Bifunctional porous hollow Cu/TiN heterojunction catalysts for ultralow overpotential and high areal capacity Li–O2 batteries

Self-supporting Cu/TiN nano-furry serves as a superior bifunctional catalyst for ORR/OER. • DFT reveals Cu/TiN heterojunctions facilitate uniform Li 2 O 2 film growth via enhanced LiO 2 affinity. • Carbon-free catalytic system effectively suppresses Li 2 CO 3 byproduct formation, reducing overpotential. • Delivers ultralow overpotential, high areal capacity and superior stability, outperforming Au-based counterparts. The major hindrance against developing high-performance lithium oxygen batteries (LOBs) lies in their infamously sluggish redox kinetic processes involving undesirable parasitic reactions, which results in large overpotential, low capacity and inferior cycling stability. The rational catalyst design is proposed as an efficient strategy to address the above issue. Herein, we have developed a self-supporting nano-furry cathode based on a Cu foam-supported hierarchical nanotube array architecture decorated with Cu/TiN nanojunctions, which contributes to a fresh bifunctional catalytic mechanism for enhancing ORR/OER catalytic kinetics. Such an integrated cathode with Cu/TiN nanojunctions catalyst enables resilient LOBs through minimizing the energy barriers and excessive input energy to form/decompose Li 2 O 2 , outperforming similar Au-based system. DFT simulation elaborates that the Cu-based heterojunctions with favorable LiO 2 -affinity tend to promote surface deposition of uniform Li 2 O 2 film, alleviating disproportionated reaction and achieving remarkably enhanced capacity. Consequently, this rationally designed cathode for LOBs achieved high area capacity up to 25.6 mAh cm −2 with a small overpotential of 0.37 V at 0.1 mA cm −2 , and exceptional cycle stability with over 350 cycles at 0.2 mA cm −2 under a fixed capacity of 0.25 mAh cm −2 . This work provides an insightful approach towards designing efficient, clean and cheap cathode with abundant metal-based catalysts for LOBs. Download: Download high-res image (278KB) Download: Download full-size image