the high degree of dispersion of Pd nanoparticles. TEM images show that Pd nanoparticles are nano-sized with almost uniform shape. EDAX shows that Pd nanoparticles successfully loaded on Co_0.5–Mn_0.5-MOF-74 catalyst. CO oxidation as a model reaction was then used to assess the catalytic performance of the prepared catalysts. The catalytic activity results show enhancement in the catalytic activities of monometallic MOFs after introducing another metal in the same framework and show an excellent improvement in CO conversion after loading with Pd nanoparticles. Furthermore, the samples that contain Pd nanoparticles exhibits higher catalytic activities which raised with increasing the content of Pd nanoparticles.

Pd nanoparticles were loaded on Co_x–Mn_(1−x)-MOF-74. 5 wt% Pd@Co_0.5–Mn_0.5-MOF-74 was the most effective catalyst for CO oxidation. The prepared catalysts displayed excellent stability during CO oxidation without significant decrease in catalytic performance.     

Core@shell structured Co–CoO@NC nanoparticles supported on nitrogen doped carbon with high catalytic activity for oxygen reduction reaction

A composite with a hierarchical structure consisting of nitrogen doped carbon nanosheets with the deposition of nitrogen doped carbon coated Co–CoO nanoparticles (Co–CoO@NC/NC) has been synthesized by a simple procedure involving the drying of the reaction mixture containing Co(NO₃)₂, glucose, and urea and its subsequent calcination. The drying step is found to be necessary to obtain a sample with small and uniformly sized Co–CoO nanoparticles. The calcination temperature has a great effect on the catalytic activity of the final product. Specifically, the sample prepared at the calcination temperature of 800 °C shows better catalytic activity of the oxygen reduction reaction (ORR). Urea in the reaction mixture is crucial to obtain the sample with the uniformly sized Co–CoO nanoparticles and also plays an important role in improving the catalytic activity of the Co–CoO@NC/NC. Additionally, there exists a strong electronic interaction between the Co–CoO nanoparticles and the NC. Most interestingly, the Co–CoO@NC/NC is highly efficient for the ORR and can deliver an ORR onset potential of 0.961 V vs. RHE and a half-wave potential of 0.868 V vs. RHE. Both the onset and half-wave potentials are higher than those of most catalysts reported previously and even close to those of the commercial Pt/C (the ORR onset and half-wave potential of the Pt/C are 0.962 and 0.861 V vs. RHE, respectively). This, together with its high stability, strongly suggests that the Co–CoO@NC/NC could be used as an efficient catalyst for the ORR.

A simple method has been developed for the synthesis of Co–CoO@NC/NC, which exhibits high and stable performance for the ORR.     

Low temperature CO oxidation catalysed by flower-like Ni–Co–O: how physicochemical properties influence catalytic performance

In this work, mesoporous Ni–Co composite oxides were synthesized by a facile liquid-precipitation method without the addition of surfactant, and their ability to catalyse a low temperature CO oxidation reaction was investigated. To explore the effect of the synergetic interaction between Ni and Co on the physicochemical properties and catalytic performance of these catalysts, the as-prepared samples were characterized using XRF, XRD, LRS, N₂-physisorption (BET), SEM, TEM, XPS, H₂-TPR, O₂-TPD and in situ DRIFTS characterization techniques. The results are as follows: (1) the doping of cobalt can reduces the size of NiO, thus massive amorphous NiO have formed and highly dispersed on the catalyst surface, resulting in the formation of abundant surface Ni²⁺ ions; (2) Ni²⁺ ions partially substitute Co³⁺ ions to form a Ni–Co spinel solid solution, generating an abundance of surface oxygen vacancies, which are vital for CO oxidation; (3) the Ni_0.8Co_0.2 catalyst exhibits the highest catalytic activity and a satisfactory stability for CO oxidation, whereas a larger cobalt content results in a decrease in activity, suggesting that the amorphous NiO phase is the dominant active phase instead of Co₃O₄ for CO oxidation; (4) the introduction of Co can alter the morphology of catalyst from plate-like to flower-like and then to dense granules. This morphological variation is related to the textural properties and catalytic performance of the catalysts. Lastly, a possible mechanism for CO oxidation reaction is tentatively proposed.

The flower-like catalyst possesses highly dispersed amorphous NiO and a high concentration of surface oxygen vacancies which are the central points for CO oxidation.     

