Search

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]

Transition metal oxalate materials have shown huge competitive advantages for applications in supercapacitors. Herein, nanostructured cobalt oxalate supported on cobalt foils has been facilely fabricated by anodization, and could directly serve as additive/binder-free electrodes for supercapacitors. The as-prepared cobalt oxalate electrodes present superior specific capacitance of 1269 F g −1 at the current density of 6 A g −1 in the galvanostatic charge/discharge test. Moreover, the retained capacitance is as high as 87.2% as the current density increases from 6 A g −1 to 30 A g −1 . More importantly, the specific capacitance of cobalt oxalate retains 91.9% even after super-long cycling of 100,000 cycles. In addition, an asymmetric supercapacitor assembled with cobalt oxalate (positive electrode) and activated carbon (negative electrode) demonstrates excellent capacitive performance with high energy density and power density. [ABSTRACT FROM AUTHOR]

• Large-pore zeolites show great performance in the alkylation of phenol(s) with alcohol(s). • Zeolite pore constraints enhance the catalytic activity of BAS in alkylation. • Low concentrations of alcohols facilitate the alkylation with phenol(s). • Olefins are more effective than alcohols to produce electrophiles. • A potential operation mode is proposed for the alkylation of phenol(s) and alcohol(s). Moderately strong BAS and spacious microporous environments (i.e., large-pore acidic zeolites HBEA and HY) are important criteria for efficient alkylation of phenols with cyclic alcohols and alkenes, while very strong BAS appear to be responsible for catalyst deactivation. BAS confined in HBEA and HY pores show substantially higher turnover frequencies compared to solids without molecularly sized pore constraints. HBEA favors the formation of mono-alkylates, while enhanced formation of di-alkylates is observed on HY. Dehydration of alcohols always dominates over the alkylation at the onset of the reaction. Carbenium ions, the direct electrophile for aromatic oxygenates, are produced mainly from the adsorption and protonation of olefins. The present study shows that for the alkylation of phenols and cyclic alcohols in apolar liquids, the alcohol concentration should be kept low to avoid the formation of unreactive surface dimers and mitigate their inhibitory effects on olefin adsorption and protonation. [ABSTRACT FROM AUTHOR]

A class of ruthenium-nickel alloy catalysts featured with nanoporous nanowires (NPNWs) were synthesized by a strategy combining rapid solidification with two-step dealloying. RuNi NPNWs exhibit excellent electrocatalytic activity and stability for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in which the RuNi-2500 NPNWs catalyst shows an OER overpotential of 327 mV to deliver a current density of 10 mA cm−2 and the RuNi-0 NPNWs catalyst requires the overpotential of 69 mV at 10 mA cm−2 showing the best HER activity in alkaline media. Moreover, the RuNi-1500 NPNWs catalyst was used as the bifunctional electrocatalyst in a two-electrode alkaline electrolyzer for water splitting, which exhibits a low cell voltage of 1.553 V and a long-term stability of 24 h at 10 mA cm−2, demonstrating that the RuNi NPNWs catalysts can be considered as promising bifunctional alkaline electrocatalysts. A class of ruthenium-nickel alloy catalysts featured with nanoporous nanowires (NPNWs) was synthesized by a strategy combined rapid solidification with two-step dealloying, in which the total cell voltage of RuNi-1500 NPNWs electrolyzer for water splitting is 1.553 V to deliver a current density of 10 mA cm−2. [Display omitted] • A two-step dealloying strategy was used to prepare RuNi catalysts. • RuNi catalysts exhibit a unique nanoporous nanowires (NPNWs) morphology. • RuNi NPNWs catalysts show excellent electrocatalytic performance for OER and HER. • RuNi NPNWs catalysts can be used as bifunctional catalysts for water splitting. [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]

The synthesis of cost-effective and high-performance electrocatalysts for water splitting is the main challenge in electrochemical hydrogen production. In this study, we adopted a high throughput method to prepare bi-metallic catalysts for oxygen/hydrogen evolution reactions (OER/HER). A series of Ni–Mo alloy electrocatalysts with tunable compositions were prepared by a simple co-sputtering method. Due to the synergistic effect between Ni and Mo, the intrinsic electrocatalytic activity of the Ni–Mo alloy electrocatalysts is improved, resulting in excellent HER and OER performances. The Ni 90 Mo 10 electrocatalyst shows the best HER performance, with an extremely low overpotential of 58 mV at 10 mA cm−2, while the Ni 40 Mo 60 electrocatalyst shows an overpotential of 258 mV at 10 mA cm−2 in OER. More significantly, the assembled Ni 40 Mo 60 //Ni 90 Mo 10 electrolyzer only needs a cell voltage of 1.57 V to reach 10 mA cm−2 for overall water splitting. [Display omitted] • A high throughput method was used to prepare Ni–Mo alloy catalysts. • Ni–Mo alloy catalysts exhibit remarkable activity and stability for HER and OER. • The Ni–Mo alloy acts as a bifunctional catalyst for overall water splitting. • The synergistic effect between Ni and Mo leads to the excellent performances. [ABSTRACT FROM AUTHOR]

