Protecting Single Atom Catalysts with Graphene/Carbon-Nitride "Chainmail".

Single-atom catalysts (SACs) possess high chemical activity but suffer from structural vulnerability owing to atom aggregation or attacks from reaction intermediates. In this work, we employed first-principles simulations to propose a design of stable and efficient transition-metal (TM) SAC protected by graphene or carbon-nitride "chainmail". We found that a single TM atom can be strongly anchored between two graphene (GR) or GR-C3N layers, forming stable sandwich structures of GR-TM-GR and C3N-TM-GR. By donating electrons to the nearby atoms of GR/C3N, TMs pass on their high catalytic activities to the chainmail. For instance, the hydrogen evolution reaction catalyzed by the single-atom Cu with C3N chainmail exhibits almost zero free energy barrier (∼0.01 eV), which outperforms commercial Pt catalyst (∼0.09 eV). Importantly, such graphene/carbon-nitride chainmail can prevent SAC TM atoms from aggregating, as well as prevent attacks of reaction intermediates. This suggests an alternative way of managing high stability and activity for SAC systems simultaneously toward practical utilization.