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Catalyst deactivation and regeneration during CO 2 reforming of bio-oil were researched in this paper. The results of XRD, TG and SEM analyses showed that the catalyst deactivation was a combination of carbon deposition and sintering. There were amorphous carbon and filamentous carbon on the catalyst surface, but amorphous carbon was the main carbon product, which was the main reason for the catalyst deactivation. The activity and stability of steam regeneration catalyst is superior to that of CO 2 and air regeneration catalyst, but steam regeneration process will consume much quantity of steam, which can be increased production cost. Air regeneration method is easy to sinter the center of catalyst. CO 2 regeneration process not only produces useful gases (C + CO 2 = 2CO), but also makes good use of greenhouse gases, which has an industrial application prospect. However, with the cycle of catalyst increasing, the activity and stability catalyst will decrease gradually during the CO 2 reforming process. • Catalyst deactivation is a combination of carbon deposition and sintering in CO 2 reforming process. • Steam regeneration is superior to that of other methods, but it will increase production cost. • CO 2 regeneration not only produces useful gases, but makes good use of greenhouse gases. [ABSTRACT FROM AUTHOR]

To improve the photocorrosion of CdS nanorod arrays (CdS NRAs), we have designed a simple and facile treatment method of in-situ hydrogenation to fabricate CdS@SnS/SnO 2 heterostructure on fluorine-doped tin oxide glass, which is a highly photostable hydrogenated CdS-based film photocatalyst (CdS NRAs-H 2 ). Over a 25-h long time irradiation, the total photocatalytic hydrogen production of hydrogenated CdS NRAs is almost 2.0 times higher than that of un-hydrogenated CdS NRAs. Moreover, the average hydrogen production rate of CdS NRAs-H 2 can steadily maintain at 23.75 μmol cm −2 h −1 with 102% of retention rate after 5 reaction cycles, while they are only 6.13 μmol cm −2 h −1 with 30% of retention rate for un-hydrogenated common CdS NRAs. The photocatalytic mechanism on enhanced activity and stability for hydrogenated CdS NRAs photocatalyst is also investigated and discussed in detail. [ABSTRACT FROM AUTHOR]

Hydrogen isotope retention of tungsten in nuclear fusion reactors is one of the hot research issues all along. In this paper, tungsten samples in different rolled surfaces were polished by mechanical processing, subsequently subjected to D 2 + irradiation and thermal desorption. To better understand the experimental observations, this study also performed molecular dynamics (MD) simulation and investigated the effects of temperature, grain number, grain boundary density, and crystal orientation on hydrogen retention. It is found that the grain number and grain boundary density of rolled tungsten increase successively in RD/TD, RD/ND, and TD/ND surfaces. The RD/ND surface exhibits the best hydrogen radiation resistance, whereas the TD/ND surface is unsatisfactory. MD simulations further indicate that hydrogen retention is more obvious with the increase of grain density in tungsten, and hydrogen atoms are more easily enriched at the grain boundaries. With the increase in temperature, the retention of hydrogen atoms in monocrystalline/polycrystalline tungsten decreases significantly. The average implantation depth of H atoms is deepest along the <111> and <112> crystalline directions, which reveals that hydrogen retention is dependent on the crystal orientations. The good agreement between the experimental data and simulation results reveals that grain boundaries play an important role in hydrogen retention. [Display omitted] • The hydrogen retention behavior is studied in W samples with different rolled surfaces. • RD/ND surface has the best hydrogen resistance, while the TD/ND surface is undesirable. • The hydrogen retention behavior depends on temperature, grain size, grain boundary density and orientation. [ABSTRACT FROM AUTHOR]

