A Homo‐Triatomic Molybdenum Cluster Catalyst Enables Synergistic Optimization of Multi‐Step Sulfur Reduction Chemistry

Abstract

ABSTRACT The isolated single‐active sites of single‐atom catalysts (SACs) often suffer from simultaneously maintaining the optimal adsorption states of multiple lithium polysulfide intermediates in sulfur redox reactions of Li–S batteries. Herein, we report a homo‐triatomic molybdenum cluster catalyst with Mo 3 –O 3 N 3 motifs embedded within a carbon matrix (Mo 3 /ONC) that addresses this challenge. The Mo 3 –O 3 N 3 motifs with a triangular configuration feature multi‐active sites and interatomic synergies, which can flexibly adjust the corresponding Mo─S pathway according to different intermediate sulfur species, thereby making the adsorption strength of all species favorable. Meanwhile, the optimized Mo─S interactions can induce more electrons to transfer from the intermediate sulfur species to the Mo 3 –O 3 N 3 catalytic sites, thus weakening the S─S bond and remarkably reducing the energy barriers for the sulfur conversion. Besides, the electrochemical and in situ spectroscopic experiments disclose that the sulfur redox kinetics on Mo 3 /ONC is significantly improved compared to the Mo‐single‐atom catalyst (Mo 1 /ONC) counterpart. As thus, the as‐designed Mo 3 /ONC catalyst renders the Li–S battery with a large rate capability of 661.2 mAh g −1 and a capacity decay as low as 0.027% per cycle at 10 C for 1200 cycles. This work provides a new perspective on the fundamental design principles of triatomic catalysts for improving the Li–S performance.