Rational design of boron-nitrogen coordinated active sites towards oxygen reduction reaction in aluminum-air batteries with robust integrated air cathode

Abstract

Rational design of cost-effective electrocatalysts for oxygen reduction reaction (ORR) is essential for developing metal-air batteries. In this work, we propose a pre-self-assembled strategy to prepare controllable B–N coordinated active sites anchored on carbon supports as an efficient electrocatalyst for ORR. The precisely coordinated B–N coordination from the pre-self-assembled boronate-amino ligands are sealed on the in-situ formed carbon dots (CDs) for preservation and further converted into B–N coordinated active sites on the carbon support. The B–N coordinated active sites anchored on the graphene aerogel (denoted as B–N-G) exhibit Pt/C competitive ORR catalytic activity in both alkaline and neutral media, which are attributed to the high content of efficient B–N coordinated active sites with expanded lattice spacing. The operando Fourier transform infrared (FTIR) spectroscopy and density functional theory (DFT) calculations explain the catalytic mechanism and identify the active sites of the B–N coordination. Furthermore, the B–N-G is directly processed into an integrated air cathode, and the Al-air batteries with the B–N-G integrated air cathode exhibit superior discharge performance and good stability in both NaOH and NaCl electrolytes. This study demonstrates a feasible pre-self-assembled approach to achieve designed B–N coordination in carbon-based electrocatalysts for metal-air batteries.