The wetting behavior of graphitic carbon in a eutectic melt of Li K molten carbonate was investigated at two different temperatures (650 and 750 °C) under two different CO 2 partial pressures. The development of the meniscus and the formation of a super-meniscus film were followed optically over a period of 24 h after partial immersion of the graphite rods. Post-test EDX analyses of the graphite surfaces exposed to the melt, above and below the meniscus, were compared to those of surfaces not exposed to the melt. The most important feature found in the EDX analyses is the non-uniform atomic distribution of oxygen both along the length of the immersed surface and in the radial cross-section of the rods exposed to the melt. In addition, the effect of pre-test exposure to gas atmospheres at various temperatures and CO 2 partial pressures was investigated. The wetting behavior is found to be influenced strongly by reactions occurring at the carbon surface before and after the start of wetting. In particular, CO produced by the reverse Boudouard reaction, which appears to be physisorbed, and chemically adsorbed oxide ion, O 2− , are inferred to play a dominant role in the development of the meniscus leading to a super-meniscus film on the graphitic surface. Several reaction mechanisms are examined to explain the results observed in this work, which agree with results of earlier work from this laboratory, in terms of CO and oxide ion formation. [ABSTRACT FROM AUTHOR]

Size effect of Pt nanoparticle (NPs) on electrocatalysis should be investigated in a wide size range and a narrow distribution. The surfactants used for size control were detrimental to exploring size effect. However, the largest size of Pt colloidal NPs was limited to ∼5 nm without surfactant, which is insufficient for investigating size effect. In this work, surfactant-free Pt colloidal NPs with a wider size range from 1.8 to 10.0 nm were synthesized by controlling the ratio of NaOH and Pt salts in the ethylene glycol by oil-bath heating. Assisted by the precise control of Pt size, the size effect on the electrooxidation of CO, methanol and ethanol was studied, showing that the optimal size varied from the specific catalytic reaction. The synthesis extended the upper limit of large Pt NPs by surfactant-free method, showing potentials in preparing other precious metal NPs with a wide size range. [Display omitted] • Wide size range synthesis of surfactant-free colloidal Pt nanoparticles in alkaline ethylene glycol. • Water accelerates the rate of particle formation. • Temperature increases the conversion of Pt precursor rather than the size. • The wide range is sufficient to study size effect on electrocatalysis. [ABSTRACT FROM AUTHOR]

The magnesium-lanthanum-hydrogen systems possess the goodish stability and high hydrogen storage capacity, which make them perspective as commercial Mg-based hydrogen storage materials. The exploration of these intriguing properties evolving from small atomic and molecule cluster to bulk phase are, to our knowledge, the longstanding challenge. Here, we perform a theoretical study on the structural and electronic properties of Mg 3 LaH n (9 ≤ n ≤ 20) clusters by using the Crystal Structure AnaLYsis by Particle Swarm Optimization method combined with density functional theory calculations. It is found that Mg 3 LaH 15 is the most stable cluster in the series, with hydrogen storage capacity of 6.6 wt% and adsorption energy of 2.76 eV. The present results offer new insights for the design and synthesis of novel hydrogen storage materials in the future. [Display omitted] • Structural and electronic properties of Mg 3 LaH n (n = 9–20) clusters are studied. • The Mg 3 LaH 15 is the most stable cluster with the HOMO-LUMO gap of 5.19 eV. • The Mg 3 LaH 15 can serve as prospective material for hydrogen storage. [ABSTRACT FROM AUTHOR]

Abstract: Novel alumina-supported cobalt nitride catalysts with Co loading ranging from 1 to 10 wt% prepared by NH3-temperature-programmed reaction were investigated as potential catalysts for preferential CO oxidation (PROX) in excess H2 at high temperatures. The formation of the Co4N phase was confirmed by a combination of XRD and XPS, and the Co 2p binding energies of Co4N reported previously were corrected to 798.2 ± 0.2 and 782.5 ± 0.2 eV. We observed that the catalytic activities of these nitrided Co/γ-Al2O3 catalysts were greatly related to their Co loadings. The nitrided 3 wt% Co/γ-Al2O3 catalyst showed the best PROX performance in temperature range of 200–220 °C, which was quite different from Co oxide precursor but was similar to Pt-group metals. [Copyright &y& Elsevier]

