Mechanistic insights into tandem amine-borane dehydrogenation and alkene hydrogenation catalyzed by [Pd(NHC)(PCy3)]

The mechanism of tandem dimethylamine-borane (NHMe₂BH₃, DMAB) dehydrogenation and alkene hydrogenation catalyzed by [Pd(NHC)(PMe₃)] are investigated by density functional theory (DFT) calculations [NHC = N,N′-bis(2,6-diisopropylphenyl) imidazole-2-ylidene]. Four possible DMAB dehydrogenation mechanisms have been carefully investigated involving concerted BH/NH activation, sequential BH/NH activation, sequential NH/BH activation, and proton transfer mechanism. DFT studies show that the NH proton transfers to ligated carbene carbon and sequential CH/BH activation is the most kinetically favorable pathway with the lowest activation barrier of 23.8 kcal/mol. For hydrogenation, it was found that a trans-dihydride Pd(II) complex, [Pd(H)₂(NHC)(PMe₃)], formed in the dehydrogenation process, serves as an effective catalyst for reduction of trans-stilbene.     

Effective excitons separation on graphene supported ZrO2TiO2 heterojunction for enhanced H2 production under solar light

A novel photocatalyst comprises of ZrO₂TiO₂ immobilized on reduced graphene oxide (rGO) – a ternary heterojunction (ZrO₂TiO₂/rGO) was synthesized by using facile chemical method. The nanocomposite was prepared with a strategy to achieve better utilization of excitons for catalytic reactions by channelizing from metal oxide surfaces to rGO support. TEM and XRD analysis results revealed the heterojunction formed between ZrO₂ and single crystalline anatase TiO₂. The mesoporous structure of ZrO₂TiO₂ was confirmed using BET analysis. The red shift in absorption edge position of ZrO₂TiO₂/rGO photocatalyst was characterized by using diffuse reflectance UV–Visible spectra. ZrO₂TiO₂/rGO showed greater interfacial charge transfer efficiency than ZrO₂TiO₂, which was evidenced by well suppressed PL intensity and high photocurrent of ZrO₂TiO₂/rGO. The suitable band gap of 1.0 wt% ZrO₂TiO₂/rGO facilitated the utilization of solar light in a wide range by responding to the light of energy equal to as well as greater than 2.95 eV by the additional formation of excited high-energy electrons (HEEs). ZrO₂TiO₂/rGO showed the enhanced H₂ production than TiO₂/rGO, which revealed the role of ZrO₂ for the effective charge separation at the heterojunction and the solar light response. The optimum loading of 1.0 wt% of ZrO₂ and rGO on TiO₂ showed the highest photocatalytic performance (7773 μmolh^?1$g_{cat}^{?1}$) for hydrogen (H₂) production under direct solar light irradiation.     

Efficient visible-light-driven hydrogen evolution over ternary MoS2/PtTiO2 photocatalysts with low overpotential

By surface-decorating PtTiO₂ hybrid catalyst with MoS₂ nanosheets, we prepared a new MoS₂/PtTiO₂ ternary system as high-performance photocatalysts. The ternary MoS₂/PtTiO₂ outperforms both the binary MoS₂TiO₂ and PtTiO₂ systems in photocatalytic hydrogen evolution with an AQY (apparent quantum yield) value of 12.54% at 420 nm, owing to the unique ternary design that creates more efficient electron transport path and electron-hole separation mechanism. Electrochemical characterization showed that the MoS₂/PtTiO₂ ternary electrode afford an efficient pathway of photo-excited electrons from TiO₂ to surface-decorated Pt nanoparticles using MoS₂ and internal Pt nanoparticles as bridges, thus significantly promoting electron transfer, reducing the system overpotential and leading to the activation of more reactive sites. This internal electron transfer pathway (TiO₂ → Pt (internal) → MoS₂ → Pt (surface)) eliminates the need of other metal cocatalysts because the Pt nanoparticles play two roles of storing the conduction band electrons of TiO₂ and acting as co-catalyst for reduction of protons to hydrogen. This unique ternary metal-semiconductor heterojunction for efficient photocatalytic hydrogen evolution provides a meaningful reference for reasonable design of other hybrid photocatalysts.     

