Atomically precise electrocatalysts for oxygen reduction reaction

Challenges in developing fuel cells provide strong stimulation to develop efficient electrocatalysts for the sluggish cathodic oxygen reduction reaction (ORR). Among various electrocatalysts, atomically precise electrocatalysts (including single-atom, dual-atom, and multi-atom clusters) have received growing attention due to their high atom-utilization efficiency and remarkable catalytic performance. To enhance ORR performance, significant efforts have been made to fine-tune their structures and identify active sites. This demands systematic study into rationalizing current results of atomically precise electrocatalysts and applying the lessons learned to innovative strategies and designs of performant catalysts. Herein, we summarize their synthesis strategies along with their engineering and ORR performances. By highlighting the structure-performance relationships, we propose some pivotal performance optimization strategies. Furthermore, key challenges and prospects in this field are discussed. This review aspires to provide atomic-level insights toward designing future ORR electrocatalysts with high selectivity, activity, and durability.