Combustion,performance and emissions of a diesel engine with H2, CH4 and H2–CH4 addition

Experiments were conducted to investigate the combustion and emission characteristics of a diesel engine with addition of hydrogen or methane for dual-fuel operation, and mixtures of hydrogen–methane for tri-fuel operation. The in-cylinder pressure and heat release rate change slightly at low to medium loads but increase dramatically at high load owing to the high combustion temperature and high quantity of pilot diesel fuel which contribute to better combustion of the gaseous fuels. The performance of the engine with tri-fuel operation at 30% load improves with the increase of hydrogen fraction in methane and is always higher than that with dual-fuel operations. Compared with ULSD–CH₄ operation, hydrogen addition in methane contributes to a reduction of CO/CO₂/HC emissions without penalty on NO_x emission. Dual-fuel and tri-fuel operations suppress particle emission to the similar extent. All the gaseous fuels reduce the geometry mean diameter and total number concentration of diesel particulate. Tri-fuel operation with 30% hydrogen addition in methane is observed to be the best fuel in reducing particulate and NO_x emissions at 70 and 90% loads.     

Hydrogen storage properties and mechanisms of the Mg(BH4)2–NaAlH4 system

Hydrogen storage properties and mechanisms of the combined Mg(BH₄)₂–NaAlH₄ system were investigated systematically. It was found that during ball milling, the Mg(BH₄)₂–xNaAlH₄ combination converted readily to the mixture of NaBH₄ and Mg(AlH₄)₂ with a metathesis reaction. The post-milled samples exhibited an apparent discrepancy in the hydrogen desorption behavior with respect to the pristine Mg(BH₄)₂ and NaAlH₄. Approximately 9.1 wt% of hydrogen was released from the Mg(BH₄)₂–2NaAlH₄ composite milled for 24 h with an onset temperature of 101 °C, which is lowered by 105 and 139 °C than that of NaAlH₄ and Mg(BH₄)₂, respectively. At initial heating stage, Mg(AlH₄)₂ decomposed first to produce MgH₂ and Al with hydrogen release. Further elevating operation temperatures gave rise to the reaction between MgH₂ and Al and the self-decomposition of MgH₂ to release more hydrogen and form the Al_0.9Mg_0.1 solid solution and Mg. Finally, NaBH₄ reacted with Mg and partial Al_0.9Mg_0.1 to liberate all of hydrogen and yield the resultant products of MgAlB₄, Al₃Mg₂ and Na. The dehydrogenated sample could take up ∼6.5 wt% of hydrogen at 400 °C and 100 atm of hydrogen pressure through a more complicated reaction process. The hydrogenated products consisted of NaBH₄, MgH₂ and Al, indicating that the presence of Mg(AlH₄)₂ is significantly favorable for reversible hydrogen storage in NaBH₄ at moderate temperature and hydrogen pressure.     

Catalytic effect of MgFe2O4 on the hydrogen storage properties of Na3AlH6–LiBH4 composite system

The effect of MgFe₂O₄ on the hydrogen storage properties of the composite Na₃AlH₆4LiBH₄ was studied for the first time, where it was found that MgFe₂O₄ addition decreased the onset desorption temperature of Na₃AlH₆4LiBH₄. Hydrogen (～9.5 wt%) was released in three stages and the dehydrogenation temperatures were reduced to 80 °C, 350 °C, and 430 °C for the first, second, and third stage, respectively. The absorption kinetics of Na₃AlH₆4LiBH₄ was also significantly improved due to the catalytic effect of MgFe₂O₄. Using Kissinger analysis, the apparent activation energies of decomposition of the Li₃AlH₆ and NaBH₄ stages in Na₃AlH₆4LiBH₄-10 wt% MgFe₂O₄ were calculated to be 72 and 141 kJ/mol, respectively. These values were considerably lower than the corresponding values for the undoped composite. X-ray diffraction analysis revealed the formation of new products such as MgO and Fe during the heating process. Our results suggest that MgFe₂O₄ enhanced the hydrogen storage properties of Na₃AlH₆4LiBH₄ through the formation of active species, such as MgO and Fe.     

