Jong Min Kim

The multiple measurement vector (MMV) problem addresses the identification of unknown input vectors that share common sparse support. Even though MMV problems have been traditionally addressed within the context of sensor array signal processing, the recent trend is to apply compressive sensing (CS) due to its capability to estimate sparse support even with an insufficient number of snapshots, in which case classical array signal processing fails. However, CS guarantees the accurate recovery in

Unsupported Pt electrocatalysts demonstrate excellent electrochemical stability when used in polymer electrolyte membrane fuel cells; however, their extreme thinness and low porosity result in insufficient surface area and high mass transfer resistance. Here, we introduce three-dimensionally (3D) customized, multiscale Pt nanoarchitectures (PtNAs) composed of dense and narrow (for sufficient active sites) and sparse (for improved mass transfer) nanoscale building blocks. The 3D-multiscale PtNA f

The directed self‐assembly (DSA) of block copolymers (BCPs) has been suggested as a promising nanofabrication solution. However, further improvements of both the pattern quality and manufacturability remain as critical challenges. Although the use of BCPs with a high Flory‐Huggins interaction parameter ( χ ) has been suggested as a potential solution, this practical self‐assembly route has yet to be developed due to their extremely slow self‐assembly kinetics. In this study, it is reported that

Polymer electrolyte membrane unitized regenerative fuel cells (PEM-URFCs) require bifunctional porous transport layers (PTLs) to play contradictory roles in a single unitized system: hydrophobicity for water drainage in the fuel cell (FC) mode and hydrophilicity for water supplement in the electrolysis cell (EC) mode. Here, we report a high-performance amphiphilic Ti PTL suitable for both FC and EC modes, thanks to alternating hydrophobic and hydrophilic channels. To fabricate the amphiphilic PT

A new direction for developing electrocatalysts for hydrogen fuel cell systems has emerged, based on the fabrication of 3D architectures. These new architectures include extended Pt surface building blocks, the strategic use of void spaces, and deliberate network connectivity along with tortuosity, as design components. Various strategies for synthesis now enable the functional and structural engineering of these electrocatalysts with appropriate electronic, ionic, and electrochemical features.

A sulfuric acid-impregnated porous organic polymer exhibited superprotonic conductivity of 2.35 × 10⁻¹ S cm⁻¹ and its mixed matrix membrane showed activation energy of 0.039 eV.

Directed self-assembly (DSA) of block copolymers (BCPs) with a high Flory–Huggins interaction parameter (χ) provides advantages of pattern size reduction below 10 nm and improved pattern quality. Despite theoretical predictions, however, the questions of whether BCPs with a much higher χ than conventional high-χ BCPs can further improve the line edge roughness (LER) and how to overcome their extremely slow self-assembly kinetics remain unanswered. Here, we report the synthesis and assembly of po

Hydrogen peroxide (H₂O₂) electrosynthesis via the 2e^- oxygen reduction reaction (ORR) is considered as a cost-effective and safe alternative to the energy-intensive anthraquinone process. However, in more practical environments, namely, the use of neutral media and air-fed cathode environments, slow ORR kinetics and insufficient oxygen supply pose significant challenges to efficient H₂O₂ production at high current densities. In this work, me

Abstract The exploitation of state‐of‐the‐art Pt/C electrocatalysts for polymer electrolyte membrane fuel cells (PEMFCs) is mostly limited, due to high Pt loading and durability issues caused by electrochemical instability of the carbon support in high potential regimes. In this study, the authors report that high‐compressive 3D Pt nanostructured thin films can considerably increase the catalytic activity and electrochemical durability of electrocatalysts under PEMFC device operating conditions.

Abstract Atomically dispersed single‐atom catalysts (SACs) on carbon supports show great promise for H 2 O 2 electrosynthesis, but conventional wet chemistry methods using particulate carbon blacks in powder form have limited their potential as two‐electron (2e − ) oxygen reduction reaction (ORR) catalysts. Here, we demonstrate high‐performance Co SACs supported on a free‐standing aligned carbon nanofiber (CNF) using electrospinning and arc plasma deposition (APD). Based on the surface oxidation

The dissolution of Ir-oxide-based catalysts remains a roadblock in the development of durable electrocatalytic oxygen evolution reaction (OER) catalysts. Both the activity and stability of Ir-based catalysts are critically dependent on the ratio of stable rutile IrO2 and unstable amorphous Ir oxide (a-IrOx), as well as the spatial relationship between them. Here, we report that the domain size in hollow ternary Ir alloy nanocages can be fine-tuned by the introduction of dopant elements during th

A higher-valent NiO catalyst, enriched with trivalent Ni (Ni 3+ ) and exposed {111} crystal facets, was developed to enhance selective two-electron oxygen reduction (2e – ORR) for electrochemical hydrogen peroxide (H 2 O 2 ) production, leading to highly efficient organic pollutant removal. The catalyst was synthesized via a precipitation method, incorporating crystal facet and cation vacancy engineering to expose active sites. It demonstrated 96 % selectivity and 59 A g −1 mass activity, attrib

Developing highly efficient Ir-based electrocatalysts for the oxygen evolution reaction (OER) has been an important agenda in spearheading the water splitting technology. In this study, the synthesis of IrCo nanocacti on CoxSy nanocages (ICS NCs) is demonstrated by utilizing CoO@CoxSy nanoparticles as reactive nanotemplates. In addition to the high catalytic activities with a low overpotential of 281 mV at 10 mA cm-2 and an outstanding mass activity of 1285 mA mgIr-1 at 1.53 V, the ICS NCs endur

The multiple measurement vector (MMV) problem addresses the identification of unknown input vectors that share common sparse support. The MMV problem has been traditionally addressed either by sensor array signal processing or compressive sensing. However, recent breakthroughs in this area such as compressive MUSIC (CS-MUSIC) or subspace-augumented MUSIC (SA-MUSIC) optimally combine the compressive sensing (CS) and array signal processing such that k - r supports are first found by CS and the re