Advancing quantum information technologies requires qubits whose coherence can be precisely engineered. Among the qubit platforms in development, molecular spin qubits (MSQs) stand out for their atomic scale tunability and chemical specificity, making them powerful candidates for sensing, simulation, and information processing. However, integrating MSQs into solid-state architectures without degrading their coherence remains a central challenge. Here, we introduce van der Waals (vdW) confinement within two-dimensional materials as a strategy for stabilizing quantum states in MSQs by engineering their local electronic, vibrational, and symmetry environments. Using cobaltocene as a model system, we show that confinement within vdW SnS2 and CdPS3 single crystals reorganizes the single-ion energy landscape and slows spin-lattice relaxation by over two orders of magnitude relative to unconfined cobaltocene. The confined MSQs adopt deterministic orientations and self-assemble into ordered, atomically precise superlattices, establishing vdW confinement as a pathway for integrating MSQs into functional quantum devices.

We have successfully combined CO2 capture and conversion, which eliminates the need for the energy-intensive steps of sorbent regeneration, CO2 compression, and transportation. The exothermic conversion process regenerates the sorbent for further capture and conversion cycles. In this study, we evaluated supported Pt catalysts (over TiO2, ZrO2, or MoO3) for converting CO2 captured in a single-component, water-lean postcombustion solvent (EEMPA) into methanol. Pt supported on MoO3 and ZrO2 showed the highest methanol productivity and selectivity, respectively, among the catalysts evaluated. This study introduces a catalyst system that substantially reduces degradation in amine carbon capture solvents and demonstrates stable catalytic performance, marking a significant advancement over previous findings. Solvent durability was best with Pt/MoO3, attributed to the lack of detectable acidic or basic sites on its surface. Both Pt/MoO3 and Pt/ZrO2 catalysts maintained stable performance over 100 h of continuous operation. The higher methanol productivity with Pt/MoO3 is likely due to the significantly high H-2 spillover under reaction conditions, which promotes the formation of oxygen vacancies. However, further mechanistic investigation is necessary to conclusively establish this relationship. The higher methanol selectivity (>99%) of Pt/ZrO2 is believed to be due to its strong basic sites, which reduce methanol adsorption and suppress methane formation. Our findings emphasize the importance of modulating acidic and basic sites on the catalyst surface to enhance methanol selectivity while preserving the integrity of the capture solvent.

Abstract Nanocrystalline (NC) transition-metal dichalcogenides have received significant attention as earth-abundant electrocatalysts for the hydrogen evolution reaction (HER). MoS2 is the most extensively studied alternative to Pt-group catalysts; however, atomistic insight into its size-dependent catalytic activity remains limited. Here, we investigate HER performance in NC MoS2 with controlled crystallite sizes (6, 11, and 48 nm). The smallest crystallites exhibit markedly enhanced HER activity and higher H2 production compared to larger counterparts, highlighting a strong size–activity relationship. To elucidate the underlying mechanism, we combine electrochemical measurements with in situ and ex situ electron spin resonance (ESR), hyperfine sublevel correlation spectroscopy (HYSCORE), electron–nuclear double resonance (ENDOR), and first-principles calculations. In situ ESR shows that potential-dependent sulfur vacancies in small crystallites actively drive HER. Advanced pulsed ESR techniques (HYSCORE and ENDOR), supported by theoretical modeling, further demonstrate that these sulfur vacancies are preferentially passivated by OH groups rather than hydrogen atoms, forming MoS2-(OH)S adsorbate–defect complexes. These results provide direct spectroscopic evidence linking crystallite size, defect chemistry, and electrocatalytic activity in MoS2. More broadly, this work establishes in situ ESR and advanced magnetic resonance methods as powerful tools for resolving active sites and reaction intermediates in electrochemical energy conversion processes.