The catalyst-free hydrolysis behaviors of NaBH4–NH3BH3 composites

NaBH₄–NH₃BH₃ composites were prepared by high-energy ball-milling processes for hydrogen generation through hydrolysis. After ball milling, there were no new phases found in the XRD patterns of NaBH₄–NH₃BH₃ composites. The experimental results demonstrate that when the molar ratios of NaBH₄–NH₃BH₃ composites range from 1:4 to 2:1, these composites can release above 90% hydrogen in 30 min at 70 °C. Comparing with neat NaBH₄ or NH₃BH₃, the hydrolysis properties of these composites are greatly enhanced. And the hydrolysis reaction mechanism is turned out to be more explicit as Na₂B₄O₅(OH)₄·8H₂O appears in the hydrolysis products. Since the preparation processes of these composites are simple and cost-effective and the hydrolysis of these composites achieves efficient hydrogen release, it is promising that this kind of composites can be applied in hydrogen generation.     

Study on the hydrogen storage properties and reaction mechanism of NaAlH4–MgH2–LiBH4 ternary-hydride system

In this paper, we report the hydrogen storage properties and reaction mechanism of NaAlH₄–MgH₂–LiBH₄ (1:1:1) ternary-hydride system prepared by ball milling. It was found that during ball milling, the NaAlH₄/MgH₂/LiBH₄ combination converted readily to the mixture of LiAlH₄/MgH₂/NaBH₄ and there is a mutual destabilization among the hydrides. Three major dehydrogenation steps were observed in the system, which corresponds to the decomposition of LiAlH₄, MgH₂, and NaBH₄, respectively. The onset dehydrogenation temperature of MgH₂ in this system is observed at around 275 °C, which is over 55 °C lower from that of as-milled MgH₂. Meanwhile, NaBH₄-relevant decomposition showed significant improvement, starts to release hydrogen at 370 °C, which is reduced by about 110 °C compared to the as-milled NaBH₄. The second and third steps decomposition enthalpy of the system were determined by differential scanning calorimetry measurements and the enthalpies were changed to be 61 and 100 kJ mol⁻¹ H₂ respectively, which are smaller than that of MgH₂ and NaBH₄ alone. From the Kissinger plot, the apparent activation energy, E_A, for the decomposition of MgH₂ and NaBH₄ in the composite was reduced to 96.85 and 111.74 kJ mol⁻¹ respectively. It is believed that the enhancement of the dehydrogenation properties was attributed to the formation of intermediate compounds, including Li–Mg, Mg–Al, and Mg–Al–B alloys, upon dehydrogenation, which change the thermodynamics of the reactions through altering the de/rehydrogenation pathway.     

Synthesis of magnetic Ag3PO4/Ag/NiFe2O4 composites towards super photocatalysis and magnetic separation

The synthesis of Ag₃PO₄/Ag was performed through in-situ deposition and photo-reduction processes with magnetic NiFe₂O₄ nanofibers towards enhanced photocatalysis performance and stability. NiFe₂O₄ inhibit the photoreduction of Ag₃PO₄ into Ag and resulted in high stability. The photocatalytic activity of Ag₃PO₄/Ag/NiFe₂O₄ samples was studied by methylene blue degrading under visible light irradiation. The Ag₃PO₄/Ag/NiFe₂O₄ photocatalyst with NiFe₂O₄ loading of 3% revealed good photocatalytic performance, high stability and quick degradation after 5 cycles. Photoluminescence spectra and photocurrent tests demonstrated that the formation of hetero-junction facilitated the separation of photo-generated carriers. The trapping experiments confirmed that h⁺ and ?OH were active species during the degradation process.     

H2 and CH4 oxidation on Gd0.2Ce0.8O1.9 infiltrated SrMoO3–yttria-stabilized zirconia anode for solid oxide fuel cells

Strontium molybdate (SrMoO₃) as an electronic conductor was incorporated with yttria-stabilized zirconia (YSZ) to form an anode scaffold for solid oxide fuel cells. Gd_0.2Ce_0.8O_1.9 (GDC) nanoparticles were introduced by wet impregnation to complete the Ni-free GDC infiltrated SrMoO₃–YSZ anode fabrication. The effects of SrMoO₃ on the electrode conductivity and GDC infiltration on the catalytic activity were examined. A pronounced performance improvement was observed both on wet H₂ and CH₄ oxidation for the 56 wt.% GDC infiltrated SrMoO₃–YSZ. In particular, the polarization resistance decreased from 8 Ω cm² to 0.5 Ω cm² under wet H₂ (3% H₂O) at 800 °C with the introduction of GDC. Under wet CH₄ at 900 °C, a maximum power density of 160 mW cm⁻² was obtained and no carbon deposition was observed on the anode. It was found that the addition of H₂O in the anode caused an increase of electrode ohmic resistance and a decrease of open circuit voltage. Redox cycling stability was investigated and only a slight drop in cell performance was observed after 5 cycles. These results suggest that GDC infiltrated SrMoO₃–YSZ is a promising anode material for solid oxide fuel cells.     

