Hydrogen-on-Demand Using Metallic Alloy Nanoparticles in Water

Abstract

Hydrogen production from water using Al particles could provide a renewable energy cycle. However, its practical application is hampered by the low reaction rate and poor yield. Here, large quantum molecular dynamics simulations involving up to 16,611 atoms show that orders-of-magnitude faster reactions with higher yields can be achieved by alloying Al particles with Li. A key nanostructural design is identified as the abundance of neighboring Lewis acid-base pairs, where water-dissociation and hydrogen-production require very small activation energies. These reactions are facilitated by charge pathways across Al atoms that collectively act as a "superanion" and a surprising autocatalytic behavior of bridging Li-O-Al products. Furthermore, dissolution of Li atoms into water produces a corrosive basic solution that inhibits the formation of a reaction-stopping oxide layer on the particle surface, thereby increasing the yield. These atomistic mechanisms not only explain recent experimental findings but also predict the scalability of this hydrogen-on-demand technology at industrial scales.

Meteorite Impact-Induced Rapid NH3 Production on Early Earth: Ab Initio Molecular Dynamics Simulation

“…In this situation, for example, adjacent two H 2 O molecules could share one H atom, and then release one H atom. The reason why H1 bonds to N1 is that the released extra H atoms induce Grotthuss-type proton hopping39. In addition, similar mechanism applies for the formation of H9-N3 bond at 0.295 ps in another example shown in Supplementary Fig.…”

Enhanced charge recombination due to surfaces and twin defects in GaAs nanostructures

“…[11][12][13][14][15] Here, electronic states are calculated 0021-8979/2015/117(5)/054307/8/$30.00 V C 2015 AIP Publishing LLC 117, 054307-1 using the projector-augmented-wave method, 23,24 which is an all-electron electronic-structure-calculation method within a frozen-core approximation. The generalized gradient approximation 25 is used for the exchange-correlation energy with nonlinear core corrections.…”

“…To answer these questions, we first perform quantum molecular dynamics (QMD) simulations, [11][12][13][14][15] which follow the trajectories of all atoms while computing interatomic forces from first-principles based density functional theory (DFT). 16,17 Simulation results reveal the existence of an intrinsic type-II (or staggered) heterostructure at the (110) GaAs surface.…”

Scalable Reactive Molecular Dynamics Simulations for Computational Synthesis

“…Despite remarkable progresses in O(N) DFT algorithms [4], the largest QMD simulations to date have been limited to N ~ 10 4 for the duration of τ = 10 -11 s [5]. Unfortunately, the spatiotemporal scales covered by QMD simulations are not sufficient for studying the synthesis of advanced materials, such as functional layered materials (LM), which have outstanding electronic, optical, magnetic and chemical properties.…”