Hierarchical Ni–Co–Mn hydroxide hollow architectures as high-performance electrodes for electrochemical energy storage

In this study, hierarchical Ni–Co–Mn hydroxide hollow architectures were successfully achieved via an etching process. We first performed the synthesis of NiCoMn-glycerate solid spheres via a solvothermal route, and then NiCoMn-glycerate as the template was etched to convert into hierarchical Ni–Co–Mn hydroxide hollow architectures in the mixed solvents of water and 1-methyl-2-pyrrolidone. Hollow architectures and high surface area enabled Ni–Co–Mn hydroxide to manifest a specific capacitance of 1626 F g⁻¹ at 3.0 A g⁻¹, and it remained as large as 1380 F g⁻¹ even at 3.0 A g⁻¹. The Ni–Co–Mn hydroxide electrodes also displayed notable cycle performance with a decline of 1.6% over 5000 cycles at 12 A g⁻¹. Moreover, an asymmetric supercapacitor assembled with this electrode exhibited an energy density of 44.4 W h kg⁻¹ at 1650 W kg⁻¹ and 28.5 W h kg⁻¹ at 12 374 W kg⁻¹. These attractive results demonstrate that hierarchical Ni–Co–Mn hydroxide hollow architectures have broad application prospects in supercapacitors.

An effective etching method is developed for the synthesis of hierarchical Ni–Co–Mn hydroxide hollow architectures, which exhibit high performance in electrochemical energy storage.     

Comparative study of mesoporous NixMn6−xCe4 composite oxides for NO catalytic oxidation

In this work, a series of mesoporous Ni_xMn_6−xCe ternary oxides were prepared to investigate their NO catalytic oxidation ability. The sample Ni₂Mn₄Ce₄ showed a 95% NO conversion at 210 °C (GHSV, ∼80 000 h⁻¹). Characterization results showed the good catalytic performance of Ni₂Mn₄Ce₄ was due to its high specific surface area, more surface oxygen and high valance manganese species, which can be ascribed to the incorporation of three elements. Based on the results of XRD, H₂-TPR, O₂-TPD and XPS, we confirmed the existence of Ni³⁺ + Mn³⁺ → Ni²⁺ + Mn⁴⁺, Ce⁴⁺ + Ni²⁺ → Ce³⁺ + Ni³⁺ in Ni₂Mn₄Ce₄, and the oxidation–reduction cycles were proved to be helpful for NO oxidation. The results from an in situ DRIFTS study indicated the presence of bidentate nitrate and monodentate nitrate species on the catalyst''s surface. The nitrate species were proved to be intermediates for NO oxidation to NO₂. A nitrogen circle mechanism was proposed to explain the possible route for NO oxidation. Nickel introduction was also helpful to improve the SO₂ resistance of the NO oxidation reaction. The activity drop of Ni₂Mn₄Ce₄ was 13.15% in the presence of SO₂, better than Mn₆Ce₄ (25.29%).

In this work, a series of mesoporous Ni_xMn_6−xCe ternary oxides were prepared to investigate their NO catalytic oxidation ability.     

Sol–gel-assisted micro-arc oxidation synthesis and characterization of a hierarchically rough structured Ta–Sr coating for biomaterials

Tantalum (Ta) is an element with high chemical stability and ductility that is used in orthopedic biomaterials. When utilized, it can produce a bioactive surface and enhance cell–material interactions, but currently, there exist scarce effective methods to introduce the Ta element onto the surface of implants. This work reported a sol–gel-assisted approach combined with micro-arc oxidation (MAO) to introduce Ta onto the surface of the titanium (TC4) substrate. Specifically, this technique produced a substrate with a hierarchically rough structured topography and introduced strontium ions into the film. The films were uniform and continuous with numerous crater-like micropores. Compared with the TC4 sample (196 ± 35 nm), the roughness of Ta (734 ± 51 nm) and Ta–Sr (728 ± 85 nm) films was significantly higher, and both films (Ta and Ta–Sr) showed increased hydrophilicity when compared with TC4, promoting cell attachment. Additionally, the in vitro experiments indicated that Ta and Ta–Sr films have the potential to enhance the recruitment of cells in the initial culture stages, and improve cell proliferation. Overall, this work demonstrated that the application of Ta and Ta–Sr films to orthopedic implants has the potential to increase the lifetime of the implants. Furthermore, this study also describes an innovative strategy to incorporate Ta into implant films.

A hierarchically rough structured Ta–Sr coating for biomaterials fabricated by a sol–gel-assisted micro-arc oxidation technique.     

