Search

Introducing bismuth (Bi) into antimony (Sb) to form Sb–Bi alloys offers a promising way to enhance the electrocatalytic activity of Sb for CO2 reduction to formate. However, there is currently a lack of mechanistic understanding of such a promotion effect. In this study, we address the knowledge gap by revealing the reaction mechanisms of Sb–Bi alloy catalyzed CO2 reduction using various in situ spectroscopic techniques. We fabricated a series of Sb–Bi alloy films via a co-sputtering method, which exhibited enhanced formate production with the increase in Bi content in the alloys. Our operando differential electrochemical mass spectroscopy (DEMS) analysis revealed the promoted suppression of the competing hydrogen evolution reaction (HER) with the increase in Bi content. The in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and Raman spectroscopy results demonstrated that the introduction of Bi into Sb not only changed the reaction intermediates from COOH* to OCHO* during the reaction but also enhanced the stabilization of OCHO* intermediates with decreasing Bi content. In addition, incorporating Bi into Sb improved the local pH near the catalyst surface to promote formate formation. Our work provides deep insights to guide the design of Sb/Bi-based catalysts for efficient electrochemical reduction of carbon dioxide (CO2R). [ABSTRACT FROM AUTHOR]

Germanium (Ge) has become a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity and decent electron/ion conductivity, but it exhibits inferior lifespan caused by dramatic volume variations during the (de)lithiation process. Herein, hierarchically, nanoporous Ge (np-Ge) was fabricated by the combination of selective phase corrosion with chemical dealloying. As an anode for LIBs, the np-Ge electrode exhibits marvelous cycling stability with capacity retentions of 1060.0 mA h g−1 at 0.2 A g−1 and 767.1 mA h g−1 at 1 A g−1 after 100 cycles. Moreover, the electrode shows excellent rate capability with a capacity retention of 844.2 mA h g−1 at 5 A g−1. Noticeably, the (de)lithiation mechanisms of np-Ge and porous Si–Ge (p-Si6Ge4) were unveiled by operando X-ray diffraction. [ABSTRACT FROM AUTHOR]

Due to the high theoretical specific capacity and low cost of Sn, developing Sn‐based anode materials with long life is the key to their practical applications in lithium‐ion batteries. Herein, novel hierarchically porous NiSn alloys with interconnected ligament‐channel networks are synthesized via a two‐step dealloying strategy, involving corrosion of an Al97.5Ni2Sn0.5 precursor in NaOH, followed by partially etching Ni in HNO3. The architecture of the obtained NiSn‐3 h alloy contains the ligaments with the scale of about 115.2 nm and nanowalls with a thickness of several nanometers on the ligament surface, which can enhance the electron/ion transport kinetics and improve the tolerance to volume variation. The NiSn‐3h electrode exhibits superior Li storage performance in terms of satisfactory rate performance and excellent cycling stability with a reversible capacity of 213.9 mAh g−1 at 1 A g−1 after 1000 cycles. More importantly, the Li storage mechanism of NiSn‐3h is unveiled by operando X‐Ray diffraction, revealing the formation of lithiation products with low crystallinity at the end of discharge. In addition, on‐line differential electrochemical mass spectroscopy is used to detect the gas evolution of the NiSn‐3h electrode during the discharge–charge processes. [ABSTRACT FROM AUTHOR]

Ag-Zn alloys are identified as highly active and selective electrocatalysts for CO2 reduction reaction (CO2RR), while how the phase composition of the alloy affects the catalytic performances has not been systematically studied yet. In this study, we fabricated a series of Ag-Zn alloy catalysts by magnetron co-sputtering and further explored their activity and selectivity towards CO2 electroreduction in an aqueous KHCO3 electrolyte. The different Ag-Zn alloys involve one or more phases of Ag, AgZn, Ag5Zn8, AgZn3, and Zn. For all the catalysts, CO is the main product, likely due to the weak CO binding energy on the catalyst surface. The Ag5Zn8 and AgZn3 catalysts show a higher CO selectivity than that of pure Zn due to the synergistic effect of Ag and Zn, while the pure Ag catalyst exhibits the highest CO selectivity. Zn alloying improves the catalytic activity and reaction kinetics of CO2RR, and the AgZn3 catalyst shows the highest apparent electrocatalytic activity. This work found that the activity and selectivity of CO2RR are highly dependent on the element concentrations and phase compositions, which is inspiring to explore Ag-Zn alloy catalysts with promising CO2RR properties. [ABSTRACT FROM AUTHOR]

Transition metal nitrogen carbon based single‐atom catalysts (SACs) have exhibited superior activity and selectivity for CO2 electroreduction to CO. A favorable local nitrogen coordination environment is key to construct efficient metal‐N moieties. Here, a facile plasma‐assisted and nitrogen vacancy (NV) induced coordinative reconstruction strategy is reported for this purpose. Under continuous plasma striking, the preformed pentagon pyrrolic N‐defects around Ni sites can be transformed to a stable pyridinic N dominant Ni‐N2 coordination structure with promoted kinetics toward the CO2‐to‐CO conversion. Both the CO selectivity and productivity increase markedly after the reconstruction, reaching a high CO Faradaic efficiency of 96% at mild overpotential of 590 mV and a large CO current density of 33 mA cm‐2 at 890 mV. X‐ray adsorption spectroscopy and density functional theory (DFT) calculations reveal this defective local N environment decreases the restraint on central Ni atoms and provides enough space to facilitate the adsorption and activation of CO2 molecule, leading to a reduced energy barrier for CO2 reduction. [ABSTRACT FROM AUTHOR]