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The need for carbon‐neutralization technologies has prompted significant interest in developing materials for CO2 reduction. Donor–acceptor (D–A) based flexible porous coordination polymers {[Zn(o‐phen)(ndc)].(guest)}n, (guest = anthracene = 1‐Ant, and pyrene = 1‐Pyr) are reported as photocatalysts for CO2RR, yielding higher order CH4 product. Electron‐rich anthracene (Ant) and pyrene (Pyr) guests are confined within nanopores, forming D–A charge transfer (CT) complexes with o‐phen ligand of the host. CT interaction enhances visible light absorption and modulates excitonic properties of the photocatalyst by electronic push‐pull effect (exciton binding energy 87 meV for 1‐Ant and 104 meV for 1‐Pyr). Electron donation capability varies from Pyr to Ant, affecting catalytic properties; 1‐Ant yields 1.24 mmolg−1 of CH4 (0.47 mmolg−1 for 1‐Pyr) with CO as minor product. A mixed‐metal multivariate PCP {[Zn0.55Co0.45(o‐phen)(ndc)].(Ant)}n, (1′‐Ant) prepared based on solid‐solution approach by substituting Zn(II) with redox‐active Co(II) enhances CH4 production (2.79 mmolg−1, ≈94% selectivity). D–A CT complex harvests visible light and channels electrons to Co(II) for CO2RR. In situ DRIFTS and theoretical studies elucidate Co(II) site's role in CO2 binding and stabilizing reaction intermediates. This work underscores guest‐modulated electron transfer in PCPs for tailoring catalytic properties by introducing a redox‐active metal in a multivariate approach. [ABSTRACT FROM AUTHOR]

The 1D array of electron donor–acceptor chromophoric organic molecules is of paramount importance for photovoltaic, catalytic and optoelectronic applications. Herein, we report coordination driven 1D arrays of an electron-donor guest (fluorene, carbazole, dibenzofuran, and dibenzothiophene) and o-phen chelator as an acceptor in a Zn-based porous coordination polymer, {[Zn(o-phen)(ndc)]·DMF} (PCP-1). All the guest-encapsulated PCPs were characterized by performing single-crystal structure determinations and showed emission driven by charge transfer. Exciton binding energies were calculated and correlated with electron-donating capabiliities of the guest molecules. [ABSTRACT FROM AUTHOR]

The synthesis of covalent organic frameworks (COFs) at bulk scale require robust, straightforward, and cost‐effective techniques. However, the traditional solvothermal synthetic methods of COFs suffer low scalability as well as requirement of sensitive reaction environment and multiday reaction time (2–10 days) which greatly restricts their practical application. Here, we report microwave assisted rapid and optimized synthesis of a donor‐acceptor (D−A) based highly crystalline COF, TzPm‐COF in second (10 sec) to minute (10 min) time scale. With increasing the reaction time from seconds to minutes crystallinity, porosity and morphological changes are observed for TzPm‐COF. Owing to visible range light absorption, suitable band alignment, and low exciton binding energy (Eb=64.6 meV), TzPm‐COF can efficaciously produce superoxide radical anion (O2.−) after activating molecular oxygen (O2) which eventually drives aerobic photooxidative amidation reaction with high recyclability. This photocatalytic approach works well with a variety of substituted aromatic aldehydes having electron‐withdrawing or donating groups and cyclic, acyclic, primary or secondary amines with moderate to high yield. Furthermore, catalytic mechanism was established by monitoring the real‐time reaction progress through in situ diffuse reflectance infrared Fourier transform spectroscopic (DRIFTS) study. [ABSTRACT FROM AUTHOR]

In essence, the utilization of renewable energy in the carbon dioxide reduction reaction (CO2RR) holds the potential to transform carbon emissions into valuable chemicals, encompassing a range of hydrocarbons and alcohols. Herein, we have implemented a redox-active triphenylamine (TPA)-based covalent organic nanosheets (CONs) as a metal-free electrocatalyst for CO2 reduction in 0.2 M phosphate buffer (pH-7.2). The reaction produced methanol as the only carbonaceous liquid product reaching a maximum faradaic efficiency (FE) of 51.6% under mild reaction conditions in aqueous medium. Moreover, the corresponding overpotential of the reaction was as low as 210 mV illustrating the superiority of this metal-free electrocatalyst. The mechanistic aspects are supported through experimental in situ RAS-IR (reflection-absorption), in situ Raman study as well as computational study. The superior performance of the electrocatalyst is believed to be due to the presence of redox-active 2-D nanosheets with exposed active sites. This work unlocks a way to produce methanol efficiently by the electrochemical reduction of CO2. [ABSTRACT FROM AUTHOR]

The energy barrier to dissociate neutral water has been lowered by the differential intermediate binding on the charge‐modulated metal centers of Co85Mo15 sheets supported on Ni‐foam (NF), where the overpotential for hydrogen evolution reaction (HER) in 1 M phosphate buffer solution (PBS) is only 50±9 mV at −10 mA cm−2. It has a turnover frequency (TOF) of 0.18 s−1, mass activity of 13.2 A g−1 at −200 mV vs. reversible hydrogen electrode (RHE), and produces 16 ml H2 h−1 at −300 mV vs. RHE, more than double that of 20 % Pt/C. The Moδ+ and Coδ− sites adsorb OH*, and H*, respectively, and the electron injection from Co to H−O−H cleaves the O−H bond to form the Mo−OH* intermediate. Operando spectral analyses indicate a weak H‐bonded network for facilitating the H2O*/OH* transport, and a potential‐induced reversal of the charge density from Co to the more electronegative Mo, because of the electron withdrawing Co−H* and Mo−OH* species. Co85Mo15/NF can also drive the complete electrolysis of neutral water at only 1.73 V (10 mA cm−2). In alkaline, and acidic media, it demonstrates a Pt‐like HER activity, accomplishing −1000 mA cm−2 at overpotentials of 161±7, and 175±22 mV, respectively. [ABSTRACT FROM AUTHOR]

Efficient solar‐driven syngas production (CO+H2 mixture) from CO2 and H2O with a suitable photocatalyst and fundamental understanding of the reaction mechanism are the desired approach towards the carbon recycling process. Herein, we report the design and development of an unique COF‐topological quantum material nano‐heterostructure, COF@TI with a newly synthesized donor‐acceptor based COF and two dimensional (2D) nanosheets of strong topological insulator (TI), PbBi2Te4. The intrinsic robust metallic surfaces of the TI act as electron reservoir, minimising the fast electron‐hole recombination process, and the presence of 6s2 lone pairs in Pb2+ and Bi3+ in the TI helps for efficient CO2 binding, which are responsible for boosting overall catalytic activity. In variable ratio of acetonitrile‐water (MeCN : H2O) solvent mixture COF@TI produces syngas with different ratios of CO and H2. COF@TI nano‐heterostructure enables to produce higher amount of syngas with more controllable ratios of CO and H2 compared to pristine COF. The electron transfer route from COF to TI was realized from Kelvin probe force microscopy (KPFM) analysis, charge density difference calculation, excited state lifetime and photoelectrochemical measurements. Finally, a probable mechanistic pathway has been established after identifying the catalytic sites and reaction intermediates by in situ DRIFTS study and DFT calculation. [ABSTRACT FROM AUTHOR]