Core–shell Pd–P@Pt–Ni nanoparticles with enhanced activity and durability as anode electrocatalyst for methanol oxidation reaction

Pd–P@Pt–Ni core–shell nanoparticles, which consisted of a Pd–P alloy as a core and Pt–Ni thin layer as a shell, were explored as electrocatalysts for methanol oxidation reaction. The crystallographic information and the electronic properties were fully investigated by X-ray diffraction and X-ray photoelectron spectroscopy. In the methanol electrooxidation reaction, the particles showed high catalytic activity and strong resistance to the poisoning carbonaceous species in comparison with those of commercial Pt/C and the as-prepared Pt/C catalysts. The excellent durability was demonstrated by electrochemically active surface area loss and chronoamperometric measurements. These results would be due to the enhanced catalytic properties of Pt by the double synergistic effects from the core part and the nickel species in the shell part.

The Pd–P@Pt–Ni core–shell nanoparticles consist of an amorphous core and a low-crystalline shell. They exhibit the excellent catalytic properties in MOR owing to the double synergistic effects from the core and the nickel species in the shell.     

Synergistic effect of Co–Ni co-bridging with MoS2 nanosheets for enhanced electrocatalytic hydrogen evolution reactions

The depletion of fossil fuels and associated environmental problems have drawn our attention to renewable energy resources in order to meet the global energy demand. Electrocatalytic hydrogen evolution has been considered a potential energy solution due of its high energy density and environment friendly technology. Herein, we have successfully synthesized a noble-metal-free Co–Ni/MoS₂ nanocomposite for enhanced electrocatalytic hydrogen evolution. The nanocomposite has been well characterized using HRTEM, elemental mapping, XRD, and XPS analysis. The as-synthesized nanocomposite exhibits a much smaller onset potential and better current density than those of Co–MoS₂, Ni–MoS₂ and MoS₂, with a Tafel value of 49 mV dec⁻¹, which is comparable to that of a commercial Pt/C catalyst. The synergistic effect and interfacial interaction of Co–Ni bimetallic nanoparticles enhances the intrinsic modulation in the electronic structure resulting in an improved HER performance. Moreover, the electrochemical impedance spectroscopic results suggest smaller resistance values for the Co–Ni/MoS₂ nanocomposite, compared to those for the charge transfer of bare nanosheets, which increase the faradaic process and in turn enhance the HER kinetics for a better performance. Our as-synthesized Co–Ni/MoS₂ nanocomposite holds great potential for the future synthesis of noble-metal-free catalysts.

A noble-metal-free Co–Ni/MoS₂ nanocomposite was synthesized, which showed enhanced electrocatalytic hydrogen evolution performance.     

Core–shell structured NaYF4:Yb,Tm@CdS composite for enhanced photocatalytic properties

NaYF₄:Yb,Tm upconversion nanocrystals with hexagonal structure possess excellent photoluminescence emission characteristics. Under near infrared (NIR) light irradiation, the Yb³⁺ ions act as sensitizers to absorb the NIR light and transform NIR light into ultraviolet (UV) and visible (Vis) light continuously. Hybrid NIR-activated photocatalysts can be fabricated by combining upconversion nanocrystals with various semiconductor nanocrystals. In this paper, NaYF₄:Yb,Tm micro-rods were hydrothermally synthesized with oleic acid as capping ligand. The NaYF₄:Yb,Tm@CdS composite was fabricated by in situ generation of CdS nanoclusters on the surface of NaYF₄:Yb,Tm micro-rods. The morphologies and structures of NaY₄:Yb,Tm and NaYF₄:Yb,Tm@CdS were characterized by XRD, SEM, TEM, XPS, UV-Vis and PL spectroscopy. The results of photocatalytic experiments indicated that the NaYF₄:Yb,Tm@CdS composite displayed photocatalytic activity under NIR irradiation. In comparison with pure CdS, the photocatalytic ability of NaYF₄:Yb,Tm@CdS composite under Vis-NIR irradiation was obviously enhanced. 82% of RhB was degraded by NaYF₄:Yb,Tm@CdS catalyst within 75 min under Vis-NIR irradiation, which was more effective than pure CdS (65% degradation of RhB).

NaYF₄:Yb,Tm upconversion nanocrystals with hexagonal structure possess excellent photoluminescence emission characteristics.     

