A high-throughput sonochemical synthesis and testing strategy was developed to discover covalent organic frameworks (COFs) for photocatalysis. In total, 76 conjugated polymers were synthesized, including 60 crystalline COFs of which 18 were previously unreported. These COFs were then screened for photocatalytic hydrogen peroxide (H2O2) production using water and oxygen. One of these COFs, sonoCOF-F2, was found to be an excellent photocatalyst for photocatalytic H2O2 production even in the absence of sacrificial donors. However, after long-term photocatalytic tests (96 h), the imine sonoCOF-F2 transformed into an amide-linked COF with reduced crystallinity and loss of electronic conjugation, decreasing the photocatalytic activity. When benzyl alcohol was introduced to form a two-phase catalytic system, the photostability of sonoCOF-F2 was greatly enhanced, leading to stable H2O2 production for at least 1 week.

Here, an effective design strategy of polymer thermoelectric materials based on structural control in doped polymer semiconductors is presented. The strategy is illustrated for two archetypical polythiophenes, e.g., poly(2,5‐bis(3‐dodecyl‐2‐thienyl)thieno[3,2‐b]thiophene) (C12‐PBTTT) and regioregular poly(3‐hexylthiophene) (P3HT). FeCl3 doping of aligned films results in charge conductivities up to 2 × 105 S cm−1 and metallic‐like thermopowers similar to iodine‐doped polyacetylene. The films are almost optically transparent and show strongly polarized near‐infrared polaronic bands (dichroic ratio >10). The comparative study of structure–property correlations in P3HT and C12‐PBTTT identifies three conditions to obtain conductivities beyond 105 S cm−1: i) achieve high in‐plane orientation of conjugated polymers with high persistence length; ii) ensure uniform chain oxidation of the polymer backbones by regular intercalation of dopant molecules in the polymer structure without disrupting alignment of π‐stacked layers; and iii) maintain a percolating nanomorphology along the chain direction. The highly anisotropic conducting polymer films are ideal model systems to investigate the correlations between thermopower S and charge conductivity σ. A scaling law S ∝ σ−1/4 prevails along the chain direction, but a different S ∝ −ln(σ) relation is observed perpendicular to the chains, suggesting different charge transport mechanisms. The simultaneous increase of charge conductivity and thermopower along the chain direction results in a substantial improvement of thermoelectric power factors up to 2 mW m−1 K−2 in C12‐PBTTT.

The dynamics of the graphene–catalyst interaction during chemical vapor deposition are investigated using in situ, time- and depth-resolved X-ray photoelectron spectroscopy, and complementary grand canonical Monte Carlo simulations coupled to a tight-binding model. We thereby reveal the interdependency of the distribution of carbon close to the catalyst surface and the strength of the graphene–catalyst interaction. The strong interaction of epitaxial graphene with Ni(111) causes a depletion of dissolved carbon close to the catalyst surface, which prevents additional layer formation leading to a self-limiting graphene growth behavior for low exposure pressures (10–6–10–3 mbar). A further hydrocarbon pressure increase (to ∼10–1 mbar) leads to weakening of the graphene–Ni(111) interaction accompanied by additional graphene layer formation, mediated by an increased concentration of near-surface dissolved carbon. We show that growth of more weakly adhered, rotated graphene on Ni(111) is linked to an initially higher level of near-surface carbon compared to the case of epitaxial graphene growth. The key implications of these results for graphene growth control and their relevance to carbon nanotube growth are highlighted in the context of existing literature.

Electrochemically active covalent organic frameworks (COFs) are promising electrode materials for Li-ion batteries. However, improving the specific capacities of COF-based electrodes requires materials with increased conductivity and a higher concentration of redox-active groups. Here, we designed a series of pyrene-4,5,9,10-tetraone COF (PT-COF) and carbon nanotube (CNT) composites (denoted as PT-COFX, where X = 10, 30, and 50 wt % of CNT) to address these challenges. Among the composites, PT-COF50 achieved a capacity of up to 280 mAh g –1 as normalized to the active COF material at a current density of 200 mA g –1 , which is the highest capacity reported for a COF-based composite cathode electrode to date. Furthermore, PT-COF50 exhibited excellent rate performance, delivering a capacity of 229 mAh g –1 at 5000 mA g –1 (18.5C). Using operando Raman microscopy the reversible transformation of the redox-active carbonyl groups of PT-COF was determined, which rationalizes an overall 4 e – /4 Li + redox process per pyrene-4,5,9,10-tetraone unit, accounting for its superior performance as a Li-ion battery electrode.

