Seungho Cho

Achieving noble‐metal‐like reactivity in earth‐abundant catalysts requires materials platforms that can simultaneously stabilize active sites and program their electronic states. Ammonia‐to‐hydrogen conversion is a demanding example, because Ru‐free catalysts must overcome the intrinsically sluggish kinetics of ammonia decomposition. Here, we report a catalyst design that couples precursor‐level cation mixing and active‐site dispersion with charge‐transfer engineering of Ni to address this challenge. Density functional theory calculations identify Cr as the most effective electron‐donating promoter for Ni among metal cations incorporable into the precursor framework. Guided by this prediction, we construct a NiCrAl reduced mixed‐metal oxide catalyst in which atomically mixed precursors stabilize highly dispersed Ni species, while Cr‐to‐Ni charge transfer generates electron‐rich Ni active sites. Multiscale spectroscopic analyses verify this electronic modulation, and combined theoretical and in situ mechanistic analyses indicate that electron‐rich Ni favors NH ₃ adsorption in a reaction‐relevant Lewis‐acid configuration, favorably modifies the dehydrogenation energetics, and weakens N ₂ binding to facilitate product desorption. NiCrAl‐RMMO reaches 95.5% NH ₃ conversion at 550°C and 22.83 mmol H ₂ g _cat ⁻¹ min ⁻¹ at 500°C, with stable operation over 100 h. More broadly, this work establishes charge‐transfer engineering in LDH‐derived mixed‐metal nanostructures as a general strategy for designing high‐performance, Ru‐free catalysts for ammonia‐to‐hydrogen conversion.

Layered titanates (LTs) offer exceptional structural and chemical tunability, enabling precise modulation of their electronic states and catalytic properties. However, systematic studies on the range of cations that can serve as intercalants for LTs remain limited, and conventional synthesis methods often require additional treatments for cation intercaltion. In this study, we present a cation‐free H ⁺ (H ₃ O ⁺ )‐intercalated LT as a versatile platform for direct cation insertion. This LT can be intercalated with single metal cations (42 metals from five groups) or a combination of 5–30 cations without structural deformation. Intercalation with alkali metals (AMs) precisely tuned the charge density of Rh species when the prepared LTs are used as catalytic supports. Among the Rh‐loaded AM‐bearing LTs, Rh/K–LT delivered the highest turnover frequency (23 685 h ⁻¹ ), surpassing those of other AM‐intercalated systems and previously reported Rh‐based heterogeneous catalysts, during propylene hydroformylation. Combined in situ/ex situ analyses and density functional theory calculations revealed that AM intercalation promotes charge transfer to Rh, thereby enhancing adsorption behavior and catalytic activity. This work establishes not only a broad cation intercalation library but also a generalizable strategy for cation engineering in LTs, highlighting the potential of intercalation‐driven charge modulation for rational catalyst design across diverse reactions.

Multielement nanostructures promise unusual properties but are constrained by crystalline frameworks limiting incorporable cations, and prevailing syntheses rely on harsh conditions restricting practicality. Here we introduce a CO₂-enabled, room-temperature route to nanostructures containing up to 30 different metal cations by coengineering cation and anion arrangements in layered-double-hydroxide-derived frameworks. The key principle is anion-cation arrangement control: CO₂-derived carbonate acts as a programmable bridging anion that, with larger-radius and higher-valent cations, drives structural reconstruction, suppresses long-range order, and relaxes radius-ratio constraints. This reorganization yields uniform cation mixing, tunable M³⁺/M²⁺ balance, and direct metal-carbonate linkages, producing ultrahigh configurational and positional disorder. The synthesis proceeds under ambient conditions in carbonated water, enabling compositional tunability, equimolar incorporation across 30 elements, and scalable, ecofriendly processing that valorizes a greenhouse gas. Leveraging anion-cation coarrangement to expand the composition space offers a general strategy for designing multielement nanomaterials with enhanced functional freedom.

Electrochemical formate (HCOO ⁻ ) production via CO ₂ reduction reaction (CO ₂ RR) holds great promise for carbon‐neutral energy systems; however, its practical implementation is significantly hindered by the high energy demand of anodic oxygen evolution reaction (OER). Replacing OER with a more energetically and economically favorable alternative anodic reaction is therefore essential. In this study, we developed a highly efficient Cu–Ag catalyst for anodic formaldehyde oxidation reaction (FOR). Systematic investigations employing in situ Raman spectroscopy and comprehensive electrochemical analyses revealed that Cu enables an earlier onset potential for FOR, and Ag enhances formaldehyde adsorption, leading to synergistically improved performance. The optimal Cu ₃ Ag ₇ catalyst exhibited superior FOR performance, with an onset potential of −0.05 V versus the reversible hydrogen electrode ( V _RHE ) and Faradaic efficiencies for HCOO ⁻ exceeding 90% from 0.1 to 0.5 V _RHE . When coupled with CO ₂ RR, the FOR||CO ₂ RR system enabled dual‐side HCOO ⁻ production, achieving a total HCOO ⁻ yield rate of 0.39 mmol h ⁻¹ cm ⁻² at an ultra‐low cell voltage of 0.5 V, surpassing the performance of previously reported electrochemical HCOO ⁻ production systems. Furthermore, this study presents a versatile anodic strategy that integrates FOR with a range of cathodic reactions, offering an energy‐efficient chemical synthesis approach for the advancement of sustainable electrochemical technologies.

