Photocatalytic CO2 reduction to value-added chemicals is limited by inefficient charge transfer and sluggish multielectron kinetics. Here, we develop a TiO2 (P25) based ternary system incorporating Pt NPs and 1T-dominant MoSe2 NSs as dual cocatalysts (i.e., Pt/TiO2-MoSe2) to direct charge flow and reaction pathways. This Pt/TM architecture accelerates charge separation and provides highly active sites for CO2 activation. The optimized Pt1.5%-TiO2-MoSe2 exhibits a CH4 evolution rate of 17.81 μmol g−1 under 5-sun illumination with ≈\u202f98% selectivity in the gas phase, achieving a 65-fold enhancement over TiO2 (P25). Under multi-sun irradiation, increased photon flux boosts activity, indicating the critical role of charge carrier density, and facilitates rapid CH4 desorption, thereby overcoming the activity-selectivity trade-off. The coexistence of static interfacial charge redistribution and dynamic photoinduced electron transfer, validated by experiment (XPS, XAS) and Density Functional Theory (DFT) quantum mechanics (QM) calculations, ensures the retention of the active 1T-MoSe2 phase and establishes an efficient TiO2 → MoSe2 → Pt charge-funneling highway. In situ DRIFTS, combined with simulated infrared spectra (DFT), identifies a *CHO-dominated pathway for the conversion (*CO→ *CHO → *CHOH → *CH2OH → *CH2 → *CH3 → CH4), and isotopic labeling confirms the CO2-to-CH4 formation. DFT results further support the cascade charge transfer and reduced energy barriers enabled by the dual cocatalyst system.
", "doi": "10.1016/j.apcatb.2026.127142", "issn": "0926-3373", "publisher": "Elsevier", "publication": "Applied Catalysis B: Environment and Energy", "publication_date": "2026-12-15", "volume": "399", "pages": "127142" }, { "id": "authors:4dyvs-5cy69", "collection": "authors", "collection_id": "4dyvs-5cy69", "cite_using_url": "https://authors.library.caltech.edu/records/4dyvs-5cy69", "type": "article", "title": "Interfacial Polymerization of TEPA and HMDI: The Role of Water", "author": [ { "family_name": "Liu", "given_name": "Biyuan", "clpid": "Liu-Biyuan" }, { "family_name": "Zhang", "given_name": "Yonglin" }, { "family_name": "Zhao", "given_name": "Ying" }, { "family_name": "Prakash", "given_name": "Prabhat", "orcid": "0000-0003-1430-2379", "clpid": "Prakash-Prabhat" }, { "family_name": "Huai", "given_name": "Liyuan", "orcid": "0000-0002-3072-9949", "clpid": "Huai-Liyuan" }, { "family_name": "Ma", "given_name": "Hancheng", "orcid": "0009-0001-2570-5029" }, { "family_name": "Luo", "given_name": "Zhengtang", "orcid": "0000-0002-5134-9240" }, { "family_name": "Goddard", "given_name": "William A., III", "orcid": "0000-0003-0097-5716", "clpid": "Goddard-W-A-III" }, { "family_name": "Yang", "given_name": "Jinglei", "orcid": "0000-0002-9413-9016" } ], "abstract": "The interfacial polymerization (IP) between tetraethylenepentamine (TEPA) and 4,4′methylenebis (cyclohexyl isocyanate) (HMDI) at the inorganic–organic solvent interface happens so fast that it is difficult to control the reaction and the morphology of the polymer. Through quantum mechanical (QM) calculations and molecular dynamics (MD) simulations, we clarify the catalytic effect of water on the rapid IP process in the organic phase. QM results reveal that a single water molecule acts as a proton transfer bridge by establishing hydrogen bonds with both TEPA and HMDI, and the hydrogen bonds lower the free energy barriers from 15.1–16.6 kcal·mol–1 (in the absence of a single water molecule) to 2.3–3.1 kcal·mol–1 (in the presence of a single water molecule) in implicit hexadecane. The interaction energy analysis, performed via the fine-tuned MACE FF, indicates that HMDI preferentially resides in the hexadecane phase, while TEPA is more likely to diffuse across the interface. The result provides an energy-based perspective for the partition in the IP process, and experimental observations confirm that polymerization occurs toward the organic phase. These findings provide direct evidence that a single water molecule facilitates IP, offering critical insights for the rational design and precise control of polymerization at the interface to enable improved regulation of reaction kinetics and polymer morphology.
