Anodically Grown Binder-Free Nickel Hexacyanoferrate Film: Toward Efficient Water Reduction and Hexacyanoferrate Film Based Full Device for Overall Water Splitting.

One of the challenges in obtaining hydrogen economically by electrochemical water splitting is to identify and substitute cost-effective earth-abundant materials for the traditionally used precious-metal-based water-splitting electrocatalysts. Herein, we report the electrochemical formation of a thin film of nickel-based Prussian blue analogue hexacyanoferrate (Ni-HCF) through the anodization of a nickel substrate in ferricyanide electrolyte. As compared to the traditionally used Nafion-binder-based bulk film, the anodically obtained binder-free Ni-HCF film demonstrates superior performance in the electrochemical hydrogen evolution reaction (HER), which is highly competitive with that shown by a Pt-plate electrode. The HER onset and the benchmark cathodic current density of 10 mA cm-2 were achieved at small overpotentials of 15 mV and 0.2 V (not iR-corrected), respectively, in 1 M KOH electrolyte, together with the long-term electrochemical durability of the film. Further, a metal-HCF-electrode-based full water-splitting device consisting of the binder-free Ni-HCF film on a Ni plate and a one-dimensional Co-HCF film on carbon paper as the electrodes for the HER and the oxygen evolution reaction (OER), respectively, was designed and was found to demonstrate very promising performance for overall water splitting.

Synthesis and characterization of new silafluorene-based copolymers for polymer solar cells.

A series of silafluorene-based copolymers, poly[9-(2-ethylhexyl)-9-dodecyl-silafluorene-2,7-diyl-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (P1), poly[9-(2-ethylhexyl)-9-dodecyl-silafluorene-2,7-diyl-alt-2,5-bis-(thiophene-2-yl)thiazolo [5,4-d]thiazole] (P2), and poly[9-(2-ethylhexyl)-9-dodecyl-silafluorene-2,7-diyl-alt-5,5-(5',8'-di-2-thienyl-2,3-bis(4-octyloxyl)phenyl)quinoxaline] (P3), were synthesized and used as donor materials in polymer solar cells (PSCs). The optical, electrochemical, and photovoltaic properties of the copolymers were investigated. The results indicate that the acceptor units in the copolymers influenced the band gap, electronic energy levels, and photovoltaic properties of the copolymers significantly. The band gaps of the copolymers were in the range 1.82-2.10 eV. Under optimized conditions, the silafluorene-based polymers showed power conversion efficiencies (PCEs) for the PSCs in the range 1.31-1.69% under AM 1.5 illumination (100 mW/cm2). Among the three copolymers, P1, which contained a benzothiadiazole acceptor unit, showed a power conversion efficiency of 1.69% with a short circuit current of 4.59 mA/cm2, open circuit voltage of 0.88 V, and a fill factor of 0.42, under AM 1.5 illumination (100 mW/cm2).