Suppressing Zn pulverization with three-dimensional inert-cation diversion dam for long-life Zn metal batteries.

Tremendous attention has been paid to the water-associated side reactions and zinc (Zn) dendrite growth on the electrode-electrolyte interface. However, the Zn pulverization that can cause continuous depletion of active Zn metal and exacerbate hydrogen evolution is severely neglected. Here, we disclose that the excessive Zn feeding that causes incomplete crystallization is responsible for Zn pulverization formation through analyzing the thermodynamic and kinetics process of Zn deposition. On the basis, we introduce 1-ethyl-3-methylimidazolium cations (EMIm+) into the electrolyte to form a Galton-board-like three-dimensional inert-cation (3DIC) region. Modeling test shows that the 3DIC EMIm+ can induce the Zn2+ flux to follow in a Gauss distribution, thus acting as elastic sites to buffer the perpendicular diffusion of Zn2+ and direct the lateral diffusion, thus effectively avoiding the local Zn2+ accumulation and irreversible crystal formation. Consequently, anti-pulverized Zn metal deposition behavior is achieved with an average Coulombic efficiency of 99.6% at 5 mA cm-2 over 2,000 cycles and superb stability in symmetric cell over 1,200 h at -30 °C. Furthermore, the Zn||KVOH pouch cell can stably cycle over 1,200 cycles at 2 A g-1 and maintain a capacity of up to 12 mAh.

Hollow Hierarchical Cu2 O-Derived Electrocatalysts Steering CO2 Reduction to Multi-Carbon Chemicals at Low Overpotentials.

The electrochemical reduction of carbon dioxide into multi-carbon products (C2+ ) using renewably generated electricity provides a promising pathway for energy and environmental sustainability. Various oxide-derived copper (OD-Cu) catalysts have been showcased, but still require high overpotential to drive C2+ production owing to sluggish carbon-carbon bond formation and low CO intermediate (*CO) coverage. Here, the dilemma is circumvented by elaborately devising the OD-Cu morphology. First, computational studies propose a hollow and hierarchical OD-Cu microstructure that can generate a core-shell microenvironment to inhibit CO evolution and accelerate *CO dimerization via intermediate confinement and electric field enhancement, thereby boosting C2+ generation. Experimentally, the designed nanoarchitectures are synthesized through a heteroseed-induced approach followed by electrochemical activation. In situ spectroscopic studies further elaborate correlation between *CO dimerization and designed architectures. Remarkably, the hierarchical OD-Cu manifests morphology-dependent selectivity of CO2 reduction, giving a C2+ Faradaic efficiency of 75.6% at a considerably positive potential of -0.55 V versus reversible hydrogen electrode.

Precursor-mediated in situ growth of hierarchical N-doped graphene nanofibers confining nickel single atoms for CO2 electroreduction.

Despite the various strategies for achieving metal-nitrogen-carbon (M-N-C) single-atom catalysts (SACs) with different microenvironments for electrochemical carbon dioxide reduction reaction (CO2RR), the synthesis-structure-performance correlation remains elusive due to the lack of well-controlled synthetic approaches. Here, we employed Ni nanoparticles as starting materials for the direct synthesis of nickel (Ni) SACs in one spot through harvesting the interaction between metallic Ni and N atoms in the precursor during the chemical vapor deposition growth of hierarchical N-doped graphene fibers. By combining with first-principle calculations, we found that the Ni-N configuration is closely correlated to the N contents in the precursor, in which the acetonitrile with a high N/C ratio favors the formation of Ni-N3, while the pyridine with a low N/C ratio is more likely to promote the evolution of Ni-N2. Moreover, we revealed that the presence of N favors the formation of H-terminated edge of sp2 carbon and consequently leads to the formation of graphene fibers consisting of vertically stacked graphene flakes, instead of the traditional growth of carbon nanotubes on Ni nanoparticles. With a high capability in balancing the *COOH formation and *CO desorption, the as-prepared hierarchical N-doped graphene nanofibers with Ni-N3 sites exhibit a superior CO2RR performance compared to that with Ni-N2 and Ni-N4 ones.

Galvanic-Cell Deposition Enables the Exposure of Bismuth Grain Boundary for Efficient Electroreduction of Carbon Dioxide.

Metallic bismuth (Bi) holds great promise in efficient conversion of carbon dioxide (CO2 ) into formate, yet the complicated synthetic routes and unobtrusive performance hinder the practical application. Herein, a facile galvanic-cell deposition method is proposed for the rapid and one-step synthesis of Bi nanodendrites. Compared to the traditional deposition method, it is found that the special galvanic-cell configuration can promote the exposure of low-angle grain boundaries. X-ray absorption spectroscopy, in situ characterizations and theoretical calculations indicate the electronical structures can be greatly tailored by the grain boundaries, which can facilitate the CO2 adsorption and intermediate formation. Consequently, the grain boundary-enriched Bi nanodendrites exhibit a high selectivity toward formate with an impressively high production rate of 557.2 µmol h-1 cm-2 at -0.94 V versus reversible hydrogen electrode, which outperforms most of the state-of-the-art Bi-based electrocatalysts with longer synthesis time. This work provides a straightforward method for rapidly fabricating active Bi electrocatalysts, and explicitly reveals the critical effect of grain boundary in Bi nanostructures on CO2 reduction.

Supercritical CO2-assisted amorphization of WO2.72 and its high-efficiency photothermal conversion.

Amorphous materials with unique atomic arrangements have attracted great attention owing to their unique optical and electronic properties. In this work, amorphization of pristine WO2.72 was successfully achieved with the assistance of supercritical carbon dioxide (SC CO2). Experimental results indicate that the obtained amorphous sample has strong optical absorbance in the near-infrared (NIR) region. Furthermore, an excellent photothermal conversion efficiency (PCE) of 52.5% indicates that it enables the capture of solar energy and converts it into thermal energy efficiently.

High-efficiency electrocatalyst for N2 conversion to NH3 based on Au nanoparticles loaded on defective WO3-x.

In this work, Au nanoparticles (NPs) grown on defective WO3-x (Au/WO3-x) show superior electrocatalytic N2 reduction activity under ambient conditions in 0.1 M KOH. At -0.2 V versus the reversible hydrogen electrode (vs. RHE), the Au/WO3-x catalyst achieves a large NH3 yield of 23.15 µg h-1 mg-1 and a high faradaic efficiency (FE) of 14.72%. Further density functional theory (DFT) calculations indicate that electron transfer between the Au nanoparticles and defective WO3-x promotes the activation of N2 molecules effectively.