\nThe increasing demand for cobalt (Co) and nickel (Ni) in energy storage and industrial applications highlights the need for their efficient separation from both primary mining and nonconventional sources. Electrowinning presents a greener alternative to incumbent solvent extraction but is hindered by the similar reduction potentials of divalent Co and Ni ions. We show that cost-effective and recyclable bioacids can modify ion solvation environments to amplify the reduction potential difference between Co and Ni, with tartaric acid achieving the highest selectivity through formation of a unique dinuclear complex. When applied to ternary lithium-ion battery leachates, the process achieves 99.1% Co purity in batch mode and, in a scalable flow system, stepwise recovery of metallic Co (95.1%), Ni (96.5%), and manganese dioxide (~100%) with high yields. Technoeconomic analysis and life-cycle assessment highlight superior economic and environmental benefits, establishing a sustainable, generalized electrochemical platform for selective Ni/Co separation from complex feedstocks.
", "doi": "10.1126/sciadv.aec7956", "pmcid": "PMC12965294", "issn": "2375-2548", "publisher": "American Association for the Advancement of Science", "publication": "Science Advances", "publication_date": "2026-03-06", "series_number": "10", "volume": "12", "issue": "10", "pages": "eaec7956" }, { "id": "authors:caahm-w2j18", "collection": "authors", "collection_id": "caahm-w2j18", "cite_using_url": "https://authors.library.caltech.edu/records/caahm-w2j18", "type": "article", "title": "Nanoconfined Grain Boundaries Increase the Conductivity of Polycrystalline Molecular Crystals", "author": [ { "family_name": "Paul", "given_name": "Shujit Chandra" }, { "family_name": "Goddard", "given_name": "William A., III", "orcid": "0000-0003-0097-5716", "clpid": "Goddard-W-A-III" }, { "family_name": "Zdilla", "given_name": "Michael J.", "orcid": "0000-0003-0212-2557" }, { "family_name": "Prakash", "given_name": "Prabhat", "orcid": "0000-0003-1430-2379", "clpid": "Prakash-Prabhat" }, { "family_name": "Wunder", "given_name": "Stephanie L.", "orcid": "0000-0002-7193-4762" } ], "abstract": "Soft-solid molecular crystals consist of crystalline grains and fluid grain boundaries (GBs) that enhance the grain binding and transport of Li+ ions between the grains. The total ionic conductivity consists of ion migration in both the grains and GBs. To unravel these contributions in adiponitrile (Adpn):LiPF6 molecular crystals, the GB volume fraction was varied by changing the size of the crystals and the Adpn:LiPF6 molar ratio. Molecular dynamics (MD) simulations indicate that ion motion was subdiffusive in the grains and \"well-diffusive\" in the GBs, with GBs characterized as disordered nanoconfined regions of higher charge carrier concentration (∼1\u202fM) than in saturated Adpn:LiPF6 solutions (0.04\u202fM), and Li+ ions predominantly solvated by cyano groups with few contact ion pairs. The diffusivity in the GBs is at least an order of magnitude higher than that in the crystalline grains. The emergent picture is the grains as a reservoir of ions that migrate to faster-conducting GBs.
