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

Li–CO 2 batteries face challenges from sluggish CO 2 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 CO 2 . 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 CO 2 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 CO 2 redox reactions, highlighting the interphasic synergy as a powerful tactic for designing high‐efficient transition metal‐based catalysts for Li–CO 2 batteries.