RESUMEN

High conversion efficiency over a wide operating potential window is important for the practical application of CO2 reduction electrocatalysis, yet that remains a huge challenge in differentiating the competing CO2 reduction and H2 evolution. Here we introduce point defects (Sn doping) and planar defects (grain boundary) into the Cu substrate. This multidimensional defect integration strategy guides the fabrication of highly diluted SnCu polycrystal, which exhibits high Faradaic efficiencies (>95%) toward CO2 electroreduction over an ultrawide potential window (ΔE = 1.3 V). The theoretical study indicates that the introduction of Sn doping and grain boundary synergistically provides an optimized electronic effect, which helps suppress H2 evolution and promotes the hydrogenation of *CO2.

RESUMEN

Electrochemical energy storage devices are ubiquitous for personal electronics, electric vehicles, smart grids, and future clean energy demand. SCs are EES devices with excellent power density and superior cycling ability. Herein, we focused on the fabrication and DFT calculations of Na3-δ-MnO2 nanocomposite, which has layered MnO2 redox-active sites, supported on carbon cloth. MnO2 has two-dimensional diffusion channels and is not labile to structural changes during intercalation; therefore, it is considered the best substrate for intercalation. Cation pre-intercalation has proven to be an effective way of increasing inter-layered spacing, optimizing the crystal structure, and improving the relevant electrochemical behavior of asymmetric aqueous supercapacitors. We successfully established Na+ pre-intercalated δ-MnO2 nanosheets on carbon cloth via one-pot hydrothermal synthesis. As a cathode, our prepared material exhibited an extended potential window of 0-1.4 V with a remarkable specific capacitance of 546 F g-1(300 F g-1 at 50 A g-1). Moreover, when this cathode was accompanied by an N-AC anode in an asymmetric aqueous supercapacitor, it illustrated exceptional performance (64 Wh kg-1 at a power density of 1225 W kg-1) and incomparable potential window of 2.4 V and 83% capacitance retention over 10,000 cycles with a great Columbic efficiency.

RESUMEN

Electrochemical carbon dioxide (CO2) reduction reaction (E-CO2RR) to formate with high selectivity driven by renewable electricity is one of the most promising routes to carbon neutrality. Herein, we developed a novel indium (In)-doped bismuth subcarbonate (BOC) nanosheets (BOC-In-x NSs) through transformation of In-doped bismuth (Bi) nanoblocks (Bi-In-x NBs). The BOC-In-0.1 NSs achieved a maximum Faraday efficiency of formate (FEformate) nearly 100% with high stability (22 h) and an appreciable average FEformate of 93.5% in a wide potential window of 450 mV. The experimental and theoretical calculations indicate that the incorporation of In into BOC nanosheets enhanced the adsorption of CO2 and the intermediates during the process of E-CO2RR, and reduced the energy barrier for the formation of formate.

Asunto(s)

Bismuto , Dióxido de Carbono , Carbonatos , Técnicas Electroquímicas , Formiatos , Indio

RESUMEN

Electrochemical reduction of CO2 to HCOOH (ERC-HCOOH) is one of the most feasible and economically valuable ways to achieve carbon neutrality. Unfortunately, achieving optimal activity and selectivity for ERC-HCOOH remains a challenge. Herein, ultrathin Bi nanosheets (NS) with lattice dislocations (LD-Bi) were prepared by the topological transformation of Bi2O2CO3 NS under high current conditions. LD-Bi exhibited excellent activity and selectivity as well as stability in ERC-HCOOH. Electrochemical tests and DFT calculations revealed that the excellent performance of LD-Bi was attributed to lattice dislocations, which can induce the production of more active sites on the catalyst surface and improve the electronic transfer ability. In addition, LD-Bi was beneficial to enhance the adsorption of CO2 and key reaction intermediates (OCHO*), thus improving the reaction kinetics. The result provides a unique perspective on the crucial role of lattice dislocations, which may have a significant impact on highly selective electrochemical conversion of CO2.

RESUMEN

It is still a great challenge to develop electrocatalysts for CO2 reduction with high product selectivity and energy conversion efficiency. In this work, Bi nanoparticles supported on polymeric carbon nitride (Bi/CN) have been prepared for CO2 electrocatalytic conversion. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analyses confirm the existence of Bi2O3 on Bi particle surface, forming Bi/Bi2O3 nanoparticles. CN, as the support, has been found not only to improve the dispersibility of Bi/Bi2O3 nanoparticles, but also to enhance the CO2 adsorption on Bi/CN surface owing to the existence of amino and cyano groups. The electronic structure of Bi/CN has been optimized by the interaction between CN and Bi: the electron transfer from Bi to CN results in electron-deficient Bi sites which stabilize CO2-, HCOO- intermediates and accelerate the formation rate of HCOOH. As a result, the maximum Faradaic efficiency of HCOOH reaches 98% at -1.3 to -1.5 V versus reversible hydrogen electrode (vs. RHE) and remains over 91% in a wide potential window of about 500 mV (-1.1 âˆ¼ -1.6 V vs. RHE). The as-obtained Bi/CN in this work shows superior performance to most of the previously reported Bi-based electrocatalysts.

RESUMEN

Flexible energy storage devices are in great demand since the advent of flexible electronics. Until now, flexible supercapacitors based on graphene analogues usually have had low operating potential windows. To this end, two dissimilar electrode materials with complementary potential ranges are employed to obtain an optimum cell voltage of 1.8 V. A low-temperature organic sol-gel method is used to prepare two different types of functionalized reduced graphene oxide aerogels (rGOA) where Ag nanorod functionalized rGOA acts as a negative electrode while polyaniline nanotube functionalized rGOA acts as a positive electrode. Both materials comprehensively exploit their unique properties to produce a device that has high energy and power densities. An assembled all-solid-state asymmetric supercapacitor gives a high energy density of 52.85 W h kg-1 and power density of 31.5 kW kg-1 with excellent cycling and temperature stability. The device also performs extraordinarily well under different bending conditions, suggesting its potential to meet the requirements for flexible electronics.

RESUMEN

A facile and cost-efficient approach to functionalize raw carbon fiber paper (CFP) used for a self-standing capacitive electrode has been proposed here. Benefiting from the improved specific surface area and surface functional groups, the functionalized CFP (F-CFP) showed much enhanced capacitive performance, 3 orders of magnitude higher than that of the raw CFP. It delivered the areal capacitance of 1275 mF cm-2 at 5 mA cm-2 with a rather wide voltage window of 1.4 V (-0.4 to 1 V vs Ag/AgCl) in 0.5 M H2SO4. However, in a neutral 1 M Na2SO4 aqueous solution, although the areal capacitance of 1115 mF cm-2 at 3 mA cm-2 is slightly smaller, the potential window is much wider (2 V, -1 to 1 V vs Ag/AgCl), indicating a high overpotential of hydrogen evolution. The areal capacitance was still as high as 722 mF cm-2 at a very fast charge-discharge current density of 50 mA cm-2, and about 66% of the initial capacitance (at 3 mA cm-2) was remained in Na2SO4, indicating considerable rate capability.