", "doi": "10.1021/acsmaterialslett.5c01267", "pmcid": "PMC12958337", "issn": "2639-4979", "publisher": "American Chemical Society", "publication": "ACS Materials Letters", "publication_date": "2026-03-02", "series_number": "3", "volume": "8", "issue": "3", "pages": "764-771" }, { "id": "authors:vx38c-z0n54", "collection": "authors", "collection_id": "vx38c-z0n54", "cite_using_url": "https://authors.library.caltech.edu/records/vx38c-z0n54", "type": "article", "title": "Structure and dynamics of CO\u2082 absorption in aqueous potassium lysinate solutions", "author": [ { "family_name": "Mukherjee", "given_name": "Uttama", "orcid": "0000-0003-4855-1875" }, { "family_name": "Prakash", "given_name": "Prabhat", "orcid": "0000-0003-1430-2379", "clpid": "Prakash-Prabhat" }, { "family_name": "Venkatnathan", "given_name": "Arun", "orcid": "0000-0001-8450-5417" } ], "abstract": "This work presents the synthesis of a molecular crystal of adiponitrile (Adpn) and LiI via a simple melting method. The molecular crystal has both Li\u207a and I\u207b channels and can be either a Li\u207a or I\u207b conductor. In the stoichiomnetric crystal (Adpn)\u2082LiI, the Li\u207a ions interact only with four C≡N groups of Adpn while the I\u207b ions are uncoordinated. Ab initio calculations indicate that the activation energy for ion hopping is less for the I\u207b (E\u2090 = 60 kJ/mol) than for the Li\u207a (E\u2090 = 93 kJ/mol) ions, and is predominantly an I\u207b conductor, with a lithium-ion transference number (t_Li\u207a) of t_Li\u207a = 0.15, no lithium plating/stripping observed in the cyclic voltammograms (CVs), and a conductivity of σ = 10\u207b\u2074 S/cm at 30 \u1d52C. With the addition of excess adiponitrile, which resides in the grain boundaries between the crystal grains, the contribution of Li\u207a ions to the conductivity increases, so that for the nonstoichiometric molecular crystal (Adpn)\u2083LiI, Li↔ Li\u207a redox reactions are observed in the CVs, t_Li\u207a = 0.63, conductivity increases to σ = 10\u207b³ S/cm 30 \u1d52C, the voltage stability window is 4V, and it is thermally stable to 130 \u1d52C, showcasing the potential of this electrolyte for advanced solid-state Li-I battery applications. The solid (Adpn)\u2083LiI minimizes migration of polyiodides, inhibiting the “shuttle” effect.
", "doi": "10.26434/chemrxiv-2025-q7r85", "publisher": "ChemRxiv", "publication_date": "2025-05-16" }, { "id": "authors:xtsfq-p9704", "collection": "authors", "collection_id": "xtsfq-p9704", "cite_using_url": "https://authors.library.caltech.edu/records/xtsfq-p9704", "type": "article", "title": "Effect of Anion Mass on Conductivity and Lithium-Ion Transference Number in the Isomorphic Cocrystals (Adpn)\u2082LiXF\u2086 (Adpn = Adiponitrile, X = P, As, Sb)", "author": [ { "family_name": "Fall", "given_name": "Birane" }, { "family_name": "Sonnenberg", "given_name": "Laura A." }, { "family_name": "Aguirre", "given_name": "Jordan R." }, { "family_name": "Paul", "given_name": "Shujit Chandra" }, { "family_name": "Prakash", "given_name": "Prabhat", "orcid": "0000-0003-1430-2379", "clpid": "Prakash-Prabhat" }, { "family_name": "Venkatnathan", "given_name": "Arun", "orcid": "0000-0001-8450-5417" }, { "family_name": "Garaga", "given_name": "Mounesha N." }, { "family_name": "Goddard", "given_name": "William A., III", "orcid": "0000-0003-0097-5716", "clpid": "Goddard-W-A-III" }, { "family_name": "Greenbaum", "given_name": "Steven G.", "orcid": "0000-0001-5497-5274" }, { "family_name": "Zdilla", "given_name": "Michael J.", "orcid": "0000-0003-0212-2557" }, { "family_name": "Wunder", "given_name": "Stephanie L.", "orcid": "0000-0002-7193-4762" } ], "abstract": "The solid lithium-ion electrolytes (Adpn)2LiXF6 (Adpn = adiponitrile, X = P, As, Sb) are isomorphic salt-solvate cocrystals with slight differences in lattice spacing (<0.15 Å). The Li+ cations are coordinated by Adpn molecules and separated from the anions so that the diffusion of the anions and cations is decoupled. As shown previously for the hexafluorphosphate analogue, (Adpn)2LiPF6, the motion of Li+ ions is through a solvate-mediated hopping mechanism, which is expected to be similar in all of the cocrystals. The crystal grains are surrounded and connected by a fluid-like grain-boundary network. Pulsed-field gradient 7Li NMR, which measures diffusion in both the grains and the grain