An efficient Ni 2 P–CdS photocatalyst for photocatalytic hydrogen evolution was synthesized by phosphorizing β-Ni(OH) 2 nanosheet with exposed (001) facets on CdS nanorods. The obtained Ni 2 P–CdS composite displays an outstanding and stable photocatalytic hydrogen generation rate of 68.47 mmol g−1 h−1 in 10 vol% lactic acid under visible light irradiation, more than 17 times higher than that for pure CdS nanorods. The transient photocurrent response, EIS measurement, Mott-Schottky plots, acidic LSV measurement, and PL spectra have proved that Ni 2 P loading can significantly improve the separation of photo-excited electron-hole pairs in CdS nanorods and enhance the hydrogen evolution capability for CdS. These improvements are achieved by features of Ni 2 P such as the high capability of trapping photo-generated electrons from CdS, lifting the total Fermi level and lowering the hydrogen evolution overpotential of the composite. The results show that β-Ni(OH) 2 precursor with a high exposure degree of (001) facet is contributed to the epitaxial formation of (001)-facet-exposed Ni 2 P co-catalyst on CdS nanorods, resulting in that the Fermi level and the hydrogen evolution overpotential of the composite can be further lifted and lowered. This study has provided a novel precursor-derived route to fabricate high-performance co-catalysts with highly exposed active facets on CdS nanorods for effective photocatalytic hydrogen evolution. • Ultrathin β-Ni(OH) 2 nanosheet precursor is employed in fabricating Ni 2 P on CdS. • β-Ni(OH) 2 nanosheet with exposed (001) facet facilitate Ni 2 P(001) growth on CdS. • Hydrogen evolution and charge separation of CdS can be markedly improved by Ni 2 P. [ABSTRACT FROM AUTHOR]

The substitution of noble metal platinum catalyst is one of the important research contents for sustainable development and is also the key to the practical application of photoelectrochemical (PEC) hydrogen production. In this work, we loaded the 1T-2H mixed phase MoS 2 on the hydrogenated anatase/rutile heterophase TiO 2 (A-H-RTNA) by hydrothermal method to prepare a new MoS 2 /A-H-RTNA electrode material. The prepared material exhibited higher carrier density, lower PL intensity and higher conductivity than Pt/A-H-RTNA because 1T-MoS 2 has more active sites and lower charge transfer resistance than Pt. With the bias voltage of −0.4 V, the optimized 16MoS 2 /A-H-RTNA as photocathode shows the largest PEC hydrogen production rate of 1840 mmol m−2 h−1, which is 2.9 and 2.2 times higher than those of A-H-RTNA (625 mmol m−2 h−1) and Pt/A-H-RTNA (848 mmol m−2 h−1), respectively. We innovatively used the prepared 16MoS 2 /A-H-RTNA film as counter electrode instead of Pt electrode to construct a PEC system without any noble-metal. The result demonstrates that the noble-metal-free MoS 2 loaded on TiO 2 electrode as counter electrode has 75% PEC activity of noble metal Pt electrode. This study develops a PEC method for hydrogen evolution, which no longer depends on precious metal platinum as cathode. A new MoS 2 /A-H-RTNA electrode with 2 times higher hydrogen production rate than Pt/A-H-RTNA was prepared by loading MoS 2 on the hydrogenated TiO 2 heterostructure film. The prepared MoS 2 /A-H-RTNA film was used as photocathode instead of Pt electrode to construct an innovative and efficient PEC system without any noble-metal. Image 1 • MoS 2 is loaded on hydrogenated anatase/rutile TiO 2 heterophase structure (A-H-RTNA). • MoS 2 /A-H-RTNA has low charge transfer resistance for photoelectrochemical (PEC) reaction. • MoS 2 /A-H-RTNA as photocathode has 2 times higher PEC hydrogen production rate than Pt/A-H-RTNA. • MoS 2 /A-H-RTNA film can be used as photocathode instead of Pt electrode. • An innovative and efficient PEC system without any noble metal is constructed. [ABSTRACT FROM AUTHOR]

