Pil J. Yoo

Abstract Electroreduction of small molecules such as H 2 O, CO 2 , and N 2 for producing clean fuels or valuable chemicals provides a sustainable approach to meet the increasing global energy demands and to alleviate the concern on climate change resulting from fossil fuel consumption. On the path to implement this purpose, however, several scientific hurdles remain, one of which is the low energy efficiency due to the sluggish kinetics of the paired oxygen evolution reaction (OER). In response,

Physically self-assembled microstructures can be realized by utilizing the stress relief process in buckling that usually leads to the formation of random wrinkles. This physical self-assembly occurs when the wrinkle formation is guided by a periodic pattern on an elastomeric mold that is simply placed on the surface of a bilayer of metal on polymer, which is then heated above its glass-transition temperature (see Figure and inside cover).

With growing interest in the photocatalytic performance of TiO2-graphene composite systems, the ternary phase of TiO2, graphene, and Ag is expected to exhibit improved photocatalytic characteristics because of the improved recombination rate of photogenerated charge carriers and potential contribution of the generation of localized surface plasmon resonance at Ag sites on a surface of the TiO2-graphene binary matrix. In this work, Ag-TiO2-reduced graphene oxide ternary nanocomposites were succes

The design and synthesis of cellular structured materials are of both scientific and technological importance since they can impart remarkably improved material properties such as low density, high mechanical strength, and adjustable surface functionality compared to their bulk counterparts. Although reducing the density of porous structures would generally result in reductions in mechanical properties, this challenge can be addressed by introducing a structural hierarchy and using mechanically

We report the full spectrum of the evolution of the wrinkle pattern formation in a thin bilayer film of an elastic metal on a viscoelastic polymer. Although the origin is different, the transition of an initial islandlike pattern to a labyrinthine structure without any change in the wavelength (q approximately t(0)) and the overall evolutionary process is strikingly similar to that in the spinodal system but the process is robust and takes place on a long time scale (about 10 days). The change i

MXene-supported CoP and Co₇Se₈ catalysts showed enhanced water-splitting activity. The oxidation process of the anion components (P and Se) of the hybrid catalysts, under OER conditions, significantly influenced the activity and stability.

Modulus-tunable ultraviolet (UV) curing molds allow not only physical patterning of imprinting but also chemical patterning of microcontact printing. The mechanical properties of the mold can be tailored by the chain length of an acrylate modulator in the cross-linking reaction. This tunability can be utilized to obtain a proper balance that is needed for a given patterning technique between the rigidity requirement (tensile modulus = 320 MPa) of a mold for patterning a fine structure and the fl

Because of the salient impact on the performance of oxygen evolution reaction (OER), the surface dynamics of precatalysts accompanying the surface oxidation and dissolution of catalytic components demands immense research attention. Accordingly, the change in the structural integrity under high current density generally results in inconsistent OER performances. To address this challenge, here, we present the intricate design of precatalysts, strategically followed by reconstruction treatment in

Exploring new single, active photocatalysts for solar-water splitting is highly desirable to expedite current research on solar-chemical energy conversion. In particular, Z-scheme-based composites (ZBCs) have attracted extensive attention due to their unique charge transfer pathway, broader redox range, and stronger redox power compared to conventional heterostructures. In the present report, we have for the first time explored Cu₃P, a new, single photocatalyst for solar-water splitti

The phenomenon of interdiffusion of polyelectrolytes during electrostatic layer-by-layer assembly has been extensively investigated in the past few years owing to the intriguing scientific questions that it poses and the technological impact of interdiffusion on the promising area of electrostatic assembly processes. In particular, interdiffusion can greatly affect the final morphology and structure of the desired thin films, including the efficacy and function of thin film devices created using

We report the critical effects the deformational stress from the elastic nature of a confined polymer layer has during the relaxation process on the buckling of thin metal-polymer bilayer systems (less than 100 nm) even above the temperature at which the polymer is in the liquid flow region. In contrast with what is generally believed, the dispersion force does not play a significant role in the buckling. We also find that the final wrinkled waves take on the shape of wormlike islands. The coars

Three types of wrinkling are found to occur in the wrinkling of a bilayer of metal and polymer on a substrate. Each type has its own unique characteristics in terms of the wrinkle growth and strain behavior. While the characteristics can be grouped into three types, five distinct wrinkling regimes exist in terms of morphological change: evolutionary, constrained evolutionary, instantaneous, unconstrained, and spinodal wrinkling. The final morphologies for these wrinkling regimes are as follows:

We introduce a simple method to pattern electrostatic assemblies of viruses onto a polyelectrolyte multilayer. The increased mobility of weak polycation chains in the multilayer above a given thickness ensures the surface mobility of viruses required for spontaneous ordering of densely packed viruses atop polymeric patterns. To pattern the polyelectrolyte multilayer film, we employ a nonconventional patterning method known as solvent-assisted capillary molding for the first time on multilayer fi