g-C3N4/TiO2可见光催化降解磺胺甲恶唑的研究

以TiO₂颗粒和三聚氰胺为原料,采用高温煅烧法制备g-C₃N₄/TiO₂复合光催化材料,研究其对仿生生态系统中磺胺类抗生素的去除效果。利用扫描电子显微镜（SEM）、X射线衍射仪(XRD)、傅里叶变换红外光谱仪（FTIR）、紫外可见分光光度计（UV-vis DRS）对g-C₃N₄/TiO₂进行表征,并研究在可见光条件下g-C₃N₄/TiO₂对溶液中磺胺甲恶唑（SMX）的光催化降解效果。结果表明,g-C₃N₄/TiO₂具有良好的光催化活性,在可见光照射下,当g-C₃N₄/TiO₂投加量为0.2 g·L^-1时,对初始质量浓度为200 μg·L^-1的SMX的去除率可达84.3%。在相同条件下,而g-C₃N₄和TiO₂只能分别去除21.0%和16.0%的SMX,同时在仿生系统中12.37 g·m^-2 g-C₃N₄/TiO₂可以去除95.35%的SMX。通过质谱分析推测,SMX可能的降解路径分别为S—N键断裂、C—N键断裂、S—C键断裂、SMX的羟基化和SMX上氨基的硝化反应,两种可能的中间产物分别为对氨基苯磺酰胺和3-氨基-5-甲基异恶唑。     

Superior low-temperature hydrogen release from the ball-milled NH3BH3–LiNH2–LiBH4 composite

In the present study, we employed a multi-component combination strategy to constitute an AB/LiNH₂/LiBH₄ composite system. Our study found that mechanically milling the AB/LiNH₂/LiBH₄ mixture in a 1:1:1 molar ratio resulted in the formation of LiNH₂BH₃ (LiAB) and new crystalline phase(s). A spectral study of the post-milled and the relevant samples suggests that the new phase(s) is likely ammoniate(s) with a formula of Li_2−x(NH₃)(NH₂BH₃)_1−x(BH₄) (0 < x < 1). The decomposition behaviors of the Li_2−x(NH₃)(NH₂BH₃)_1−x(BH₄)/xLiAB composite were examined using thermal analysis and volumetric method in a wide temperature range. It was found that the composite exhibited advantageous dehydrogenation properties over LiAB and LiAB·NH₃ at moderate temperatures. For example, it can release ∼7.1 wt% H₂ of purity at temperature as low as 60 °C, with both the dehydrogenation rate and extent far exceeding that of LiAB and LiAB·NH₃. A selectively deuterated composite sample has been prepared and examined to gain insight into the dehydrogenation mechanism of the Li_2−x(NH₃)(NH₂BH₃)_1−x(BH₄)/xLiAB composite. It was found that the LiBH₄ component does not participate in the dehydrogenation reaction at moderate temperatures, but plays a key role in strengthening the coordination of NH₃. This is believed to be a major mechanistic reason for the favorable dehydrogenation property of the composite at moderate temperatures.     

Improved hydrogen storage performance of MgH2–NaAlH4 composite by addition of TiF3

In a previous paper, it was demonstrated that a MgH₂–NaAlH₄ composite system had improved dehydrogenation performance compared with as-milled pure NaAlH₄ and pure MgH₂ alone. The purpose of the present study was to investigate the hydrogen storage properties of the MgH₂–NaAlH₄ composite in the presence of TiF₃. 10 wt.% TiF₃ was added to the MgH₂–NaAlH₄ mixture, and its catalytic effects were investigated. The reaction mechanism and the hydrogen storage properties were studied by X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry (DSC), temperature-programmed-desorption and isothermal sorption measurements. The DSC results show that MgH₂–NaAlH₄ composite milled with 10 wt.% TiF₃ had lower dehydrogenation temperatures, by 100, 73, 30, and 25 °C, respectively, for each step in the four-step dehydrogenation process compared to the neat MgH₂–NaAlH₄ composite. Kinetic desorption results show that the MgH₂–NaAlH₄–TiF₃ composite released about 2.4 wt.% hydrogen within 10 min at 300 °C, while the neat MgH₂–NaAlH₄ sample only released less than 1.0 wt.% hydrogen under the same conditions. From the Kissinger plot, the apparent activation energy, E_A, for the decomposition of MgH₂, NaMgH₃, and NaH in the MgH₂–NaAlH₄–TiF₃ composite was reduced to 71, 104, and 124 kJ/mol, respectively, compared with 148, 142, and 138 kJ/mol in the neat MgH₂–NaAlH₄ composite. The high catalytic activity of TiF₃ is associated with in situ formation of a microcrystalline intermetallic Ti–Al phase from TiF₃ and NaAlH₄ during ball milling or the dehydrogenation process. Once formed, the Ti–Al phase acts as a real catalyst in the MgH₂–NaAlH₄–TiF₃ composite system.     

