Jeong Gyu Kim

Abstract Solar‐driven photo‐to‐chemical conversion is an interesting approach for energy harvesting and storage with high sustainability. To achieve high photo‐to‐chemical conversion efficiency, it is important to develop cost‐effective and stable catalysts with high activity. Metal oxides provide an interesting platform for the development of efficient catalysts owing to their abundance, high stability, and tunable band edges. Their performance highly depends on the rational design of heterostr

Graphene quantum dots (GQDs) have been considered as a novel material because their electronic and optoelectronic properties can be tuned by controlling the size and the functional groups of GQDs. Here we report the synthesis of reduction-controlled GQDs and their application to bulk heterojunction (BHJ) solar cells with enhanced power conversion efficiency (PCE). Three different types of GQDs--graphene oxide quantum dots (GOQDs), 5 h reduced GQDs, and 10 h reduced GQDs--were tested in BHJ solar

Tungsten trioxide (WO3) films with a mesoporous morphology, high transparency, and monoclinic phase crystallinity were prepared using polyethyleneglycol (PEG) as a surfactant and their photoelectrochemical properties were measured. By controlling the weight ratio of the tungsten precursor to PEG, a sphere-like WO3 nanoparticle film with high transparency can be synthesized. The photocurrent responses of the films under 1 sun solar light illumination were measured. Due to the high transparency of

Abstract A versatile use of a sulfur self‐doped biochar derived from Camellia japonica (camellia) flowers is demonstrated as a multifunctional catalyst for overall water splitting and a supercapacitor. The native sulfur content in the camellia flower facilitates in situ self‐doping of sulfur, which highly activates the camellia‐driven biochar (SA‐Came) as a multifunctional catalyst with the enhanced electron‐transfer ability and long‐term durability. For water splitting, an SA‐Came‐based electro

Abstract Plasmonic metal nanostructures have been extensively investigated to improve the performance of metal oxide photoanodes for photoelectrochemical (PEC) solar water splitting cells. Most of these studies have focused on the effects of those metal nanostructures on enhancing light absorption and enabling direct energy transfer via hot electrons. However, several recent studies have shown that plasmonic metal nanostructures can improve the PEC performance of metal oxide photoanodes via anot

Phosphorylation of the histone variant H2AX forms γ-H2AX that marks DNA double-strand break (DSB). Here, we generated the sequencing-based maps of H2AX and γ-H2AX positioning in resting and proliferating cells before and after ionizing irradiation. Genome-wide locations of possible endogenous and exogenous DSBs were identified based on γ-H2AX distribution in dividing cancer cells without irradiation and that in resting cells upon irradiation, respectively. γ-H2AX-enriched regions of endogenous o

The design of nonprecious bifunctional electrocatalysts with high activity and prolonged durability in a wide pH range is essential for the development of the highly efficient, cost-effective, and simplified overall water splitting systems. Here, we report core–shell structured MXene@carbon (MX@C) nanodot hybrids with high bifunctional activity, where N-doped carbon shells are grown in a heteroepitaxial manner strongly interacting with the MXene core. The resulting MX@C nanodot hybrids show enha

Abstract Ammonia is considered as an alternative fuel resource for a sustainable green future. The production of ammonia involves the electrochemical nitrogen reduction reaction (NRR), which has gained considerable attention due to its eco-friendly resources and nonharmful byproducts. Even with the manifold works on NRR, the technique has not reached the industrial scale because of the impediments of NRR electrocatalysts, and in addition, state-of-the-art electrocatalysts have not yet been disco

This review summarizes recent advances in synthesis strategies, structural engineering, and unique properties of transition metal nitrides, along with the critical discussion on electrode designs for supercapacitors to meet commercial standards.

Abstract To further increase the open‐circuit voltage ( V oc ) of perovskite solar cells (PSCs), many efforts have been devoted to doping the TiO 2 electron transport/selective layers by using metal dopants with higher electronegativity than Ti. However, those dopants can introduce undesired charge traps that hinder charge transport through TiO 2 , so the improvement in the V oc is often accompanied by an undesired photocurrent density–voltage ( J–V ) hysteresis problem. Herein, it is demonstrat

Abstract The development of an efficient pH‐universal hydrogen evolution reaction (HER) electrocatalyst is essential for practical hydrogen production. Here, an efficient and stable pH‐universal HER electrocatalyst composed of the strongly coupled 2D NiCo 2 S 4 and 2D ReS 2 nanosheets (NiCo 2 S 4 /ReS 2 ) is demonstrated. The NiCo 2 S 4 /ReS 2 2D–2D nanocomposite is directly grown on the surface of the carbon cloth substrate, which exhibits excellent HER performance with overpotentials of 85 and

Ammonia, as an efficient hydrogen carrier, is emerging as an alternative energy resource to replace fossil fuels in the carbon–neutral era. Hydrogen production by water electrolysis seeks a lower potential dependent anodic reaction to overcome its energy-inefficiency that originates from the high potential anodic oxygen evolution reaction (OER). In this work, nickel phosphide supported on nitrogen doped-carbon (Ni 2 P@N-C) was prepared by one-pot synthesis for the bifunctional activity of hydrog

Abstract Fiber‐shaped sensors are useful for the simple fabrication of textile‐based electronics, which have excellent wearability and conformal adaptability for ubiquitous healthcare systems. In the case of temperature monitoring using highly deformable textronics for diagnostics, the device operation can be hindered by strain‐induced interferences when various movements are performed. An intrinsic strain‐insensitive fiber‐type temperature sensor with compressed micro‐wrinkles is demonstrated.

Graphene quantum dots (GQDs), a newly emerging 0-dimensional graphene based material, have been widely exploited in optoelectronic devices due to their tunable optical and electronic properties depending on their functional groups. Moreover, the dispersibility of GQDs in common solvents depending on hydrophobicity or hydrophilicity can be controlled by chemical functionalization, which is particularly important for homogeneous incorporation into various polymer layers. Here we report that a surf