Electrochemical formate (HCOO ⁻ ) production via CO ₂ reduction reaction (CO ₂ RR) holds great promise for carbon‐neutral energy systems; however, its practical implementation is significantly hindered by the high energy demand of anodic oxygen evolution reaction (OER). Replacing OER with a more energetically and economically favorable alternative anodic reaction is therefore essential. In this study, we developed a highly efficient Cu–Ag catalyst for anodic formaldehyde oxidation reaction (FOR). Systematic investigations employing in situ Raman spectroscopy and comprehensive electrochemical analyses revealed that Cu enables an earlier onset potential for FOR, and Ag enhances formaldehyde adsorption, leading to synergistically improved performance. The optimal Cu ₃ Ag ₇ catalyst exhibited superior FOR performance, with an onset potential of −0.05 V versus the reversible hydrogen electrode ( V _RHE ) and Faradaic efficiencies for HCOO ⁻ exceeding 90% from 0.1 to 0.5 V _RHE . When coupled with CO ₂ RR, the FOR||CO ₂ RR system enabled dual‐side HCOO ⁻ production, achieving a total HCOO ⁻ yield rate of 0.39 mmol h ⁻¹ cm ⁻² at an ultra‐low cell voltage of 0.5 V, surpassing the performance of previously reported electrochemical HCOO ⁻ production systems. Furthermore, this study presents a versatile anodic strategy that integrates FOR with a range of cathodic reactions, offering an energy‐efficient chemical synthesis approach for the advancement of sustainable electrochemical technologies.

Enhancing Li⁺ transport while ensuring safety is crucial for the development of high-energy density batteries. While nanomaterials boost ionic conductivity in quasi-solid state gel electrolyte (QSE), the transport mechanisms remain unclear. This study presents a synthetic strategy utilizing tailored two-dimensional saponite clay additives with a controlled organic cation configuration to achieve superior Li-ion conductivity in QSE. This optimized configuration enables rapid, uniform Li⁺ movement through controlled interlayers and effective anion trapping within aligned surfactant domains. Consequently, a pseudo-trilayer configuration of organoclay serves as a fast Li⁺ transport pathway in the QSE, leading to a high Li⁺ transference number of 0.71 and stable cycling performance for 1000 h. Moreover, batteries utilizing the pseudo-trilayer organoclay demonstrate compatibility with the LiNi_0.9Mn_0.05Co_0.05O₂ cathode, maintaining 86.7% capacity retention after 200 cycles. This work suggests a design strategy for advanced QSE that precisely controls the Li⁺ transport route, contributing to a high energy density with minimal additives.

Efficient and robust bifunctional electrocatalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are critical for high‐performance zinc‐air batteries (ZABs). However, balancing OER and ORR activity in a single catalyst remains challenging due to the different mechanisms during charging and discharging. Here, a scalable strategy is presented for enhancing both reactions by integrating two‐dimensional OER‐ and ORR‐active components onto a carbon‐based conductive substrate with abundant anchoring sites, via high‐shear exfoliation. The heterostructure catalyst demonstrates exceptional bifunctionality, achieving an extremely low overpotential difference of 0.63 V. First‐principles calculations confirm a strong chemical compatibility between the active components and substrate. In scaled‐up ZAB applications, the catalyst delivers a high peak power density of 1569 mW cm ⁻² , and an outstanding cycling stability over 300 h (1800 cycles). This work highlights a versatile approach for designing multifunctional electrocatalysts, advancing scalable energy conversion and storage technologies.

To commercialize the technology of photoelectrochemical hydrogen production, it is essential to surpass the US. Department of Energy target of 0.36 mmol h⁻¹ cm⁻² for 1-sun hydrogen production rate. In this study, we utilize crystalline silicon, which can exhibit the highest photocurrent density (43.37 mA cm⁻²), as the photoelectrode material. However, achieving bias-free water splitting (>1.6 V) remains challenging due to the intrinsic low photovoltage of crystalline silicon (0.6 V). To address this limitation, we replace water oxidation with low-potential furfural oxidation, enabling not only bias-free hydrogen production but also dual hydrogen production at both the cathodic and anodic sides. This approach results in a record 1-sun hydrogen production rate of 1.40 mmol h⁻¹ cm⁻², exceeding the Department of Energy target by more than fourfold.