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The Ti sublayer affects the morphology and catalytic performances of the sputtered Ni film on carbon fiber paper in electrocatalytic hydrogenation of benzaldehyde, by increasing the adhesion strength between Ni and substrate, facilitating electron/ion transfer, and enriching the local concentration of hydronium ions. [Display omitted] • Magnetron sputtering was used to synthesize free-standing film electrocatalysts. • Working pressure during sputtering was altered to refine the nanoscale structures. • The Ti sublayer between Ni and CFP changes the surface morphology of Ni film. • The Ti sublayer facilitates electron/ion transfer and highly increases the activity. • In-situ IR study reveals Ti sublayer enriches local concentration of hydronium ions. Highly effective free-standing electrocatalysts are demanded to reduce biomass-oriented aldehydes to alcohols. Magnetron sputtering is efficient to produce film-based catalysts, but depositing transition metals on carbon fiber paper (CFP) faces the challenge of weak adhesion. Here we introduced a strategy with sputtered Ti as a sublayer to enhance the adhesion between Ni and CFP, and systematically studied the changes in morphology and catalytic performances. Different from the dense structure of Ni directly sputtered on CFP, the Ni on Ti sublayer demonstrates a column-channel architecture, and shows fast electron/ion transfer and stable structure during the reaction. Moreover, the microstructure of Ni film was further modified by regulating the working pressure during sputtering. The enhanced electrocatalytic performance with Ti sublayer is ascribed to the higher adhesion strength, the faster electron/ion transfer and the enriched local concentration of hydronium ions, which are confirmed by electrochemical impedance spectroscopy and in-situ surface-enhanced infrared absorption spectroscopy. [ABSTRACT FROM AUTHOR]

In this work, we prepare a series of NiCu alloy film catalysts with different contents by magnetron sputtering to investigate the synergistic effect between Ni and Cu in electrocatalytic hydrogenation of benzaldehyde. The results show that alloying of Ni and Cu can significantly enhance the electrocatalytic activity of benzaldehyde hydrogenation. With the increase of Ni content, the conversion rate of benzaldehyde increases two to three orders of magnitude, and the Faradaic efficiency of the Ni-rich catalysts is higher than that of the Cu-rich catalysts. In addition, the alloy composition affects the relative coverages of H and benzaldehyde, leading to different reaction orders in benzaldehyde. The boosted electrocatalytic activity with the increase of Ni content is in accordance with the electrochemical impedance spectroscopy that increasing Ni content can decrease the charge transfer resistance of the alloy catalysts. [Display omitted] • A series of NiCu film catalysts were prepared by magnetron sputtering. • NiCu alloy catalysts improve the ECH of benzaldehyde. • The increasing Ni content decreases the charge transfer resistance of NiCu alloys. [ABSTRACT FROM AUTHOR]