boundaries, indicated that the Li diffusion coefficients for the cocrystals were similar (<DLi+> = 1.77 × 10–6 cm2/s). The transference numbers for Li+ ions in Adpn2LiPF6 measured by PFG-NMR at 80 °C, tLi+,PFG = 0.54, is in great agreement with tLi+,MD = 0.54 - predicted by molecular dynamics simulations at 27 °C using a grain-boundary atomistic model. Lithium-ion transference numbers, tLi+, calculated from steady-state impedance spectroscopy are 0.53, 0.63, and 0.83 for X = P, As, and Sb cocrystals, respectively, showing a lower contribution of anion charge carriers, with increasing mass of the anions, to the conductivity of these cocrystalline electrolytes. Diffusion coefficients for the AsF6– and SbF6– anions were calculated using measured values of σ and tLi+ and decreased with increasing mass of the anion in the order DPF6- > DAsF6- > DSbF6-. Conductivities of the cocrystals measured by EIS are in the order σ(Adpn2LiPF6) > σ(Adpn2LiAsF6) > σ(Adpn2LiSbF6), while conductivities of 0.04 M solutions of the salts in Adpn decreased slightly in the opposite order LiSbF6 > LiAsF6 > LiPF6. The latter reflects better dissociation (and thus a greater number of free ions) of Li+ from the heavier, more polarizable anions in dilute solution, attributed to hard–soft acid–base theory. In contrast, in the solid cocrystal, all ions are separated, and so conductivity is governed by the hopping ability of the ions, where the heavier anions diffuse more slowly. Since the total conductivity decreases in the opposite order, MD simulations suggest that the cations and anions in the nanoconfined regions of the grain boundaries are more concentrated and are exchangeable with the bulk phase grains.
", "doi": "10.1021/acs.chemmater.4c01374", "issn": "0897-4756", "publisher": "American Chemical Society", "publication": "Chemistry of Materials", "publication_date": "2025-03-11", "series_number": "5", "volume": "37", "issue": "5", "pages": "1798-1809" }, { "id": "authors:rdkdz-k1w33", "collection": "authors", "collection_id": "rdkdz-k1w33", "cite_using_url": "https://authors.library.caltech.edu/records/rdkdz-k1w33", "type": "article", "title": "Recombination of Autodissociated Water Ions in a Nanoscale Pure Water Droplet", "author": [ { "family_name": "Kwon", "given_name": "Soonho", "orcid": "0000-0002-9225-3018", "clpid": "Kwon-Sooho" }, { "family_name": "Prakash", "given_name": "Prabhat", "orcid": "0000-0003-1430-2379", "clpid": "Prakash-Prabhat" }, { "family_name": "Cao", "given_name": "Yixiang", "clpid": "Cao-Yixiang" }, { "family_name": "Houle", "given_name": "Frances A.", "orcid": "0000-0001-5571-2548", "clpid": "Houle-Frances-A" }, { "family_name": "Goddard", "given_name": "William A., III", "orcid": "0000-0003-0097-5716", "clpid": "Goddard-W-A-III" } ], "abstract": "The recombination of water ions has diverse scientific and practical implications, ranging from acid-base chemistry and biological systems to planetary environments and applications in fuel cell and carbon conversion technologies. While spatial confinement affects the physicochemical properties of water dynamics, its impact on the recombination process has rarely been studied. In this work, we investigate the dynamics of water, the water ion distribution, and the ion recombination process in water droplets as a function of droplet size through molecular dynamics simulations and adaptive quantum mechanical/molecular mechanical calculations. We compare the dynamics of recombination in water droplet sizes ranging from 100 to 18\u202f000 waters, both in their interiors and on their surfaces. We found that the self-diffusion of water dramatically decreases in droplets with a diameter below 2.2 nm. Using a classical RexPoN force-field, we found that the ions in 1000 H2O's spend almost 50% of the time on the surface and 0.5 nm beneath it with a slight preference for OH- ion to reside longer on the surface. We estimate that, on average, recombination in these drops occurs at 400 ps in 1000 H2O's and 1 ns in 3000 H2O's. We also found that recombination is not limited by the local structure of the surface or the size of the droplet but can be influenced by the geometry of the water wire connecting the ions as they approach each other, which can often prevent recombination. Our results provide insights to the reaction microenvironments presented by nanoscopic water droplets.
