Nanoheterointerface Engineering in Hierarchical Porous Alloy/LDH Catalysts for High-Efficiency Li-CO₂ Batteries

Li-CO₂ batteries face challenges from sluggish CO₂ redox kinetics, causing high polarization, poor reversibility, and low energy efficiency. Herein, an interphasic synergy between two-dimentional MnAl-layer double hydroxide (LDH) nanosheets and three-dimentional hierarchical nanoporous (HP)-NiMnAl alloy (HP-NiMnAl alloy∩MnAl-LDH) is reported for facilitating the elelctrochemical recycling reactions of CO₂. The HP-NiMnAl alloy∩MnAl-LDH, featuring hierarchical pore channels and massive nano-heterointerfaces, is readily assembled by adjusting the corrosion of Al from a Ni-Mn-Al master alloy, accompanied by limited oxidation reactions of low-coordinated Al and Mn atoms. The HP-NiMnAl metallic sponge, comprising nanograins of diverse intermetallic and Ni with interlaced boundaries, constructs trans-dimensional heterointerfaces with MnAl-LDH nanosheets while delivering ample pore channels for mass transfer, a robust network for electron transport, and a large surface area for abundant catalytic sites. In situ differential electrochemical mass spectrometry demonstrates that the ratio between the evolved CO₂ and the transferred electrons during the battery charging process is close to the theoretical value of 3/4. This demonstrates the high efficacy of the HP-NiMnAl alloy∩MnAl-LDH for driving the reversible CO₂ redox reactions, highlighting the interphasic synergy as a powerful tactic for designing high-efficient transition metal-based catalysts for Li-CO₂ batteries.