A Cu 2 O/(001)TiO 2 @Ti 3 C 2 T x photocatalyst was synthesized via a wet-chemistry reduction method by N, N-dimethylformamide (DMF). By scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), it was revealed that the surface coverage of photocatalyst increased with the loading amount of Cu 2 O, while the particle size of Cu 2 O did not change significantly. The photocatalytic activity and mechanism of ternary Cu 2 O/(001)TiO 2 @Ti 3 C 2 T x photocatalyst heavily depend on the surface coverage of copper species. When the surface coverage of photocatalyst by Cu 2 O was low, the Ti 3 C 2 T x acted as hole reservoir. Cu 2 O was firstly reduced in situ to metallic copper by excited electrons. Then the reverse movement of carriers enabled the spatial separation of photogenerated electron-hole pairs, and afforded relatively high hydrogen evolution (more than 1100 μmol h−1 (g CuO x TiO 2)−1). When the coverage of Cu 2 O on (001)TiO 2 @Ti 3 C 2 T x was too high at high loading amounts, Ti 3 C 2 T x failed to play the role of hole trapping. Under that circumstance, the photocatalytic reaction follows p-n junction mechanism, leading to low hydrogen productivity. The results here shed light on the relationship between structure and activity of Cu 2 O/(001)TiO 2 @Ti 3 C 2 T x , which was conducive to the development of the MXene-based photocatalysts. Image 1 • A Cu 2 O–TiO 2 –Ti 3 C 2 T x ternary catalyst fabricated by a solvent reduction method. • The loading amount and surface coverage of Cu 2 O can be easily adjusted. • The hydrogen evolution activity can be manipulated by the amount of copper species. • The photocatalytic reaction mechanism depends on the surface coverage of Cu 2 O. [ABSTRACT FROM AUTHOR]

A facile method of loading CoS x nanosheet onto CdS nanorod has been designed, and the prepared CdS-CoS x composite catalyst exhibited significantly improved performance for photocatalytic hydrogen evolution compared with CdS catalyst. This composite catalyst was also used as a photoanode for photoelectrochemical (PEC) hydrogen production. The hydrogen production rate reached 168.6 μmol cm−2 h−1 (37.77 L m−2 h−1) under the simulated solar light, which is 2.7 times that of CdS and the same as that of CdS–Pt. In addition, in the Na 2 S–Na 2 SO 3 system for PEC hydrogen production, an abnormal relationship between photocurrent and the hydrogen production yield was found. By designing a series of experiments, the photocatalytic and photoelectrochemical characteristics for hydrogen production were reasonably revealed for the first time. In this work, the prepared structured catalyst is easy to be recycled, and CoS x can replace precious metal Pt, showing a promising application. Image 1 • CoS x as co-catalyst is loaded on CdS nanorod by a facile method. • CdS-CoS x has good activity and stability for photoelectrochemical (PEC) reaction. • PEC activity of CdS-CoS x as photoanode for H 2 production is the same as that of CdS–Pt. • An abnormal relationship between photocurrent and hydrogen production is found. • The reaction network in Na 2 S–Na 2 SO 3 system for PEC H 2 production is proposed. [ABSTRACT FROM AUTHOR]

In photocatalytic field, it is a significant challenge to synthesize cocatalyst with high performance, noble-metal free and facile methods to recycle. Herein, carbon layer coated Fe 3 C (Fe 3 C@C) nanoparticles were prepared by one-step method and for the first time utilized as highly efficient cocatalysts for improving visible-light-driven hydrogen evolution activity of g-C 3 N 4. The photocatalytic hydrogen evolution rate of optimal Fe 3 C@C/g-C 3 N 4 was about 27.2 times of bare g-C 3 N 4 samples. Furthermore, the Fe 3 C@C/g-C 3 N 4 composite catalyst showed excellent stability and reusability. The apparent quantum yield (AQY) of the optimized FeC@C/g- C 3 N 4 reaches 0.501% and 0.124% at 400 nm and 420 nm, respectively. The AQY of the FeC@C/g- C 3 N 4 is 26.2 times higher than that of g-C 3 N 4 at 400 nm Fe 3 C@C has an extraordinary cocatalytic effect for g-C 3 N 4 photocatalytic hydrogen evolution mainly due to three aspects: Firstly, the Fe 3 C acts as a trap to lure electrons because of its lower Fermi energy level and higher conductivity, which can increase the hydrogen production activity by trapping the photogenerated electrons produced by g-C 3 N 4 ; Secondly, the coated carbon layer can provide chemical protection for Fe 3 C nanoparticles and promote the transfer of photogenic electrons, thus further improving the efficiency and stability of photocatalytic hydrogen production; Thirdly, the strong magnetic property of Fe 3 C@C nanoparticles gives Fe 3 C@C/g-C 3 N 4 photocatalysts the advantages of low cost and high recovery efficiency. It is believed that this work provides a new strategy and possibility for the application of photocatalytic hydrogen production. • Carbon layer coated Fe 3 C (Fe 3 C@C) nanoparticles are prepared by one-step method. • The Fe 3 C@C as cocatalyst for boosting photocatalytic performance of g-C 3 N 4. • Fe 3 C@C/g-C 3 N 4 photocatalyst possesses strong magnetism and is easy to be recycled. • The Fe 3 C can efficiently trap the photogenerated electrons generated by g-C 3 N 4. • The carbon layer can provide chemical protection for Fe 3 C nanoparticles. [ABSTRACT FROM AUTHOR]