Mesocrystalline Ta2O5 nanosheets supported PdPt nanoparticles for efficient photocatalytic hydrogen production

We successfully synthesized mesocrystalline Ta₂O₅ nanosheets supported bimetallic PdPt nanoparticles by the photo-reduction method. The as-prepared mesocrystalline Ta₂O₅ nanosheets in this work showed amazing visible-light absorption, mainly because of the formation of oxygen vacancy defects. And the as-prepared bimetallic PdPt/mesocrystalline Ta₂O₅ nanaosheets also showed highly enhanced UV–Vis light absorption and highly improved photocatalytic activity for hydrogen production in comparison to that of commercial Ta₂O₅, mesocrystalline Ta₂O₅ nanosheets, Pd/mesocrystalline Ta₂O₅ nanosheets and Pt/mesocrystalline Ta₂O₅ nanosheets. The highest photocatalytic hydrogen production rate of PdPt/mesocrystalline Ta₂O₅ nanaosheets was 21529.52 g^?1 h^?1, which was about 21.2 times of commercial Ta₂O₅, and the apparent quantum efficiency of PdPt/mesocrystalline Ta₂O₅ nanaosheets for hydrogen production was about 16.5% at 254 nm. The highly enhanced photocatalytic activity was mainly because of the significant roles of PdPt nanoparticles for accelerating the charge separation and transport upon illumination. The as-prepared PdPt/mesocrystalline Ta₂O₅ nanaosheets in this work could serve as an efficient photocatalyst for green energy production.     

Highly efficient hydrogen evolution catalysis based on MoS2/CdS/TiO2 porous composites

Efficient production of hydrogen through visible-light-driven water splitting mechanism using semiconductor-based composites has been identified as a promising strategy for converting light into clean H₂ fuel. However, researchers are facing lots of challenges such as light absorption and electron-hole pair recombination and so on. Here, new sheet-shaped MoS₂ and pyramid-shaped CdS in-situ co-grown on porous TiO₂ photocatalysts (MoS₂CdSTiO₂) are successfully obtained via mild sulfuration of MoO₃ and CdO coexisted inside porous TiO₂ monolith by a hydrothermal route. The scanning electron microscopy and transmission electron microscopy results exhibit that the MoS₂CdSTiO₂ composites have average pore size about 500 nm. The 3%MoS₂10%CdSTiO₂ demonstrated excellent photocatalytic activity and high stability for a hydrogen production with a high H₂-generation rate of 4146 μmol h^?1 g^?1 under visible light irradiation even without noble-metal co-catalysts. The super photocatalytic performance of the visible-light-driven hydrogen evolution is predominantly attributed to the synergistic effect. The conduction band of MoS₂ facilitates in transporting excited electrons from visible-light on CdS to the porous TiO₂ for catalytic hydrogen production, and holes to MoS₂ for inhibiting the photocorrosion of CdS, respectively, leading to enhancing the efficient separation of electrons and holes.     

Achieving the dehydriding reversibility and elevating the equilibrium pressure of YFe2 alloy by partial Y substitution with Zr

To overcome the hydrogen-induced amorphization and phase disproportionation in the fast de-/hydrogenation of YFe₂, the alloying of partial substituting Y with Zr was carried out to obtain Y_1?xZr_xFe₂ (x = 0.1, 0.2, 0.3, 0.5) alloys. All YZrFe alloys remained single C15 Laves phase structure at states of as-annealed, hydrogenated and dehydrogenated. With the increasing of Zr content, the YZrFe alloys showed the decrease in the lattice constants and hydrogenation capacity, but the increase in the dehydrogenation capacity and dehydriding equilibrium pressure. The alloy Y_0.9Zr_0.1Fe₂ showed maximum initial hydrogenation capacity of 1.87 wt% H, while the alloy Y_0.5Zr_0.5Fe₂ showed highest desorption capacity of 1.26 wt% with obvious dehydriding plateau. Based on experiment analysis and first principle calculation of binding energy, the great improvement in the dehydriding thermodynamics for YZrFe alloys is attributed to the change in the unit cell volume, electron concentration and stability of hydrides due to the Zr substitution.     