Magnetite (Fe 3 O 4) has become a potential anode material in lithium ion batteries (LIBs) because of its high theoretical capacity and low cost, but is impeded for application by its low conductivity and large volume change during cycling. Herein, the Fe 3 O 4 @C-500 composite was fabricated via the one-step pyrolytic carbonization of commercial ammonium ferric citrate (AFC), which is simple and environmentally friendly. As an anode in LIBs, the Fe 3 O 4 @C-500 electrode shows superior specific capacity, long cycling stability and excellent rate performance. Such remarkable performance can be attributed to the formation of the architecture with carbon (C) matrix, not only buffering the volume change and inhibiting the aggregation of internal Fe 3 O 4 nanoparticles during (de)lithiation, but also elevating the electron conductivity. In situ X-ray diffraction (XRD) results demonstrate that the (de)lithiated mechanism of the Fe 3 O 4 @C-500 electrode involves a full electrochemically-driven amorphization upon cycling. Furthermore, the full cell assembled with Fe 3 O 4 @C-500 and LiFePO 4 (LFP) electrodes shows outstanding electrochemical performance, demonstrating its practical energy storage application. [Display omitted] • Fe 3 O 4 @C-500 was fabricated via one-step pyrolytic carbonization of AFC. • Fe 3 O 4 @C-500 delivers good performance by nanoengineering, C matrix and amorphization. • The (de)lithiated mechanism of Fe 3 O 4 @C-500 electrode was probed by in situ XRD. • The full cell presents excellent electrochemical performances. [ABSTRACT FROM AUTHOR]

Exploring highly efficient and robust electrocatalysts to replace the noble metal-based electrocatalysts for alkaline oxygen evolution reaction (OER) is vital and challenging for the conversion of renewable energy. Herein, a novel element incorporation strategy is proposed to synthesize the multi-metallic selenide of (Ni,Fe,Co)Se 2 nanosheets anchored on a stainless steel mesh substrate (NiFeCoSe/SSM). The multi-metallic hybrid film (NiFeCo/SSM) obtained by a co-sputtering method is converted to the (Ni,Fe,Co)Se 2 nanosheets through an alloying-dealloying-selenization process, in which Co and Fe atoms replace part of Ni atoms in the NiSe 2 lattice. The as-obtained NiFeCoSe/SSM displays efficient OER performances in alkaline solutions with an overpotential of 228 mV at 20 mA cm−2 (268 mV at 50 mA cm−2), and a small Tafel slope of 69.8 mV dec−1 in 1.0 M KOH. Furthermore, the NiFeCoSe/SSM electrode demonstrates a remarkable catalytic stability as long as 24.0 h, and its initial nanosheet structure can be well retained after the durability test. Such excellent OER performances of NiFeCoSe/SSM can be attributed to the unique nanosheet structure and the optimized electronic structure due to the synergistic effect among different metallic elements. • A novel element incorporation strategy is proposed to obtain multi-metallic selenide. • Co and Fe atoms replace part of Ni atoms in the NiSe 2 lattice. • The NiFeCoSe/SSM displays efficient OER performances in alkaline solution. • Synergistic effect among metallic elements causes optimized electronic structure. [ABSTRACT FROM AUTHOR]

For lithium ion batteries (LIBs), low electronic conductivity of CuO leads to rapid capacity decay and poor structural stability. Herein, we successfully fabricate three-dimensional CuO nanoflake arrays coated Cu foam by facile and efficient electrochemical oxidation. When being applied as anode material for LIBs, the CuO electrodes deliver stable reversible capacities of 523.9 mA h g −1 at 0.5 A g −1 , 376.1 mA h g −1 at 1.0 A g −1 and 322.7 mA h g −1 at 2.0 A g −1 with high coulombic efficiency (>99%) after 100 cycles. A long cycle life of up to 400 cycles at 2.0 A g −1 is also achieved with the retention capacity of 193.5 mA h g −1 . Moreover, the electrode exhibits excellent rate capability and can regain its original capacities as reversing to the low current densities. Noticeably, on-line differential electrochemical mass spectrometry and in situ Raman measurements confirm the formation of solid electrolyte interface film and the conversion mechanism for the CuO electrodes, respectively. The superior lithium storage performance can be attributed to the favorable nanoflake structures with high surface area and the perfect electrical contact between CuO and Cu substrate. [ABSTRACT FROM AUTHOR]