Ionene - ionic liquid (IL) composites are promising materials for CO2 separation, yet a molecular-level understanding of their structure and its impact on CO2 speciation, solubility, rotation, and diffusivity remains unclear. Herein, using multimodal nuclear magnetic resonance (NMR), time-of-flight secondary ion mass spectrometry (ToF-SIMS), atomic force microscopy (AFM), and molecular dynamics (MD) simulations, we reveal that the composites contain IL-rich domains extending across hundreds of nanometres within the ionene matrix, and these bicontinuous domains span the entire membrane depth. CO2 also absorbs into the ionene matrix, with the distribution between two CO2 species varying with temperature and time. The rotational correlation times of these two species are on the timescale of 0.1 and 1 ns, respectively. As IL content increases, the ionic domains expand, resulting in higher CO2 solubility due to enhanced molecular dynamics and increased free volume in both ionene backbones and IL-rich regions. Although CO2 diffusion in the membranes is an order of magnitude slower than in bulk IL, the activation energy for CO2 diffusion remains comparable. Ionene-IL composites represent a promising platform for designing CO2 separation membranes, offering enhanced CO(2)diffusion and selectivity through IL-rich domains, and increased CO2 solubility and mechanical integrity from the ionene matrix.

Cryogenic time-of-flight secondary ion mass spectrometry (cryo ToF-SIMS) has emerged as a powerful tool for investigating molecular interactions, speciation, and dynamics in materials for CO2 capture. In this study, we apply cryo ToF-SIMS to probe interactions between CO2, water, and PEEK-ionene membranes—a promising material for direct CO2 capture due to its selectivity, durability, and efficiency. Despite this potential, the mechanisms governing CO2 diffusion and the influence of water vapor on CO2 behavior remain unclear. To address this, we loaded PEEK-ionene membranes with 13CO2 and D2O and employed cryo ToF-SIMS to visualize the 3D distribution of CO2 and water within the membrane. While prior studies suggest that 13CO2 is absorbed under ambient conditions, our cryo ToF-SIMS analysis revealed no enhancement of the 13C/12C ratio, suggesting weak CO2-membrane interactions. As a result, CO2 vaporizes even at low temperatures (−140°C) under vacuum conditions. In contrast, D2O displayed a relatively homogeneous distribution in the membrane, suggesting stronger water-membrane interactions via hydrogen bonding (18–20 kJ/mol). Interestingly, CO2 was not detected in D2O-loaded membranes, indicating minimal interference from water vapor on CO2 diffusion. As a comparison, the cryo ToF-SIMS data show that 13CO2 can readily react with a basic Na2CO3 aqueous solution to form NaH13CO3. These findings demonstrate cryo ToF-SIMS as a critical technique for understanding gas-water-membrane interactions, offering insights for membrane functionalization to improve CO2 capture efficiency.

Carbon-based materials, such as graphite and its functionalized/doped derivatives, are promising lightweight layered materials for hydrogen activation and storage. Their propensity to control the thermodynamics of hydrogen binding and the kinetics of hydrogen mobility strongly depends on the speciation and the arrangement of dopants. In this study, we demonstrate precise control over dopant speciation and clustering in nitrogen-containing layered carbon materials during hydrothermal synthesis. Through extensive spectroscopic characterization and first principles simulations, we demonstrate that the formation of N-motifs can be controlled by the choice of precursor and synthesis temperature. The distinct three-dimensional architecture and porosity in graphene oxide and carbon nitride-derived materials furnish a synthetic pathway for precise control over the local and global structure of nitrogen-doped carbon materials and their activity toward the activation of molecular hydrogen.