Abstract A facile method is proposed to prepare cobalt supported on nitrogen-doped porous carbon material with high graphitization degree by using chitosan as carbon source, urea as soft template and poloxamer as dispersant. The prepared cobalt-carbon material (Co@NPC) shows that uniformly distributed cobalt nanoparticles are encapsulated in nitrogen-doped porous carbon bundle with large specific surface area. When Co@NPC is applied as electrode in hydrogen evolution reaction, it exhibits superior electrocatalytic performance with low overpotential (η 10 = 259 mV), small Tafel slope (99 mV dec−1) and high stability with 83% of its original current density remained after 6 h electrochemical test in 1 M potassium hydroxide electrolyte. Graphical abstract A facile method is proposed to prepare cobalt or cobalt oxide supported on nitrogen-doped porous carbon material, exhibiting superior electrochemical performance for hydrogen evolution reaction. Image 1 Highlights • A facile method is reported for preparing Co/N-doped porous carbon bundles (Co/NPC). • The effect of urea as soft template on surface structure of NPC is clearly revealed. • Co/NPC exhibits superior electrocatalytic performance for hydrogen evolution. • Co in Co/NPC plays important role in the reaction of hydrogen evolution. [ABSTRACT FROM AUTHOR]

Photocatalytic water splitting into hydrogen is a very attractive and desirable technology to realize sustainable and renewable green energy conversion. Up to now, many research results have confirmed that cocatalyst such as Pt is essential for a high efficiency photocatalytic H 2 evolution system. In a traditional view, the cocatalyst should be closely combined with the photocatalyst to achieve a high H 2 or O 2 photo-productive rate. In this work, an unusual point has been put forward that the suitable loading position of cocatalyst Pt for film-type TiO 2 catalyst is on the bare Fluorine-doped tin oxide (FTO) substrate instead of on the surface of TiO 2 in the electrolyte solutions. Especially, in acidic electrolyte, the hydrogen production rate of this new designed catalyst with Pt loaded on FTO (TiO 2 -Pt/FTO) reaches 2.4 times that of the common catalyst with Pt loaded on TiO 2 (Pt/TiO 2 -FTO). According to the experiment results, it is supposed that this loading way of cocatalyst on the substrate can construct a self-bias photocatalytic electrochemical cell system, drive electrolyte ions' movement directionally, and obtain high photocatalytic H 2 production efficiency. The universality of this innovation has been verified by CdS and CdS@TiO 2 film-type catalysts. This study provides a new guide in exploring high-efficiency film-type photocatalytic system for water splitting into hydrogen in the electrolyte solution. [ABSTRACT FROM AUTHOR]

CuO 1− x cluster-modified TiO 2 (CuO 1− x /TiO 2 ) photocatalysts were prepared by an in-situ photoreduction deposition of Cu on TiO 2 powder support using copper acetate as a Cu source. The prepared samples without any Pt co-catalyst present an especially high photocatalytic H 2 -evolution activity under solar light irradiation with 5% glycerol as sacrificial agent. The optimal CuO 1− x /TiO 2 catalyst with only 1 wt% CuO 1− x exhibits a high activity of 1725 μmol h −1 g −1 for H 2 evolution, which reaches 120 times that of TiO 2 . The high photocatalytic activity of H 2 production is attributed to the highly dispersed CuO 1− x nano clusters on the surface of the TiO 2 . In addition, Pt/CuO 1− x /TiO 2 was also prepared by loading Pt on CuO 1− x /TiO 2 sample, and its photocatalytic hydrogen evolution activity is enhanced 1.8 times compared with that of Pt/TiO 2 for overall water splitting reaction under solar light, demonstrating that a small amount CuO 1− x wondrously improves the photocatalytic activity of Pt/TiO 2 for overall water splitting reaction. This paper reports an economic and simple approach to prepare a photocatalyst with high hydrogen-production activity. [ABSTRACT FROM AUTHOR]