Raman spectroscopic observation of dehydrogenation in ball-milled LiNH2–LiBH4–MgH2 nanoparticles

In situ Raman spectroscopy was used to monitor the dehydrogenation of ball-milled mixtures of LiNH₂–LiBH₄–MgH₂ nanoparticles. The as-milled powders were found to contain a mixture of Li₄BN₃H₁₀ and Mg(NH₂)₂, with no evidence of residual LiNH₂ or LiBH₄. It was observed that the dehydrogenation of both of Li₄BN₃H₁₀ and Mg(NH₂)₂ begins at 353 K. The Mg(NH₂)₂ was completely consumed by 415 K, while Li₄BN₃H₁₀ persisted and continued to release hydrogen up to 453 K. At higher temperatures Li₄BN₃H₁₀ melts and reacts with MgH₂ to form Li₂Mg(NH)₂ and hydrogen gas. Cycling studies of the ball-milled mixture at 423 K and 8 MPa (80 bar) found that during rehydrogenation of Li₄BN₃H₁₀ Raman spectral modes reappear, indicating partial reversal of the Li₄BN₃H₁₀ to Li₂Mg(NH)₂ transformation.     

The hydrogen storage properties and reaction mechanism of the NaAlH4 + Ca(BH4)2 composite system

The hydrogen storage properties and reaction mechanism of the combined NaAlH₄ + Ca(BH₄)₂ (2:1) composite system was investigated in the present study. Analyses show that after 6 h of milling, the NaAlH₄ + Ca(BH₄)₂ combination fully converted to the mixture of Ca(AlH₄)₂ + NaBH₄, and a metathesis reaction occurred between the hydrides. Four major dehydrogenation stages were observed in the system, which corresponds to the decomposition of Ca(AlH₄)₂, CaAlH₅, CaH₂ and NaBH₄, respectively. The onset desorption temperature of the composite system is reduced to 125 °C, which is much lower than a unary component of NaAlH₄ and Ca(BH₄)₂. The de/rehydrogenation kinetics of the composite system had improve at a higher temperature. From the Kissinger plot, the apparent activation energies for the decomposition of CaAlH₅ and NaBH₄ in the composite system were reduced to 142.9 and 146.5 kJ/mol, respectively. It is believed that the formation of AlCa, AlB and CaB alloys during the dehydrogenation process is responsible for the distinct reduction in the onset desorption temperature and kinetics enhancement of the 2NaAlH₄ + Ca(BH₄)₂ composite system.     

Steam reforming of ethanol over Co3O4–Fe2O3 mixed oxides

Co₃O₄, Fe₂O₃ and a mixture of the two oxides Co–Fe (molar ratio of Co₃O₄/Fe₂O₃ = 0.67 and atomic ratio of Co/Fe = 1) were prepared by the calcination of cobalt oxalate and/or iron oxalate salts at 500 °C for 2 h in static air using water as a solvent/dispersing agent. The catalysts were studied in the steam reforming of ethanol to investigate the effect of the partial substitution of Co₃O₄ with Fe₂O₃ on the catalytic behaviour. The reforming activity over Fe₂O₃, while initially high, underwent fast deactivation. In comparison, over the Co–Fe catalyst both the H₂ yield and stability were higher than that found over the pure Co₃O₄ or Fe₂O₃ catalysts. DRIFTS-MS studies under the reaction feed highlighted that the Co–Fe catalyst had increased amounts of adsorbed OH/water; similar to Fe₂O₃. Increasing the amount of reactive species (water/OH species) adsorbed on the Co–Fe catalyst surface is proposed to facilitate the steam reforming reaction rather than decomposition reactions reducing by-product formation and providing a higher H₂ yield.     

