Incorporating finite temperature into materials by design for nonstoichiometric complex functional oxides

Enabled by dramatic advancements in computational capabilities and the tightening integration of theory and experiment, materials by design is rapidly becoming a leading paradigm in materials science. However, to most effectively accelerate the pace of materials design and discovery, first-principles calculations must move closer to experimental reality by taking into account the finite temperature effects corresponding to typical growth and/or operating conditions. Our work aims to develop capabilities to incorporate these finite temperature effects, which include atomic and magnetic disorder as well as the temperature dependence of the free energies of solids, into modern materials by design. Please click Additional Files below to see the full abstract

Solar thermochemical water splitting: Advances in materials and methods

Photoelectrochemical (PEC) water splitting, termed artificial photosynthesis, converts solar energy into hydrogen by harvesting a narrow spectrum of visible light using photovoltaics integrated with water-splitting electrocatalysts. While conceptually attractive, critical materials issues currently challenge technology development(1) and economic viability(2). Despite decades of active research, this approach has not been demonstrated at power levels above a few watts, or for more than a few days of operation. High-temperature solar thermochemical (STCH) water splitting is an alternative approach that converts solar energy into hydrogen by using the deceptively simple metal oxide-based thermochemical cycle presented in figure 1. The STCH process requires very high temperatures, achieved by collecting and concentrating solar energy. Unlike PEC, two-step metal oxide water-splitting cycles have been demonstrated at the 100kW scale(3), and continuous operation at even higher power levels is nearing pre-commercial demonstration (HYDROSOL-3D). Nonetheless STCH, like PEC, faces critical materials issues that must be addressed for this technology to achieve commercial success. Please click Additional Files below to see the full abstract

Fuel cells for electrochemical energy conversion

This short article provides an overview of fuel cell science and technology. This article is intended to act as a “primer” on fuel cells that one can use to begin a deeper investigation into this fascinating and promising technology. You will learn what fuel cell are, how they work, and what significant advantages and disadvantages they present

Fuel cells for electrochemical energy conversion

This short article provides an overview of fuel cell science and technology. This article is intended to act as a “primer” on fuel cells that one can use to begin a deeper investigation into this fascinating and promising technology. You will learn what fuel cell are, how they work, and what significant advantages and disadvantages they present

Electrochemical nanopatterning of Ag on solid-state ionic conductor RbAg[sub 4]I[sub 5] using atomic force microscopy

This report introduces an electrochemical nanopatterning technique performed under ambient conditions without involving a liquid vessel or probe-to-sample material transfer. Patterning is accomplished by solid-state electrochemical nanodeposition of Ag clusters on the surface of the solid ionic conductor RbAg4I5 using an atomic force microscopy probe. Application of negative voltage pulses on the probe relative to an Ag film counter electrode on an RbAg4I5 sample induces nanometer-sized Ag deposition on the ion conductor around the probe. The patterned Ag particles are 0.5-70 nm high and 20-700 nm in diameter. The effect of the amplitude and duration of bias voltage on the size and shape of deposited Ag clusters is also shown

An ab Initio Investigation of Proton Stability at BaZrO₃ Interfaces

Growing evidence that proton chemistry at the perovskite interface influences both proton conduction and catalyst activity has motivated more thorough examinations of proton behavior in these interfacial environments. This study utilizes density functional theory to examine proton stability at two prominent perovskite interfaces, the perovskite surface and perovskite–metal heterointerface, to identify opportunities to screen for perovskites with enhanced functionality. An analysis of the perovskite surface revealed fluctuations in proton stability as a function of the depth below the surface that leads to a barrier for proton mobility. The addition of a metal heterointerface can act to decrease this barrier by stabilizing protons near the surface. Finally, an electronic structure parameter, the p-band center, was identified as a useful predictor for proton adsorption energies in uniform perovskite structures, such as the perovskite surface and bulk, where detailed analyses reveal how local characteristics alter proton stability