", "doi": "10.1021/jacs.4c15103", "issn": "0002-7863", "publisher": "American Chemical Society", "publication": "Journal of the American Chemical Society", "publication_date": "2025-02-26", "series_number": "8", "volume": "147", "issue": "8", "pages": "6583\u20136593" }, { "id": "authors:3whnp-y8857", "collection": "authors", "collection_id": "3whnp-y8857", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230615-812890000.24", "type": "article", "title": "Linker mediated enhancement in reusability and regulation of Pb(II) removal mechanism of Cu-centered MOFs", "author": [ { "family_name": "Goyal", "given_name": "Prateek", "clpid": "Goyal-Prateek" }, { "family_name": "Menon", "given_name": "Dhruv", "orcid": "0000-0001-6264-8660", "clpid": "Menon-Dhruv" }, { "family_name": "Jain", "given_name": "Pahuni", "clpid": "Jain-Pahuni" }, { "family_name": "Prakash", "given_name": "Prabhat", "orcid": "0000-0003-1430-2379", "clpid": "Prakash-Prabhat" }, { "family_name": "Misra", "given_name": "Superb K.", "orcid": "0000-0001-5551-2706", "clpid": "Misra-Superb-K" } ], "abstract": "Our study demonstrates improved hydrolytic stability of Cu-centered MOFs through linker selection, resulting in enhanced and selective Pb(II) removal with contrasting removal mechanisms. A simple one-pot solvothermal process was employed to synthesize Copper 1,3,5-Benzene-Tricarboxylic Acid (Cu-BTC) MOF, Copper Imidazolate (Cu-Im) MOF and Copper Nicotinic Acid (Cu-NA) MOF, respectively. The synthesis of these MOFs was confirmed using characterization techniques such as XPS, XRD, FTIR and ICP-OES. Water stability studies using experimental and modelling approaches demonstrated that substituting the 1,3,5-benzene-tricarboxylic acid linker with either imidazolate or nicotinic acid, enhanced the hydrostability of the Cu-centered MOF from under 2 h to over 48 h, while showing a high Pb(II) adsorption capacity of 492 mg g\u22121. This improved hydrostability was observed across acidic and basic pH and at elevated temperatures. The improved stability of Cu-Im significantly enhanced its reusability and showed Pb(II) adsorption for 3 cycles, with 99.5 % removal efficiency at the end of the 3rd cycle and a desorption efficiency of 92.7 %. The experimental data obtained were substantiated with modelling studies (density functional theory) to gain insights into the 2D structure of Cu-Im and compare the hydrolytic stability of Cu-BTC and Cu-Im. Cu-Im, when tested on textile effluent showed a Pb(II) removal efficiency of 99 % within 2 h of treatment. This study opens up the possibility of using linker selection and design as a strategy to enhance the hydrostability of Cu-centered MOFs and in the process improve its applicability for environmental remediation applications.", "doi": "10.1016/j.seppur.2023.123941", "issn": "1383-5866", "publisher": "Elsevier", "publication": "Separation and Purification Technology", "publication_date": "2023-08-01", "volume": "318", "pages": "Art. No. 123941" }, { "id": "authors:vcz2t-vb387", "collection": "authors", "collection_id": "vcz2t-vb387", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230412-109103400.5", "type": "article", "title": "Theoretical Assessment of Carbon Dioxide Reactivity in Methylpiperidines: A Conformational Investigation", "author": [ { "family_name": "Mukherjee", "given_name": "Uttama", "orcid": "0000-0003-4855-1875", "clpid": "Mukherjee-Uttama" }, { "family_name": "Prakash", "given_name": "Prabhat", "orcid": "0000-0003-1430-2379", "clpid": "Prakash-Prabhat" }, { "family_name": "Venkatnathan", "given_name": "Arun", "orcid": "0000-0001-8450-5417", "clpid": "Venkatnathan-Arun" } ], "abstract": "In this work, the possible mechanisms for the reactions of CO\u2082 with various positional isomers of methylpiperidines (MPs) (N-MP, 2-MP, 3-MP, and 4-MP) including the effect of aqueous solvation have