CO2 reforming of CH4 by combination of cold plasma jet and Ni/γ-Al2O3 catalyst

CO₂ reforming of CH₄ to synthesis gas was investigated by cold plasma jet (CPJ) only and combination of cold plasma jet with Ni/γ-Al₂O₃ catalyst at atmospheric pressure. The higher selectivity of H₂ and CO, and higher energy efficiency was obtained by this novel process. The optimum experimental conditions are: CH₄ = 3.33 Nl/min, CO₂ = 5.00 Nl/min, N₂ = 8.33 Nl/min, and the input power at 770 W. The results showed that, for the plasma only, the conversions of CH₄ and CO₂ were 46% and 34%, the selectivities of CO and H₂ were 85% and 78%, the energy efficiency was 2.9 mmol/kJ, respectively; for the combination of cold plasma jet with Ni/γ-Al₂O₃ catalyst, the conversions of CH₄ and CO₂ were increased by 14% and 6%, the yield of H₂ and CO increased by 18% and 11%, the energy efficiency reached at 3.7 mmol/kJ, respectively. And the catalyst hasn't accessorial heating. The CPJ method has the advantage of simple processing and is easy to be industrialized.     

Processing analysis of the ternary LiNH2–MgH2–LiBH4 system for hydrogen storage

In this article, we investigate the ternary LiNH₂–MgH₂–LiBH₄ hydrogen storage system by adopting various processing reaction pathways. The stoichiometric ratio of LiNH₂:MgH₂:LiBH₄ is kept constant with a 2:1:1 molar ratio. All samples are prepared using solid-state mechano-chemical synthesis with a constant rotational speed, but with varying milling duration. Furthermore, the order of addition of parent compounds as well as the crystallite size of MgH₂ are varied before milling. All samples are intimate mixtures of Li–B–N–H quaternary hydride phase with MgH₂, as evidenced by XRD and FTIR measurements. It is found that the samples with MgH₂ crystallite sizes of approximately 10 nm exhibit lower initial hydrogen release at a temperature of 150 °C. Furthermore, it is observed that the crystallite size of Li–B–N–H has a significant effect on the amount of hydrogen release with an optimum size of 28 nm. The as-synthesized hydrides exhibit two main hydrogen release temperatures, one around 160 °C and the other around 300 °C. The main hydrogen release temperature is reduced from 310 °C to 270 °C, while hydrogen is first reversibly released at temperatures as low as 150 °C with a total hydrogen capacity of ∼6 wt.%. Detailed thermal, capacity, structural and microstructural properties are discussed and correlated with the activation energies of these materials.     

Rh promoted and ZrO2/Al2O3 supported Ni/Co based catalysts: High activity for CO2 reforming,steam–CO2 reforming and oxy–CO2 reforming of CH4

Ni (2.5 wt%) and Co (2.5 wt%) supported over ZrO₂/Al₂O₃ were prepared by following a hydrolytic co-precipitation method. The synthesized catalysts were further promoted by Rh incorporation (0.01–1.00 wt%) and tested for their catalytic performance for dry CO₂ reforming, combined steam–CO₂ reforming and oxy–CO₂ reforming of methane for production of syngas. The catalysts were characterized by using N₂ physical adsorption, XRD, H₂–TPR, SEM, CO₂–TPD, NH₃–TPD, TEM and TGA. The results revealed that ZrO₂ phase was in crystalline form in the catalysts along with amorphous Al oxides. Ni and Co were confirmed to be in their respective spinel phases that were reducible to metallic form at 800 °C under H₂. Ni and Co were well dispersed with their nano-crystalline nature. The catalyst with 0.2% loading of Rh showed superior performance in the studied reactions for reforming of methane. This catalyst also showed good coke resistance ability for dry CO₂ reforming reaction with 3.8 wt% of carbon formation during the reaction as compared to 11.6 wt% carbon formation over the catalyst without Rh. The catalyst performance was stable throughout the reaction time for CH₄ conversions, irrespective of carbon formation with slight decline (～1%) in CO₂ conversion. For dry CO₂ reforming reaction, this catalyst showed good conversion for both CH₄ and CO₂ (67.6% and 71.8% respectively) with a H₂/CO ratio of 0.84, while for the Oxy-CO₂ reforming reaction, the activity was superior with CH₄ and CO₂ conversions (73.7% and 83.8% respectively) and H₂/CO ratio of 1.05.     