Effects of Sm on Fe–Mn catalysts for Fischer–Tropsch synthesis

Sm-promoted FeMn catalysts were prepared by the co-precipitation method and characterized by N₂ adsorption, XRD, CO-TPD, H₂-TPD, CO₂-TPD, H₂-TPR, XPS and MES. It was found that compared with the un-promoted catalyst, when Sm was added at a proper content, the catalyst showed a larger BET surface area and promoted the formation of iron particles with a smaller size. The presence of Sm could increase the surface charge density of iron, which enhanced the Fe–C bond and promoted the stability and amount of CO dissociated adsorption, as confirmed by XPS and CO-TPD. Furthermore, according to MES, Sm could promote the formation of Fe₅C₂, which was the active phase of FTS. In addition, Sm could also enhance the basicity of the catalysts and suppress the H₂ adsorption capacity, which inhibited the hydrogenation reaction and the conversion of olefins to paraffins, as verified by the results of CO₂-TPD and H₂-TPD. According to the FTS performance results, compared with the observations for the un-promoted catalysts, when the molar ratio of Sm to Fe was 1%, the CO conversion increased from 63.4% to 70.4%, the sum of light olefins in the product distribution increased from 26.6% to 32.6, and the ratio of olefins to paraffins increased to 4.18 from 4.09.

The effect of samarium on iron-based catalysts for Fischer–Tropsch synthesis was investigated.     

Effect of Ce doping on the structure–activity relationship of MoVOx composite metal oxides

A series of Ce-doped MoVO_x composite metal oxide catalysts were prepared by the rotary evaporation method. The effects of Ce doping ratio on the crystal phase composition, morphology and surface properties of the catalysts were investigated. The results show that the crystal phase composition of samples with different Ce doping content is also obviously different. When the doping amount is small, V_0.95Mo_0.97O₅ is the main crystal phase, while MoO₃ is dominant when the doping amount is large. The Ce-doped catalyst showed obvious rod-shaped morphology and its average single point pore diameter and the number of acidic sites increased. Compared to the un-doped MoVO_x, the pore size of the sample synthesized at a Mo/Ce atomic ratio of 10/1 exhibited an increase of 41.11 nm. In addition, the effect of Ce doping on the catalytic performance of MoVO_x was investigated with the selective oxidation of benzyl alcohol as a probe reaction. After doping, the MoVO_x catalyst showed improved benzyl alcohol conversion and selectivity to benzaldehyde. At a Mo/Ce atomic ratio of 10/1, the conversion rate of benzyl alcohol reaches 83.26%, which is 64.56% higher than that without doping, and the highest product yield can reach 76.47%.

Ce-doped MoVO_x with disperse rod-shaped exhibits excellent catalytic performance in selective oxidation of benzyl alcohol.     

Efficient Ce–Co composite oxide decorated Au nanoparticles for catalytic oxidation of CO in the simulated atmosphere of a CO2 laser

Gold nanoparticles have a high activity for CO oxidation, making them suitable to be used in a CO₂ laser which maintains its efficiency and stability via the recombination of CO and O₂ produced by the CO₂ decomposition. However, the high concentration of CO₂ in the working environment greatly reduces the activity of the catalyst and makes the already unstable gold nanoparticles even more so. A novel Au/Ce-Co-O_x/Al₂O₃ gold catalyst, prepared by a deposition precipitation method in this study, displays high activity and good stability for CO oxidation in a simulated atmosphere of a CO₂ laser with the feed gases containing a high concentration of CO₂ up to 60 vol% but a low concentration of O₂ for the stoichiometric reaction with CO. An excellent performance for CO oxidation under CO₂-rich conditions could be achieved by decorating the surface of the Al₂O₃ support with Ce–Co composite oxides. The strong interaction between gold and the composite support, accompanied by the increase of labile lattice oxygen species and the decrease of surface basicity, led to a high CO oxidation rate and resistance towards CO₂ poisoning.

Novel Au/Ce-Co-O_x/Al₂O₃ showed a very excellent performance for CO oxidation in the simulated atmosphere of CO₂-laser mainly due to SMSI and labile lattice oxygen.     

