AuCu Alloy Nanoparticle Embedded Cu Submicrocone Arrays for Selective Conversion of CO2 to Ethanol.

The CO2 reduction reaction (CO2 RR) driven by renewable electricity represents a promising strategy toward alleviating the energy shortage and environmental crisis facing humankind. Cu species, as one type of versatile electrocatalyst for the CO2 RR, attract tremendous research interest. However, for C2 products, ethanol formation is commonly less favored over Cu electrocatalysts. Herein, AuCu alloy nanoparticle embedded Cu submicrocone arrays (AuCu/Cu-SCA) are constructed as an active, selective, and robust electrocatalyst for the CO2 RR. Enhanced selectivity for EtOH is gained, whose Faradaic efficiency (FE) reaches 29 ± 4%, while ethylene formation is relatively inhibited (16 ± 4%) in KHCO3 aqueous solution. The ratio between partial current densities of EtOH and C2 H4 (jEtOH /jC2H4 ) can be tuned in the range from 0.15 ± 0.27 to 1.81 ± 0.55 by varying the Au content of the electrocatalysts. The combined experimental and theoretical calculation results identify the importance of Au in modifying binding energies of key intermediates, such as CH2 CHO*, CH3 CHO*, and CH3 CH2 O*, which consequently modify the activity and selectivity (jEtOH /jC2H4 ) for the CO2 RR. Moreover, AuCu/Cu-SCA also shows high durability with both the current density and FEEtOH being largely maintained for 24 h electrocatalysis.

Facile synthesis of Al-doped NiO nanosheet arrays for high-performance supercapacitors.

Electrode material design is the key to the development of asymmetric supercapacitors with high electrochemical performances and stability. In this work, Al-doped NiO nanosheet arrays were synthesized using a facile hydrothermal method followed by a calcination process, and the synthesized arrays exhibited a superior pseudocapacitive performance, including a favourable specific capacitance of 2253 ± 105 F g-1 at a current density of 1 A g-1, larger than that of an undoped NiO electrode (1538 ± 80 F g-1). More importantly, the arrays showed a high-rate capability (75% capacitance retention at 20 A g-1) and a high cycling stability (approx. 99% maintained after 5000 cycles). The above efficient capacitive performance benefits from the large electrochemically active area and enhanced conductivity of the arrays. Furthermore, an assembled asymmetric supercapacitor based on the Al-doped NiO arrays and N-doped multiwalled carbon nanotube ones delivered a high specific capacitance of 192 ± 23 F g-1 at 0.4 A g-1 with a high-energy density of 215 ± 15 Wh kg-1 and power density of 21.6 kW kg-1. Additionally, the asymmetric device exhibited a durable cyclic stability (approx. 100% retention after 5000 cycles). This work with the proposed doping method will be beneficial to the construction of high-performance supercapacitor systems.

Highly Active, Durable Ultrathin MoTe2 Layers for the Electroreduction of CO2 to CH4.

The electroreduction of CO2 to CH4 is a highly desirable, challenging research topic. In this study, an electrocatalytic system comprising ultrathin MoTe2 layers and an ionic liquid electrolyte for the reduction of CO2 to methane is reported, efficiently affording methane with a faradaic efficiency of 83 ± 3% (similar to the best Cu-based catalysts reported thus far) and a durable activity of greater than 45 h at a relatively high current density of 25.6 mA cm-2 (-1.0 VRHE ). The results obtained can facilitate research on the design of other transition-metal dichalcogenide electrocatalysts for the reduction of CO2 to valuable fuels.