AuNi alloy nanoparticles supported on reduced graphene oxide as highly efficient electrocatalysts for hydrogen evolution and oxygen reduction reactions

Bimetallic nanoparticles of Au and Ni in the form of alloy nanostructures with varying Ni content are synthesized on reduced graphene oxide (rGO) sheets via a simple solution chemistry route and tested as electrocatalysts towards the hydrogen evolution (HE) and oxygen reduction (OR) reactions using polarization and impedance studies. The AuNi alloy NPs/rGO nanocomposites display excellent electrocatalytic activity which is found to improve with increasing Ni content in the AuNi/rGO alloy nanocomposites. For HER, the best AuNi alloy NPs/rGO electrocatalyst, the one with the highest Ni content, exhibits high activity with an onset overpotential approaching zero versus the reversible hydrogen electrode and an overpotential of only 37 mV at 10 mA cm^?2. Additionally, a low Tafel slope of 33 mV dec^?1 and a high exchange current density of 0.6 mA cm^?2 are measured which are very close to those of commercial Pt/C catalyst. Also, in the ORR tests, this electrocatalyst displays comparable activity to Pt/C. The Koutecky–Levich plots referred to a 4-electron mechanism for the reduction of dissolved O₂ on the AuNi alloy NPs/rGO catalyst. The electrocatalyst thus demonstrates excellent activity towards HER and ORR. Additionally, it exhibits outstanding operational durability and activation after 10,000^th cycles assuring its practical applicability.     

Self-supported Ni3S2@MoS2 core/shell nanorod arrays via decoration with CoS as a highly active and efficient electrocatalyst for hydrogen evolution and oxygen evolution reactions

A hierarchically porous MoS₂ on Ni₃S₂ nanorod array on Ni foam (MoS₂/Ni₃S₂/NF) was firstly fabricated through a simple microwave-assisted hydrothermal method, and then followed by electrochemical deposition approach in which MoS₂/Ni₃S₂/Ni foam is decorated with CoS (CoSMoS₂/Ni₃S₂/NF). In contrast to conventional hydrothermal approach, microwave irradiation accelerates the synthesis of MoS₂/Ni₃S₂/Ni foam from time of >20 h–2 h. The characterization of CoSMoS₂/Ni₃S₂/NF by scanning electron microscope (SEM) and high resolution transmission electron microscope (HRTEM) indicate that a whole scale of 1D the Ni₃S₂ nanorods were hierarchically integrated with MoS₂ and CoS nanosheets. The as-synthesized CoSMoS₂/Ni₃S₂/NF hybrid not only endows the ease transport of electrons along Ni₃S₂ nanorods to Ni foam, but also accommodates maximal exposure of active edge sites to the reactants through hierarchically porous CoS doped MoS₂ nanosheets, accomplishing the promoted kinetics and activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). By electrochemical measurements such as linear sweep voltammetry (LSV) and electrochemical impedance spectroscope (EIS), we find that the CoSMoS₂/Ni₃S₂/NF hybrid shows markedly enhanced electrochemical performance for both HER and OER. Specifically, the optimal CoSMoS₂/Ni₃S₂/NF8C possesses the low overpotentials (η₁₀) of 85 and 225 mV at current density (|j|) of 10 mA cm^?2 in 1.0 M KOH and the small 62.3 and 46.1 mV dec^?1 Tafel slope for HER and OER, respectively, outperforming those of most of the current noble metal-free electrocatalysts. These results highlight the fact that CoSMoS₂/Ni₃S₂/NF is a high-performance, noble-metal-free electro-catalyst, and provide a potential avenue toward achieving an enhanced electrocatalytic activity towards both in HER and OER. Yet the duration of the as prepared catalyst in OER still need to be improved.     

Advance fuel cells using Al2O3-nNaAlO2 composite as ion-conducting membrane

In present work, we reported an novel oxide-salt Al₂O₃NaAlO₂ composite, which was prepared by mixing Al₂O₃ and Na₂CO₃ two phase materials in different weight ratio, and then sintering at 1100 °C. The X-ray diffraction pattern, scanning-electron microscope and impedance spectra are applied to characterize the crystal structure, morphology and electrical properties of the Al₂O₃NaAlO₂ composite. The Al₂O₃NaAlO₂ composite as electrolyte membrane was sandwiched by two pieces of Ni_0.8Co_0.15Al_0.05Li-oxide (NCAL) electrode layer to construct advanced fuel cell. Optimizing the weight ratio of Al₂O₃ and NaAlO₂, such cell delivered an highest power density of 789 mW/cm² and an open circuit voltage (V_oc) of 1.13 V at 575 °C. The superior performance is mainly due to the excellent ion-conducting of Al₂O₃NaAlO₂ composites and the outstanding catalysis activity of the NCAL eletrodes. The EIS results revealed that the Al₂O₃NaAlO₂ composite possessed superior ionic conductivity of 0.121 S/cm at 575 °C. The interfacial effects between oxide-salt two phase including space-charge and structural misfit at the interface region dominated the ion transport for Al₂O₃NaAlO₂ composite.     

