Cu₃P Nanoarrays Derived from 7,7,8,8-Tetracyanoquinodimethane for High-Rate Electrocatalytic Oxygen Reactions of Lithium-Oxygen Batteries

Efficient electrocatalysis at the cathode is crucial for addressing the challenges faced by lithium-oxygen batteries (LOBs), including limited stability and low-rate capability. To develop an efficient cathode for aprotic LOBs, self-supported copper phosphide nanoarrays on carbon cloth are prepared at different heating rates via a phosphidation process using CuTCNQ nanoarrays. Different ramping rates have effects on particle size and intrinsic interaction, which in turn affect their catalytic properties. When phosphidation is carried out at a slow rate, it results in the formation of smaller, evenly distributed Cu₃P particles on the nanoarrays (SG-Cu₃P NAs/CC) compared to fast rate phosphidation (FG-Cu₃P NAs/CC). As a result, SG-Cu₃P NAs/CC exhibits lower resistance and a higher concentration of active sites than FG-Cu₃P NAs/CC. The SG-Cu₃P NAs/CC demonstrates LOBs with a low overpotential of 1.51 V at a high current rate of 1 mA cm^-2 and a long cycle life of 115 cycles at 0.1 mA cm^-2. The in situ Raman spectroscopy supports that Li₂O₂ is uniformly formed and decomposed on the SG-Cu₃P NAs/CC surface. This study provides a compelling approach for the precise fabrication and analysis of binder-free, self-supported copper phosphides as highly efficient and stable materials for bifunctional oxygen electrocatalysis.