Hydrothermal aging (HTA) and chemical poisoning are two primary factors contributing to the real-world degradation of Cu-SSZ-13 SCR catalysts. Investigating field-returned samples offers valuable insights into performance degradation caused by these mechanisms. However, the simultaneous presence of both deactivation pathways complicates the isolation of their individual effects in post-mortem analyses. In this study, we separately prepared model Cu-SSZ-13 SCR catalysts subjected to hydrothermal-aging and sulfur-induced chemical poisoning. Using various characterization techniques, we elucidated the specific role of each aging process in catalyst deactivation and compared the results to real-world field-aged catalysts. Our findings show that hydrothermal aging at 650 degrees C for 100 h caused dealumination of the zeolite framework but no significant CuOx cluster formation. In contrast, sulfur aging (via sulfur exposure, calcination at 550 degrees C, and desulfation up to 750 degrees C) led to CuOx formation without any observable dealumination. On model catalysts, sulfur poisoning was found to reduce Cu mobility and the amount of active Cu sites, thus degrading catalyst activity. Although some activity was recovered upon desulfation, a portion of the initial catalyst activity remained irreversibly lost due to CuOx formation. We demonstrate that this occurs because sulfated species impede the ability of multi-nuclear Cu species (e.g., Cu dimers) to split back into their isolated form, leading to CuSO4-clusters that oxidatively desulfate to CuOx species. This degradation pathway explains the significant reduction in activity of field-aged samples, where substantial CuSO4-cluster accumulation leads to reduced active Cu and subsequent conversion to CuOx. The conclusions from model catalysts were extended directly to field-aged commercial samples, elucidating the decline in activity and chemical properties during field deployment.

The morphological variation of four semicrystalline polyamides─PA6, PA11, PA66, and PA612─under 250 psi hydrogen gas exposure was investigated using 13C cross-polarization (CP) and direct-polarization (DP) magic angle spinning (MAS) NMR. Additionally, two-dimensional 13C-1H wide-line separation (2D WISE) NMR provided insight into site-specific molecular dynamics. While all samples exhibited broadly similar segmental mobilities, PA6 showed slightly enhanced mobility at carbonyl sites, whereas PA612 displayed reduced mobility. The average chain mobility followed the trend: PA612 > PA6 > PA11 > PA66. Quantitative 13C NMR revealed the presence of a mobile amorphous or interfacial phase, most prevalent in PA11 (16%) and least in PA612 (9%). Initial crystallinity was highest in PA11 (36%) and lowest in PA612 (21%). Hydrogen exposure led to a marked reduction in crystallinity─up to 38% in PA612─followed by partial recovery upon depressurization. Site-specific analysis indicated the lowest crystallinity at carbonyl sites, with the unit end sites (CO and NH sites) showing distinct behavior between one-monomer (PA6 and PA11) and two-monomer (PA66 and PA612) polyamides. These findings suggest that hydrogen preferentially interacts with carbonyl and amide groups. A strong correlation was observed between chain mobility, the degree of crystallinity, and the reduction in the crystalline phase resulting from pressurization with 250 psi H2 gas. Among the polyamides studied, PA66 exhibited the greatest resistance to hydrogen-induced morphological changes, attributed to its higher crystallinity and reduced chain mobility. This underscores the importance of structural rigidity in enhancing polymer resilience under high-pressure hydrogen environments.

The effects of short-chain branching (SCB) on phase distribution, free volume formation, and structural stability in polyethylene under hydrogen pressurization were investigated using medium- and high-density polyethylene (MDPE and HDPE) samples (MDPE-M, MDPE-I, HDPE-G, and HDPE-D). Comprehensive nuclear magnetic resonance (NMR) techniques, including liquid-state 1H/13C NMR and solid-state 1H/129Xe NMR under 250 psi hydrogen and xenon atmospheres, respectively, were employed to characterize SCB content, semicrystalline phase distribution, chain mobility, and free volume. SCB levels ranged from 1.94 to 2.66 branches per 1000 carbon atoms, with a free volume range of 0.297-0.533 cm3/g and a consistent free volume element diameter of ∼0.63 nm. Hexene branches correlated positively with free volume formation, whereas longer branches, such as heptene and octene, suppressed it. Increased SCB content and SCB length reduced crystallinity and chain mobility. Results support a mechanistic model in which randomly distributed SCBs enhance chain stiffness and hydrogen permeability into crystalline regions. In contrast, a lower SCB content allows greater chain flexibility and contraction under hydrogen pressure, limiting gas penetration into the crystalline phase. Hydrogen accumulation in the amorphous phase contributes to crystalline stabilization through resistive stress, yielding a higher failure strain strength under hydrogen pressure. These effects are attributed to hydrogen's smaller kinetic diameter, enabling access to pore networks inaccessible to air, such as nitrogen and oxygen.

