Graphical For the first time, gold (Au) concave nanocubes are generated in high uniformity via a silver(Ag)-free seeded growth. Due to the advantage in pure element, they are serving as an ideal research model to investigate the exact contribution role of crystal facet in electrocatalysis. Using ethanol oxidation reaction as a model reaction, both experimental and theoretical evidences are provided. We report a silver-free synthesis of gold (Au) concave nanocubes (CNCs) that involves the direct deposition of Au atoms over spherical Au seeds under well-controlled reaction kinetics and surface capping. The elementally-pure composition makes them ideal research candidate towards validating structural advantage of concave surface in electrocatalytic oxidation of ethanol. In particular, the as-obtained Au CNCs exhibited an enhanced specific activity and reaction kinetics, but weakened long-term stability, as compared to quasi-spherical counterparts. Theoretical simulations suggest that the high-index planes represent a high catalytic performance for ethanol oxidation. The current work offers an effective synthetic strategy that successfully excludes the necessary and wide use of Ag + ions in controlled synthesis of pure Au nanocrystals with a concave cubic shape, shedding light on the rational design of fuel cell electrocatalyst from the perspective of crystal facet effect.
Han Xu,Rutao Meng,Xuejun Xu,Yue Liu,Yali Sun,Yi Zhang
Alkali metal is the requirement for highly efficient Cu 2 ZnSn(S, Se) 4 (CZTSSe) solar cells, thus it is crucial to additionally incorporate alkali metal into the absorber layer for flexible solar cells. However, the efficiency of flexible CZTSSe devices reported to date, based on the conventional alkali incorporation strategies, still lags behind those made on rigid substrates. One of the main issues is the inability to control the alkali content and distribution in the absorber layer. Here, a facile alkaline incorporation approach is proposed, effectively regulating the content and distribution of alkali metals in the film. Such a method can spontaneously tailor the alkali metal content to a proper level, thus leading to the suppression of non-radiative recombination and a better carrier transport through the enhanced film quality and the optimized band binding structure. Finally, a champion flexible CZTSSe solar cell with an efficiency of 11.88% is achieved, the highest reported efficiency for a CZTSSe solar cell without noble Ag doping. This study affords an innovative spontaneous alkali-doping design for the preparation of high-performance flexible CZTSSe solar cells and provides a deeper insight into the extent of alkali metal doping.
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