An in-situ DRIFTS-MS study of the photocatalytic H2 production from ethanol(aq) vapour over Pt/TiO2 and PtGa/TiO2 catalysts

In this paper, Pt/TiO₂ and PtGa/TiO₂ catalysts with similar Pt dispersion and similar structural and morphological characteristics were compared in the H₂ production from the phototransformation of aqueous solutions of ethanol. Catalysts were characterized by means of N₂ adsorption-desorption, XRD, Raman, H₂-TPR, UV–Vis diffuse reflectance spectroscopy, XPS and CO chemisorption. The photocatalytic reaction was carried out in liquid and vapour phase. The photocatalytic transformation of ethanol_(aq) vapour over Pt/TiO₂ and PtGa/TiO₂ catalysts was studied by in situ DRIFTS-MS. Differences in the photocatalytic transformation of ethanol_(aq) over Pt/TiO₂ and PtGa/TiO₂ were determined. The effect of Ga is analysed in the light of the evolution of surface species under photocatalytic reaction conditions.     

Hydrogen-iodide decomposition over PdCeO2 nanocatalyst for hydrogen production in sulfur-iodine thermochemical cycle

A highly active and stable catalyst for hydrogen-iodide decomposition reaction in sulfur-iodine (SI) cycle has been prepared in the form of PdCeO₂ nanocatalyst by sol-gel method with different calcination temperatures (300 °C, 500 °C, and 700 °C). XRD and TEM confirmed a size around 6–8 nm for PdCeO₂ particles calcined at 300 °C. Raman study revealed large number oxygen vacancies in PdCeO₂-300 when compared to PdCeO₂-500 and PdCeO₂-700. With increase in calcination temperature, the average particle size increased whereas the specific surface area and number of oxygen vacancies decreased. Hydrogen-iodide catalytic-decomposition was carried out in the temperature range of 400°C–550 °C in a quartz-tube, vertical, fixed-bed reactor with 55 wt % aqueous hydrogen-iodide feed over PdCeO₂ catalyst using nitrogen as a carrier gas. PdCeO₂-300 showed hydrogen-iodide conversion of 23.3%, which is close to the theoretical equilibrium conversion of 24%, at 550 °C. It also showed a reasonable stability with a time-on-stream of 5 h.     

Analysis of H2 and CO production via solar thermochemical reacting system of NiFe2O4 redox cycles combined with CH4 partial oxidation

Thermal reduction of the partial oxidation of CH₄NiFe₂O₄ followed by oxidation with H₂O and CO₂ was numerically investigated for H₂ and CO production. P1 radiation model was used to account for radiative heat transfer. The synergistic effect of the reactivity of Fe/Ni exhibited a very promising strategy for producing 45% of syngas with 2.54 ratios of H₂:CO at the first step and 55% of syngas with 2.34 ratios of H₂:CO at the second step. The increase in incident radiation heat flux to 437.69 kW/m² resulted in higher reduction kinetics of species conversion until the formation of oxygen carriers consisting of 65% of FeO, 35% of NiFe and 2.6% of carbon deposition. However, during the reduction process, the decrease in total pressure to 0.05 MPa enhanced the species reactivity and the production of H₂ and CO while minimizing carbon deposition. Moreover, the oxidation temperature, operating pressure and the concentration of oxidizing species have strong impacts on the oxidation kinetics. Unlike high thermal reduction process, increasing the total pressure to 1 MPa has favorable effects on syngas production at oxidation step.     

Fabrication of CdS/NiFe LDH heterostructure for improved photocatalytic hydrogen evolution from aqueous methanol solution

2D CdS/NiFe LDH (short for layered double hydroxide) heterostructures were designed and fabricated by following a facile in-situ growth method. The CdS nanoparticles are well dispersed on the surface of NiFe LDH to form nanoscale heterojunctions, as suggested from the TEM and elemental mapping images. The composites with optimum CdS amount (15 wt%) take on notably higher hydrogen evolution activity (469 μmol h^?1 g^?1) than the independent CdS and NiFe LDH from aqueous methanol solution under xenon lamp irradiation. The nano-heterojunction notably promotes the H₂ evolution kinetics and greatly suppresses the recombination of photo-induced electrons and holes, which is responsible for the enhanced photocatalytic activity of the composites, as demonstrated by the reducing onset potential and increasing photocurrent of the composites in the photoelectrochemical experiments. The possible photocatalytic mechanism is proposed on the basis of the defined position of energy band edges.     