The present contribution provides clarity to N2O formation mechanisms and key influencing factors during low temperature NH3-SCR, with the goal of enabling the rational design of advanced SCR catalysts with low greenhouse gas impact. By studying more than 50 small pore Cu-exchanged zeolite SCR catalyst samples, including model catalysts synthesized in our laboratories and state-of-the-art industrial catalysts, we explored a wide range of factors affecting N2O formation. These factors included Cu loading, support Si/Al ratio, support topology, catalyst aging, reaction temperature and reactant feed composition effects. We probed N2O formation under both steady-state SCR, and during NH4NO3 decomposition via temperature programmed desorption (TPD). Finally, we used DFT to probe energetics of possible N2O formation pathways. Based on these studies, we confirm that low temperature N2O formation occurs via multiple reaction pathways that all involve NH4NO3 and are supported by Cu moieties that facilitate in-situ NO oxidation to NO2.

Anchoring divalent metal ions in the same zeolite framework with similar Si/Al ratio selectively as zeolite‐bound M +2 or [M +2 ‐OH] +1 cationic species enables critical comparison of the species’ intrinsic reactivity for industrially and fundamentally relevant reactions. H‐BEA zeolites with similar Si/Al ratios but differing framework Al siting were used to anchored multiple divalent metal cations (Ni, Pd, Pt, Cr, Cu) in the zeolite micropores. State‐of‐the‐art infrared (IR) spectroscopy, electron paramagnetic resonance (EPR) measurements, including two‐dimensional pulsed HYSCORE EPR, extended X‐ray absorption fine structure (EXAFS), and density functional theory (DFT) calculations together provide unambiguous evidence for the selective formation of divalent metal cations as M +2 /2Al species (for H‐BEA prepared in the conventional hydroxide media), and [M +2 OH] +1 /1Al species for H‐BEA prepared in HF. Solid‐state proton‐decoupled triple‐quantum magic‐angle spinning (3Q MAS) NMR measurements confirmed contrasting Al distributions in the two H‐BEA zeolites, which led to a contrasting divalent cation speciation. The reactivities of the two cationic species were explored for catalytic and adsorptive applications in both organometallic homogeneous and heterogeneous catalysis. This work demonstrates their divergent reactivity in ethylene dimerization, ethylene oxidation (Wacker process), selective catalytic reduction (SCR) of NO, NO adsorption, and methane oxidation. Both M +2 /2Al and [M +2 OH] +1 /1Al cations are both active for ethylene dimerization, but [M +2 OH] +1 /1Al species show higher reaction rates for each Pd, Ni, Pt. [M +2 OH] +1 /1Al is active for acetaldehyde formation in Wacker ethylene oxidation. A new active site for ethylene oligomerization is proposed that possesses a terminal OH group (Cr‐OH) in Phillips catalysts evident by a nearly inactive isolated Cr +2 /2Al species that contrast an active Cr─OH motif.

Carbon capture, utilization and storage is a key yet cost-intensive technology for the fight against climate change. Single-component water-lean solvents have emerged as promising materials for post-combustion CO2 capture, but little is known regarding their mechanism of action. Here we present a combined experimental and modelling study of single-component water-lean solvents, and we find that CO2 capture is accompanied by the self-assembly of reverse-micelle-like tetrameric clusters in solution. This spontaneous aggregation leads to stepwise cooperative capture phenomena with highly contrasting mechanistic and thermodynamic features. The emergence of well-defined supramolecular architectures displaying a hydrogen-bonded internal core, reminiscent of enzymatic active sites, enables the formation of CO2-containing molecular species such as carbamic acid, carbamic anhydride and alkoxy carbamic anhydrides. This system extends the scope of adducts and mechanisms observed during carbon capture. It opens the way to materials with a higher CO2 storage capacity and provides a means for carbamates to potentially act as initiators for future oligomerization or polymerization of CO2.

