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The most stable structures of Ge6M (M = Ge, Al) clusters and reactions of Ge6M clusters with a single water molecule are investigated theoretically by density functional theory (DFT) calculation and reaction pathway search method at the same level. The calculated binding energies of Ge7 and Ge6Al clusters show that the stabilities of two clusters are close. The most stable geometric structures and electronic structures of Ge6M@H2O complex and reaction pathways of Ge6M with a single H2O molecule are predicted. All geometric structures of reactants, intermediate products, final products and transition states are confirmed by frequency analysis. Our results show that both of Ge7 and Ge6Al clusters can completely release H2 from water after a three steps reaction and both reactions are endothermic. The calculated adsorption energies and energy barriers indicate that the dopant Al atom will improve the reactivity between Ge7 cluster and water. The NPA charge of Ge7O and Ge6AlO means both of them can react with another H2O molecule.

Nafion based proton exchange membrane (PEM) has long been used as conventional PEM in direct methanol fuel cell (DMFC) industry. However, the high cost of Nafion membrane and other drawbacks like high methanol crossover hinder the advancement of this industry. This study aims to develop a low cost membrane using sulfonated poly ether ether ketone (SPEEK) polymer. Silica and silicotungstic acid (SiWA) were incorporated into the membrane matrix using solution casting method. The optimum loading of the additives was tuned and it is discovered that the SPEEK membrane containing 10 wt% of silica and 5 wt% of SiWA has the best performance due to its high proton conductivity and moderately low methanol permeability. The performance of the membrane can further be enhanced by adding (3-aminopropyl)triethoxysilane (APTES) and carbonyldiimidazole (CDI) as coupling agents. Inclusion of APTES and CDI in SPEEK could not only improve the compatibility between organic SPEEK and inorganic additives, but also improve the homogeneity and dispersity of the additives. As a result, the resultant membrane with a better dimensional stability achieves high selectivity (10.60 × 104 S.s/cm3) up to 6.5 times more than pristine SPEEK membrane and 1.3 times higher than the commercial Nafion 117 membrane.

Monodisperse CuNi nanoparticles are conveniently prepared by the reduction of cupric acetate and nickel(II) acetylacetonate in the presence of oleylamine and borane tributylamine under inert gas atmosphere. It is found that among the CuNi system, Cu0.9Ni0.1 shows the best performance for catalyzing the dehydrogenation of ammonia borane. In total, 2.5 equiv. of hydrogen per ammonia borane is generated even at room temperature with an initial turnover frequency value of 212.3 mol of H2·(mol of Cu0.9Ni0.1)−1·h−1, which is comparable to the best Pd-based catalyst ever reported. The remarkable catalytic performance is attributed to the mild affiliation of oleylamine (OAm) to NPs, which not only stabilizes NPs to maintain good dispersion but also leaves sufficient surface active sites to facilitate the catalytic reaction. This low-cost and high catalytic performance catalyst makes it an exciting alternative towards the application of ammonia borane as a hydrogen storage material for fuel cell applications.

(2LiNH 2 + MgH 2 ) system is one of the most promising hydrogen storage materials due to its suitable operation temperature and high reversible hydrogen storage capacity. In applications, impurities such as CO, CO 2 , O 2 , N 2 and CH 4 are potential factors which may influence its performance. In the present work, H 2 containing 1 mol% N 2 , H 2 containing 1 mol% CH 4 , and H 2 containing 0.1 mol% O 2 are employed as the hydrogenation gas source, and respectively participates in the reaction to investigate the effect of N 2 , CH 4 and O 2 on the hydrogen sorption properties of (2LiNH 2 + MgH 2 ) system. The results indicate that when H 2 containing 1 mol% N 2 or H 2 containing 1 mol% CH 4 is employed as the hydrogen source for the (Mg(NH 2 ) 2 + 2LiH) system, the hydrogen desorption properties are unaffected. Also there is no change in the phase structure. But when H 2 containing 0.1 mol% O 2 is employed as the hydrogen source, two new stable phases, LiNH 2 and MgO are formed. The hydrogen capacity of the (Mg(NH 2 ) 2 + 2LiH) system gradually declines from about 5 wt.% to 4.41 wt.% after 7 cycles of hydrogenation and dehydrogenation, and it can't be restored to the initial level when use purified hydrogen again. Because the small part of (LiNH 2 + LiH) system can't release H 2 completely at 220 °C, leading to that a small part of (NH 2 ) − can't be converted to NH 2− successfully. The hydrogen desorption kinetics decreases and the dehydrogenation activation energy increases from 133.3 kJ/mol to 139.9 kJ/mol after 20 cycles of hydrogenation and dehydrogenation. The main reason is that the new products of LiNH 2 and MgO are formed on the surface of materials particles, preventing the substance transmission during the dehydrogenation process. After re-mechanically milling, the kinetics can be recovered to the initial level, but the hydrogen capacity is not fully recovered.

Preparation of hydride–graphite compacts serves as an effective method to improve the volumetric hydrogen storage density and the effective thermal conductivity for light complex hydrides. This paper presents the effects of compaction pressure and expanded natural graphite (ENG) content on the hydrogen storage properties of the Mg(NH 2 ) 2 –2LiH–0.07KOH compacts. The results show that the hydrogen desorption kinetics of the 1st sorption cycle decreases with the increase of the compaction pressure. However, the compacts exhibit the similar hydrogen desorption kinetics and capacities from the 2nd sorption cycles on regardless of the compaction pressure. The ENG addition significantly enhances the desorption kinetics because of the improvement of the heat transfer performance of the hydride. Furthermore, the volumetric hydrogen storage density of the hydride reaches 47 g/L after the compaction at 365 MPa, but it reduces by increasing the ENG content.