A room-temperature Ag 3 Ga-mediated liquid EGaSn anode with improved wettability for advanced Mg ion batteries. [Display omitted] • The room-temperature Ag 3 Ga-mediated liquid EGaSn anode was simply prepared for MIBs. • Ag 3 Ga can improve the wettability of EGaSn on the substrate and provide capacity. • ssm-Ag 3 Ga-EGaSn shows superior electrochemical performance in half and full cells. • Reaction mechanism of the Ag 3 Ga-mediated liquid EGaSn anode was unveiled. Liquid metals with a self-healing property can address the passivation issue of Mg metal and the huge volume variation problem of solid alloy-type anodes in rechargeable magnesium ion batteries (MIBs). Liquid Ga-based anodes show great potentials in MIBs, however, being operated at room temperature is a great challenge. Herein, a novel strategy is proposed to enhance the room-temperature Mg storage performance of liquid eutectic GaSn (EGaSn) alloy through constructing a bifunctional intermetallic compound (Ag 3 Ga) layer on the current collector. This Ag 3 Ga layer could greatly improve the wettability of EGaSn on the substrate in the electrolyte environment. Moreover, operando X-ray diffraction confirms that Ag 3 Ga could participate the reversible alloying/dealloying reactions during the discharge/charge processes and thus provide an extra capacity. Eventually, the Ag 3 Ga-mediated EGaSn anode exhibits outstanding electrochemical performance towards Mg storage in both half and full cells at room temperature (∼24 and 21 °C), as benchmarked with state-of-the-art anodes in MIBs. Specially, the MIBs could be stably cycled up to 600 cycles in the half cell configuration, and 100 cycles in the full cell assembly. This work provides useful information on the development of advanced anodes for MIBs. [ABSTRACT FROM AUTHOR]

• 3D Cu current collectors were gained by painting-alloying-dealloying and annealing. • The porous structure of 3D Cu was regulated by altering Ga mass and annealing. • The relationships between porous layer depth and performance were explored. • The Li deposition behaviors on 3D/2D Cu were clarified. Lithium metal anode has shown great potentials for achieving high energy density due to its high theoretical capacity and low redox potential, but its application is impeded by the dendrite proliferation and unstable solid electrolyte interface. Herein, three-dimensional (3D) porous Cu current collectors were fabricated via the combination of painting-alloying-dealloying with subsequent annealing, where the depth and length scale of the porous layer can be facilely regulated by controlling the alloying and annealing processes. In lithium metal batteries, the relationship between the Li deposition behavior and the porous layer depth was explored in detail via electrochemical measurements and ex-situ scanning electron microscopy. Notably, the A-3D Cu-14 current collector with the porous layer depth of around 34.5 µm exhibits long lifespan over 430 h at 1 mA cm−2 and low voltage hysteresis, in comparison with the pristine Cu foil and the porous Cu with thinner porous layers. The superior electrochemical performance of A-3D Cu-14 can be attributed to the enhanced suppression effect upon the Li dendrite deriving from the more accommodation capability of its thick porous layer, as well as the better homogenization of the Li+ ion flux caused by the porous structure. Furthermore, the Li@A-3D Cu-14 | LiFePO 4 full cell shows excellent cycling stability and rate capability in full battery tests. Dealloying-induced modulation upon porous layer depth of three-dimensional copper current collector to stabilize the lithium batteries. [Display omitted] [ABSTRACT FROM AUTHOR]

Antimony (Sb) as a low-toxic and cost-effective metal is a promising material to catalyse CO 2 electroreduction to formate with practical viability. However, monometallic Sb suffers from intrinsically low catalytic activity and the competing hydrogen evolution. Here, we report nanoporous Sb-Bi alloys for substantially improving the catalytic activity of Sb and suppressing hydrogen evolution. The optimal Sb-Bi alloy exhibits a maximum Faradaic efficiency of 95.8 % toward formate production, surpassing the 11.6 % of monometallic Sb counterpart. Operating the catalyst in the flow cell demonstrates a formate partial current density of 734 mA cm−2 and cathodic energy efficiency of 59 % at a moderate overpotential of 800 mV, representing a record formate-production performance so far. Experimental and theoretical studies indicate that the Sb-Bi interactions activate Sb sites to selectively stabilize *OCHO intermediates, facilitating CO 2 -to-formate conversion. This work offers insights in manipulating bimetallic interactions to transform inert materials into active catalysts for efficient electrocatalysis. [Display omitted] • Sb-Bi interactions induce electrocatalytic switching from HER to CO 2 ER. • Sb 2 Bi 6 exhibits a maximum formate selectivity of 95.8 % in an H-type cell. • Sb 2 Bi 6 achieves a record formate activity of 734 mA cm−2 in a flow cell. • Sb-Bi interactions facilitate Sb sites to stabilize *OCHO for formate formation. [ABSTRACT FROM AUTHOR]