Tuning the work function of graphite nanoparticles edge termination.

Graphite nanoparticles are important in energy materials applications such as lithium-ion batteries (LIBs), supercapacitors and as catalyst supports. Tuning the work function of the nanoparticles allows local control of lithiation behaviour in LIBs, and the potential of zero charge of electrocatalysts and supercapacitors. Using large scale density functional theory (DFT) calculations, we find that the surface termination of multilayer graphene nanoparticles can substantially modify the work function.

An Electronic Structure Investigation of PEDOT with AlCl Anions-A Promising Redox Combination for Energy Storage Applications.

In this work, we use density functional theory to investigate the electronic structure of poly(3,4-ethylenedioxythiophene) (PEDOT) oligomers with co-located AlCl anions, a promising combination for energy storage. The 1980s bipolaron model remains the dominant interpretation of the electronic structure of PEDOT despite recent theoretical progress that has provided new definitions of bipolarons and polarons. By considering the influence of oligomer length, oxidation or anion concentration and spin state, we find no evidence for many of the assertions of the 1980s bipolaron model and so further contribute to a new understanding.

Machine learning for data-driven design of high-safety lithium metal anode.

Here, we present a protocol for developing an inorganic-organic hybrid interphase layer using the self-assembled monolayers technique to enhance the surface of the lithium metal anode. We describe steps for extracting organic molecules from open-sourced databases and calculating their microscopic properties. We then detail procedures for developing a machine learning model for predicting the ionic diffusion barrier and preparing the inputs for prediction.

Recent advances in developing multiscale descriptor approach for the design of oxygen redox electrocatalysts.

Oxygen redox electrocatalysis is the crucial electrode reaction among new-era energy sources. The prerequisite to rationally design an ideal electrocatalyst is accurately identifying the structure-activity relationship based on the so-called descriptors which link the catalytic performance with structural properties. However, the quick discovery of those descriptors remains challenging.

Twisting Dynamics of Large Lattice-Mismatch van der Waals Heterostructures.

van der Waals (vdW) homo/heterostructures are ideal systems for studying interfacial tribological properties such as structural superlubricity. Previous studies concentrated on the mechanism of translational motion in vdW interfaces. However, detailed mechanisms and general properties of the rotational motion are barely explored.

Design Guidelines for Two-Dimensional Transition Metal Dichalcogenide Alloys.

Two-dimensional (2D) materials and transition metal dichalcogenides (TMD) in particular are at the forefront of nanotechnology. To tailor their properties for engineering applications, alloying strategies-used successfully for bulk metals in the last century-need to be extended to this novel class of materials. Here we present a systematic analysis of the phase behavior of substitutional 2D alloys in the TMD family on both the metal and the chalcogenide site.

UItra-low friction and edge-pinning effect in large-lattice-mismatch van der Waals heterostructures.

Two-dimensional heterostructures are excellent platforms to realize twist-angle-independent ultra-low friction due to their weak interlayer van der Waals interactions and natural lattice mismatch. However, for finite-size interfaces, the effect of domain edges on the friction process remains unclear. Here we report the superlubricity phenomenon and the edge-pinning effect at MoS/graphite and MoS/hexagonal boron nitride van der Waals heterostructure interfaces.

Electrochemistry from first-principles in the grand canonical ensemble.

Progress in electrochemical technologies, such as automotive batteries, supercapacitors, and fuel cells, depends greatly on developing improved charged interfaces between electrodes and electrolytes. The rational development of such interfaces can benefit from the atomistic understanding of the materials involved by first-principles quantum mechanical simulations with Density Functional Theory (DFT). However, such simulations are typically performed on the electrode surface in the absence of its electrolyte environment and at constant charge.

Electronic structure calculations in electrolyte solutions: Methods for neutralization of extended charged interfaces.

