Mechanistic Insights into Hydration of Solid Oxides

Some of the solid oxide materials, used in solid oxide fuel and electrolysis cells, are known to conduct protons once they are hydrated. However, the mechanisms by which solid oxide materials get hydrated is not clear. By performing detailed density functional theory calculations, we investigate hydration of two typical solid oxides with a single-crystal structurea proton-conducting yttrium-doped strontium zirconate (SZY) and an oxide ion-conducting yttria-stabilized zirconia (YSZ). We suggest a four-step process to understand the hydration of solid oxideswater adsorption on the surface, proton migration from the surface to bulk, proton migration in the bulk, and oxide ion vacancy migration in the bulk. The hydroxide ion migration with a lower energy barrier, compared to the proton hopping mechanism, is proposed for the conduction of proton between the surface and subsurface of the perovskite oxide. Our analysis provides mechanistic insights into the hydration of single-crystal SZY and nonhydration of single-crystal YSZ. The study presented here not only explains the hydration of materials but also provides the importance of structural rearrangement when a proton is incorporated into the bulk of the solid oxide material

MOESM1 of Methane potentials of wastewater generated from hydrothermal liquefaction of rice straw: focusing on the wastewater characteristics and microbial community compositions

Additional file 1: Table S1. Characteristics of rice straw and the following line is standard error of each value; Table S2. Number of the high-quality sequences; Figure S1. COD, TOC and pH values of HTLWW samples under different HTL conditions; Figure S2. Comparison of methane production potentials of samples 200 °C–0.5 h, 260 °C–0.5 h and 200 °C–4 h

Doping-Induced Tunable Wettability and Adhesion of Graphene

We report that substrate doping-induced charge carrier density modulation leads to the tunable wettability and adhesion of graphene. Graphene’s water contact angle changes by as much as 13° as a result of a 300 meV change in doping level. Upon either n- or p-type doping with subsurface polyelectrolytes, graphene exhibits increased hydrophilicity. Adhesion force measurements using a hydrophobic self-assembled monolayer-coated atomic force microscopy probe reveal enhanced attraction toward undoped graphene, consistent with wettability modulation. This doping-induced wettability modulation is also achieved via a lateral metal–graphene heterojunction or subsurface metal doping. Combined first-principles and atomistic calculations show that doping modulates the binding energy between water and graphene and thus increases its hydrophilicity. Our study suggests for the first time that the doping-induced modulation of the charge carrier density in graphene influences its wettability and adhesion. This opens up unique and new opportunities for the tunable wettability and adhesion of graphene for advanced coating materials and transducers