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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]

Alloying Ni with Pd lowers the overpotential of benzaldehyde hydrogenation and obtains a reaction rate 20 times higher than that of Ni at 0.1 V vs. RHE, which is ascribed to the lower binding energy of benzaldehyde on the metal surface revealed by the in-situ IR study. [Display omitted] • Nanoporous nanowire NiPd alloys were synthesized using a dealloying method. • Alloying Ni and Pd lowers the overpotential of ECH of benzaldehyde. • The activity of NiPd alloy is comparable with Pd. • In-situ IR study reveals that Pd tunes the binding strength of adsorbed benzaldehyde. Ni is one of the most promising catalysts in aldehydes hydrogenation, although the high overpotential and low Faradaic efficiency limit its electrocatalytic performances. Here we introduce an effective and facile alloying strategy to tune the electronic structure of Ni. We demonstrate that alloying Pd to Ni can significantly boost the electrocatalytic performances of benzaldehyde hydrogenation and lower the overpotential to the level of pure Pd. Pd introduction enhances the electrocatalytic hydrogenation process over hydrogen evolution reaction (HER), and results in an increased Faradaic efficiency. The npnw-Ni 82 Pd 18 catalyst shows the optimal atomic ratio of Ni and Pd among the explored catalysts, and achieved a turnover frequency (TOF) value of 1387 mol mol metal -1h-1 at -0.1 V vs. reversible hydrogen electrode (RHE), higher than that of npnw-Ni (60 mol mol metal -1h-1) and comparable to np-Pd (1306 mol mol metal -1h-1) under the same reaction conditions. In-situ surface-enhanced infrared absorption spectroscopy study reveals that the electronic interactions between Ni and Pd would activate the adsorbed benzaldehyde, and therefore result in an enhanced activity in benzaldehyde hydrogenation. [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]