Density functional theory (DFT) is often used for simulating extended materials such as infinite crystals or surfaces, under periodic boundary conditions (PBCs). In such calculations, when the simulation cell has non-zero charge, electrical neutrality has to be imposed, and this is often done via a uniform background charge of opposite sign ("jellium"). This artificial neutralization does not occur in reality, where a different mechanism is followed as in the example of a charged electrode in electrolyte solution, where the surrounding electrolyte screens the local charge at the interface.

Controllable Heteroatom Doping Effects of CrCoP Nanoparticles: a Robust Electrocatalyst for Overall Water Splitting in Alkaline Solutions.

The effect of doping Cr on the electrocatalytic activity of CoP supported on carbon black (CrCoP/CB) for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline solution was investigated. A beneficial improvement in the performance of CoP toward HER and OER was discovered. For the HER at -200 mV overpotential, the turnover frequency (TOF) increases almost 6-fold from 0.

Exploring the Stability of Twisted van der Waals Heterostructures.

Recent research showed that the rotational degree of freedom in stacking 2D materials yields great changes in the electronic properties. Here, we focus on an often overlooked question: are twisted geometries stable and what defines their rotational energy landscape? Our simulations show how epitaxy theory breaks down in these systems, and we explain the observed behavior in terms of an interplay between flexural phonons and the interlayer coupling, governed by the moiré superlattice. Our argument, applied to the well-studied MoS/graphene system, rationalizes experimental results and could serve as guidance to design twistronic devices.

A quick and versatile one step metal-organic chemical deposition method for supported Pt and Pt-alloy catalysts.

A simple, modified Metal-Organic Chemical Deposition (MOCD) method for Pt, PtRu and PtCo nanoparticle deposition onto a variety of support materials, including C, SiC, BC, LaB, TiB, TiN and a ceramic/carbon nanofiber, is described. Pt deposition using Pt(acac) as a precursor is shown to occur a mixed solid/liquid/vapour precursor phase which results in a high Pt yield of 90-92% on the support material. Pt and Pt alloy nanoparticles range 1.

Non-equilibrium crystallization pathways of manganese oxides in aqueous solution.

Aqueous precipitation of transition metal oxides often proceeds through non-equilibrium phases, whose appearance cannot be anticipated from traditional phase diagrams. Without a precise understanding of which metastable phases form, or their lifetimes, targeted synthesis of specific metal oxides can become a trial-and-error process. Here, we construct a theoretical framework to reveal the nanoscale and metastable energy landscapes of Pourbaix (E-pH) diagrams, providing quantitative insights into the size-dependent thermodynamics of metastable oxide nucleation and growth in water.

Electronic metal-support interaction enhanced oxygen reduction activity and stability of boron carbide supported platinum.

Catalysing the reduction of oxygen in acidic media is a standing challenge. Although activity of platinum, the most active metal, can be substantially improved by alloying, alloy stability remains a concern. Here we report that platinum nanoparticles supported on graphite-rich boron carbide show a 50-100% increase in activity in acidic media and improved cycle stability compared to commercial carbon supported platinum nanoparticles.

Mechano-electrochemistry effects due to deformation of copper oxide films.

In an attempt to elucidate the relationship and underlying processes of metal oxidation under stress, we combined the electrochemical characterisation with Density-Functional-Theory (DFT) calculations to interrogate the (100) surface of copper. The oxidised (100) surface shows a missing-row reconstruction, which is believed to be driven by surface stress. Hence, additional mechanical stimuli might have a significant impact on the onset of Cu oxidation.

Electrocatalytic performance of fuel cell reactions at low catalyst loading and high mass transport.

An alternative approach to the rotating disk electrode (RDE) for characterising fuel cell electrocatalysts is presented. The approach combines high mass transport with a flat, uniform, and homogeneous catalyst deposition process, well suited for studying intrinsic catalyst properties at realistic operating conditions of a polymer electrolyte fuel cell (PEFC). Uniform catalyst layers were produced with loadings as low as 0.