been explored using quantum chemical methods. The major pathways investigated for CO\u2082 capture in aqueous amines are carbamate formation, its hydrolysis, and the bicarbonate formation (CO\u2082 + H\u2082O + MP) reaction. The calculations indicate that an axial orientation for the methyl group and an equatorial for the COO\u207b group could be energetically ideal in the carbamate product of MPs. The proton abstraction step in the carbamate pathway is almost barrierless for the zwitterion-amine route, while a much higher energy barrier is observed for the zwitterion-H\u2082O route. During carbamate hydrolysis, the addition of even two explicit water molecules does not exhibit any notable effect on the already high energy barrier associated with this reaction. This indicates that bicarbonate formation is less likely to occur via carbamate hydrolysis. The calculations suggest that, although the carbamate pathway is kinetically favored, the MP carbamate could still be a minor product, especially for sterically hindered conformations, and the bicarbonate pathway should be predominant in aqueous MPs.", "doi": "10.1021/acs.jpca.3c00406", "issn": "1089-5639", "publisher": "American Chemical Society", "publication": "Journal of Physical Chemistry A", "publication_date": "2023-04-13", "series_number": "14", "volume": "127", "issue": "14", "pages": "3123-3132" }, { "id": "authors:03m93-c8507", "collection": "authors", "collection_id": "03m93-c8507", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211012-211827323", "type": "article", "title": "Reaction Mechanism and Energetics of Decomposition of Tetrakis(1,3-dimethyltetrazol-5-imidoperchloratomanganese(II)) from Quantum-Mechanics-based Reactive Dynamics", "author": [ { "family_name": "Zybin", "given_name": "Sergey V.", "clpid": "Zybin-Sergey-V" }, { "family_name": "Morozov", "given_name": "Sergey I.", "orcid": "0000-0001-6226-5811", "clpid": "Morozov-Sergey-I" }, { "family_name": "Prakash", "given_name": "Prabhat", "orcid": "0000-0003-1430-2379", "clpid": "Prakash-Prabhat" }, { "family_name": "Zdilla", "given_name": "Michael J.", "orcid": "0000-0003-0212-2557", "clpid": "Zdilla-Michael-J" }, { "family_name": "Goddard", "given_name": "William A., III", "orcid": "0000-0003-0097-5716", "clpid": "Goddard-W-A-III" } ], "abstract": "Energetic materials (EMs) are central to construction, space exploration, and defense, but over the past 100 years, their capabilities have improved only minimally as they approach the CHNO energetic ceiling, the maximum energy density possible for EMs based on molecular carbon\u2013hydrogen\u2013nitrogen\u2013oxygen compounds. To breach this ceiling, we experimentally explored redox-frustrated hybrid energetic materials (RFH EMs) in which metal atoms covalently connect a strongly reducing fuel ligand (e.g., tetrazole) to a strong oxidizer (e.g., ClO\u2084). In this Article, we examine the reaction mechanisms involved in the thermal decomposition of an RFH EM, [Mn(Me\u2082TzN)(ClO\u2084]\u2084 (3, Tz = tetrazole). We use quantum-mechanical molecular reaction dynamics simulations to uncover the atomistic reaction mechanisms underlying this decomposition. We discover a novel initiation mechanism involving oxygen atom transfer from perchlorate to manganese, generating energy that promotes the fission of tetrazole into chemically stable species such as diazomethane, diazenes, triazenes, and methyl azides, which further undergo exothermic decomposition to finally form stable N\u2082, H\u2082O, CO, CO\u2082, Mn-based clusters, and additional incompletely combusted products.", "doi": "10.1021/jacs.1c04847", "issn": "0002-7863", "publisher": "American Chemical Society", "publication": "Journal of the American Chemical Society", "publication_date": "2021-10-20", "series_number": "41", "volume": "143", "issue": "41", "pages": "16960-16975" } ]