The concentration of CO in the high-purity hydrogen from sorption-enhanced steam reforming (SESR) processes is usually too high to be directly used in fuel cells. Herein, we report a production of fuel-cell grade H 2 with <30 ppm CO through SESR of glycerol (SESRG), a by-product of biodiesel manufacture. High purity H 2 can be produced by employing a catalyst-sorbent hybrid material composed of Ni as catalyst, CaO as CO 2 sorbent and Ca 12 Al 14 O 33 as spacer. By introducing copper as promoter, the performance of the bi-functional catalyst could be modified to produce a 97.15 vol% purity of H 2 with 28 ppm CO. With an optimized Ni/Cu ratio, the 7.5Ni–7.5Cu catalyst shows the excellent stability for producing about 97% H 2 with <30 ppm CO for ten cycles. The characterizations and model reaction tests indicate that copper can affect CO, CO 2 hydrogenation and water gas shift reaction to adjust the performance of SESRG reaction. The results presented here show the promise of tuning the catalyst composition for achieving high quality H 2 through SESR processes. [ABSTRACT FROM AUTHOR]

In recent years, tremendous efforts have been devoted to develop new photocatalyst with wide spectrum response for H 2 generation from water or aqueous solution. In this work, CdS nanoparticles (NPs) have been immobilized on hydrogenated three-dimensional (3D) branched TiO 2 nanorod arrays, resulting in a highly efficient photocatalyst, i.e, CdS/H-3D-TiO 2 . In addition, electrochemical reduction of H + ion is identified as a limiting step in the photocatalytic generation of H 2 at this catalyst, while here a Pt wired photocatalysis system (CdS/H-3D-TiO 2 /Pt-wire) is designed to overcome this barrier. Without the application of potential bias, visible light photocatalytic hydrogen production rate of CdS/H-3D-TiO 2 /Pt-wire is 18.42 μmol cm −2 h −1 , which is 11.2 times that of CdS/H-3D-TiO 2 without Pt (1.64 μmol cm −2 h −1 ). The Pt wire acts as an electron super highway between the FTO substrate and H + ions to evacuate the generated electrons to H + ions and catalyze the reduction reaction and consequently generate H 2 gas. This work successfully offers a novel direction for dramatic improvement in H 2 generation efficiency in photocatalysis field. [ABSTRACT FROM AUTHOR]

Two kinds of branched hydrogenated TiO 2 nanorod arrays, i.e., hydrogenated TiO 2 nanorod supported hydrogenated TiO 2 branch arrays (H-BTNRs) and hydrogenated TiO 2 nanorod supported unhydrogenated TiO 2 branch arrays (B/H-TNRs), have been successfully designed and prepared by a facile approach. Under simulated solar light, the prepared B/H-TNRs have the highest hydrogen evolution rate of 6.65 μmol cm −2 h −1 , which is 4.7 and 2.4 times those of hydrogenated TiO 2 nanorod arrays (H-TNRs) and H-BTNRs, respectively. This study indicates that the heterostructure design of the unhydrogenated TiO 2 branch and hydrogenated TiO 2 nanorod promotes the separation of charge carries on the interface and enhances photocatalytic hydrogen evolution. [ABSTRACT FROM AUTHOR]