(2LiNH 2 + MgH 2 ) system is one of the most promising hydrogen storage materials due to its suitable operation temperature and high reversible hydrogen storage capacity. In studies and applications, impurities such as CO, CO 2 , O 2 , N 2 and CH 4 are potential factors which may influence its performance. In the present work, hydrogen containing 1 mol% CO is employed as the hydrogenation gas source, and directly participates in the reaction to investigate the effect of CO on the hydrogen sorption properties of (2LiNH 2 + MgH 2 ) system. The results indicate that the hydrogen capacity of the (Mg(NH 2 ) 2 + 2LiH) system declines from 5 wt.% to 3.45 wt.% after 6 cycles of hydrogenation and dehydrogenation, and can not restore to its initial level when use purified hydrogen again. The hydrogen desorption kinetics decreases obviously and the dehydrogenation activation energy increases from 133.35 kJ/mol to 153.35 kJ/mol. The main reason for these is that two new products Li 2 CN 2 and MgO appear after (2LiNH 2 + MgH 2 ) react with CO. They are formed on the surface of materials particles, which may not only cause a permanent loss of NH 2− , but also prevent the substance transmission during the reaction process. After re-mechanically milling, both kinetics and dehydrogenation activation energy can be recovered to the initial level.

Formic acid has been widely regarded as a safe and sustainable hydrogen storage material. Despite tremendous efforts, developing low-noble-metal-loading material with high activity for the dehydrogenation of formic acid remains a great challenge. Here, carbon supported highly homogeneous trimetallic NiAuPd alloy nanoparticles are prepared and employed as catalyst for the selective dehydrogenation of formic acid. Unexpectedly, at Ni molar contents as high as 40%, the resultant Ni 0.40 Au 0.15 Pd 0.45 /C exhibits high activity and 100% hydrogen selectivity for hydrogen generation from formic acid aqueous solution without any additives even at 298 K. Such a low-noble-metal-loading catalyst with high activity may greatly encourage the practical application of formic acid as a hydrogen storage material.

CeO x -induced amorphization of CoPt nanoparticles (NPs) is achieved by a facile co-reduction method using sodium borohydride (NaBH 4 ) as the reducing agent at room temperature (298 K) under ambient atmosphere. The investigation results indicate that CeO x plays a critical role in transferring the crystalline CoPt nanoalloy into the amorphous one. To our surprise, the resultant Co 0.65 Pt 0.30 (CeO x ) 0.05 NPs exhibit high catalytic kinetic performance with 72.1% hydrogen (H 2 ) selectivity for the H 2 generation from hydrous hydrazine (N 2 H 4 ) within only a few minute at 298 K. Although complete conversion is not achieved, but the initial turnover frequency value of 194.8 h −1 for the present amorphous catalyst is much higher than that of crystalline one. Moreover, such a highly rapid catalyst may greatly encourage the practical application of hydrous N 2 H 4 as a hydrogen storage material.

This paper investigates a facile and one-step synthesis of trimetallic magnetic Cu@FeNi core–shell nanoparticles, which are composed of crystalline Cu cores and amorphous FeNi shells, at room temperature under ambient atmosphere within 2 min. It is found that among the Cu@FeNi system, Cu 0.4 @Fe 0.1 Ni 0.5 shows the best synergistic performance for catalyzing the hydrolytic dehydrogenation of ammonia borane with the activation energy of 32.9 kJ/mol, being lower than most of the reported data, and the catalytic activity of Cu 0.4 @Fe 0.1 Ni 0.5 is much better than its monometallic, bimetallic and trimetallic counterparts whether in states of pure metals, alloys or physical mixtures. Further, the present catalyst has a good recycle stability with an easy magnetic separation method.

An amorphous nickel catalyst stabilized by poly(N-vinyl-2-pyrrolidone) (PVP) was synthesized by reduction in an aqueous NaBH4/NH3BH3 solution. Both the bare nickel catalyst and the PVP stabilized nickel catalyst contain grains with an amorphous structure after the reduction. The PVP stabilized nickel catalyst maintains high activity for hydrolysis of NH3BH3 to generate a stoichiometric amount of hydrogen with the cycle number up to 5, while the reaction rate in the presence of the bare nickel catalyst decreases with cycle number. After five cycles, the PVP stabilized nickel catalyst maintains the amorphous structure, while the agglomeration of nickel in the bare nickel catalyst is observed. The results indicate that PVP prevents agglomeration and crystallization of nickel nanoparticles, leading to higher durability than the bare nickel catalyst.

Boron- and nitrogen-based chemical hydrides are expected to be potential hydrogen carriers for PEM fuel cells because of their high hydrogen contents. Significant efforts have been devoted to decrease their dehydrogenation and hydrogenation temperatures and enhance the reaction kinetics. This article presents an overview of the boron- and nitrogen-based compounds as hydrogen storage materials.

The electrochemical behavior of ammonia borane on an Au electrode in the absence and presence of thiourea (TU) was detailedly investigated by cyclic voltammetry (CV). In the absence of TU, the feature of the CV is fairly complex affected by both the hydrolysis and the direct oxidation of ammonia borane. With the aid of TU, known as an effective inhibitor for the formation and recombination of adsorbed H radicals associated with ammonia borane hydrolysis, the two peaks at 414 and 0 mV may be attributed to direct electrooxidation of ammonia borane at Au electrode. These two peaks are particularly important for the practical direct ammonia borane fuel cell (DABFC). Additionally, the Tafel slope (b ¼ 0.15 V) and charge transfer coefficient (a ¼ 0.604) were obtained as well as number of electrons exchanged (n ¼ 2) in the ammonia borane oxidation at the Au/solution interface in the presence of TU.