One-pot synthesis of ultrasmall PtAg nanoparticles decorated on graphene as a high-performance catalyst toward methanol oxidation

A one-pot synthesis method is utilized for the fabrication of ultrasmall platinum-silver nanoparticles decorated on graphene (PtAg/G) catalyst. This method has several advantages such as inexpensiveness, simplicity, low temperature, surfactant free, reductant free, being environmentally friendly and greenness. In this work, graphene and silver formate were dispersed in ultrapure water in an ultrasonic bath at 25 °C followed by through a galvanic displacement reaction; to prepare PtAg/G, PtCl₂ was added to the suspension under mild stirring condition. The morphology, crystal structure and chemical compositions of the as-fabricated PtAg/G and Pt/C catalysts were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Energy dispersive X-ray spectroscopy (EDS) techniques. Electrochemical techniques, including cyclic voltammetry (CV) and chronoamperometry (CA) measurements were used to analyze the electrochemical activity of the PtAg/G and Pt/C catalysts. The TEM images illustrate the uniform distribution of ultrasmall PtAg nanoparticles with the average size of 2–3 nm on the graphene nanosheets. The PtAg/G promoted the current density 2.46 times as much as Pt/C with a negative shift in onset oxidation potential and peak potential for oxidation reaction of methanol. Besides, the novel PtAg/G catalyst shows large electrochemically active surface area, lower apparent activation energy, and higher levels of durability in comparison to the Pt/C catalyst for the oxidation of methanol. The PtAg/G catalyst depicts extraordinary catalytic performance and stability to those of the Pt/C catalyst toward methanol oxidation in alkaline media.     

In-situ synthesis of well dispersed CoP nanoparticles modified CdS nanorods composite with boosted performance for photocatalytic hydrogen evolution

Development of photocatalysts with characters of low-cost, environment friendliness, visible light response and good performance is vital for the transformation of solar energy into hydrogen fuel. Here, we constructed CoPCdS nanorods hybrid composites via a novel two-step in-situ growth method for the first time. The obtained CoPCdS composites exhibited remarkably enhanced photocatalytic performance and excellent stability in comparison with bare CdS nanorods. Notably, the optimum H₂ evolution rate of 1 wt%CoPCdS was 9.11 times higher than that of pristine CdS. The apparent quantum efficiency of the photocatalyst was calculated to be 11.6%. The superior activity of this material could be attributed to the role of well dispersed CoP nanoparticles and the intimate interface between CoP cocatalysts and CdS nanorods, which efficiently accelerated the separation and transfer of photogenerated electrons. This work provided a new in-situ growth method for the preparation of transition metal phosphides coated photocatalysts with boosted photocatalytic activity of hydrogen evolution.     

Bismuth doped TiO2 as an excellent photocathode catalyst to enhance the performance of microbial fuel cell

Bismuth impregnation on pure TiO₂ (BiTiO₂) was carried out and tested in microbial fuel cell (MFC) as photocathode catalyst. UV–Visible spectral observation confirmed higher catalytic activity of BiTiO₂ under visible light irradiation with reduced band gap of 2.80 eV as compared to pure TiO₂ (3.26 eV). Electrochemical impedance spectroscopy also showed two times higher exchange current density with lower charge transfer resistance for BiTiO₂ (1.90 Ω) than pure TiO₂ (3.95 Ω), thus confirming it as superior oxygen reduction reaction catalyst. MFC operated with BiTiO₂ could generate a maximum power density of 224 mW m^?2, which was higher than MFC with Pt as cathode catalyst (194 mW m^?2) and much higher than MFCs with TiO₂ catalyzed cathode (68 mW m^?2) and without any cathode catalyst (60 mW m^?2). The results thus promote Bi doped TiO₂ as a superior low-cost alternative to the costly Pt catalyst to take this MFC technology forward for field application.     

Cobalt doped Ni based ordered mesoporous catalysts for CO2 methanation with enhanced catalytic performance

Ordered mesoporous NiCo/Al₂O₃ nanocomposites were synthesized for use as CO₂ methanation catalysts via an evaporation-induced self-assembly method. Owing to its improved H₂ chemisorption capacity, the ordered mesoporous NiCo/Al₂O₃ catalyst with 10 wt% NiO and 3 wt% Co₃O₄ (10N3COMA) exhibited enhanced catalytic activity, which achieved the maximum CO₂ conversion of 78% and CH₄ selectivity of 99% at 400 °C, 0.1 MPa, 10000 mL g^?1 h^?1. In the 60 h-lifetime test, the ordered mesoporous 10N3COMA catalyst showed superior anti-sintering property at 500 °C due to the confinement effect of the ordered mesostructure.     