In situ X-ray absorption spectroscopy study of CuO–NiO/CeO2–ZrO2 oxides: redox characterization and its effect in catalytic performance for partial oxidation of methane

In this work we analyze the effect of adding CuO to a NiO/Ce_0.9Zr_0.1O₂ oxide by in situ X-ray absorption near-edge structure XANES technique in Ce L3, Ni K and Cu K absorption edges in terms of sample reducibility and catalytic activity. The oxidation states of Ce, Ni and Cu cations are followed up during temperature programmed reduction (TPR) experiments in diluted hydrogen and during catalytic tests for partial oxidation of methane (POM) reaction. Redox behavior was correlated to conventional fixed bed reactor results. The effect of firing temperature, crystallite size, CeO₂–ZrO₂ support and the presence of Cu and/or Ni as an active phase is also analyzed. Results showed a beneficial effect of CuO addition in terms of Ce and Ni reduction. A stronger interaction of NiO species with the support was revealed upon analysis of XANES reduction profiles in sample NiO/ZDC in contrast to bimetallic CuO–NiO/ZDC sample. Reduction onset temperature was found to depend on Ni crystallite size, being markedly promoted when samples exhibited low values of crystallite size both in supported and non-supported CuO–NiO species. In situ catalytic experiments for partial oxidation of methane showed a clear interplay between the redox behavior from the Ce in the CeO₂–ZrO₂ support and the Ni from the active phase. Sample NiO/ZDC exhibited a continuous reduction of Ce cations in CH₄ : O₂ feed flow, carbon formation was detected in X-ray Powder Diffraction (XPD) patterns and Ni re-oxidation was found to take place, clear indications of catalyst deactivation. In contrast, sample CuO–NiO/Ce_0.9Zr_0.1O₂ displayed a slight re-oxidation of Ce and no re-oxidation of Ni altogether with the suppression of carbon formation.

In situ X-Ray Absorption (XAS) experiments in reducing atmospheres (H₂ and CH₄ : O₂) uncovered Ce, Ni and Cu redox interplay during catalytic experiments.     

3D web freestanding RuO2–Co3O4 nanowires on Ni foam as highly efficient cathode catalysts for Li–O2 batteries

The mechanism of Li–O₂ batteries is based on the reactions of lithium ions and oxygen, which hold a theoretical higher energy density of approximately 3500 W h kg⁻¹. In order to improve the practical specific capacity and cycling performance of Li–O₂ batteries, a catalytically active mechanically robust air cathode is required. In this work, we synthesized a freestanding catalytic cathode with RuO₂ decorated 3D web Co₃O₄ nanowires on nickel foam. When the specific capacity was limited at 500 mA h g⁻¹, the RuO₂–Co₃O₄/NiF had a stable cycling life of up to 122 times. The outstanding performance can be primarily attributed to the robust freestanding Co₃O₄ nanowires with RuO₂ loading. The unique 3D web nanowire structure provides a large surface for Li₂O₂ growth and RuO₂ nanoparticle loading, and the RuO₂ nanoparticles help to promote the round trip deposition and decomposition of Li₂O₂, therefore enhancing the cycling behavior. This result indicates the superiority of RuO₂–Co₃O₄/NiF as a freestanding highly efficient catalytic cathode for Li–O₂ batteries.

Freestanding RuO₂–Co₃O₄ nanowires on Ni foam were synthesized and applied as a cathode in Li–O₂ battery. This cathode can deliver a high capacity of 9620 mA h g⁻¹ and stable long-term operation exceeding 122 cycles at 100 mA g⁻¹.     

Manganese–cerium mixed oxides supported on rice husk based activated carbon with high sulfur tolerance for low-temperature selective catalytic reduction of nitrogen oxides with ammonia

A rice husk-derived activated carbon supported manganese–cerium mixed oxide catalyst (Mn–Ce/RAC) was prepared by an impregnation method and tested for the selective catalytic reduction of nitrogen oxides with ammonia (NH₃-SCR). 5 wt% Mn–Ce/RAC catalyst showed the highest activity, yielding nearly 100% NO_x conversion and N₂ selectivity at 240 °C at a space velocity of 30 000 h⁻¹. Compared with commercial activated carbon supported manganese–cerium mixed oxide catalyst (Mn–Ce/SAC), a higher SCR performance with good SO₂ tolerance could be observed in the tested temperature range over the Mn–Ce/RAC catalyst. The characterization results revealed that the Mn–Ce/RAC catalyst had a higher Mn⁴⁺/Mn³⁺ ratio, amount of chemisorbed oxygen and more Brønsted acid sites than the Mn–Ce/SAC catalyst. The XRD analysis indicated that Mn–Ce oxides were highly dispersed on the RAC support. These properties of Mn–Ce/RAC assisted the SCR reaction. Moreover, in situ DRIFTS results demonstrated that sulfate species formation on Mn–Ce/RAC was much less in the presence of SO₂ than that of Mn–Ce/SAC, which might be ascribed to the reduced alkalinity of the catalyst by the presence of SiO₂ in RAC.

