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The Li–CO2 battery often suffers from high overpotential and limited capacity due to the challenges associated with the adsorption of Li+ and CO2 and the decomposition of Li2CO3. Herein, hexagonal rich-stepped NiSe crystals are in situ achieved on a three-dimensional (3D) free-standing porous Ni skeleton with double continuous channel architecture (namely p-Ni@NiSe-50) through an in situ selenization process. Structural characterization and theoretical calculation are applied to demonstrate the synergistic effects of marco/microstructural design and electronic band structure regulation. As a result, the adsorption/desorption of Li+ and CO2 and the formation/decomposition of Li2CO3 are effectively promoted, simultaneously, enabling an enhanced capacity and reversibility of p-Ni@NiSe-50 as the cathode of Li–CO2 battery. An ultra-low overpotential of 0.46 V and a remarkably high energy efficiency of 83.8% (20 μA cm−2) are achieved, along with a high full discharge specific capacity of 8844 μAh cm−2. Excellent long-term cycling stability (cycles up to 1000 h at a voltage gap of 1.14 V) of p-Ni@NiSe-50 is also obtained. The results of this work would provide a new insight and strategy to develop high-performance alkali metal-air batteries. Multi-scale synergistic effect of combining the cathode macroscopic structure design and the microscopic band structure design of NiSe was demonstrated to promote the adsorption of Li+ and CO2, as well as the decomposition of Li2CO3, so as to achieve ultra-low voltage gap and high capacity of Li-CO2 batteries. [ABSTRACT FROM AUTHOR]

Bifunctional catalysts (OER/ORR) require lower overpotentials and fast mass transfer, but developing transition metal-based bifunctional catalysts that can satisfy these requirements remains a major challenge. Herein, a composite consisting of FeCo alloy nanoparticles uniformly loaded on three-dimensional (3D) hierarchical porous nitrogen-doped carbon (FeCo/HP-NC) is rationally designed. The electronic modulation of the FeCo alloy can provide a favorable electronic structure for the OER/OER reaction, while the hierarchical porous carbon structure can facilitate not only the accessible channels but also the mass transfer for electrocatalytic reactions. Thus, FeCo/HP-NC provides modest overpotentials (E1/2 = 0.83 V, η = 0.335 V). In particular, when compared with commercially available noble catalysts, FeCo/HP-NC offers a higher power density, more stable voltage (1.43 V), and stability that exceeds 300 h as the cathode. As for this investigation, strategies for increasing the catalytic performance of oxygen electrocatalysis and the power density of energy storage applications could be proposed. [ABSTRACT FROM AUTHOR]

The development of efficient nonplatinum electrocatalysts with enhanced oxygen reduction reaction (ORR) activity and stability is of crucial importance for the commercial application of fuel cells and metal–air batteries. Metallenes exhibit excellent performance in energy and catalysis due to their unique physicochemical and electronic properties. In particular, the ultrahigh proportion of under-coordinated metal atomic sites in metallenes enhances the atom utilization and intrinsic activity, which endows them with considerable potential for catalytic applications. Herein, the synthesized two-dimensional (2D) ultrathin porous Pd metallene with amorphous/crystalline phase coexistence exhibits enhanced alkaline oxygen reduction properties, as evidenced by four-electron selectivity, lower overpotential (E1/2 = 0.944 V), high mass activity (MA = 1.44 mA/μgPd), and solid stability (only loss of 7 mV in half-wave potential after 10,000 potential cycles). Such high performance of Pd metallene is attributed to amorphous/crystalline heterophases, 2D morphology, and porous structure. DFT calculations demonstrate that the ORR catalytic performance can be effectively promoted by the amorphous structure with a modulated electronic structure. The amorphous/crystalline coexisting porous Pd metallene with excellent catalytic performance can provide the reference for metallene materials design in various fields. This study presents a scientific basis to understand the mechanism of 2D amorphous phase nanostructures for boosting the electrocatalytic performance. [ABSTRACT FROM AUTHOR]

Conversion-type electrode materials have gained massive research attention in sodium-ion batteries (SIBs), but their limited reversibility hampers practical use. Herein, we report a bifunctional nanoreactor to boost highly reversible sodium-ion storage, wherein a record-high reversible degree of 85.65% is achieved for MoS2 anodes. Composed of nitrogen-doped carbon-supported single atom Mn (NC-SAMn), this bifunctional nanoreactor concurrently confines active materials spatially and catalyzes reaction kinetics. In-situ/ex-situ characterizations including spectroscopy, microscopy, and electrochemistry, combined with theoretical simulations containing density functional theory and molecular dynamics, confirm that the NC-SAMn nanoreactors facilitate the electron/ion transfer, promote the distribution and interconnection of discharging products (Na2S/Mo), and reduce the Na2S decomposition barrier.As a result, the nanoreactor-promoted MoS2 anodes exhibit ultra-stable cycling with a capacity retention of 99.86% after 200 cycles in the full cell. This work demonstrates the superiority of bifunctional nanoreactors with two-dimensional confined and catalytic effects, providing a feasible approach to improve the reversibility for a wide range of conversion-type electrode materials, thereby enhancing the application potential for long-cycled SIBs., (© 2024 Wiley‐VCH GmbH.)