Tuning Reconstruction Level of Precatalysts to Design Advanced Oxygen Evolution Electrocatalysts

Surface reconstruction engineering is an effective strategy to promote the catalytic activities of electrocatalysts, especially for water oxidation. Taking advantage of the physicochemical properties of precatalysts by manipulating their structural self-reconstruction levels provide a promising methodology for achieving suitable catalysts. In this review, we focus on recent advances in research related to the rational control of the process and level of surface transformation ultimately to design advanced oxygen evolution electrocatalysts. We start by discussing the original contributions to surface changes during electrochemical reactions and related factors that can influence the electrocatalytic properties of materials. We then present an overview of current developments and a summary of recently proposed strategies to boost electrochemical performance outcomes by the controlling structural self-reconstruction process. By conveying these insights, processes, general trends, and challenges, this review will further our understanding of surface reconstruction processes and facilitate the development of high-performance electrocatalysts beyond water oxidation.

Tribological behavior comparisons of high chromium stainless and mild steels against high-speed steel and ceramics at high temperatures

High-temperature tribology, which is often involved during hot metal forming, is controlled via oxidation on a rubbing surface. However, for high chromium stainless steel (ST), where oxidation is strongly inhibited, the effect of counterface materials on tribological behavior is yet to be elucidated. In this study, the effects of counterfaces on the tribological behavior of 253MA ST and mild steel (MS) are investigated via a ball-on-disc test at 900 °C using a 20 N load. The results reveal that high-speed steel (HSS) experiences severe abrasive wear with MS and causes severe sticking problems with ST. Si3N4 and SiC present substantially stronger abrasive wear resistance than HSS with MS, and the friction coefficients are dependent on the type of ceramic. Both ceramics can facilitate the establishment of a thick tribo-oxide layer (> 3 µm) on ST to prevent sticking; however, this is accompanied by severe pull-out and fracture wear. The effects of the counterface on the mechanical properties of the tribo-oxide layer, near-surface transformation, and the responses of the tribo-oxide layer to friction and wear are discussed. This study contributes to the understanding of interfacial tribological behaviors when different types of tools are used on MS and ST.

Non-Covalent Bonding Caught in Action: From Amorphous-to-Cocrystalline Molecular Thin Films

<p>We demonstrate the solvent-free amorphous-to-cocrystalline transformations of nanoscale molecular films. Exposing amorphous films to vapors of a haloarene results in the formation of a cocrystalline coating. This transformation proceeds by gradual strengthening of halogen-bonding interactions as a result of the crystallization process. The gas-solid diffusion mechanism involves formation of an amorphous metastable phase prior to crystallization of the films. <i>In-situ </i>optical microscopy shows mass transport during this process, which is confirmed by cross-section analysis of the final structures using focused ion beam (FIB) milling combined with scanning electron microscopy (SEM). Nanomechanical measurements support the role of rigidity of the amorphous films influences the crystallization process. This surface transformation results in molecular arrangements that are not readily obtained through other means. Whereas cocrystals grown in solution crystallize in a monoclinic centrosymmetric space group, whereas the on-surface halogen-bonded assembly crystallizes into a noncentrosymmetric material with a bulk second-order non-linear optical (NLO) response.<br></p>

Non-Covalent Bonding Caught in Action: From Amorphous-to-Cocrystalline Molecular Thin Films

<p>We demonstrate the solvent-free amorphous-to-cocrystalline transformations of nanoscale molecular films. Exposing amorphous films to vapors of a haloarene results in the formation of a cocrystalline coating. This transformation proceeds by gradual strengthening of halogen-bonding interactions as a result of the crystallization process. The gas-solid diffusion mechanism involves formation of an amorphous metastable phase prior to crystallization of the films. <i>In-situ </i>optical microscopy shows mass transport during this process, which is confirmed by cross-section analysis of the final structures using focused ion beam (FIB) milling combined with scanning electron microscopy (SEM). Nanomechanical measurements support the role of rigidity of the amorphous films influences the crystallization process. This surface transformation results in molecular arrangements that are not readily obtained through other means. Whereas cocrystals grown in solution crystallize in a monoclinic centrosymmetric space group, whereas the on-surface halogen-bonded assembly crystallizes into a noncentrosymmetric material with a bulk second-order non-linear optical (NLO) response.<br></p>

The Land Sparing, Water Surface Use Efficiency, and Water Surface Transformation of Floating Photovoltaic Solar Energy Installations

Floating photovoltaic solar energy installations (FPVs) represent a new type of water surface use, potentially sparing land needed for agriculture and conservation. However, standardized metrics for the land sparing and resource use efficiencies of FPVs are absent. These metrics are critical to understanding the environmental and ecological impacts that FPVs may potentially exhibit. Here, we compared techno-hydrological and spatial attributes of four FPVs spanning different climatic regimes. Next, we defined and quantified the land sparing and water surface use efficiency (WSUE) of each FPV. Lastly, we coined and calculated the water surface transformation (WST) using generation data at the world’s first FPV (Far Niente Winery, California). The four FPVs spare 59,555 m2 of land and have a mean land sparing ratio of 2.7:1 m2 compared to ground-mounted PVs. Mean direct and total capacity-based WSUE is 94.5 ± 20.1 SD Wm−2 and 35.2 ± 27.4 SD Wm−2, respectively. Direct and total generation-based WST at Far Niente is 9.3 and 13.4 m2 MWh−1 yr−1, respectively; 2.3 times less area than ground-mounted utility-scale PVs. Our results reveal diverse techno-hydrological and spatial attributes of FPVs, the capacity of FPVs to spare land, and the utility of WSUE and WST metrics.