Ankit K. Yadav

Achieving sustainable carbon capture under realistic, humid conditions remains a central challenge for decarbonization technologies. Here we report an ultramicroporous oxofluorovanadate metal‐organic framework, Ni(pyrazine) ₂ (VOF ₄ ), that dynamically regulates competitive adsorption through reversible redox chemistry. Under humid dilute CO ₂ streams (4 vol%), water chemisorbs at vanadium centers in the form of hydroxide ligands and induces a reversible V(+4)|V(+5) transformation to an isoreticular phase, Ni(pyrazine) ₂ (VO(OH)F ₄ ), while CO ₂ is engaged in strong physisorption within pyrazine‐lined pore regions. This redox‐driven compartmentalization of H ₂ O and CO ₂ results in a dynamic breakthrough CO ₂ capacity of 2.04 ± 0.07 mmol/g, sustained for up to 50 cycles and showing resilience under intense humidification or steam exposure. These findings establish redox‐adaptive adsorption in BVR‐X as a unique design paradigm, enabling scalable and durable carbon capture under realistic operating conditions.

Achieving sustainable carbon capture under realistic, humid conditions remains a central challenge for decarbonization technologies. Here we report an ultramicroporous oxofluorovanadate metal‐organic framework, Ni(pyrazine) ₂ (VOF ₄ ), that dynamically regulates competitive adsorption through reversible redox chemistry. Under humid dilute CO ₂ streams (4 vol%), water chemisorbs at vanadium centers in the form of hydroxide ligands and induces a reversible V(+4)|V(+5) transformation to an isoreticular phase, Ni(pyrazine) ₂ (VO(OH)F ₄ ), while CO ₂ is engaged in strong physisorption within pyrazine‐lined pore regions. This redox‐driven compartmentalization of H ₂ O and CO ₂ results in a dynamic breakthrough CO ₂ capacity of 2.04 ± 0.07 mmol/g, sustained for up to 50 cycles and showing resilience under intense humidification or steam exposure. These findings establish redox‐adaptive adsorption in BVR‐X as a unique design paradigm, enabling scalable and durable carbon capture under realistic operating conditions.

Metal-organic frameworks (MOFs) offer a structurally tunable platform for photocatalysis, yet their activity for hydrogen evolution is often constrained by inefficient charge separation and reliance on metal cocatalysts. Herein, a family of MOFs, BVR-19-M, constructed from divalent transition metal ions (M = Mg2+, Mn2+, Cu2+, Zn2+, Cd2+) and the aliphatic amino acid l-cystine is reported. Among them, BVR-19-Zn exhibits the highest photocatalytic activity, enabled by the zinc’s filled d-orbitals and the redox-active disulfide l-cystine ligand, promoting intraligand charge transfer (ILCT). Uniquely, the disulfide (S–S) bridges within BVR-19-Zn undergo transient homolytic cleavage upon light irradiation, generating a thiyl radical and thiolate anion pair that actively mediate charge separation and drive hydrogen evolution in the absence of a co-catalyst. Open-shell metal ions incorporated into BVR-19-M either introduce a mid-gap state that serves as a recombination center or promote metal-centric charge transfer, both of which diminish photocatalytic efficiency. The radical anion-mediated ILCT mechanism introduces a distinct molecular design strategy for MOFs, demonstrating how disulfide redox chemistry can be harnessed to unlock efficient, sustainable photocatalysis.

Low-concentration ammonia detection is critical for applications in environmental monitoring, agricultural production, and occupational health protection. To enhance the material's gas-detection capability, a nanocomposite of a MOF and a conducting polymer was synthesized via in situ polymerization and systematically optimized for chemiresistive ammonia sensing. By varying the UiO-66 loading, the trade-off between gas-accessible surface area and electrical conductivity was established. A contactless spray-deposition technique was developed to fabricate composite films on compact interdigitated electrode platforms, overcoming the limitations of conventional drop-casting methods in film uniformity and device reproducibility. The optimized 5 wt % UiO-66/PANI sensor demonstrated exceptional performance, with 138% sensitivity at 100 ppb ammonia, representing nearly a three-fold improvement over pristine PANI (48% at 100 ppb). The sensor exhibited excellent selectivity toward ammonia over common interfering gases, robust stability across varying humidity conditions, and consistent performance over long-term cyclic testing. An open-space demonstration in a laboratory environment validated the sensor's real-time ammonia-monitoring capability, with performance comparable to that of a commercial ammonia sensor. This work provides a systematic approach to optimizing MOF/conducting polymer composites for gas-sensing applications via a reliable selected-area deposition method. The results demonstrate the potential of UiO-66/PANI nanocomposites as a practical platform for ammonia detection in environmental and industrial settings.

Mitigating rising atmospheric CO2 levels remains one of the most pressing global challenges. Among emerging solutions, solid adsorbent technologies offer efficient, reusable, and economically viable routes for CO2 capture. Here, we contribute to this field by introducing a crystal-engineering strategy for zeolitic imidazolate framework-8 (ZIF-8), a robust and scalable metal–organic framework (MOF) synthesized under green, room-temperature conditions. Controlled wet chemical etching generates surface and bulk defects and exposes new crystal faces, increasing the number of coordinatively unsaturated Zn sites available for spermine grafting. This dual modification leads to an 84-fold enhancement in CO2 uptake at 40 mbar compared to pristine ZIF-8. Breakthrough experiments (4 vol % CO2 balanced with N2) under both dry and humid conditions confirm selective and stable CO2 capture, retaining ∼90% of uptake even at 75% relative humidity. In situ 13CO2 solid-state NMR provides direct molecular-level evidence of carbamate formation, confirming chemisorption interactions. Our findings demonstrate that wet chemical etching coupled with amine grafting is an attractive strategy for modulating bulk and surface reactivity in MOFs, unlocking previously inaccessible Zn sites and enabling high-performance, humidity-tolerant CO2 capture under industrially relevant conditions.

Homochiral MOFs with tunable pore sizes enable controlled adsorption of racemic drugs, achieving up to 76.1% enantiomeric excess for l -penicillamine through proximity-driven interactions.

Metal-organic frameworks (MOFs) are porous, crystalline materials known for their structural versatility and high thermal stability, making them promising candidates for light-emitting diode applications. Distinct classes of MOFs, such as multivariate (MTV)-MOFs and MOF-on-MOFs, introduce heterogeneity by incorporating multiple ligands within a single unit cell (MTV-MOFs) or by stacking different MOFs on top of each other (MOF-on-MOF). Although these strategies improve their properties, the mechanisms of energy transfer between their heterogeneous components and their effects on optical properties, such as quantum yields, remain poorly understood. In this study, we demonstrate that MOF heterostructures significantly improve quantum yield compared to single-ligand-based MOFs. Using Zr-UiO-67 as the base MOF, we generated an array of MOF-on-MOFs and analogous MTV-MOFs utilizing other Zr-MOFs constructed from 4,4’-azobenzenedicarboxylate or 4,4’-stilbenedicarboxylate linkers. Our results demonstrate that, although the emission color coordinates for the stilbene-based materials are identical, the MTV-MOFs increase the quantum yield from 8.2% to 10.2%, whereas the MOF-on-MOFs reach a quantum yield of up to 40.0%.