Incorporation of pollutants, e.g., heavy metals, or critical elements, e.g., lithium, as impurities in mineral phases can significantly affect their mobility or sequestration in the environment. Even when present at low concentrations, impurities can alter the solubility and reactivity of the host mineral. In this study, we investigate the incorporation of trace amounts of iron (Fe3+) and chromium (Cr3+) during the crystal growth of the aluminum (Al3+) hydroxide, gibbsite, a major component of bauxite ores, an important soil mineral, and a dominant mineral phase in stored radioactive wastes. Using a comprehensive suite of analytical techniques, we show that both Cr3+ and Fe3+ can be incorporated into the gibbsite lattice during coprecipitation by replacing Al3+ in octahedral sites. These small amounts are consistent with limited to no structural isomorphism shared between Al3+ and Cr3+/Fe3+ hydroxide precipitates, nor room temperature miscibility of their isostructural M2O3 oxide forms, in contrast with oxyhydroxide forms where Al3+ and Fe3+ share similar structural topologies. Despite the limited uptake of Cr3+/Fe3+, we show that these impurities have significant implications for gibbsite dissolution behavior. The limited uptake of Cr3+/Fe3+ (e.g. 0.43% Cr3+ and 0.4% Fe3+), we show that these impurities have significant implications for gibbsite dissolution behavior and subsequent reactivity in complex environments.

Solar photoexcitation of chromophoric groups in dissolved organic matter (DOM), when coupled to photoreduction of ubiquitous Fe( III)-oxide nanoparticles, can significantly accelerate DOM degradation in near-surface terrestrial systems, but the mechanisms of these reactions remain elusive. We examined the photolysis of chromophoric soil DOM coated onto hematite nanoplatelets featuring (001) exposed facets using a combination of molecular spectroscopies and density functional theory (DFT) computations. Reactive oxygen species (ROS) probed by electron paramagnetic resonance (EPR) spectroscopy revealed that both singlet oxygen and superoxide are the predominant ROS responsible for DOM degradation. DFT calculations confirmed that Fe(II) on the hematite (001) surface, created by interfacial electron transfer from photoexcited chromophores in DOM, can reduce dioxygen molecules to superoxide radicals (similar to O2-) through a one-electron transfer process. 1H nuclear magnetic resonance (NMR) and electrospray ionization Fouriertransform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) spectroscopies show that the association of DOM with hematite enhances the cleavage of aromatic groups during photodegradation. The findings point to a pivotal role for organic matter at the interface that guides specific ROS generation and the subsequent photodegradation process, as well as the prospect of using ROS signatures as a forensic tool to help interpret more complicated field-relevant systems.

Hydrogenation is a critical reaction in the chemical industry, yielding a range of important compounds such as fine chemicals, pharmachemicals and agrochemicals. However, conventional hydrogenation typically requires pressurized hydrogen, high temperatures and involves noble metal catalysts. We proposed a two-step hydrogenation process, utilizing water as the hydrogen source for the industrially important reduction of nitroarenes to anilines. A metal or reduced metal oxide, which can be obtained from solar thermal or electrochemical reduction, acts as the active site for nitrobenzene adsorption, H2O dissociation and in-situ hydrogen generation. Among the 15 metal and reduced metal oxides investigated, Zn and Sn emerged as highly efficient catalysts for the reduction of a broad range of organic nitro compounds under mild conditions, with H2 utilization efficiency 1–2 orders of magnitude above the state-of-the-art. The presented protocol provides extra dimensions for designing and optimizing conventional hydrogenation process with an alternative pathway. The reactive hydrogen atoms generated in-situ effectively overcome the barriers associated with hydrogen gas dissolution and its subsequent dissociation on the catalyst surface, thereby greatly enhancing the overall effectiveness for the hydrogenation reaction. This research potentially establishes a sustainable, generally applicable alternative to conventional hydrogenation methods, simultaneously presenting a viable solution for renewable energy storage.

