Ji-Hyun Jang

We demonstrate the electronic structure engineering of iron antimony oxide (FeSbO ₄ , FSO) through heteroatom (Ti, Zn) doping and controlled oxygen vacancy formation for efficient electrocatalytic water splitting. Heteroatom incorporation elevates intrinsic electrical conductivity to accelerate charge transfer during the hydrogen evolution reaction (HER). Simultaneously, surface oxygen vacancies polarize the local electronic environment at Fe active sites, optimizing the adsorption energetics of oxygen‐containing intermediates to significantly boost oxygen evolution reaction (OER) performance. Ti‐doped FSO with moderate oxygen vacancies (TFSO ₃₀ ) achieves outstanding HER activity (300 mV at 50 mA/cm ² , Tafel slope of 119.38 mV/dec) due to vacancy‐induced electronic modulation. In contrast, higher oxygen vacancy concentration (TFSO ₆₀ ) drives superior OER performance (188 mV at 50 mA/cm ² , Tafel slope of 76.18 mV/dec) compared to IrO _2, primarily driven by charge redistribution and the generation of high‐valence active metal species. Density functional theory (DFT) calculations confirm that Ti doping and oxygen vacancies synergistically tune the electronic structure, promote charge transport, and lower reaction energy barriers to accelerate overall water‐splitting kinetics. Overall, this work highlights Ti‐doped FSO as an efficient, earth‐abundant electrocatalyst and provides useful insights into defect‐engineering strategies for catalytic energy conversion.

Owing to the chemical inertness of sp ³ C–C bonds in polymers, their activation under mild conditions poses a significant barrier to both plastic upcycling and graphitization. Here, we demonstrate a straightforward, solvent-free, one-step mechanochemical method that directly transforms various plastic waste into a critical material, graphite, under ambient conditions (T < 30°C). Facilitated by reactive metals such as Mg, this process requires only ~ 1.8% of the energy input used in traditional methods while delivering graphite with 92% sp ² carbon content, 80.4% reaction yield, and 15.3% C/O by mol. Both experimental data and theoretical calculations support the formation of carbides and their conversion into graphite, collectively revealing a carbide–graphite pathway that operates without heat, harsh solvents, extreme temperatures, or inert atmospheres, which are traditionally essential. Experiments further reveal that metals more reactive than carbon (Al, Mg, and Ca) can promote the breakdown and graphitization of a wide range of materials, including non-graphitizable, contaminated, and unsorted plastic waste, as well as biomass. This process dramatically reduces thermal energy demands, requiring less than 8% of the input used in pyrolysis and only 1.5% of that required for conventional graphitization. Beyond scalable and safer waste valorization, the resulting graphite functions effectively in Zn-ion batteries and pencils, and establishes a broadly applicable, ambient-temperature platform for carbon waste conversion, opening new directions in solid-state radical chemistry and circular carbon technologies.

Hybrid tin oxo clusters (SnOCs) have emerged as promising molecular resists for electron‐beam (EB) and extreme‐ultraviolet (EUV) lithography; however, their patterning mechanisms remain poorly understood due to the coupled effects of ligand electronics, cluster nuclearity, and electron‐induced fragmentation. In this study, we demonstrate a ligand‐mediated nuclearity tuning strategy that enables the selective synthesis of Sn ₆ ‐ and Sn ₃ ‐based clusters using electron‐donating carboxylate and electron‐withdrawing diphenylphosphinate ligands, respectively. Density functional theory calculations, electrostatic potential analysis, and bond dissociation energy evaluations show that ligand electronic properties dictate the preferred electron‐driven cleavage pathways. Sn ₆ clusters predominantly undergo Sn–alkyl bond scission, whereas aromatic phosphinate ligands in Sn ₃ clusters stabilize the framework and suppress ligand fragmentation. These trends are supported by XPS and TOF‐SIMS analyses, which reveal extensive alkyl cleavage and organic–inorganic crosslinking in Sn ₆ ‐based resists, in contrast to minimal ligand decomposition and a robust Sn─O─P network in Sn ₃ systems. As a result, Sn ₆ clusters exhibit high EB sensitivity ( D ₀ = 285 µC cm ⁻² ) and sub‐30 nm resolution, while Sn ₃ clusters deliver ultra‐low line‐edge roughness (1.02 nm) and excellent pattern fidelity. This work identifies nuclearity as a chemically tunable parameter for rational molecular‐resist design.