H2 and CO production over a stable Ni–MgO–Ce0.8Zr0.2O2 catalyst from CO2 reforming of CH4

Ni–Ce_0.8Zr_0.2O₂ and Ni–MgO–Ce_0.8Zr_0.2O₂ catalysts were investigated for H₂ production from CO₂ reforming of CH₄ reaction at a very high gas hourly space velocity of 480,000 h⁻¹. Ni–MgO–Ce_0.8Zr_0.2O₂ exhibited higher catalytic activity and stability (CH₄ conversion >95% at 800 °C for 200 h). The outstanding catalytic performance is mainly due to the basic nature of MgO and an intimate interaction between Ni and MgO.     

Ag/Al2O3(Li2O)/g-C3N4光催化乙醇制取环氧乙烷

本文制备了一系列Ag/Al₂O₃(Li₂O)/g-C₃N₄复合催化剂,考察了其可见光催化乙醇制取环氧乙烷的性能。Li₂O可调变Al₂O₃表面的酸性,从而降低了主要副产物乙醛的选择性。Ag/Al₂O₃(Li₂O) 在g-C₃N₄上的负载量对产物环氧乙烷的选择性有较大影响,当Ag/Al₂O₃(Li₂O) 负载量为5wt%时,乙醇具有较高的转换率,且环氧乙烷的选择性高达100%。     

Effective nanoconfinement of 2LiBH4–MgH2 via simply MgH2 premilling for reversible hydrogen storages

To improve nanoconfinement of LiBH₄ and MgH₂ in carbon aerogel scaffold (CAS), particle size reduction of MgH₂ by premilling technique before melt infiltration is proposed. MgH₂ is premilled for 5 h prior to milling with LiBH₄ and nanoconfinement in CAS to obtained nanoconfined 2LiBH₄–premilled MgH₂. Significant confinement of both LiBH₄ and MgH₂ in CAS, confirmed by SEM–EDS–mapping results, is achieved due to MgH₂ premilling. Due to effective nanoconfinement, enhancement of CAS:hydride composite weight ratio to 1:1, resulting in increase of hydrogen storage capacity, is possible. Nanoconfined 2LiBH₄–premilled MgH₂ reveals a single–step dehydrogenation at 345 °C with no B₂H₆ release, while dehydrogenation of nanoconfined sample without MgH₂ premilling performs in multiple steps at elevated temperatures (up to 430 °C) together with considerable amount of B₂H₆ release. Activation energy (E_A) for the main dehydrogenation of nanoconfined 2LiBH₄–premilled MgH₂ is considerably lower than those of LiBH₄ and MgH₂ of bulk 2LiBH₄–MgH₂ (ΔE_A = 31.9 and 55.8 kJ/mol with respect to LiBH₄ and MgH₂, respectively). Approximately twice faster dehydrogenation rate are accomplished after MgH₂ premilling. Three hydrogen release (T = 320 °C, P(H₂) = 3–4 bar) and uptake (T = 320–325 °C, P(H₂) = 84 bar) cycles of nanoconfined 2LiBH₄–premilled MgH₂ reveal up to 4.96 wt. % H₂ (10 wt. % H₂ with respect to hydride composite content), while the 1st desorption of nanoconfined sample without MgH₂ premilling gives 4.30 wt. % of combined B₂H₆ and H₂ gases. It should be remarked that not only kinetic improvement and B₂H₆ suppression are obtained by MgH₂ premilling, but also the lowest dehydrogenation temperature (T = 320 °C) among other modified 2LiBH₄–MgH₂ systems is acquired.     

Effects of MoS2 addition on the hydrogen storage properties of 2LiBH4–MgH2 systems

A 2LiBH₄–MgH₂–MoS₂ composite was prepared by solid-state ball milling, and the effects of MoS₂ as an additive on the hydrogen storage properties of 2LiBH₄–MgH₂ system together with the corresponding mechanism were investigated. As shown in the TG–DSC and MS results, with the addition of 20 wt.% of MoS₂, the onset dehydrogenation temperature is reduced to 206 °C, which is 113 °C lower than that of the pristine 2LiBH₄–MgH₂ system. Meanwhile, the total dehydrogenation amount can be increased from 9.26 wt.% to 10.47 wt.%, and no gas impurities such as B₂H₆ and H₂S are released. Furthermore, MoS₂ improves the dehydrogenation kinetics, and lowers the activation energy (E_a) 34.49 kJ mol⁻¹ of the dehydrogenation reaction between Mg and LiBH₄ to a value lower than that of the pristine 2LiBH₄–MgH₂ sample. According to the XRD test, Li₂S and MoB₂ are formed by the reaction between LiBH₄ and MoS₂, which act as catalysts and are responsible for the improved hydrogen storage properties of the 2LiBH₄–MgH₂ system.