Ferrocene-Boosted Nickel Sulfide Nanoarchitecture for Enhanced Alkaline Water Splitting.

Enhanced electrocatalysts that are cost-effective, durable, and derived from abundant resources are imperative for developing efficient and sustainable electrochemical water-splitting systems to produce hydrogen. Therefore, the design and development of non-noble-based catalysts with more environmentally sustainable alternatives in efficient alkaline electrolyzers are important. This work reports ferrocene (Fc)-incorporated nickel sulfide nanostructured electrocatalysts (Fc-NiS) using a one-step facile solvothermal method for water-splitting reactions. Fc-NiS exhibited exceptional electrocatalytic activity under highly alkaline conditions, evident from its peak current density of 345 mA cm-2, surpassing the 153 mA cm-2 achieved by the pristine nickel sulfide (NiS) catalysts. Introducing ferrocene enhances electrical conductivity and facilitates charge transfer during water-splitting reactions, owing to the inclusion of iron metal. Fc-NiS exhibits a very small overpotential of 290 mV at 10 mA cm-2 and a Tafel slope of 50.46 mV dec-1, indicating its superior charge transfer characteristics for the three-electron transfer process involved in water splitting. This outstanding electrocatalytic performance is due to the synergistic effects embedded within the nanoscale architecture of Fc-NiS. Furthermore, the Fc-NiS catalyst also shows a stable response for the water-splitting reactions. It maintains a steady current density with an 87% retention rate for 25 hours of continuous operation, indicating its robustness and potential for prolonged electrolysis processes.

Toward Improved Lifetimes of Organic Solar Cells under Thermal Stress: Substrate-Dependent Morphological Stability of PCDTBT:PCBM Films and Devices.

Morphological stability is a key requirement for outdoor operation of organic solar cells. We demonstrate that morphological stability and lifetime of polymer/fullerene based solar cells under thermal stress depend strongly on the substrate interface on which the active layer is deposited. In particular, we find that the stability of benchmark PCDTBT/PCBM solar cells under modest thermal stress is substantially increased in inverted solar cells employing a ZnO substrate compared to conventional devices employing a PEDOT: PSS substrate. This improved stability is observed to correlate with PCBM nucleation at the 50 nm scale, which is shown to be strongly influenced by different substrate interfaces. Employing this approach, we demonstrate remarkable thermal stability for inverted PCDTBT:PC70BM devices on ZnO substrates, with negligible (<2%) loss of power conversion efficiency over 160 h under 85 °C thermal stress and minimal thermally induced "burn-in" effect. We thus conclude that inverted organic solar cells, in addition to showing improved environmental stability against ambient humidity exposure as widely reported previously, can also demonstrate enhanced morphological stability. As such we show that the choice of suitable substrate interfaces may be a key factor in achieving prolonged lifetimes for organic solar cells under thermal stress conditions.

High-performance ambipolar diketopyrrolopyrrole-thieno[3,2-b]thiophene copolymer field-effect transistors with balanced hole and electron mobilities.

Ambipolar OFETs with balanced hole and electron field-effect mobilities both exceeding 1 cm(2) V(-1) s(-1) are achieved based on a single-solution-processed conjugated polymer, DPPT-TT, upon careful optimization of the device architecture, charge injection, and polymer processing. Such high-performance OFETs are promising for applications in ambipolar devices and integrated circuits, as well as model systems for fundamental studies.