Iron oxide (α-Fe₂O₃) is an attractive photoanode for photoelectrochemical water splitting because of its abundance, suitable band gap, and stability in water, yet its practical use remains limited by poor charge transport and sluggish water oxidation. Here we show that these limitations can be addressed using a Ge and Ti co-doped Fe₂O₃ photoanode that couples glycerol oxidation with cathodic hydrogen evolution under simulated one-sun illumination (100 mW cm^–2). In 1.0 M NaOH containing 2.0 M glycerol, the photoanode delivers a photocurrent density of 8.87 mA cm^–2 at 1.23 V versus the reversible hydrogen electrode, above the practical benchmark of 8.1 mA cm^–2. Ge incorporation also enables selective oxidation of glycerol to tartronic acid, a value-added product of glycerol oxidation. Electrochemical analyses and density functional theory calculations suggest that Ge and Ti co-doping improves charge utilisation, while Ge additionally promotes the tartronic acid-forming pathway.

Solar‐driven interfacial steam generation (ISSG) has emerged as a promising strategy for decentralized freshwater production. However, developing scalable solar evaporators that combine high evaporation performance, environmental compatibility, and stable operation under varying solar angles remains challenging. Here, we report a compound‐eye‐inspired three‐dimensional solar evaporator based on graphite‐containing PET nanofoam (GPF). The GPF was produced by upcycling polyethylene terephthalate (PET) waste. The nonsolvent‐induced phase separation process produces a mesoporous and moldable structure with tunable water transport properties, enabling the construction of hemispherical multi‐surface evaporators. This architecture provides angle‐insensitive solar exposure and an enlarged water‐wetted evaporative interface within a fixed projected footprint. As a result, the optimized evaporator achieved a projected‐area‐normalized evaporation rate of 3.44 kg m ^{− 2} h ^{− 1} under 1‐sun illumination. In outdoor operation, the integrated evaporation‐condensation module produced a freshwater yield of up to 24.4 kg m ^{− 2} over 14 h under natural sunlight. The enhanced performance arises from the combined effects of expanded evaporation‐active area, capillary‐sustained water transport, side‐surface evaporation, and internal heat redistribution. This result indicates that the 3D‐CE improves evaporation through coupled transport and thermal effects, rather than through surface‐area enlargement alone. This work presents a potential route for converting waste PET into functional solar evaporators for decentralized freshwater production.

Bismuth vanadate (BiVO₄, BVO) is a widely studied photoanode material for photoelectrochemical (PEC) water splitting due to its suitable band gap, which enables efficient visible light absorption. However, its practical performance is significantly limited by poor charge carrier separation and low mobility, resulting in high recombination rates and reduced photocatalytic efficiency. To overcome these challenges, we propose a novel doping strategy involving the substitution of V⁵⁺ sites with cations of varying oxidation states, specifically 4⁺, 5⁺, and 6⁺ to modulate the structural, electronic, and catalytic properties of BVO. Using density functional theory (DFT) calculations, we systematically investigate the impact of these dopants on the crystal structure, electronic band structure, charge transport behavior, and oxygen evolution reaction (OER) energetics. Among the doped systems, Ti⁴⁺-doped BVO (Ti-BVO) demonstrates superior OER performance, primarily due to a reduced hole effective mass and an improved charge carrier mobility of 0.3802 cm² V⁻¹ s⁻¹ for holes and 0.1527 cm² V⁻¹ s⁻¹ for electrons. Additionally, the increased diffusion lengths for holes (99.2 nm) and electrons (62.89 nm) contribute to more efficient charge separation and transport. The calculated overpotential for Ti-BVO is significantly reduced to 0.41 V, compared to 0.97 V for pristine BVO, indicating a substantial improvement in reaction kinetics. These findings provide valuable insights for designing BVO-based next-generation photoanode materials.

