Defect electrocatalytic mechanism: concept, topological structure and perspective

Carbon-based materials have been attracting intense interest for electrocatalysis due to their various

merits, such as abundance, low cost, high conductivity and tunable molecular structures. However,

to date, the electrochemical activities of these electrocatalysts are mainly attributed to different active

dopants (e.g. N, B, P or S), leading to a common concept that heteroatom doping is essential for

carbon-based electrocatalysts. Recently, we presented a new concept where the specific topological

defects could activate the oxygen reduction reaction (ORR) and developed a facile method to create

such unique defects. Subsequent research has extended this new mechanism to other reactions, such

as the hydrogen and oxygen evolution reactions (HER and OER) and confirmed that heteroatom doping

is not essential but that these defects can serve as actives sites for electrochemical reactions. This new

theory then creates a new research direction in electrocatalysis. In this short review, we summarise the

origin and presentation of the defect mechanism concept, the possible topological defect structures

that are effective for electrochemical reactions, the formation of desirable defects, the challenges in the

synthesis and characterization of typical defects and future research directions on the electrochemical

defect mechanism.