rystalline covalent organic frameworks (COFs) have received much attention because of their use in catalysis, adsorption, separation, chemosensing, drug delivery and energy storage and production [1][2][3] . The traditional route to COFs is solvothermal synthesis 4 , but this often requires the use of sealed, pressurized tubes, elevated reaction temperatures (120-200 °C), long reaction times (2-7 days) and toxic organic solvents. These drawbacks provide an incentive to develop alternative methods to synthesize COFs.Alternatives to solvothermal syntheses include microwave synthesis 5 and room-temperature syntheses using catalysts 6,7 . These routes can be much faster than solvothermal syntheses, with reaction times of 1-2 h. However, it is still desirable to avoid the use of toxic organic solvents and metal catalysts. Solid-state synthesis is one route that eliminates bulk solvent use and reduces waste generation. p-Toluenesulfonic acid, a strong solid acid, was first used as the catalyst for solid-state COF synthesis by Kandambeth et al. 8 . However, a large quantity of p-toluenesulfonic acid (~6 molar equiv. based on the amine monomers) was required during the synthesis, and high temperatures (90-170 °C) for one minute to two days were needed to obtain the crystalline COFs 9,10 . Mechanochemical synthesis is another promising solid-state route. The first examples of COF mechanosynthesis were reported by Biswal et al. 11 . Solvent-free mechanochemical processes offer the potential for large-scale COF synthesis, but such studies are rare and the COFs produced have limited crystallinity and porosity 12 . For example, the mechanically synthesized COFs TpPa-1, TpPa-2 and TpBD had only moderate crystallinity and low Brunauer-Emmet-Teller (BET) surface areas (61 m 2 g -1 for TpPa-1, 56 m 2 g -1 for TpPa-2 and 35 m 2 g -1 for TpBD) compared with those of their solvothermal analogues 11 . Recent work by Emmerling et al. 13 showed that alternative activation methods, such as supercritical CO 2 drying 14,15 , may allow access to the porosity of mechanochemically prepared COFs.

low specific capacity of 73 mAh g −1 at 500 mA g −1 in a Li-ion cell. However, the electrochemical performance was greatly enhanced by forming the tube-type core-shell structure of the composites (DAPQ-COFX). Using this approach, we achieved specific capacities of up to 162 mAh g −1 at 500 mA g −1 . By varying the composition of the DAPQ-COFX composite, it was found that DAPQ-COF50, which contained 50 wt% of CNT, exhibited the highest utilization of the redox-active sites (95%). Notably, the DAPQ-COF50 composite presents the best rate performance in COF-based electrode materials reported so far, facilitating ultrafast charge/discharge rates as high as 50 A g −1 -this means that the device can be fully charged in just 11 s.

The synthesis of three-dimensional (3D) covalent organic frameworks (COFs) requires high-connectivity polyhedral building blocks or the controlled alignment of building blocks. Here, we use the latter strategy to assemble square-planar cobalt­(II) phthalocyanine (PcCo) units into the nbo topology by using tetrahedral spiroborate (SPB) linkages that were chosen to provide the necessary 90° dihedral angles between neighboring PcCo units. This yields a porous 3D COF, SPB-COF-DBA, with a noninterpenetrated nbo topology. SPB-COF-DBA shows high crystallinity and long-range order, with 11 resolved diffraction peaks in the experimental powder X-ray diffraction (PXRD) pattern. This well-ordered crystal lattice can also be imaged by using high-resolution transmission electron microscopy (HR-TEM). SPB-COF-DBA has cubic pores and exhibits permanent porosity with a Brunauer–Emmett–Teller (BET) surface area of 1726 m2 g–1.

Iridium oxide is the gold‐standard catalyst for the oxygen evolution reaction (OER) in acidic media due to its unmatched activity and stability. Here, a new catalyst architecture comprising a nanoneedle network of iridium‐containing oxides assembled into macroporous micrometric particles with ≈75% of porosity is reported. The rationally designed porous hierarchical structure optimizes the accessibility of reactants and products to the surface of the nanoparticles and maximizes catalyst activity. The materials are easily prepared from aqueous solutions by an industrially viable spray‐drying route through an evaporation self‐assembly mechanism. The versatility of the process enables the preparation of mixed oxides with low iridium content, particles with tunable crystallinity, and various iridium surface species with high electrochemical activity. Highly porous Ir0.7Ru0.3O2 outperforms commercial iridium oxide. These materials also represent an ideal platform to assess the reactivity of the iridium and oxygen species involved in the oxygen evolution reaction. Furthermore, it is demonstrated that these highly porous particles are optimal building blocks to be integrated into catalyst layers, without the drawbacks associated with the use of discrete nanoparticles. Fresh‐ and end‐of‐test membrane–electrode assemblies' characterization shows that their particular architecture is preserved upon catalyst layer preparation and after operation in a proton‐exchange membrane electrolysis cell.