Freshwater scarcity demands innovative solutions that combine efficiency, durability, and scalability. Here, CuMnCrO ₄ (CMCO), is presented as a ternary spinel oxide photothermal absorber introduced for the first time in solar desalination, synthesized via co‐substitution of Mn ₃ O ₄ with Cu and Cr. This multi‐cation design narrows the bandgap from 2.3 to 1.49 eV, markedly enhancing solar absorption across the visible and near‐infrared spectrum and enabling efficient light‐to‐heat conversion. Unlike conventional carbon or single‐oxide‐based systems, CMCO demonstrates record‐high evaporation performance of 4.1 kg m ⁻² h ⁻¹ under 1‐sun, positioning it among the most efficient oxide‐based ISSG materials reported to date. Equally novel is the integration of CMCO with a cotton fabric substrate and hydrophobic polyester strips in an inverted U‐shaped configuration, which ensures continuous water wicking, localized salt separation, and mechanical robustness. This architecture delivers stable operation over three weeks without salt accumulation, overcoming a long‐standing challenge in ISSG. Furthermore, the system retains high efficiency under strongly acidic/alkaline conditions and in oil‐ or dye‐contaminated water, demonstrating unique resilience rarely reported in solar desalination systems. Finally, the modular design enables straightforward scalability from laboratory‐scale strips to large‐area panels. Together, these advances establish CMCO‐based systems as a new materials platform for practical, durable, and scalable solar desalination, offering a sustainable pathway toward addressing global water scarcity.

Hematite (αFe ₂ O ₃ ) photoanodes, when integrated with an oxygen evolution co‐catalyst (OEC), offer several advantages for sustainable green hydrogen production via photoelectrochemical cells (PECs). However, intrinsic limitations such as restricted surface charge transfer and sluggish oxygen evolution reaction (OER) kinetics in OEC‐decorated hematite photoanodes pose significant challenges for practical PEC water splitting applications. This study presents an innovative strategy to overcome these drawbacks by decorating the hematite surface with an oxygen‐deficient double perovskite oxide layer, PrBa _0.5 Sr _0.5 Co _1.5 Fe _0.5 O _{6‐ δ} (PBSCF), serving as an OEC, with the goal of simultaneously enhancing surface charge transfer and OER kinetics. Notably, an S‐scheme heterojunction is formed between the PBSCF layer and doped hematite, and theoretical calculations confirm efficient electron transfer within the heterostructure. Leveraging these advantageous features, the Si:Ti‐Fe ₂ O ₃ /PBSCF photoanode exhibits a significant increase in photocurrent density, ≈1.4 times higher, reaching 3.70 mA cm ⁻² at 1.23 V _RHE , along with a noticeable shift in the onset potential. Furthermore, the photoanode demonstrates exceptional PEC operational stability for 120 h, attributed to the uniform contact provided by the PBSCF layer. Overall, this work highlights the potential of perovskite oxide‐based materials to enhance PEC water splitting systems and paves the way for their broader application in the pursuit of a sustainable energy future.

As the demand for nanoscale semiconductors grows, Advanced resist materials for next‐generation lithography becomes increasingly critical. Expanding the range of available resists, particularly those incorporating metals, is essential to advancing lithographic technologies. Metal‐based photoresists have attracted attention due to their inherently high etch resistance, yet many suffer from poor pattern robustness, limited solution stability, and the need for photoacid generators (PAGs). Here, a zirconium (Zr)‐based oxo cluster bonded with benzoic acid (Zr‐OCB) photoresist that overcomes these limitations through a molecular design strategy is presented. This molecularly designed resist strengthens patterned features through dimerization and oligomerization under exposure, while benzoate ligands provide stability via strong coordination with the Zr cluster. This study demonstrates a new class of structurally defined, PAG‐free metal‐based hybrid resists with superior pattern fidelity and formulation stability. This allowed for the formation of high‐resolution patterns with a feature size of sub‐40 nm, a sensitivity of 1905 µC cm ^{− 2} , a low line edge roughness of 3.1 nm, and excellent solution stability for up to 6 months, highlighting its potential for industrial applications. This work presents a promising Zr‐based hybrid resist, offering enhanced stability and simplified processing, making it a valuable candidate for next‐generation lithography.