A rice husk derived catalyst exhibited high SCR activity and excellent SO₂ + H₂O tolerance.     

Hybrid ZnO–graphene electrode with palladium nanoparticles on Ni foam and application to self-powered nonenzymatic glucose sensing

A self-powered nonenzymatic glucose sensor electrode boasts the advantages of both a glucose sensor and fuel cell. Herein, an electrode composed of ZnO–graphene hybrid materials on nickel foam (NF) is prepared by electrodeposition of Pd NPs. The electrode is characterized systematically and the dependence of electrocatalytic oxidation of glucose on the concentrations of KOH and glucose, temperature, and potential limit in the anodic direction is investigated. The Pd/NF-ZnO–G electrode shows high catalytic activity, sensitivity, stability, and selectivity in glucose detection, as exemplified by an electrocatalytic glucose oxidation current of 222.2 mA cm⁻² under alkaline conditions, high linearity in the glucose concentration range from 5 μM to 6 mM (R² = 0.98), and high sensitivity of 129.44 μA mM⁻¹⁻¹ cm⁻². The Pd/NF-ZnO–G electrode which exhibits superior electrocatalytic activity under alkaline conditions has large potential in nonenzymatic glucose sensing and direct glucose fuel cells and is suitable for miniaturized self-powered nonenzymatic glucose sensing.

A self-powered nonenzymatic glucose sensor electrode boasts the advantages of both a glucose sensor and fuel cell.     

A new highly active La2O3–CuO–MgO catalyst for the synthesis of cumyl peroxide by catalytic oxidation

In this study, different magnesium, copper, lanthanide single metal, and composite multimetal oxide catalysts were prepared via the coprecipitation route for the aerobic oxidation of cumene into cumene hydroperoxide. All catalysts were characterized using several analytical techniques, including XRD, SEM, EDS, FT-IR, BET, CO₂-TPD, XPS, and TG-DTG. La₂O₃–CuO–MgO shows higher oxidation activity and yield than other catalysts. The results of XRD and SEM studies show that the copper and magnesium particles in the catalyst are smaller in size and have a distribution over a larger area due to the introduction of the lanthanum element. The CO₂-TPD results confirmed that the catalyst has more alkali density and alkali strength, which can excite active sites and prevent the decomposition of cumene hydroperoxide. XPS results show that due to the promotional effect of La₂O₃, there are more lattice and active oxygen species in the catalyst, which can effectively utilize the lattice defects under the strong interaction between metal oxides for rapid adsorption and activation, thus improving the oxidation performance. Besides, La₂O₃–CuO–MgO exhibits good stability and crystalline structure due to its high oxygen mobility inhibiting coking during the cycle stability test. Finally, the possible reaction pathway and promotional mechanism on La₂O₃–CuO–MgO in cumene oxidation are proposed. We expect this study to shed more light on the nature of the surface-active site(s) of La₂O₃–CuO–MgO catalyst for cumene oxidation and the development of heterogeneous catalysts with high activity in a wide range of applications.

The La₂O₃–CuO–MgO catalyst acts on the oxidation of cumene and shows excellent catalytic activity through the coordination of surface and interior.     

Recyclable MFe2O4 (M = Mn,Zn, Cu,Ni, Co) coupled micro–nano bubbles for simultaneous catalytic oxidation to remove NOx and SO2 in flue gas

NO_x can be efficiently removed by micro–nano bubbles coupling with Fe³⁺ and Mn²⁺, but the catalyst cannot be reused and the adsorption wastewater should be treated. This work developed a new technology that uses micro–nano bubbles and recyclable MFe₂O₄ to simultaneously remove NO_x and SO₂ from flue gas, and clarified the effectiveness and reaction mechanism. MFe₂O₄ (M = Mn, Zn, Cu, Ni and Co) prepared by a hydrothermal method was characterized. The results show that MFe₂O₄ can be activated to produce ˙OH which can accelerate the oxidation absorption of NO_x. Compared with no catalyst, the NO_x conversion rate increased from 32.85% to 83.88% in the NO_x–SO₂–MFe₂O₄-micro–nano bubble system, while the removal rate of SO₂ can reach 100% at room temperature. The catalytic activities of MFe₂O₄ showed the following trend: CuFe₂O₄ > ZnFe₂O₄ > MnFe₂O₄ > CoFe₂O₄ > NiFe₂O₄. The results provide a new idea for the application of advanced oxidation processes in flue gas treatment.

NO_x-SO₂-MFe₂O₄-micro–nano bubbles system for NO_x removal.