The hierarchical Ag NPs with a bimodal size distribution were auto-decorated on the surface of rice-like N-TiO 2 (named h-Ag/N-TiO 2 ) by semiconductor-metal double excitation process under solar light irradiation. The photoinduced growth process of self-assembled h-Ag/N-TiO 2 and its photocatalytic mechanism of photo-splitting ethanol into hydrogen have been discussed in detail. The synthesized h-Ag/N-TiO 2 as a plasmonic photocatalyst for photo-splitting ethanol exhibited a higher hydrogen production rate (4.7 mmol h −1 g −1 ) than Ag NPs universally loaded N-TiO 2 (3.4 mmol h −1 g −1 ) and pure N-TiO 2 (2.1 mmol h −1 g −1 ). This work presents a reversed photo-induced synthesis strategy to design a stable Ag-TiO 2 plasmonic photocatalyst with high photocatalytic efficiency under solar light. A better understanding of this solar light induced self-assembled process for Ag-TiO 2 is crucial in developing metal-semiconductor system for solar energy materials. [ABSTRACT FROM AUTHOR]

Abstract: The influence of the electrodeposition potential on the morphology of Cu2O/TiO2 nanotube arrays (Cu2O/TNA) and their visible-light-driven photocatalytic activity for hydrogen evolution have been investigated for the first time in this work. The photocatalytic hydrogen evolution rate of the as-prepared Cu2O/TNA at the deposition potential of −0.8 V was about 42.4 times that of the pure TNA under visible light irradiation. This work demonstrated a feasible and simple electrodeposition method to fabricate an effective and recyclable visible-light-driven photocatalyst for hydrogen evolution. [Copyright &y& Elsevier]

Abstract: Cu(OH)2/TNAs photocatalyst was prepared by loading Cu(OH)2 nanoparticles on TiO2 nanotube arrays (TNAs) using a chemical bath deposition method. The amount of Cu(OH)2 loaded on the arrays was controlled by the repeated deposition times. The prepared catalyst was used to generate hydrogen under simulated solar light irradiation, and the results demonstrated that the hydrogen yield of Cu(OH)2/TNAs was 20.3 times that of the pure TNAs. Furthermore, the photocatalytic efficiency for hydrogen production decreased only 5.8% after five cycles, indicating that Cu(OH)2/TNAs photocatalyst showed excellent stability and reusability. This work presents an applicable and facile method to fabricate a highly active and stable photocatalyst for hydrogen production. [Copyright &y& Elsevier]

Abstract: Palladium-based membranes are attractive for their nearly perfect permselectivity to hydrogen. Membrane modules, consisting of a membrane foil, porous stainless steel substrate, test frame and flange were assembled and tested in an electrically heated vessel. Instantaneous hydrogen permeation flux was measured. Influences of operation conditions on the membrane performance were examined. Microstructure and morphology of the membrane surface and the cross-sectional surface of the substrate and membrane foil were characterized by scanning electron microscopy. It was observed that for an operation temperature higher than 755 K, the hydrogen permeation flux through the membrane module with 0.2 μm grade porous 316L stainless steel substrate decayed continuously due to the inter-metallic diffusion between the membrane and the substrate. For a temperature of around 869 K–943 K, a stable hydrogen permeation flux through the membrane module with 0.5 μm grade stainless steel substrate was observed. Pretreatment of the 0.5 μm grade substrate with polishing and etching helped to smooth the membrane foil surface. However, it changed the surface structure of the material and led to a decrease in hydrogen permeability. Under the conditions investigated, the permeation factor of the module increased by raising the hydrogen pressure in the vessel side and decreasing the membrane module temperature. By decreasing the hydrogen exit partial pressure by sweep gas, the membrane module permeation flux increased, while the permeation factor decreased. [Copyright &y& Elsevier]

Abstract: An equilibrium model of steam methane reforming coupled with in-situ membrane separation for hydrogen production was developed. The model employed Sievert’s Law for membrane separation and minimum Gibbs energy model for reactions. The reforming and separation processes were coupled by the mass balance. The model assumed a continuously stirred tank reactor for the fluidized bed hydrodynamics. The model predictions for a typical case were compared with those from the model of Ye et al. which assumed a plug flow for bed hydrodynamics. The model predictions show satisfactory agreement with experimental data in the literatures. The influences of reactor pressure, temperature, steam to carbon ratio, and permeate side hydrogen partial pressure on solid carbon, NHx and NOx formation were studied using the model. [ABSTRACT FROM AUTHOR]