MgH2@Mg(BH4)2 Core-Shell-like Nanostructures: Synthesis, Hydrolysis Performance, and Promotion Mechanism.

The hydrolysis of hydrides, represented by MgH2, delivers substantial capacity and presents an appealing prospect for an on-site hydrogen supply. However, the sluggish hydrolysis kinetics and low hydrogen yield of MgH2 caused by the formation of a passivation Mg(OH)2 layer hinder its practical application. Herein, we present a dual strategy encompassing microstructural design and compounding, leading to the successful synthesis of a core-shell-like nanostructured MgH2@Mg(BH4)2 composite, which demonstrates excellent hydrolysis performance. Specifically, the optimal composite with a low Ea of 9.05 kJ mol-1 releases 2027.7 mL g-1 H2 in 60 min, and its hydrolysis rate escalates to 1356.7 mL g-1 min-1 H2 during the first minute at room temperature. The nanocoating Mg(BH4)2 plays a key role in enhancing the hydrolysis kinetics through the release of heat and the formation of local concentration of Mg2+ field after its hydrolysis. This work offers an innovative concept for the design of hydrolysis materials.

Breaking the Passivation: Sodium Borohydride Synthesis by Reacting Hydrated Borax with Aluminum.

A significant obstacle in the large-scale applications of sodium borohydride (NaBH4 ) for hydrogen storage is its high cost. Herein, we report a new method to synthesize NaBH4 by ball milling hydrated sodium tetraborate (Na2 B4 O7 ⋅ 10H2 O) with low-cost Al or Al88 Si12 , instead of Na, Mg or Ca. An effective strategy is developed to facilitate mass transfer during the reaction by introducing NaH to enable the formation of NaAlO2 instead of dense Al2 O3 on Al surface, and by using Si as a milling additive to prevent agglomeration and also break up passivation layers. Another advantage of this process is that hydrogen in Na2 B4 O7 ⋅ 10H2 O serves as a hydrogen source for NaBH4 generation. Considering the low cost of the starting materials and simplicity in operation, our studies demonstrate the potential of producing NaBH4 in a more economical way than the commercial process.

Closing the Loop for Hydrogen Storage: Facile Regeneration of NaBH4 from its Hydrolytic Product.

Sodium borohydride (NaBH4 ) is among the most studied hydrogen storage materials because it is able to deliver high-purity H2 at room temperature with controllable kinetics via hydrolysis; however, its regeneration from the hydrolytic product has been challenging. Now, a facile method is reported to regenerate NaBH4 with high yield and low costs. The hydrolytic product NaBO2 in aqueous solution reacts with CO2 , forming Na2 B4 O7 ⋅10 H2 O and Na2 CO3 , both of which are ball-milled with Mg under ambient conditions to form NaBH4 in high yield (close to 80 %). Compared with previous studies, this approach avoids expensive reducing agents such as MgH2 , bypasses the energy-intensive dehydration procedure to remove water from Na2 B4 O7 ⋅10 H2 O, and does not require high-pressure H2 gas, therefore leading to much reduced costs. This method is expected to effectively close the loop of NaBH4 regeneration and hydrolysis, enabling a wide deployment of NaBH4 for hydrogen storage.

A novel andrographolide derivative AL-1 exerts its cytotoxicity on K562 cells through a ROS-dependent mechanism.

Andrographolide-lipoic acid conjugate (AL-1) is a new in-house synthesized chemical entity, which was derived by covalently linking andrographolide with lipoic acid. However, its anti-cancer effect and cytotoxic mechanism remains unknown. In this study, we found that AL-1 could significantly inhibit cell viability of human leukemia K562 cells by inducing G2/M arrest and apoptosis in a dose-dependent manner. Thirty-one AL-1-regulated protein alterations were identified by proteomics analysis. Gene ontology and ingenuity pathway analysis revealed that a cluster of proteins of oxidative redox state and apoptotic cell death-related proteins, such as PRDX2, PRDX3, PRDX6, TXNRD1, and GLRX3, were regulated by AL-1. Functional studies confirmed that AL-1 induced apoptosis of K562 cells through a ROS-dependent mechanism, and anti-oxidant, N-acetyl-L-cysteine, could completely block AL-1-induced cytotoxicity, implicating that ROS generation played a vital role in AL-1 cytotoxicity. Accumulated ROS resulted in oxidative DNA damage and subsequent G2/M arrest and mitochondrial-mediated apoptosis. The current work reveals that a novel andrographolide derivative AL-1 exerts its anticancer cytotoxicity through a ROS-dependent DNA damage and mitochondrial-mediated apoptosis mechanism.

Alloying Pt into Ni partially amorphous for promoted alkaline hydrogen production.

Aiming at the sluggish water dissociation step in alkaline hydrogen evolution reaction (HER), the platinum-nickel alloy material (PtNi10/C) featuring unique crystalline/amorphous structure supported on carbon black is deliberately designed and fabricated via a reversely rapid co-precipitation and mild thermal reduction strategy. Electrochemical results show that only 66 mV of overpotential is needed for PtNi10/C to drive a current density of 10 mA cm-2 at a lower platinum loading (8.3 µgPt cm-2 geo), which is much lower than that of other catalysts with a single metal source(S-Ni/C and S-Pt/C) and even the commercial Pt/C catalyst (20 wt%). The target catalyst also exhibits smaller tafel slope value (16.73 mV dec-1) and electrochemical impedance value, enabling a fast kinetics rate for water dissociation. Partial crystallization facilitates moderate adsorption of intermediates, while the high-valence Ni(II) and Pt(II) species serve as pivotal driving force for the kinetic dissociation of water. The unique microstructure of PtNi10/C shows a remarkable advantage toward HER in alkaline but acidic medium. In addition, other transition metal-based catalysts following the similar protocol are also fabricated and present varying degrees of HER performance. Hence, the facile and rapid co-precipitation/thermal reduction strategy proposed in this study provides some guidelines for designing high-efficiency alkaline HER catalysts.

In Situ Formation of Li2SiO3-Li-NaCl Interface on Si and Its Effect on Hydrogen Evolution.

Silicon has emerged as a competitive candidate for hydrolytic hydrogen production due to its high theoretical hydrogen yield, low cost, and on-demand availability. However, the hydrolysis reaction is extremely restrained by passivated SiO2, including the original one on the Si surface and the generated one during hydrolysis, and almost no hydrogen is produced in pure water. Herein, the original SiO2 surface has been effectively removed by milling micro-Si mixed with a small amount of Li metal and NaCl. An artificial soluble interface on Si has been established containing Li2SiO3, Li, and NaCl. Once micro-Si is placed into water, fresh Si surface can be exposed and a weak LiOH solution can be generated due to the fast dissolution of the interface layer, resulting in the rapid liberation of hydrogen gas. Accordingly, the modified micro-Si displays a significantly enhanced hydrogen production in pure water at 30 °C (1213 mL g-1 H2 within 3.0 h), which is 2.0 and 4.7 times higher than that observed for ball-milled Si and raw Si in 0.06 M LiOH solution, respectively. In addition, it also exhibited an outstanding operation compatibility for practical uses. This work has proposed a green, effective, and scalable strategy to promote hydrogen production from the hydrolysis of Si-based systems.