Developing efficient electrocatalysts for urea oxidation reaction (UOR) can be a promising alternative strategy to substitute the sluggish oxygen evolution reaction (OER), thereby producing hydrogen at a lower cell-voltage. Herein, we synthesized a binder-free thin film of ultrathin sheets of bimetallic Cu-Fe-based metal–organic frameworks (Cu/Fe-MOFs) on a nickel foam via a drop-casting route. In addition to the scalable route, the drop-casted film-electrode demonstrates the lower UOR potentials of 1.59, 1.58, 1.54, 1.51, 1.43 and 1.37 V vs. RHE to achieve the current densities of 2500, 2000, 1000, 500, 100 and 10 mA cm−2, respectively. These UOR potentials are relatively lower than that acquired by the pristine Fe-MOF-based film-electrode synthesized via a similar route. For example, at 1.59 V vs. RHE, the Cu/Fe-MOF electrode exhibits a remarkably ultra-high anodic current density of 2500 mA cm—2, while the pristine Fe-MOF electrode exhibits only 949.10 mA cm−2. It is worth noting that the Cu/Fe-MOF electrode at this potential exhibits an OER current density of only 725 mA cm—2, which is far inconsequential as compared to the UOR current densities, implying the profound impact of the bimetallic cores of the MOFs on catalyzing UOR. In addition, the Cu/Fe-MOF electrode also exhibits a long-term electrochemical robustness during UOR.

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We synthesized and characterized a series of pyrene units incorporated into benzo [1,2-b:4,5-b′]dithiophene-based random copolymers. Concentration-dependent pyrene-driven self-assembly in the copolymers was systematically investigated using measurements of the copolymer optical and electrochemical properties, the hole mobilities extracted from the field-effect transistor and the space charge limited current, and the photovoltaic characteristics. We additionally studied the morphological changes using differential scanning calorimetry (DSC), synchrotron X-ray diffraction analysis, AFM, and TEM. The Py−Py interactions were found to facilitate the formation of fibrous structures. As the Py content increased, multiple Py−Py interactions within a few polymer chains dominated the interchain interactions to produce a more ordered phase but less interconnectivity among many polymer chains. A threshold quantity of the Py moieties enabled the Py−Py interactions to propagate over many polymer chains to form a highly interconnected structure that improved hole transport pathways and, thus, the photovoltaic performances of resulting bulk heterojunction polymer solar cells (5.03 → 7.52%).

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