The simultaneous removal of radionuclides technetium-99 and iodine-129 from an actual decontaminated Hanford tank waste sample (a mixture of decontaminated waste from tanks 241-AP-105 and 241-AP-107) was demonstrated for the first time in this work. A series of commercially available ion exchange resins were evaluated in batch contact tests in the tank waste, and all showed removal of both Tc and I. The highest Tc removal from the tank waste was observed for Purolite A530e while the highest iodine removal was observed for ResinTech SIR-110-MP. Isotherm tests in simulated tank waste with these two resins showed that the SIR-110-HP-MP had consistently higher K-d for both pertechnetate and iodide; with much higher K-d than previous works on Tc removal from Hanford waste. As such, the SIR-110-MP was evaluated in a dual-column (lead/lag) test processing 5.2L of the tank waste mixture showing 50 % breakthrough of Tc on the lead column and no significant breakthrough on the lag after 641 bed volumes (BV, 6 mL size) while significant iodine breakthrough (>50 %) occurred after 28 BV. The limited iodine uptake was attributed to the column conditions generating mass transfer limitations. A fraction of the Tc and I was not captured by the resin (<10 %) in either the batch tests or column tests. The iodine fraction is not iodate and is likely organo-iodide. The fraction of the Tc was identified as a non-pertechnetate species which is the first time non-pertechnetate has been identified in AP-105 and AP-107 tanks. This non-pertechnetate fraction contained Tc(I) and for the first time a stable Tc(VI) species in Hanford waste was identified..

Utilizing H-BEA zeolites with similar Si/Al ratios but with different Al site distributions we show that the divalent metal cations (Ni, Pd, Pt, Cr, Cu) can be dispersed predominantly as either M(II)/2Al species (for conventional zeolite prepared in the hydroxide media) or as [M(II)-OH]/1Al species (for H-BEA prepared in HF). M(II) species are active in ethylene dimerization. However, Pd(II)-OH and Ni(II)-OH species, that were not previously prepared or evaluated for this reaction, are even more catalytically active. M(II)-OH species in zeolite can activate ethylene via formation of C2H4--M(II)-OC2H5 species which can eliminate butene restoring M(II)-OH species. We also reveal that Pt(II) and Pt(II)-OH in zeolite, not previously known to catalyze ethylene dimerization on solid materials, are in fact catalytically active. This synthetic realization further exemplifies the different NO adsorption aspects of these materials. Both Pd(II) and Pd(II)-OH are active for NO adsorption, the latter desorbing NO at higher temperature than isolated Pd(II). Notably, Pd(II)-OH is active for Wacker oxidation chemistry of ethylene into acetaldehyde, whereas Pd(II) is less active: this clarifies the missing mechanistic aspects of Wacker oxidation by homogeneous complexes. The presence of OH ligand in the Pd(II) first coordination sphere is important for reactivity. Further, we show that Cr/2Al in H-BEA is inactive for ethylene oligomerization, whereas Cr-OH has ethylene dimerization activity, illuminating a previously unknown possibility that Cr-OH species could be an active species for Cr/silica Phillips ethylene oligomerization catalysts.

Reported are the syntheses, structural characterizations, and luminescence properties of three novel [UO2Cl4]2- bearing compounds containing substituted 1,1'-dialkyl-4,4'-bipyridinum dications (i.e., viologens). These compounds undergo photoinduced luminescence quenching upon exposure to UV radiation. This reactivity is concurrent with two phenomena: radicalization of the uranyl tetrachloride anion and photoelectron transfer to the viologen which constitutes the formal transfer of one electron from [UO2Cl4]2- to the viologen species. This behavior is elucidated using electron paramagnetic resonance (EPR) spectroscopy and further probed through a series of characterization and computational techniques including Rehm-Weller analysis, time-dependent density functional theory (TD-DFT), and density of states (DOS). This work provides a systematic study of the photoreactivity of the uranyl unit in the solid state, an under-described aspect of fundamental uranyl chemistry.