Li-CO₂ batteries are among the most intriguing techniques for balancing the carbon cycle, but are challenged by the annoyed thermodynamic barrier of the Li₂CO₃ decomposition reaction. Herein, we demonstrate the electrocatalytic performances of two-dimensional (2D) CoAl-layer double hydroxide (LDH) nanosheets can be significantly improved by trans-dimensional crosslinking with three-dimensional (3D) multilevel nanoporous (MP)-RuCoAl alloy (MP-RuCoAl alloy⊥CoAl-LDH). The MP-RuCoAl alloy⊥CoAl-LDH with multiscale pore channels and abundant nano-heterointerface is directly prepared by controllable etching Al from a Ru-Co-Al master alloy along with simultaneous partial oxidization of Al and Co atoms. The MP-RuCoAl is composed of various intermetallic compounds and Ru with abundant grain boundaries, and forms numerous heterointerface with 2D CoAl-LDH nanosheets. The multiscale porous metallic network benefits mass and electron transportation as well as discharge product storage and enables a rich multiphase reaction interface. In situ differential electrochemical mass spectrometry shows that the mass-to-charge ratio in the charging process is ~ 0.733 which is consistent with the theoretical value of 3/4, stating that the reversible co-decomposition of Li₂CO₃ and C can be achieved with the MP-RuCoAl alloy⊥CoAl-LDH. The Ketjen black (KB)/MP-RuCoAl⊥CoAl-LDH battery demonstrates a high cyclability for over 2270 h (227 cycles) with a lower voltage gap stabilized at ~ 1.3 V at 200 mA·g⁻¹. Our findings here provide useful guidelines for developing high efficiency transition metal based electrocatalysts by coupling with conductive porous substrate for impelling the development of practical Li-CO₂ battery systems.

Electrocatalytic water splitting via hydrogen evolution reaction (HER) represents one of promising strategies to gain hydrogen energy. In current work, self-supporting Co_0.85Se nanosheets network anchored on Co plate (Co_0.85Se NSs@Co) is fabricated by employing easily tailorable Co metal plate as the source conductive substrate. The scalable dealloying and hydrothermal selenization strategy was employed to build one layer of three dimensional interlinking Co_0.85Se nanosheets network on the surface of Co plate. Benefiting from bulky integrated architecture and rich active sites, the as-made Co_0.85Se NSs@Co exhibits superior electrocatalytic activity and long-term catalytic durability toward HER. It only requires lower overpotentials of 121 and 162 mV to drive the current density of 10 mA·cm^-2 for hydrogen evolution in 0.5 M H₂SO₄ and 1 M KOH solution. Especially, no evident activity decay occurs upon 1,500 cycles or continuous test for 20 h at 10 mA·cm^-2 in both acidic and alkaline electrolytes. With the merits of exceptional performances, scalable production, and low cost, the self-supporting Co_0.85Se NSs@Co holds prospective application potential as stable and binder-free electrocatalysts for hydrogen generation in a wide range of electrolyte.

Nanoporous (NP) Si/Cu composites are fabricated by means of alloy refining followed by facile electroless dealloying in mild conditions. NP-Si/Cu composites with a three-dimensional porous network nanoarchitecture with different Cu contents are obtained by changing the feeding ratio of alloy precursors. Owing to the rich porosity and integration of conductive Cu into a nanoporous Si backbone, the NP-Si₈₅Cu₁₅ composite exhibits modified conductivity and reduced volumetric expansion/fracture during repeated charging-discharging processes in lithium-ion batteries (LIBs), thus exhibiting much higher cycling reversibility than NP-Si₉₂Cu₈ and pure NP-Si. With the advantages of unique performance and easy preparation, NP-Si/Cu composite has potential for application as an advanced anode material for LIBs.