Bimetallic Pt-M electrocatalysts supported on single-wall carbon nanotubes for hydrogen and methanol electrooxidation in fuel cells applications

A series of PtRu and PtMo bimetallic catalysts were prepared via a chemical reduction method by bubbling CO to form carbonyl compounds as metal precursors. In both cases the PtRu and PtMo bimetallic electrocatalysts achieved the maximum activity when the amount of Ru and Mo in the material was 50%wt. The physicochemical characterization of the electrocatalytic materials through X-ray diffraction (XRD) and transmission electron microscopy (TEM) has determined the presence of bimetallic structures. The electrochemical characterization using cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and polarization curves in Proton Exchange Membrane Fuel Cells (PEMFC) and Direct Methanol Fuel Cell (DMFC) allowed to systematically investigate the electrocatalytic activity of the synthesized materials for the electrooxidation of hydrogen and methanol. The PtRu/SWCNT electrocatalysts showed a higher current density at least 7-fold and 3-fold compared with Pt/SWCNT and PtMo/SWCNT electrocatalysts, respectively. Besides, the Pt50%–Ru50%/SWCNT exhibited a shifting to negative values in the onset potential reaction for the electrooxidation of methanol of 200 mV in comparison with Pt100%/SWCNT and Pt50%–Mo50%/SWCNT electrocatalysts. The experimental and simulated polarization curves obtained from DMFC show that PtRu/SWCNT and PtMo/SWCNT electrocatalysts exhibited higher power and current densities values compared with the Pt/SWCNT electrocatalyst. The membrane-electrode assembly (MEA) with Nafion^® and the PtRu/SWCNT electrocatalysts showed an open-circuit voltage value of 0.730 V, significantly higher than that the values for the MEAs with Pt/SWCNT (0.663 V) and PtMo/SWCNT (0.633 V), respectively.     

Rare earth metal Gd influenced defect sites in N doped TiO2: Defect mediated improved charge transfer for enhanced photocatalytic hydrogen production

In this experimental studies, we report the synthesis of TiO₂ co-doped by both cationic and anionic sites by simple sol-gel based method. All the prepared samples exhibit the anatase crystalline morphology however, showed lattice distortion caused by the displacement of Ti⁴⁺ sites by Gd³⁺. The improved visible absorption is witnessed by the Gd and N co-doping with an assured redshift in the absorption edge. The N and Gd displacement inside TiO₂ lattice accompanied by the creation of OTiN and GdOTi bonds are characterized by the X-ray photoelectron spectra. The strong resonance signal by Gd4f electrons in the electron paramagnetic resonance spectroscopy further substantiate the displacement of lattice cites of TiO₂ by Gd³⁺ ions. The longevity of the photo produced charges observed in fluorescence spectra of Gd and N co-doped TiO₂ is because of the effective transfer of charges to the defect sites. The aforementioned catalysts are tested for their capacity for the H₂ production from water splitting. The 2 wt% gadolinium and nitrogen co-doped TiO₂ has shown 10764 μmol g^?1 H₂ production which is 26 times higher than the commercial Degussa P-25 catalyst. The enhanced activity for hydrogen production can be attributed to factors such as increased absorptivity under visible light and effective charge carrier separation.     

SBA-15 supported mesoporous Ni and Co catalysts with high coke resistance for dry reforming of methane

In this study, the activity of the mesoporous SBA-15 supported Ni, Co and NiCo catalysts prepared by the wet-impregnation were investigated in dry reforming of methane reaction. The catalysts were characterized by XRD, TPR, N₂ adsorption-desorption isotherms, SEM, TEM and TG/DT techniques before and/or after activity tests. N₂ adsorption-desorption isotherm of the all catalysts were consistent with Type IV isotherm, indicating mesoporous structures. TEM images of bimetallic NiCo catalysts clearly proved the presence of characteristic honeycomb structure. Incorporation Co into SBA-15 supported Ni catalysts inhibited the agglomeration of the nickel particles due to the formation of NiCo alloy. Activity test results showed that bimetallic 4Ni1Co@SBA-15 catalyst (Ni/Co:4/1) gave highly promising activity with high methane (73%) and carbon dioxide (89%) conversion values at 750 °C. Co incorporation into SBA-15 supported Ni catalyst significantly decreased the coke formation during dry reforming of methane.